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1
Zhang, XiaoHong, YuJi Miao, XiaoDan Hu, Rui Min, PeiDang Liu i HaiQian Zhang. "Gamma Radiation-Induced Damage in the Zinc Finger of the Transcription Factor IIIA". Bioinorganic Chemistry and Applications 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/1642064.
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A zinc finger motif is an element of proteins that can specifically recognize and bind to DNA. Because they contain multiple cysteine residues, zinc finger motifs possess redox properties. Ionizing radiation generates a variety of free radicals in organisms. Zinc finger motifs, therefore, may be a target of ionizing radiation. The effect of gamma radiation on the zinc finger motifs in transcription factor IIIA (TFIIIA), a zinc finger protein, was investigated. TFIIIA was exposed to different gamma doses from 60Co sources. The dose rates were 0.20 Gy/min and 800 Gy/h, respectively. The binding capacity of zinc finger motifs in TFIIIA was determined using an electrophoretic mobility shift assay. We found that 1000 Gy of gamma radiation impaired the function of the zinc finger motifs in TFIIIA. The sites of radiation-induced damage in the zinc finger were the thiol groups of cysteine residues and zinc (II) ions. The thiol groups were oxidized to form disulfide bonds and the zinc (II) ions were indicated to be reduced to zinc atoms. These results indicate that the zinc finger motif is a target domain for gamma radiation, which may decrease 5S rRNA expression via impairment of the zinc finger motifs in TFIIIA.
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GREEN, Andrew, i Bibudhendra SARKAR. "Alteration of zif268 zinc-finger motifs gives rise to non-native zinc-co-ordination sites but preserves wild-type DNA recognition". Biochemical Journal 333, nr 1 (1.07.1998): 85–90. http://dx.doi.org/10.1042/bj3330085.
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Zinc fingers are among the major structural motifs found in proteins that are involved in eukaryotic gene regulation. Many of these zinc-finger domains are involved in DNA binding. This study investigated whether the zinc-co-ordinating (Cys)2(His)2 motif found in the three zinc fingers of zif268 could be replaced by a (Cys)4 motif while still preserving DNA recognition. (Cys)2(His)2-to-(Cys)4 mutations were generated in each of the three zinc fingers of zif268 individually, as well as in fingers 1 and 3, and fingers 2 and 3 together. Whereas finger 1 and finger 3 tolerate the switch, such an alteration in finger 2 renders the polypeptide incapable of DNA recognition. The protein–DNA interaction was examined in greater detail by using a methylation-interference assay. The mutant polypeptides containing the (Cys)4 motif in fingers 1 or 3 recognize DNA in a manner identical to the wild-type protein, suggesting that the (Cys)4 motif appears to give rise to a properly folded finger. Additional results indicate that a zif268 variant containing a (Cys)2(His)(Ala) arrangement in finger 1 is also capable of DNA recognition in a manner identical to the wild-type polypeptide. This appears to be the first time that such alterations, in the context of an intact DNA-binding domain, have still allowed for specific DNA recognition. Taken together, the work presented here enhances our understanding of the relationship between metal ligation and DNA-binding by zinc fingers.
3
MAURER-STROH, SEBASTIAN, HE GAO, HAO HAN, LIES BAETEN, JOOST SCHYMKOWITZ, FREDERIC ROUSSEAU, LOUXIN ZHANG i FRANK EISENHABER. "MOTIF DISCOVERY WITH DATA MINING IN 3D PROTEIN STRUCTURE DATABASES: DISCOVERY, VALIDATION AND PREDICTION OF THE U-SHAPE ZINC BINDING ("HUF-ZINC") MOTIF". Journal of Bioinformatics and Computational Biology 11, nr 01 (luty 2013): 1340008. http://dx.doi.org/10.1142/s0219720013400088.
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Data mining in protein databases, derivatives from more fundamental protein 3D structure and sequence databases, has considerable unearthed potential for the discovery of sequence motif—structural motif—function relationships as the finding of the U-shape (Huf-Zinc) motif, originally a small student's project, exemplifies. The metal ion zinc is critically involved in universal biological processes, ranging from protein-DNA complexes and transcription regulation to enzymatic catalysis and metabolic pathways. Proteins have evolved a series of motifs to specifically recognize and bind zinc ions. Many of these, so called zinc fingers, are structurally independent globular domains with discontinuous binding motifs made up of residues mostly far apart in sequence. Through a systematic approach starting from the BRIX structure fragment database, we discovered that there exists another predictable subset of zinc-binding motifs that not only have a conserved continuous sequence pattern but also share a characteristic local conformation, despite being included in totally different overall folds. While this does not allow general prediction of all Zn binding motifs, a HMM-based web server, Huf-Zinc, is available for prediction of these novel, as well as conventional, zinc finger motifs in protein sequences. The Huf-Zinc webserver can be freely accessed through this URL ( http://mendel.bii.a-star.edu.sg/METHODS/hufzinc/ ).
