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Artykuły w czasopismach na temat "Hox proteins"
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Shen, W. F., J. C. Montgomery, S. Rozenfeld, J. J. Moskow, H. J. Lawrence, A. M. Buchberg i C. Largman. "AbdB-like Hox proteins stabilize DNA binding by the Meis1 homeodomain proteins." Molecular and Cellular Biology 17, nr 11 (listopad 1997): 6448–58. http://dx.doi.org/10.1128/mcb.17.11.6448.
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Recent studies show that Hox homeodomain proteins from paralog groups 1 to 10 gain DNA binding specificity and affinity through cooperative binding with the divergent homeodomain protein Pbx1. However, the AbdB-like Hox proteins from paralogs 11, 12, and 13 do not interact with Pbx1a, raising the possibility of different protein partners. The Meis1 homeobox gene has 44% identity to Pbx within the homeodomain and was identified as a common site of viral integration in myeloid leukemias arising in BXH-2 mice. These integrations result in constitutive activation of Meis1. Furthermore, the Hoxa-9 gene is frequently activated by viral integration in the same BXH-2 leukemias, suggesting a biological synergy between these two distinct classes of homeodomain proteins in causing malignant transformation. We now show that the Hoxa-9 protein physically interacts with Meis1 proteins by forming heterodimeric binding complexes on a DNA target containing a Meis1 site (TGACAG) and an AbdB-like Hox site (TTTTACGAC). Hox proteins from the other AbdB-like paralogs, Hoxa-10, Hoxa-11, Hoxd-12, and Hoxb-13, also form DNA binding complexes with Meis1b, while Hox proteins from other paralogs do not appear to interact with Meis1 proteins. DNA binding complexes formed by Meis1 with Hox proteins dissociate much more slowly than DNA complexes with Meis1 alone, suggesting that Hox proteins stabilize the interactions of Meis1 proteins with their DNA targets.
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Mann, Richard S., i Markus Affolter. "Hox proteins meet more partners". Current Opinion in Genetics & Development 8, nr 4 (sierpień 1998): 423–29. http://dx.doi.org/10.1016/s0959-437x(98)80113-5.
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Zhang, Jianxuan, Jae-Hung Shieh, Liren Liu, Magdalena Plasilova, Yue Zhang, Gianni Morrone, Malcolm A. S. Moore i Pengbo Zhou. "Ubiquitin-Proteolytic Control of HOX Homeodomain Proteins." Blood 108, nr 11 (16.11.2006): 1121. http://dx.doi.org/10.1182/blood.v108.11.1121.1121.
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Abstract The HOX homeodomain proteins are key regulators of hematopoiesis. HOX genes are expressed in primitive hematopoietic cells, and their prompt downregulation is associated with hematopoietic differentiation and maturation. Although transcriptional inactivation of HOX genes during hematopoietic differentiation has been established, little is known about the biochemical mechanisms underlying the subsequent removal of HOX proteins. We have previously shown that the CUL-4A ubiquitin ligase controls the stability of HOXA9 by promoting its ubiquitination and proteasome-dependent degradation. Interfering with CUL-4A biosynthesis results in altered HOXA9 protein levels, which is mirrored by the impairment of myeloid progenitor cells to undergo proper terminal differentiation into granulocytes. Here we show that additional HOX proteins are also subjected to CUL-4A-mediated ubiquitination and destruction. Consistently, the HOX homeodomain, which is highly conserved among all HOX proteins, is responsible for controlling their stability. Silencing of CUL-4A by RNA-mediated interference in human umbilical cord blood CD34+ cells significantly perturbs their self-renewal, expansion, and differentiation properties. These results reveal a novel regulatory mechanism of hematopoiesis by ubiquitin-dependent proteolysis. Recent studies on the biochemical mechanisms underlying HOX ubiquitination and by which leukemogenic HOX fusions evade CUL-4A-dependent degradation will be presented.
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Shen, Wei-fang, Keerthi Krishnan, H. J. Lawrence i Corey Largman. "The HOX Homeodomain Proteins Block CBP Histone Acetyltransferase Activity". Molecular and Cellular Biology 21, nr 21 (1.11.2001): 7509–22. http://dx.doi.org/10.1128/mcb.21.21.7509-7522.2001.
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ABSTRACT Despite the identification of PBC proteins as cofactors that provide DNA affinity and binding specificity for the HOX homeodomain proteins, HOX proteins do not demonstrate robust activity in transient-transcription assays and few authentic downstream targets have been identified for these putative transcription factors. During a search for additional cofactors, we established that each of the 14 HOX proteins tested, from 11 separate paralog groups, binds to CBP or p300. All six isolated homeodomain fragments tested bind to CBP, suggesting that the homeodomain is a common site of interaction. Surprisingly, CBP-p300 does not form DNA binding complexes with the HOX proteins but instead prevents their binding to DNA. The HOX proteins are not substrates for CBP histone acetyltransferase (HAT) but instead inhibit the activity of CBP in both in vitro and in vivo systems. These mutually inhibitory interactions are reflected by the inability of CBP to potentiate the low levels of gene activation induced by HOX proteins in a range of reporter assays. We propose two models for HOX protein function: (i) HOX proteins may function without CBP HAT to regulate transcription as cooperative DNA binding molecules with PBX, MEIS, or other cofactors, and (ii) the HOX proteins may inhibit CBP HAT activity and thus function as repressors of gene transcription.
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Martinou, Eirini, Giulia Falgari, Izhar Bagwan i Angeliki M. Angelidi. "A Systematic Review on HOX Genes as Potential Biomarkers in Colorectal Cancer: An Emerging Role of HOXB9". International Journal of Molecular Sciences 22, nr 24 (14.12.2021): 13429. http://dx.doi.org/10.3390/ijms222413429.
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Emerging evidence shows that Homeobox (HOX) genes are important in carcinogenesis, and their dysregulation has been linked with metastatic potential and poor prognosis. This review (PROSPERO-CRD42020190953) aims to systematically investigate the role of HOX genes as biomarkers in CRC and the impact of their modulation on tumour growth and progression. The MEDLINE, EMBASE, Web of Science and Cochrane databases were searched for eligible studies exploring two research questions: (a) the clinicopathological and prognostic significance of HOX dysregulation in patients with CRC and (b) the functional role of HOX genes in CRC progression. Twenty-five studies enrolling 3003 CRC patients, showed that aberrant expression of HOX proteins was significantly related to tumour depth, nodal invasion, distant metastases, advanced stage and poor prognosis. A post-hoc meta-analysis on HOXB9 showed that its overexpression was significantly associated with the presence of distant metastases (pooled OR 4.14, 95% CI 1.64–10.43, I2 = 0%, p = 0.003). Twenty-two preclinical studies showed that HOX proteins are crucially related to tumour growth and metastatic potential by affecting cell proliferation and altering the expression of epithelial-mesenchymal transition modulators. In conclusion, HOX proteins may play vital roles in CRC progression and are associated with overall survival. HOXB9 may be a critical transcription factor in CRC.
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Pellerin, I., C. Schnabel, K. M. Catron i C. Abate. "Hox proteins have different affinities for a consensus DNA site that correlate with the positions of their genes on the hox cluster". Molecular and Cellular Biology 14, nr 7 (lipiec 1994): 4532–45. http://dx.doi.org/10.1128/mcb.14.7.4532-4545.1994.
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The hox genes, members of a family of essential developmental regulators, have the intriguing property that their expression in the developing murine embryo is colinear with their chromosomal organization. Members of the hox gene family share a conserved DNA binding domain, termed the homeodomain, which mediates interactions of Hox proteins with DNA regulatory elements in the transcriptional control regions of target genes. In this study, we characterized the DNA binding properties of five representative members of the Hox family: HoxA5, HoxB4, HoxA7, HoxC8, and HoxB1. To facilitate a comparative analysis of their DNA binding properties, we produced the homeodomain regions of these Hox proteins in Escherichia coli and obtained highly purified polypeptides. We showed that these Hox proteins interact in vitro with a common consensus DNA site that contains the motif (C/G)TAATTG. We further showed that the Hox proteins recognize the consensus DNA site in vivo, as determined by their ability to activate transcription through this site in transient transfection assays. Although they interact optimally with the consensus DNA site, the Hox proteins exhibit subtle, but distinct, preferences for DNA sites that contain variations of the nucleotides within the consensus motif. In addition to their modest differences in DNA binding specificities, the Hox proteins also vary in their relative affinities for DNA. Intriguingly, their relative affinities correlate with the positions of their respective genes on the hox cluster. These findings suggest that subtle differences in DNA binding specificity combined with differences in DNA binding affinity constitute features of the "Hox code" that contribute to the selective functions of Hox proteins during murine embryogenesis.
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Pellerin, I., C. Schnabel, K. M. Catron i C. Abate. "Hox proteins have different affinities for a consensus DNA site that correlate with the positions of their genes on the hox cluster." Molecular and Cellular Biology 14, nr 7 (lipiec 1994): 4532–45. http://dx.doi.org/10.1128/mcb.14.7.4532.
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The hox genes, members of a family of essential developmental regulators, have the intriguing property that their expression in the developing murine embryo is colinear with their chromosomal organization. Members of the hox gene family share a conserved DNA binding domain, termed the homeodomain, which mediates interactions of Hox proteins with DNA regulatory elements in the transcriptional control regions of target genes. In this study, we characterized the DNA binding properties of five representative members of the Hox family: HoxA5, HoxB4, HoxA7, HoxC8, and HoxB1. To facilitate a comparative analysis of their DNA binding properties, we produced the homeodomain regions of these Hox proteins in Escherichia coli and obtained highly purified polypeptides. We showed that these Hox proteins interact in vitro with a common consensus DNA site that contains the motif (C/G)TAATTG. We further showed that the Hox proteins recognize the consensus DNA site in vivo, as determined by their ability to activate transcription through this site in transient transfection assays. Although they interact optimally with the consensus DNA site, the Hox proteins exhibit subtle, but distinct, preferences for DNA sites that contain variations of the nucleotides within the consensus motif. In addition to their modest differences in DNA binding specificities, the Hox proteins also vary in their relative affinities for DNA. Intriguingly, their relative affinities correlate with the positions of their respective genes on the hox cluster. These findings suggest that subtle differences in DNA binding specificity combined with differences in DNA binding affinity constitute features of the "Hox code" that contribute to the selective functions of Hox proteins during murine embryogenesis.
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Scott, Matthew P. "Hox proteins reach out round DNA". Nature 397, nr 6721 (luty 1999): 649–51. http://dx.doi.org/10.1038/17685.
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Kyba, Michael. "Modulating the malignancy of Hox proteins". Blood 129, nr 3 (19.01.2017): 269–70. http://dx.doi.org/10.1182/blood-2016-11-751909.
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Rinaldi, Lucrezia, Andrew J. Saurin i Yacine Graba. "Fattening the perspective of Hox protein specificity through SLiMming". International Journal of Developmental Biology 62, nr 11-12 (2018): 755–66. http://dx.doi.org/10.1387/ijdb.180306yg.
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The functional identification and dissection of protein domains has been a successful approach towards the understanding of Hox protein specificity. However, only a few functional protein domains have been identified; this has been a major limitation in deciphering the molecular modalities of Hox protein action. We explore here, by in silico survey of short linear motifs (SLiMs) in Hox proteins, the contribution of SLiMs to Hox proteins, focusing on the mouse, chick and Drosophila Hox complement. Our findings reveal a widespread and uniform distribution of SLiMs along Hox protein sequences and identify the most apparent features of Hox associated SLiMs. While few motifs have been associated with Hox proteins so far, this work suggests that many more contribute to Hox protein functions. The potential and difficulties to apprehend the full contribution of SLiMs in controlling Hox protein functions are discussed.
Rozprawy doktorskie na temat "Hox proteins"
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Goh, Siew-Lee. "Functional studies of MEIS1, a HOX co-factor". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103200.
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HOX proteins are evolutionarily conserved homeodomain-containing transcription factors involved in hematopoiesis and patterning during embryogenesis. Their tasks as master regulators of embryonic development are achieved in large part through their ability to interact with co-factors of the PBX and MEIS/PREP families, which constitute the broader three amino-acid loop extension (TALE) class of homeodomain proteins. HOX, MEIS, and PBX have been implicated in leukemic hematopoiesis due to their association with hematological malignancies. The oncogenic function of MEIS1 in accelerating the onset of acute myeloid leukemia induced by HOX was mapped to its C-terminal transactivation domain, which is responsive to PKA signaling. This thesis extends our understanding regarding the mechanism by which MEIS1A executes its C-terminal transactivation function in vivo. We describe the involvement of CREB and its co-activators CBP and TORC in conferring the PKA-responsiveness of the ME1S1A C terminus. CREB mutants that fail to bind CBP or TORC also fail to promote PKA induction mediated by the C terminus of ME1S1A. TORC was further shown to be capable of bypassing the need for PKA to activate transcription by MEIS1, an ability endowed by its physical interaction with MEIS1. Chromatin immunoprecipitation (ChIP) demonstrated a concerted recruitment of endogenous MEIS1, TORC2, and CREB proteins on ME1S1 target genes. In addition, this thesis also characterizes the promoter of the murine Meis1 gene. Meis1 possesses multiple transcription start sites upstream of its translation initiation site. We identified a ME1S·PBX consensus recognition site within the Meis1 promoter and showed that PBX1 binds to this sequence in vitro. Our ChIP assay results further suggest an autoregulatory mode for the Meis1 gene as revealed by a co-occupancy of endogenous CREB, TORC2, PBX1, and MEIS1 itself on the Meis1 promoter. Collectively, this thesis proposes a mechanistic action conferred by CREB, CBP and TORC in the PKA-inducible transactivation of ME1S1A, and provides new information on the Meis1 promoter.
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Svingen, Terje, i n/a. "Hox Transcription Factors: Their Involvement in Human Cancer Cells and In Vitro Functional Specificity". Griffith University. School of Biomolecular and Biomedical Science, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050830.135356.
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Hox genes are regulatory genes encoding small proteins containing a highly conserved 61-amino acid motif, the homeodomain, that enables Hox proteins to bind to DNA at specifically recognised binding sites and transcriptionally activate their target genes. In mammalian species there are 39 Hox genes and they are structural and functional homologs of the Drosophila homeotic complex (Horn-C). During embryogenesis and early development the Hox genes are expressed in a spatiotemporal fashion, where they operate as master transcriptional regulators. Hox genes are further expressed in fully differentiated adult cells, potentially in a tissue-specific manner involving maintenance of the normal phenotype. In selected oncogenic transformations, dysregulated Hox gene expression has been observed, indicating an involvement of these transcriptional regulators in carcinogenesis and metastasis. Utilising quantitative real-time PCR assays, these studies investigated the expression patterns of 20 Hox genes and two wellcharacterised Hox cofactors (Pbx and Meis) in malignant and non-malignant human breast and skin cancer cells. Dysregulated Hox expression was observed for all malignancies tested, of which some misexpressed Hox genes seemed random, whereas other Hox transcripts showed altered levels potentially corresponding with the invasive capacity of the cells. Also, the Hox cofactors Pbx and Meis showed no marked changes in expression levels from the non-malignant to the malignant phenotypes, indicating that it is dysregulated Hox gene expression rather than dysregulated gene expression of Hox cofactors that potentially commit the cell to redifferentiate and undergo oncogenic transformation. Although the Hox proteins are known to be key transcriptional regulators of development, the mechanisms by which they gain their in vivo functional specificity is still largely unknown. They all show strikingly similar transcriptional specificity in vitro, yet show unique specificity in their in vivo environment. This paradox has been the subject of intense scrutiny, however very few direct Hox target genes have been identified, making it a difficult task to decipher the exact manner in which Hox proteins exert their functional potential. Therefore, the studies presented herein were aimed at identifying further Hox target genes in the human system. Utilising differential display approaches, several potential downstream target genes were isolated. Substantiated with real-time PCR assays, one of these potential targets was selected as a likely direct Hox gene target, and as such subjected to further studies. By the combination of bioinformatic analyses, transfection protocols and luciferase assays, a gene encoding the SR-related protein SRrpl3O was shown to be trans-activated in vitro by HOXD4 via a putative Hox binding element within its promoter region. This is the first reported link between Hox transcription factors and the SR and SR-related family of pre-mRNA splicing proteins, offering a new and exciting insight into the complex nature of Hox functional specificity. Finally, this thesis also puts forward new ideas regarding how the Hox proteins gain their transcriptional and functional specificity. Utilising bioinformatic tools in conjunction with performing an extensive review of the disparate catalogue of Hox-related research reports, work herein offers the first comprehensive analysis of the mammalian Hox gene targets in relation to their promoter structures, as well as with respect to the expanded Hox DNA-binding elements. This work reports that identified Hox targets generally contain TATA-less core promoters, many of which have several GC-box elements. The Hox binding elements show no apparent preference regarding their location relative to the transcription start site (TSS), as they are found both upstream and downstream of the TSS, as well as being located close to proximal core promoter elements for some genes and at more distant positions in other gene promoters. Finally, the core Hox binding element TAAT/ATTA contains only part of the necessary recognition sequence involved in Hox-DNA binding, and the notion that flanking base pairs dictate trans-regulatory potential is further explored with the hypothesis that the immediate 3' base pair dictates an activator/repressor-switch of the Hox trans-regulatory effect.
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Svingen, Terje. "Hox Transcription Factors: Their Involvement in Human Cancer Cells and In Vitro Functional Specificity". Thesis, Griffith University, 2005. http://hdl.handle.net/10072/365774.
Pełny tekst źródłaStreszczenie:
Hox genes are regulatory genes encoding small proteins containing a highly conserved 61-amino acid motif, the homeodomain, that enables Hox proteins to bind to DNA at specifically recognised binding sites and transcriptionally activate their target genes. In mammalian species there are 39 Hox genes and they are structural and functional homologs of the Drosophila homeotic complex (Horn-C). During embryogenesis and early development the Hox genes are expressed in a spatiotemporal fashion, where they operate as master transcriptional regulators. Hox genes are further expressed in fully differentiated adult cells, potentially in a tissue-specific manner involving maintenance of the normal phenotype. In selected oncogenic transformations, dysregulated Hox gene expression has been observed, indicating an involvement of these transcriptional regulators in carcinogenesis and metastasis. Utilising quantitative real-time PCR assays, these studies investigated the expression patterns of 20 Hox genes and two wellcharacterised Hox cofactors (Pbx and Meis) in malignant and non-malignant human breast and skin cancer cells. Dysregulated Hox expression was observed for all malignancies tested, of which some misexpressed Hox genes seemed random, whereas other Hox transcripts showed altered levels potentially corresponding with the invasive capacity of the cells. Also, the Hox cofactors Pbx and Meis showed no marked changes in expression levels from the non-malignant to the malignant phenotypes, indicating that it is dysregulated Hox gene expression rather than dysregulated gene expression of Hox cofactors that potentially commit the cell to redifferentiate and undergo oncogenic transformation. Although the Hox proteins are known to be key transcriptional regulators of development, the mechanisms by which they gain their in vivo functional specificity is still largely unknown. They all show strikingly similar transcriptional specificity in vitro, yet show unique specificity in their in vivo environment. This paradox has been the subject of intense scrutiny, however very few direct Hox target genes have been identified, making it a difficult task to decipher the exact manner in which Hox proteins exert their functional potential. Therefore, the studies presented herein were aimed at identifying further Hox target genes in the human system. Utilising differential display approaches, several potential downstream target genes were isolated. Substantiated with real-time PCR assays, one of these potential targets was selected as a likely direct Hox gene target, and as such subjected to further studies. By the combination of bioinformatic analyses, transfection protocols and luciferase assays, a gene encoding the SR-related protein SRrpl3O was shown to be trans-activated in vitro by HOXD4 via a putative Hox binding element within its promoter region. This is the first reported link between Hox transcription factors and the SR and SR-related family of pre-mRNA splicing proteins, offering a new and exciting insight into the complex nature of Hox functional specificity. Finally, this thesis also puts forward new ideas regarding how the Hox proteins gain their transcriptional and functional specificity. Utilising bioinformatic tools in conjunction with performing an extensive review of the disparate catalogue of Hox-related research reports, work herein offers the first comprehensive analysis of the mammalian Hox gene targets in relation to their promoter structures, as well as with respect to the expanded Hox DNA-binding elements. This work reports that identified Hox targets generally contain TATA-less core promoters, many of which have several GC-box elements. The Hox binding elements show no apparent preference regarding their location relative to the transcription start site (TSS), as they are found both upstream and downstream of the TSS, as well as being located close to proximal core promoter elements for some genes and at more distant positions in other gene promoters. Finally, the core Hox binding element TAAT/ATTA contains only part of the necessary recognition sequence involved in Hox-DNA binding, and the notion that flanking base pairs dictate trans-regulatory potential is further explored with the hypothesis that the immediate 3' base pair dictates an activator/repressor-switch of the Hox trans-regulatory effect.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Full Text
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Phelan, Michael Leo. "A molecular analysis of functional differences between hox proteins". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0026/NQ37012.pdf.
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Choo, Siew Woh. "The in vivo specificity of HOX proteins in Drosophila". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609425.
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Iaroshenko, V. (Vladislav). "Role of human HOX-proteins in different cancer types". Bachelor's thesis, University of Oulu, 2019. http://jultika.oulu.fi/Record/nbnfioulu-201905221901.
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Abstract. HOX-proteins are master regulators of embryogenesis. They determine the body plan along the anterior-posterior axis. Apart from their fundamental function in ontogenesis, they are also connected with different cancer types in adult organisms. Their aberrant expression may influence cell growth and support the development of cancer in many different ways. HOX-proteins appear to be a noticeable diagnostic and therapeutic target.
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Litim-Mecheri, Isma. "Spécificité des protéines Hox : Rôle des motifs connus et découverte de nouveaux motifs". Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22096.
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Les gènes Hox sont responsables de l’identité des segments le long de l’axe antéro-postérieur. Ils sont évolutivement conservés et codent des facteurs de transcription. In vitro, toutes les protéines Hox se lient à des séquences nucléotidiques très similaires via un domaine de liaison à l’ADN très conservé, l’homéodomaine (HD). Cette faible spécificité de liaison à l’ADN in vitro contraste avec leur spécificité d’action in vivo. Une manière d’expliquer ce paradoxe est que les protéines Hox agissent en interaction avec des protéines cofacteurs, dont le mieux caractérisé est Extradenticle (Exd) chez la drosophile, Pbx chez les mammifères (collectivement appelés PBC). L’interaction Hox-PBC s’appui sur un motif conservé chez la presque totalité des protéines Hox, situé en amont de l’HD, le motif Hexapeptide (HX). Des travaux récents au sein de notre équipe ont montré l’existence d’un nouveau mode d’interaction Hox-PBC, non-générique, médié par un motif spécifique à certains groupes de paralogies seulement, et situé en en C-terminal de l’HD. Ceci souligne que les interactions Hox-PBC, qui spécifient la fonction des protéines Hox, reposent sur de modes multiples d’interaction.Mes travaux de thèse ont porté sur le mode d’action des protéines Hox, en étudiant la fonction de trois motifs ayant un rôle démontré ou potentiel dans le recrutement du cofacteur Exd par la protéine Hox de drosophile AbdominalA (AbdA). L’approche empruntée visait à analyser de manière globale la manière dont chacun de ces motifs pris isolément, ou en interaction, définit la fonction d’AbdA. Les conclusions de ce travail soulignent l’absence de pléiotropie fonctionnelle et un haut degré d’interactivité entre ces motifs. Le second volet de ma thèse a été d’initier la découverte de nouveaux motifs fonctionnels au sein des protéines Hox. J’ai abordé cette question en sélectionnant des modules phylogénétiquement conservés. Afin d’évaluer leur fonction, ces motifs ont été mutés et l’impact de leur mutation a été analysé in vitro et in vivo. Les résultats obtenus ont permis l’identification d’au moins un domaine protéique qui contribue de manière prédominante à la fonction de la protéine DfdHox genes are responsible for the identity of segments along the antero-posterior axis. They are evolutionarily conserved and encode transcription factors. In vitro, all Hox proteins bind to a similar nucleotide sequence via a highly conserved DNA binding domain, the homeodomain (HD). This low specificity of DNA binding in vitro contrasts with their specificity in vivo. One way to explain this paradaox is that Hox protein function with protein cofactors, best represented by Extradenticle (Exd) in Drosophila, Pbx in mammals (collectivaly refered as PBC). Hox-PBC interaction relies on a motif located upstream of the HD, conserved in most Hox proteins, the Hexapeptide (HX). Recent work in our group identified a novel mode of Hox-PBC interaction, non-generic, specific to a subset only of Hox paralog groups, and relying on a motif located C-terminal to the HD. This highlight plasticity in Hox-PBC interaction.My PhD work aimed at investigating the mode of action of Hox protein, by studying the function of three protein motifs, with known or putative role in Exd recruitment by the Drosophila Hox protein AbdominalA (AbdA). The approach taken aimed at analyzing, using a large functional window, how these motifs, taken in isolation or collectively, define AbdA protein activity. Conclusions highlight the absence of pleitropy and a high degree of functional interaction for these protein motifs. The second part of my PhD work has been to initiate the search for novel functionally important protein motifs within Hox proteins. This was approached by selecting phylogenetically conserved motifs, and addressing their function in vitro and in vivo following motif mutations. At least one functional domain was isolated, that contributes predominantly to Dfd protein function
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Weicksel, Steven E. "hox Gene Regulation and Function During Zebrafish Embryogenesis: A Dissertation". eScholarship@UMMS, 2013. https://escholarship.umassmed.edu/gsbs_diss/692.
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Hox genes encode a conserved family of homeodomain containing transcription factors essential for metazoan development. The establishment of overlapping Hox expression domains specifies tissue identities along the anterior-posterior axis during early embryogenesis and is regulated by chromatin architecture and retinoic acid (RA). Here we present the role nucleosome positioning plays in hox activation during embryogenesis. Using four stages of early embryo development, we map nucleosome positions at 37 zebrafish hox promoters. We find nucleosome arrangement to be progressive, taking place over several stages independent of RA. This progressive change in nucleosome arrangement on invariant sequence suggests that trans-factors play an important role in organizing nucleosomes. To further test the role of trans-factors, we created hoxb1b and hoxb1a mutants to determine if the loss of either protein effected nucleosome positions at the promoter of a known target, hoxb1a. Characterization of these mutations identified hindbrain segmentation defects similar to targeted deletions of mouse orthologs Hoxa1 and Hoxb1 and zebrafish hoxb1b and hoxb1a morpholino (MO) loss-of-function experiments. However, we also identified differences in hindbrain segmentation as well as phenotypes in facial motor neuron migration and reticulospinal neuron formation not previously observed in the MO experiments. Finally, we find that nucleosomes at the hoxb1a promoter are positioned differently in hoxb1b-/- embryos compared to wild-type. Together, our data provides new insight into the roles of hoxb1b and hoxb1a in zebrafish hindbrain segmentation and reticulospinal neuron formation and indicates that nucleosome positioning at hox promoters is dynamic, depending on sequence specific factors such as Hox proteins.
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Weicksel, Steven E. "hox Gene Regulation and Function During Zebrafish Embryogenesis: A Dissertation". eScholarship@UMMS, 2010. http://escholarship.umassmed.edu/gsbs_diss/692.
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Hox genes encode a conserved family of homeodomain containing transcription factors essential for metazoan development. The establishment of overlapping Hox expression domains specifies tissue identities along the anterior-posterior axis during early embryogenesis and is regulated by chromatin architecture and retinoic acid (RA). Here we present the role nucleosome positioning plays in hox activation during embryogenesis. Using four stages of early embryo development, we map nucleosome positions at 37 zebrafish hox promoters. We find nucleosome arrangement to be progressive, taking place over several stages independent of RA. This progressive change in nucleosome arrangement on invariant sequence suggests that trans-factors play an important role in organizing nucleosomes. To further test the role of trans-factors, we created hoxb1b and hoxb1a mutants to determine if the loss of either protein effected nucleosome positions at the promoter of a known target, hoxb1a. Characterization of these mutations identified hindbrain segmentation defects similar to targeted deletions of mouse orthologs Hoxa1 and Hoxb1 and zebrafish hoxb1b and hoxb1a morpholino (MO) loss-of-function experiments. However, we also identified differences in hindbrain segmentation as well as phenotypes in facial motor neuron migration and reticulospinal neuron formation not previously observed in the MO experiments. Finally, we find that nucleosomes at the hoxb1a promoter are positioned differently in hoxb1b-/- embryos compared to wild-type. Together, our data provides new insight into the roles of hoxb1b and hoxb1a in zebrafish hindbrain segmentation and reticulospinal neuron formation and indicates that nucleosome positioning at hox promoters is dynamic, depending on sequence specific factors such as Hox proteins.
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Rinaldi, Lucrezia. "Novel functions for Hox proteins in the development of the spinal cord". Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0261/document.
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Les gènes Hox codent des facteurs de transcription à homéodomaines conservés qui coordonnent la spécification de l'identité régionale du corps pendant le développement des animaux bilatériens. Au nombre de 39 chez les vertébrés supérieurs, ils sont organisés en 4 complexes (A à D) sur les chromosomes. Treize groupes de gènes paralogues occupent des positions, des modes d'expression et des fonctions similaires. En plus de leurs fonctions spécifiques, des études récentes ont mis en évidence des fonctions "génériques", communes en dehors des groupes de paralogie. L'objectif de cette thèse était de rechercher de nouvelles fonctions génériques des protéines Hox vertébrées, en se concentrant sur le développement de la moelle épinière chez l’embryon de poulet et de souris. Nous avons identifié deux de ces fonctions, impliquant en particulier les gènes Hox du complexe B. La première concerne le contrôle de l’autophagie, qui a été précédemment établi dans le corps gras de Drosophile. Mon travail a établi la dynamique spatio-temporelle de l'autophagie et des protéines Hox au cours du développement de la moelle épinière. Ces dynamiques ont permis de suggérer un rôle générique pour les protéines Hox dans la répression de l'autophagie, qui a été confirmé par gain de fonction chez l’embryon de poulet. La deuxième fonction générique des protéines Hox concerne le contrôle de la neurogenèse. L'étude de l'expression des gènes Hox a mis en évidence une expression prédominante des gènes Hox du complexe B dans la zone intermédiaire du tube neural, où ils activent l'expression du gène Lzts1, dont le produit module la signalisation AKT pour finalement contrôler la différenciation neuronaleHox genes encode conserved homeodomain transcription factors that coordinate the specification of regional body identity during the development of bilaterian animals. There are 39 Hox genes in higher vertebrates, organized into four complexes (named A to D) on the chromosomes. Thirteen groups of paralogue genes occupy similar positions within the complexes and exhibit similar modes of expression and functions. In addition to their specific functions, for which these transcription factors are well known, some recent studies are suggestive of "generic" functions, i.e. functions common outside paralogy groups. The goal of this thesis was to look for generic functions of vertebrate Hox proteins, focusing on the development of the spinal cord in chick and mouse. We identified two such functions, implying B cluster Hox genes. The first regards the potential of Hox proteins to control autophagy, which was previously established for Drosophila Hox proteins in the fat body. My work established the spatio temporal dynamic of autophagy during spinal cord development in chick and mouse embryos. This dynamic identified complementary autophagy and Hox patterns, suggesting a generic role for Hox proteins in the repression of autophagy, which could be confirmed by gain of function in chick embryo. The second Hox generic function regards the control of spinal cord neurogenesis. The study of Hox expression highlighted a predominant expression of B cluster Hox genes in the neural tube Intermediate Zone (IZ), where they activate the expression of the Lzts1 gene, the product of which modulates AKT signaling to ultimately control neuronal differentiation
Książki na temat "Hox proteins"
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Graba, Yacine. Hox genes: Methods and protocols. New York: Humana Press, 2014.
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How proteins work. New York: Garland Science, 2012.
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1946-, Liepa George U., red. Dietary proteins: How they alleviate disease and promote better health. Champaign, Ill: American Oil Chemistsʼ Society, 1992.
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Allen, John F. How does protein phosphorylation regulate photosynthesis?. Amsterdam: Elsevier, 1992.
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Gelderloos, Peter. How nonviolence protects the state. Cambridge, Mass: South End Press, 2007.
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Gelderloos, Peter. How nonviolence protects the state. Harrisonburg, VA: Signalfire Press, 2005.
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Gelderloos, Peter. How nonviolence protects the state. Cambridge, MA: South End Press, 2006.
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Susanne, Brakmann, i Johnsson Kai, red. Directed molecular evolution of proteins: Or how to improve enzymes for biocatalysis. Weinheim: Wiley-VCH, 2002.
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Ezrin, Calvin. The endocrine control diet: How to beat the metabolic trap and lose weight permanently. New York: Harper & Row, 1990.
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Church discipline: How the church protects the name of Jesus. Wheaton, Ill: Crossway, 2012.
Znajdź pełny tekst źródłaCzęści książek na temat "Hox proteins"
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Agrawal, Pavan, i L. S. Shashidhara. "ChIP for Hox Proteins from Drosophila Imaginal Discs". W Methods in Molecular Biology, 241–53. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-1242-1_15.
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Grawenhoff, Julia, Sebastian Baumann i Sebastian P. Maurer. "In Vitro Reconstitution of Kinesin-Based, Axonal mRNA Transport". W Methods in Molecular Biology, 547–68. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-1990-2_29.
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AbstractMotor protein-driven transport of mRNAs on microtubules and their local translation underlie important neuronal functions such as development, growth cone steering, and synaptic plasticity. While there is abundant data on how membrane-bound cargoes such as vesicles, endosomes, or mitochondria are coupled to motor proteins, surprisingly little is known on the direct interactions of RNA–protein complexes and kinesins or dynein. Provided the potential building blocks are identified, in vitro reconstitutions coupled to Total Internal Reflection Microscopy (TIRF-M) are a powerful and highly sensitive tool to understand how single molecules dynamically interact to assemble into functional complexes. Here we describe how we assemble TIRF-M imaging chambers suitable for the imaging of single protein–RNA complexes. We give advice on optimal sample preparation procedures and explain how a minimal axonal mRNA transport complex can be assembled in vitro. As these assays work at picomolar-range concentrations of proteins and RNAs, they allow the investigation of molecules that cannot be obtained at high concentrations, such as many large or disordered proteins. This now opens the possibility to study how RNA-binding proteins (RBPs), RNAs, and microtubule-associated proteins act together in real-time at single-molecule sensitivity to create cytoplasmic mRNA distributions.
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Sljoka, Adnan. "Structural and Functional Analysis of Proteins Using Rigidity Theory". W Sublinear Computation Paradigm, 337–67. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-4095-7_14.
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AbstractOver the past two decades, we have witnessed an unprecedented explosion in available biological data. In the age of big data, large biological datasets have created an urgent need for the development of bioinformatics methods and innovative fast algorithms. Bioinformatics tools can enable data-driven hypothesis and interpretation of complex biological data that can advance biological and medicinal knowledge discovery. Advances in structural biology and computational modelling have led to the characterization of atomistic structures of many biomolecular components of cells. Proteins in particular are the most fundamental biomolecules and the key constituent elements of all living organisms, as they are necessary for cellular functions. Proteins play crucial roles in immunity, catalysis, metabolism and the majority of biological processes, and hence there is significant interest to understand how these macromolecules carry out their complex functions. The mechanical heterogeneity of protein structures and a delicate mix of rigidity and flexibility, which dictates their dynamic nature, is linked to their highly diverse biological functions. Mathematical rigidity theory and related algorithms have opened up many exciting opportunities to accurately analyse protein dynamics and probe various biological enigmas at a molecular level. Importantly, rigidity theoretical algorithms and methods run in almost linear time complexity, which makes it suitable for high-throughput and big-data style analysis. In this chapter, we discuss the importance of protein flexibility and dynamics and review concepts in mathematical rigidity theory for analysing stability and the dynamics of protein structures. We then review some recent breakthrough studies, where we designed rigidity theory methods to understand complex biological events, such as allosteric communication, large-scale analysis of immune system antibody proteins, the highly complex dynamics of intrinsically disordered proteins and the validation of Nuclear Magnetic Resonance (NMR) solved protein structures.
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Young, V. R., i P. L. Pellett. "How to Evaluate Dietary Protein". W Milk Proteins, 7–36. Heidelberg: Steinkopff, 1989. http://dx.doi.org/10.1007/978-3-642-85373-9_3.
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Jencks, W. P. "How Does ATP Make Work?" W Protein Structure and Protein Engineering, 1–5. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-74173-9_1.
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Kangueane, Pandjassarame, i Christina Nilofer. "Hot Spots at the Protein-Protein Interface". W Protein-Protein and Domain-Domain Interactions, 87–92. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-7347-2_7.
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Lamichhane, Rajan. "How Proteins Recognize RNA". W Biophysics of RNA-Protein Interactions, 3–21. New York, NY: Springer New York, 2019. http://dx.doi.org/10.1007/978-1-4939-9726-8_1.
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White, Stephen H., Gunnar von Heijne i Donald M. Engelman. "How Proteins Shape Membranes". W Cell Boundaries, 235–64. New York: Garland Science, 2021. http://dx.doi.org/10.1201/9780429341328-8.
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Goodsell, David S. "How Evolution Shapes Proteins". W Atomic Evidence, 51–58. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-32510-1_8.
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Bill, Roslyn M., Leigh Revers i Iain B. H. Wilson. "Sugars And Proteins: How They Get It Together". W Protein Glycosylation, 85–145. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-4939-0_3.
Pełny tekst źródłaStreszczenia konferencji na temat "Hox proteins"
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Zhou, Pengbo, Jennifer Lee, Jianxuan Zhang, Liren Liu, Jae-Hung Shieh i Malcolm A. S. Moore. "Abstract 1157: Ubiquitin-proteolytic control of HOX homeodomain proteins in normal and malignant hematopoiesis". W Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-1157.
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Munch, Katharina, Claire Berton-Carabin, Karin Schroen i Simeon Stoyanov. "Plant protein-stabilized emulsions: Implications of protein and non-protein components for lipid oxidation". W 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/zznf4565.
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The use of plant proteins to stabilize oil-in-water (O/W) emulsions has been an increasing trend lately. The complexity of the available plant protein ingredients, along with the proteins’ physicochemical properties, require advanced processing that typically leads to substantial concentrations of non-protein components in the final isolates or concentrates. It is known that those components, such as polyphenols, phytic acid or phospholipids, can have a strong influence on the oxidative stability of emulsions. Thus, to understand the oxidative stability of plant protein-stabilized emulsions, the influence of the non-protein components also needs to be considered. Many food emulsions, such as mayonnaise or infant formula, are stabilized by not only proteins, but also phospholipids. Such an interfacial protein-phospholipid combination can also be found in oleosomes, natural lipid droplets which show a high oxidative stability. This stability has been attributed to their interfacial architecture in which oleosins and phospholipids form a tight physical barrier against pro-oxidant species. However, while the antioxidant properties of proteins are widely reported, the contribution of phospholipids to lipid oxidation in plant protein-based emulsions remains underexplored.
In this work, we investigated how mixed interfacial plant proteins and phospholipids may be rationally used to control the oxidative stability of O/W emulsions. The interfacial composition was modulated by varying the ratio between pea proteins and sunflower phosphatidylcholine (PC) while keeping the total concentration of pea proteins constant. Increasing the phospholipid-to-protein ratio led to a monotonic decrease in the concentration of proteins and an increase of phospholipids at the interface, while the oxidative stability of those O/W emulsions changed in a non-monotonic pattern. The results were put in perspective by embedding them in a context of reviewing the potential implications of typical components in plant protein ingredients on lipid oxidation.
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Truskett, Thomas M. "How Concentration and Crowding Impact Protein Stability: Insights From a Coarse-Grained Model". W ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192239.
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Much of the current understanding of the protein folding problem derives from studies of proteins in dilute solutions. However, in many systems of scientific and engineering interest, proteins must fold in concentrated, heterogeneous environments. Cells are crowded with many molecular species, and chaperones often sequester proteins and promote rapid folding. Proteins are also present in high concentrations in the manufacture, storage, and delivery of biotherapeutics. How does crowding generally affect the stability of the native state? Are all crowding agents created equal? If not, can generic structural or chemical features forecast their effects on protein stability?
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Rao, Jiajia. "Tuning plant protein for improved functionality and flavor profile: From field to application". W 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/xqxj4886.
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Recently, plant proteins are gaining in popularity as consumers are looking to rebalance their diet with more plant-based options. As such, there is a need to understand the potential of these plant proteins to deliver nutrition and functionality in various food products. However, plant proteins are still under-utilization in food and beverage industry due to their characteristic beany and off flavor, lower technical functionality, such as limited solubility, and some negative taste attributes. In general, plant protein can be obtained from pulses, cereals and oilseeds. Each plant has a unique protein structure and composition, thus protein extracted from different plant has different functional properties and performance in food. In general, plant contain non-protein components including starch, fiber and oil. High purity of plant protein are often extracted to by removing all abovementioned non-protein components through extraction processing. One would expect different extraction methods can influence protein functionality through denaturation, modification, hydrolysis and cross-linking. This talk begins with the discussion of how different plant variety and processing impact on protein functionality using hemp protein as an example. Selective physical and chemical modification methods (e.g., soluble complexes, pH shift, maillard reaction, phosphorylation) for generating novel protein constructs with preferable solubility, foaming, and emulsification properties, thermal stability, and flavor profiles will be comprehensively discussed by using pea protein isolate (PPI) as a representative. In general, protein solubility could be improved by means of abovementioned three methods. Maillard-driven synthesis of the cross-linked PPI-gum arabic conjugates greatly improved the flavor profile and functionality of PPI. In terms of phosphorylation, sodium hexametaphosphate (SHMP) is a good candidate to form phosphorylated PPI with enhanced functionalities including foaming, emulsifying properties and thermal stability. Our results suggested that protein structure-function researches are valuable in tailoring proteins for specific functional outcomes and expanding the availability of plant proteins.
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Shahbazi, Zahra, Horea T. Ilies¸ i Kazem Kazerounian. "Protein Molecules as Natural Nano Bio Devices: Mobility Analysis". W ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13021.
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Proteins are nature’s nano-robots in the form of functional molecular components of living cells. The function of these natural nano-robots often requires conformational transitions between two or more native conformations that are made possible by the intrinsic mobility of the proteins. Understanding these transitions is essential to the understanding of how proteins function, as well as to the ability to design and manipulate protein-based nano-mechanical systems [1]. Modeling protein molecules as kinematic chains provides the foundation for developing powerful approaches to the design, manipulation and fabrication of peptide based molecules and devices. Nevertheless, these models possess a high number of degrees of freedom (DOF) with considerable computational implications. On the other hand, real protein molecules appear to exhibits a much lower mobility during the folding process than what is suggested by existing kinematic models. The key contributor to the lower mobility of real proteins is the formation of Hydrogen bonds during the folding process.
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Kirkpatrick, Emma, i Mac Marshall. "Spotlight on sustainability: How growing consumer preferences are changing the plant-based protein industry". W 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/gggk2278.
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Plant-based proteins have been on the rise over the past few years, with U.S. retail sales of plant-based proteins hitting $7 billion in 2020. Sustainability is at the forefront of this shift, especially as Gen Z and Millennials continue to gain purchasing power. Today, 42 percent of Americans believe their individual food or beverage purchases can have moderate to significant impact on the environment. And of those who view this as significant, 67 percent say environmental sustainability is a key purchase driver in their food choices, according to IFICF. As plant-based protein options become increasingly popular, it is important for companies to find new, effective ways to market not only the nutritional benefits, but also the sustainability of the ingredients to meet growing consumer preferences. This creates an ongoing challenge for companies that now have to balance differentiating themselves from other brands in the growing market, while also highlighting the benefits of individual sources of plant-based proteins to consumers. In this presentation, we'll take a deep dive into why companies are turning toward plant-based proteins and how they are marketing the sustainability of product ingredients to consumers to help drive industry growth and accountability. Hear from plant-based protein expert and consultant, Jean Heggie, on 1) the growing consumer demand for sustainable ingredients and product traceability, 2) how food companies are adapting to this industry shift and 3) why sustainability marketing plays a key role in plant-based product growth. Jean will share information on the recently launched on-package Sustainable U.S. Soy Mark as a powerful case study example. Attendees will also hear about research that illuminates sustainability food trends, as well as new information on the sustainability and nutrition of plant-based proteins, like soy.
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Gear, LR A., D. Freas i J. D. Carty. "EARLY (< 5 SEC) PHOSPHORYLATIONS OF PLATELET PROTEINS FOLLOWING ACTIVATION BY ADP AND ADRENALIN, SEPARATELY AND IN COMBINATION". W XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643640.
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Understanding the earliest events (< 1 sec) in signal transduction of platelets is important, since there is evicenee that “shape change,” aggregation and secretion can all begin within this period. We have employed a guenched-flow approach to study these early events and found that thrombin can induce rapid phosphorylation of myosin light-chain kinase (20K) and a 47K protein (Blood, 67, 1738, 1986). To investigate the role of rapid phosphorylations in platelet activation, we have studied the influence of adrenalin and ADP during early (0.3 to 5 sec) stimulation. Aggregation in washed human platelets was assessed by following the loss of single particles and phosphorylation by analysing 32P-labeled proteins after gel electrophoresis. 15 µM adrenalin (without ADP) did not initiate significant aggregation or phosphorylation of myosin light chain (MLC). Phosphorylation of the 47K protein was increased by 20% at 5 sec. 0.5 µM ADP did not induce significant aggregation, but increased phosphorylation of MLC by 130% and the 47 protein by 20%. The combination of 0.5 µM ADP and 15 uM adrenalin induced significant aggregation by 0,3 sec (7.6%), which increased to 25.6% by 5 sec. Interestingly, MLC or 47K protein phosphorylation was not increased above control levels. However, the phosphorylation of four other proteins (77K, 102K, 140K and 185K), which previously had been very rapid (<1 sec) and reversible with 0.5 µM ADP alone, was now maintained, peaking at 3 sec. 10 µM ADP caused small sustained increases in phosphorylation of the same proteins. Adrenalin also caused rapid increases in the phosphorylation of 27K, 213 and 250K proteins. High levels of ADP (10 µM) only increased the 213 and 250K proteins; therefore the 27K protein appears adrenalin specific. Analysis of these early platelet phosphorylations will help understand how they are linked to initiation and maintenance of aggregation. Supported by NIH HL-27014.
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Devaki, Neksha. "Utilization of mildly fractionated pea proteins for the development of heat-stable beverage emulsions". W 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/ivne6416.
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Pulse proteins are currently being extensively used for the development of various food products. In this work we focused on the utilization of pulse proteins in the development of beverage emulsions. Soluble proteins solution (2.5 wt%), separated from pea protein concentrate (PPC) via centrifugation at 4000×g for 1 minute, was directly used to prepare 5 wt% canola oil-in-water emulsions using high-pressure homogenization. It was hypothesized that soluble protein extracted via mild fractionation would preserve protein functionality and confer better stability to emulsions when compared to original PPC solutions. The emulsions were characterized by measuring the droplet size, zeta potential and creaming velocity. Emulsions were also subjected to environmental stresses including heat treatment, change in pH (2 and 7) and the addition of salt (0.0 M to 1 M). The initial average droplet sizes of pH 7 emulsions were around 300 nm at various salt concentrations, which did not change significantly after 1 week. The pH 2 emulsions initially showed extensive aggregation, with the average droplet and aggregate sizes ranging from 3.0 to 8.8 µm with an increase in salt concentration, which however, decreased significantly to below 1 µm after 1 week, due to breakdown of droplet aggregates over time. Upon heating the emulsions to 90 °C, extensive droplet aggregation was observed in all emulsions leading to emulsion destabilization. To prevent heat-induced emulsion destabilization, soluble protein solution was heated, and the emulsions were made under hot conditions to overcome the problem of protein and droplet aggregation-induced emulsion destabilization. Based on different emulsion characterization tests, it was found that 0.5 M salt-added heated-protein-stabilized emulsion at pH 7 had the highest stability with the lowest average droplet size (below 300 nm). Heat treated soluble pea proteins accompanied with NaCl could serve as a potential high-value emulsifiers for the beverage industry.
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Hojilla-Evangelista, Milagros, i Roque Evangelista. "Green' Production of Protein Isolate from Novel Golden Pennycress Seeds". W 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/trho6904.
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A new field pennycress variety with golden yellow seeds (TT8) was developed to enhance protein properties and for use as an alternative plant protein source. The chemical and functional properties of TT8 proteins have not been determined. Additionally, alternatives to hexane for defatting are being sought due to negative consumer perception on the use of petroleum-based solvents for food processing. In this research, alcohol defatting of the TT8 ground seeds and saline extraction (AL-SE) of the protein were evaluated as approaches for protein production and compared with the previous hexane defatting/saline extraction (HX-SE) techniques. Seeds were ground (final particle size 250-350 μ) and then defatted with anhydrous ethanol or hexane (60°C) until residual oil content was around 0.7%. Protein extraction from defatted meal was done using our saline-based method (1: 10 w/v, 0.1 M NaCl, 2 h, 50°C) for wild pennycress. Alcohol defatted meal was more protein-enriched (49% protein) than hexane-defatted meal (39% protein), but its protein yield and extraction efficiency were reduced. AL-SE protein had lower purity (85% protein) than did the HX-SE protein (94%). Solubility (73-98%) of AL-SE protein from pH 2-8.5 was notably greater than those observed for HX-SE protein. Foaming capacity (125-145 mL), foam stability (90-93% remaining foam after 15 min), emulsifying activity index (141-236 m2/g protein), and emulsion stability index (15-26 min) were also improved in the AL-SE protein. Overall, TT8 protein was more soluble than wild pennycress protein from pH 2-7 and showed better foaming and emulsifying properties. This work demonstrated that proteins with desirable properties can be produced by AL-SE from TT8, a new golden pennycress variety.
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Buehler, Markus J., i Sebastien Uzel. "Deformation and Failure of Collagenous Tissues: A Multi-Scale Study". W ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-205480.
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Fibrous proteins constitute critical building blocks of life, forming biological materials such as hair, bone, skin, spider silk or cells, which play an important role in providing key mechanical functions in biological systems. However, the fundamental atomistic and molecular deformation and fracture mechanisms of biological protein materials remain largely unknown, partly due to a lack of understanding of how individual protein building blocks respond to mechanical load.
Raporty organizacyjne na temat "Hox proteins"
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Daddario, Sunshine. The Role of HOX Proteins in Androgen-Independent Prostate Cancer. Fort Belvoir, VA: Defense Technical Information Center, listopad 2008. http://dx.doi.org/10.21236/ada494966.
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Daddario, Sunshine. The Role of HOX Proteins in Androgen-Independent Prostate Cancer. Fort Belvoir, VA: Defense Technical Information Center, listopad 2006. http://dx.doi.org/10.21236/ada470623.
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Herman, Eliot D., Gad Galili i Alan Bennett. Recognition and Disposal of Misfolded Seed Proteins. United States Department of Agriculture, sierpień 1994. http://dx.doi.org/10.32747/1994.7568791.bard.
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This project was directed at determining mechanisms involved in storage of intrinsic and foreign storage proteins in seeds. Seeds constitute the majority of direct and indirect food. Understanding how seeds store proteins is important to design approaches to improve the quality of seed proteins through biotechnology. In the Israeli part of this project we have conducted investigations to elucidate the mechanisms involved in assembling wheat storage proteins into ER-derived protein bodies. The results obtained have shown how domains of storage protein molecules are critical in the assembly of protein bodies. In the US side of this project the fate of foreign and engineered proteins expressed in seeds has been investigated. Engineering seed proteins offers the prospect of improving the quality of crops. Many foreign proteins are unstable when expressed in transgenic seeds. The results obtained have demonstrated that sequestering foreign proteins in the ER or ER-derived protein bodies stabilizes the proteins permitting their accumulation. The collaboration conducted in this project has advanced the understanding how protein bodies are assembled and the potential to use the ER and protein bodies to store engineered proteins that can enhance the composition of seeds.
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Epel, Bernard L., Roger N. Beachy, A. Katz, G. Kotlinzky, M. Erlanger, A. Yahalom, M. Erlanger i J. Szecsi. Isolation and Characterization of Plasmodesmata Components by Association with Tobacco Mosaic Virus Movement Proteins Fused with the Green Fluorescent Protein from Aequorea victoria. United States Department of Agriculture, wrzesień 1999. http://dx.doi.org/10.32747/1999.7573996.bard.
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The coordination and regulation of growth and development in multicellular organisms is dependent, in part, on the controlled short and long-distance transport of signaling molecule: In plants, symplastic communication is provided by trans-wall co-axial membranous tunnels termed plasmodesmata (Pd). Plant viruses spread cell-to-cell by altering Pd. This movement scenario necessitates a targeting mechanism that delivers the virus to a Pd and a transport mechanism to move the virion or viral nucleic acid through the Pd channel. The identity of host proteins with which MP interacts, the mechanism of the targeting of the MP to the Pd and biochemical information on how Pd are alter are questions which have been dealt with during this BARD project. The research objectives of the two labs were to continue their biochemical, cellular and molecular studies of Pd composition and function by employing infectious modified clones of TMV in which MP is fused with GFP. We examined Pd composition, and studied the intra- and intercellular targeting mechanism of MP during the infection cycle. Most of the goals we set for ourselves were met. The Israeli PI and collaborators (Oparka et al., 1999) demonstrated that Pd permeability is under developmental control, that Pd in sink tissues indiscriminately traffic proteins of sizes of up to 50 kDa and that during the sink to source transition there is a substantial decrease in Pd permeability. It was shown that companion cells in source phloem tissue export proteins which traffic in phloem and which unload in sink tissue and move cell to cell. The TAU group employing MP:GFP as a fluorescence probe for optimized the procedure for Pd isolation. At least two proteins kinases found to be associated with Pd isolated from source leaves of N. benthamiana, one being a calcium dependent protein kinase. A number of proteins were microsequenced and identified. Polyclonal antibodies were generated against proteins in a purified Pd fraction. A T-7 phage display library was created and used to "biopan" for Pd genes using these antibodies. Selected isolates are being sequenced. The TAU group also examined whether the subcellular targeting of MP:GFP was dependent on processes that occurred only in the presence of the virus or whether targeting was a property indigenous to MP. Mutant non-functional movement proteins were also employed to study partial reactions. Subcellular targeting and movement were shown to be properties indigenous to MP and that these processes do not require other viral elements. The data also suggest post-translational modification of MP is required before the MP can move cell to cell. The USA group monitored the development of the infection and local movement of TMV in N. benthamiana, using viral constructs expressing GFP either fused to the MP of TMV or expressing GFP as a free protein. The fusion protein and/or the free GFP were expressed from either the movement protein subgenomic promoter or from the subgenomic promoter of the coat protein. Observations supported the hypothesis that expression from the cp sgp is regulated differently than expression from the mp sgp (Szecsi et al., 1999). Using immunocytochemistry and electron microscopy, it was determined that paired wall-appressed bodies behind the leading edge of the fluorescent ring induced by TMV-(mp)-MP:GFP contain MP:GFP and the viral replicase. These data suggest that viral spread may be a consequence of the replication process. Observation point out that expression of proteins from the mp sgp is temporary regulated, and degradation of the proteins occurs rapidly or more slowly, depending on protein stability. It is suggested that the MP contains an external degradation signal that contributes to rapid degradation of the protein even if expressed from the constitutive cp sgp. Experiments conducted to determine whether the degradation of GFP and MP:GFP was regulated at the protein or RNA level, indicated that regulation was at the protein level. RNA accumulation in infected protoplast was not always in correlation with protein accumulation, indicating that other mechanisms together with RNA production determine the final intensity and stability of the fluorescent proteins.
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Morrison, Mark, i Joshuah Miron. Molecular-Based Analysis of Cellulose Binding Proteins Involved with Adherence to Cellulose by Ruminococcus albus. United States Department of Agriculture, listopad 2000. http://dx.doi.org/10.32747/2000.7695844.bard.
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At the beginning of this project, it was clear that R. albus adhered tightly to cellulose and its efficient degradation of this polysaccharide was dependent on micromolar concentrations of phenylacetic acid (PAA) and phenylpropionic acid (PPA). The objectives for our research were: i) to identify how many different kinds of cellulose binding proteins are produced by Ruminococcus albus; ii) to isolate and clone the genes encoding some of these proteins from the same bacterium; iii) to determine where these various proteins were located and; iv) quantify the relative importance of these proteins in affecting the rate and extent to which the bacterium becomes attached to cellulose. BARD support has facilitated a number of breakthroughs relevant to our fundamental understanding of the adhesion process. First, R. albus possesses multiple mechanisms for adhesion to cellulose. The P.I.'s laboratory has discovered a novel cellulose-binding protein (CbpC) that belongs to the Pil-protein family, and in particular, the type 4 fimbrial proteins. We have also obtained genetic and biochemical evidence demonstrating that, in addition to CbpC-mediated adhesion, R. albus also produces a cellulosome-like complex for adhesion. These breakthroughs resulted from the isolation (in Israel and the US) of spontaneously arising mutants of R. albus strains SY3 and 8, which were completely or partially defective in adhesion to cellulose, respectively. While the SY3 mutant strain was incapable of growth with cellulose as the sole carbon source, the strain 8 mutants showed varying abilities to degrade and grow with cellulose. Biochemical and gene cloning experiments have been used in Israel and the US, respectively, to identify what are believed to be key components of a cellulosome. This combination of cellulose adhesion mechanisms has not been identified previously in any bacterium. Second, differential display, reverse transcription polymerase chain reaction (DD RT-PCR) has been developed for use with R. albus. A major limitation to cellulose research has been the intractability of cellulolytic bacteria to genetic manipulation by techniques such as transposon mutagenesis and gene displacement. The P.I.'s successfully developed DD RT- PCR, which expanded the scope of our research beyond the original objectives of the project, and a subset of the transcripts conditionally expressed in response to PAA and PPA have been identified and characterized. Third, proteins immunochemically related to the CbpC protein of R. albus 8 are present in other R. albus strains and F. intestinalis, Western immunoblots have been used to examine additional strains of R. albus, as well as other cellulolytic bacteria of ruminant origin, for production of proteins immunochemically related to the CbpC protein. The results of these experiments showed that R. albus strains SY3, 7 and B199 all possess a protein of ~25 kDa which cross-reacts with polyclonal anti-CbpC antiserum. Several strains of Butyrivibrio fibrisolvens, Ruminococcus flavefaciens strains C- 94 and FD-1, and Fibrobacter succinogenes S85 produced no proteins that cross-react with the same antiserum. Surprisingly though, F. intestinalis strain DR7 does possess a protein(s) of relatively large molecular mass (~200 kDa) that was strongly cross-reactive with the anti- CbpC antiserum. Scientifically, our studies have helped expand the scope of our fundamental understanding of adhesion mechanisms in cellulose-degrading bacteria, and validated the use of RNA-based techniques to examine physiological responses in bacteria that are nor amenable to genetic manipulations. Because efficient fiber hydrolysis by many anaerobic bacteria requires both tight adhesion to substrate and a stable cellulosome, we believe our findings are also the first step in providing the resources needed to achieve our long-term goal of increasing fiber digestibility in animals.
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Yalovsky, Shaul, i Julian Schroeder. The function of protein farnesylation in early events of ABA signal transduction in stomatal guard cells of Arabidopsis. United States Department of Agriculture, styczeń 2002. http://dx.doi.org/10.32747/2002.7695873.bard.
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Loss of function mutations in the farnesyltransferase β subunit gene ERA1 (enhanced response to abscisic acid), cause abscisic acid hypersensitivity in seedlings and in guard cells. This results in slowed water loss of plants in response to drought. Farnesyltransferase (PFT) catalyses the attachment of the 15-carbon isoprenoid farnesyl to conserved cysteine residues located in a conserved C-terminal domain designated CaaX box. PFT is a heterodimeric protein comprised of an a and b sununits. The a subunit is shared between PFT and geranylgeranyltransferase-I (PGGTI) which catalyses the attachemt of the 20-carbon isoprenoid geranylgeranyl to CaaX box proteins in which the last amino acid is almost always leucine and in addition have a polybasic domain proximal to the CaaL box. Preliminary data presented in the proposal showed that increased cytoplasmic Ca2+ concentration in stomal guard cells in response to non-inductive ABA treatements. The goals set in the proposal were to characterize better how PFT (ERA1) affects ABA induced Ca2+ concentrations in guard cells and to identify putative CaaX box proteins which function as negative regulators of ABA signaling and which function is compromised in era1 mutant plants. To achieve these goals we proposed to use camelion Ca2+ sensor protein, high throughput genomic to identify the guard cell transcriptome and test prenylation of candidate proteins. We also proposed to focus our efforts of RAC small GTPases which are prenylated proteins which function in signaling. Our results show that farnesyltransferaseprenylates protein/s that act between the points of ABA perception and the activation of plasma membrane calcium influx channels. A RAC protein designated AtRAC8/AtRop10 also acts in negative regulation of ABA signaling. However, we discovered that this protein is palmitoylated and not prenylated although it contains a C-terminal CXXX motif. We further discovered a unique C-terminal sequence motif required for membrane targeting of palmitoylatedRACs and showed that their function is prenylation independent. A GC/MS based method for expression in plants, purification and analysis of prenyl group was developed. This method would allow highly reliable identification of prenylated protein. Mutants in the shared α subunit of PFT and PGGT-I was identified and characterized and was shown to be ABA hypersensitive but less than era1. This suggested that PFT and PGGT-I have opposing functions in ABA signaling. Our results enhanced the understanding of the role of protein prenylation in ABA signaling and drought resistance in plants with the implications of developing drought resistant plants. The results of our studies were published 4 papers which acknowledge support from BARD.
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Asenath-Smith, Emily, Emily Jeng, Emma Ambrogi, Garrett Hoch i Jason Olivier. Investigations into the ice crystallization and freezing properties of the antifreeze protein ApAFP752. Engineer Research and Development Center (U.S.), wrzesień 2022. http://dx.doi.org/10.21079/11681/45620.
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Antifreeze proteins (AFPs) allow biological organisms, including insects, fish, and plants, to survive in freezing temperatures. While in solution, AFPs impart cryoprotection by creating a thermal hysteresis (TH), imparting ice recrystallization inhibition (IRI), and providing dynamic ice shaping (DIS). To leverage these ice-modulating effects of AFPs in other scenarios, a range of icing assays were performed with AFPs to investigate how AFPs interact with ice formation when tethered to a surface. In this work, we studied ApAFP752, an AFP from the beetle Anatolica polita, and first investigated whether removing the fusion protein attached during protein expression would result in a difference in freezing behavior. We performed optical microscopy to examine ice-crystal shape, micro-structure, and the recrystallization behavior of frozen droplets of AFP solutions. We developed a surface chemistry approach to tether these proteins to glass surfaces and conducted droplet-freezing experiments to probe the interactions of these proteins with ice formed on those surfaces. In solution, ApAFP752 did not show any DIS or TH, but it did show IRI capabilities. In surface studies, the freezing of AFP droplets on clean glass surfaces showed no dependence on concentration, and the results from freezing water droplets on AFP-decorated surfaces were inconclusive.
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Ohad, Nir, i Robert Fischer. Regulation of Fertilization-Independent Endosperm Development by Polycomb Proteins. United States Department of Agriculture, styczeń 2004. http://dx.doi.org/10.32747/2004.7695869.bard.
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Arabidopsis mutants that we have isolated, encode for fertilization-independent endosperm (fie), fertilization-independent seed2 (fis2) and medea (mea) genes, act in the female gametophyte and allow endosperm to develop without fertilization when mutated. We cloned the FIE and MEA genes and showed that they encode WD and SET domain polycomb (Pc G) proteins, respectively. Homologous proteins of FIE and MEA in other organisms are known to regulate gene transcription by modulating chromatin structure. Based on our results, we proposed a model whereby both FIE and MEA interact to suppress transcription of regulatory genes. These genes are transcribed only at proper developmental stages, as in the central cell of the female gametophyte after fertilization, thus activating endosperm development. To test our model, the following questions were addressed: What is the Composition and Function of the Polycomb Complex? Molecular, biochemical, genetic and genomic approaches were offered to identify members of the complex, analyze their interactions, and understand their function. What is the Temporal and Spatial Pattern of Polycomb Proteins Accumulation? The use of transgenic plants expressing tagged FIE and MEA polypeptides as well as specific antibodies were proposed to localize the endogenous polycomb complex. How is Polycomb Protein Activity Controlled? To understand the molecular mechanism controlling the accumulation of FIE protein, transgenic plants as well as molecular approaches were proposed to determine whether FIE is regulated at the translational or posttranslational levels. The objectives of our research program have been accomplished and the results obtained exceeded our expectation. Our results reveal that fie and mea mutations cause parent-of-origin effects on seed development by distinct mechanisms (Publication 1). Moreover our data show that FIE has additional functions besides controlling the development of the female gametophyte. Using transgenic lines in which FIE was not expressed or the protein level was reduced during different developmental stages enabled us for the first time to explore FIE function during sporophyte development (Publication 2 and 3). Our results are consistent with the hypothesis that FIE, a single copy gene in the Arabidopsis genome, represses multiple developmental pathways (i.e., endosperm, embryogenesis, shot formation and flowering). Furthermore, we identified FIE target genes, including key transcription factors known to promote flowering (AG and LFY) as well as shoot and leaf formation (KNAT1) (Publication 2 and 3), thus demonstrating that in plants, as in mammals and insects, PcG proteins control expression of homeobox genes. Using the Yeast two hybrid system and pull-down assays we demonstrated that FIE protein interact with MEA via the N-terminal region (Publication 1). Moreover, CURLY LEAF protein, an additional member of the SET domain family interacts with FIE as well. The overlapping expression patterns of FIE, with ether MEA or CLF and their common mutant phenotypes, demonstrate the versatility of FIE function. FIE association with different SET domain polycomb proteins, results in differential regulation of gene expression throughout the plant life cycle (Publication 3). In vitro interaction assays we have recently performed demonstrated that FIE interacts with the cell cycle regulatory component Retinobalsoma protein (pRb) (Publication 4). These results illuminate the potential mechanism by which FIE may restrain embryo sac central cell division, at least partly, through interaction with, and suppression of pRb-regulated genes. The results of this program generated new information about the initiation of reproductive development and expanded our understanding of how PcG proteins regulate developmental programs along the plant life cycle. The tools and information obtained in this program will lead to novel strategies which will allow to mange crop plants and to increase crop production.
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Avni, Adi, i Gitta L. Coaker. Proteomic investigation of a tomato receptor like protein recognizing fungal pathogens. United States Department of Agriculture, styczeń 2015. http://dx.doi.org/10.32747/2015.7600030.bard.
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Maximizing food production with minimal negative effects on the environment remains a long-term challenge for sustainable food production. Microbial pathogens cause devastating diseases, minimizing crop losses by controlling plant diseases can contribute significantly to this goal. All plants possess an innate immune system that is activated after recognition of microbial-derived molecules. The fungal protein Eix induces defense responses in tomato and tobacco. Plants recognize Eix through a leucine-rich-repeat receptor- like-protein (LRR-RLP) termed LeEix. Despite the knowledge obtained from studies on tomato, relatively little is known about signaling initiated by RLP-type immune receptors. The focus of this grant proposal is to generate a foundational understanding of how the tomato xylanase receptor LeEix2 signals to confer defense responses. LeEix2 recognition results in pattern triggered immunity (PTI). The grant has two main aims: (1) Isolate the LeEix2 protein complex in an active and resting state; (2) Examine the biological function of the identified proteins in relation to LeEix2 signaling upon perception of the xylanase elicitor Eix. We used two separate approaches to isolate receptor interacting proteins. Transgenic tomato plants expressing LeEix2 fused to the GFP tag were used to identify complex components at a resting and activated state. LeEix2 complexes were purified by mass spectrometry and associated proteins identified by mass spectrometry. We identified novel proteins that interact with LeEix receptor by proteomics analysis. We identified two dynamin related proteins (DRPs), a coiled coil – nucleotide binding site leucine rich repeat (SlNRC4a) protein. In the second approach we used the split ubiquitin yeast two hybrid (Y2H) screen system to identified receptor-like protein kinase At5g24010-like (SlRLK-like) (Solyc01g094920.2.1) as an interactor of LeEIX2. We examined the role of SlNRC4a in plant immunity. Co-immunoprecipitation demonstrates that SlNRC4a is able to associate with different PRRs. Physiological assays with specific elicitors revealed that SlNRC4a generally alters PRR-mediated responses. SlNRC4a overexpression enhances defense responses while silencing SlNRC4 reduces plant immunity. We propose that SlNRC4a acts as a non-canonical positive regulator of immunity mediated by diverse PRRs. Thus, SlNRC4a could link both intracellular and extracellular immune perception. SlDRP2A localizes at the plasma membrane. Overexpression of SlDRP2A increases the sub-population of LeEIX2 inVHAa1 endosomes, and enhances LeEIX2- and FLS2-mediated defense. The effect of SlDRP2A on induction of plant immunity highlights the importance of endomembrane components and endocytosis in signal propagation during plant immune . The interaction of LeEIX2 with SlRLK-like was verified using co- immunoprecipitation and a bimolecular fluorescence complementation assay. The defence responses induced by EIX were markedly reduced when SlRLK-like was over-expressed, and mutation of slrlk-likeusing CRISPR/Cas9 increased EIX- induced ethylene production and SlACSgene expression in tomato. Co-expression of SlRLK-like with different RLPs and RLKs led to their degradation, apparently through an endoplasmic reticulum-associated degradation process. We provided new knowledge and expertise relevant to expression of specific be exploited to enhance immunity in crops enabling the development of novel environmentally friendly disease control strategies.
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Coplin, David L., Shulamit Manulis i Isaac Barash. roles Hrp-dependent effector proteins and hrp gene regulation as determinants of virulence and host-specificity in Erwinia stewartii and E. herbicola pvs. gypsophilae and betae. United States Department of Agriculture, czerwiec 2005. http://dx.doi.org/10.32747/2005.7587216.bard.
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Gram-negative plant pathogenic bacteria employ specialized type-III secretion systems (TTSS) to deliver an arsenal of pathogenicity proteins directly into host cells. These secretion systems are encoded by hrp genes (for hypersensitive response and pathogenicity) and the effector proteins by so-called dsp or avr genes. The functions of effectors are to enable bacterial multiplication by damaging host cells and/or by blocking host defenses. We characterized essential hrp gene clusters in the Stewart's Wilt of maize pathogen, Pantoea stewartii subsp. stewartii (Pnss; formerly Erwinia stewartii) and the gall-forming bacterium, Pantoea agglomerans (formerly Erwinia herbicola) pvs. gypsophilae (Pag) and betae (Pab). We proposed that the virulence and host specificity of these pathogens is a function of a) the perception of specific host signals resulting in bacterial hrp gene expression and b) the action of specialized signal proteins (i.e. Hrp effectors) delivered into the plant cell. The specific objectives of the proposal were: 1) How is the expression of the hrp and effector genes regulated in response to host cell contact and the apoplastic environment? 2) What additional effector proteins are involved in pathogenicity? 3) Do the presently known Pantoea effector proteins enter host cells? 4) What host proteins interact with these effectors? We characterized the components of the hrp regulatory cascade (HrpXY ->7 HrpS ->7 HrpL ->7 hrp promoters), showed that they are conserved in both Pnss and Fag, and discovered that the regulation of the hrpS promoter (hrpSp) may be a key point in integrating apoplastic signals. We also analyzed the promoters recognized by HrpL and demonstrated the relationship between their composition and efficiency. Moreover, we showed that promoter strength can influence disease expression. In Pnss, we found that the HrpXY two-component signal system may sense the metabolic status of the bacterium and is required for full hrp gene expression in planta. In both species, acyl-homoserine lactone-mediated quorum sensing may also regulate epiphytic fitness and/or pathogenicity. A common Hrp effector protein, DspE/WtsE, is conserved and required for virulence of both species. When introduced into corn cells, Pnss WtsE protein caused water-soaked lesions. In other plants, it either caused cell death or acted as an Avr determinant. Using a yeast- two-hybrid system, WtsE was shown to interact with a number of maize signal transduction proteins that are likely to have roles in either programmed cell death or disease resistance. In Pag and Pab, we have characterized the effector proteins HsvG, HsvB and PthG. HsvG and HsvB are homologous proteins that determine host specificity of Pag and Pab on gypsophila and beet, respectively. Both possess a transcriptional activation domain that functions in yeast. PthG was found to act as an Avr determinant on multiple beet species, but was required for virulence on gypsophila. In addition, we demonstrated that PthG acts within the host cell. Additional effector genes have been characterized on the pathogenicity plasmid, pPATHₚₐg, in Pag. A screen for HrpL- regulated genes in Pnsspointed up 18 candidate effector proteins and four of these were required for full virulence. It is now well established that the virulence of Gram-negative plant pathogenic bacteria is governed by Hrp-dependent effector proteins. However; the mode of action of many effectors is still unresolved. This BARD supported research will significantly contribute to the understanding of how Hrp effectors operate in Pantoea spp. and how they control host specificity and affect symptom production. This may lead to novel approaches for genetically engineering plants resistant to a wide range of bacterial pathogens by inactivating the Hrp effectors with "plantabodies" or modifying their receptors, thereby blocking the induction of the susceptible response. Alternatively, innovative technologies could be used to interfere with the Hrp regulatory cascade by blocking a critical step or mimicking plant or quorum sensing signals.