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Gebelein, Brian, i Raul Urrutia. "Sequence-Specific Transcriptional Repression by KS1, a Multiple-Zinc-Finger–Krüppel-Associated Box Protein". Molecular and Cellular Biology 21, nr 3 (1.02.2001): 928–39. http://dx.doi.org/10.1128/mcb.21.3.928-939.2001.
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ABSTRACT The vertebrate genome contains a large number of Krüppel-associated box–zinc finger genes that encode 10 or more C2-H2 zinc finger motifs. Members of this gene family have been proposed to function as transcription factors by binding DNA through their zinc finger region and repressing gene expression via the KRAB domain. To date, however, no Krüppel-associated box–zinc finger protein (KRAB-ZFP) and few proteins with 10 or more zinc finger motifs have been shown to bind DNA in a sequence-specific manner. Our laboratory has recently identified KS1, a member of the KRAB-ZFP family that contains 10 different C2-H2 zinc finger motifs, 9 clustered at the C terminus with an additional zinc finger separated by a short linker region. In this study, we used a random oligonucleotide binding assay to identify a 27-bp KS1 binding element (KBE). Reporter assays demonstrate that KS1 represses the expression of promoters containing this DNA sequence. Deletion and site-directed mutagenesis reveal that KS1 requires nine C-terminal zinc fingers and the KRAB domain for transcriptional repression through the KBE site, whereas the isolated zinc finger and linker region are dispensable for this function. Additional biochemical assays demonstrate that the KS1 KRAB domain interacts with the KAP-1 corepressor, and mutations that abolish this interaction alleviate KS1-mediated transcriptional repression. Thus, this study provides the first direct evidence that a KRAB-ZFP binds DNA to regulate gene expression and provides insight into the mechanisms used by multiple-zinc-finger proteins to recognize DNA sequences.
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Hasegawa, Atsushi, Hiroshi Kaneko, Daishi Ishihara, Masahiro Nakamura, Akira Watanabe, Cecelia D. Trainor, Yamamoto Masayuki i Ritsuko Shimizu. "GATA1 Changes DNA-Binding Fashion in a Binding-Site-Specific Manner and Alters Transcriptional Activity during Erythropoiesis". Blood 126, nr 23 (3.12.2015): 3584. http://dx.doi.org/10.1182/blood.v126.23.3584.3584.
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Abstract GATA1 is a transcription factor that coordinately regulates multiple target genes during the development and differentiation of erythroid and megakaryocytic lineages through binding to GATA motif (A/T)GATA(A/G). GATA1 has four functional domains, i.e., two transactivation domains reside in amino- and carboxyl- terminus, which transactivate GATA1 target genes redundantly and/or cooperatively, and two zinc-finger domains in the middle of the protein. The two zinc finger domains of GATA1 have been characterized extensively and their links to human diseases have also been identified. Carboxyl-terminal side zinc (C)-finger is essential for the DNA binding of GATA1, whereas amino-terminal side zinc (N)-finger retains insufficient binding activity to the GATA motifs by itself, but contributes to stabilize the binding of C-finger to a double GATA site arranged in a palindromic manner. Of note, while this two-finger structure is conserved in six distinct vertebrate GATA factors, there exist GATA factors with single zinc finger in non-vertebrates, indicating that only the C-finger and following basic tail region are evolutionary conserved in both vertebrate and non-vertebrate GATA factors. In our transgenic rescue analyses, GATA1 lacking the N-finger (ΔNF-GATA1) supports, if not completely, the erythropoiesis in mice, but mice without C-finger (ΔCF-GATA1) die in utero showing similar phenotype to the mice with complete loss-of-GATA1-function. Therefore, roles that the N-finger plays have been assumed to be evolutionally acquired features during molecular evolution. In this study, we have examined GATA-motif configuration-specific modulation of GATA1 function by using composite GATA elements in which two GATA motifs aligned side-by-side, either tandem or palindromic. We have defined changes in the GATA1 binding and transactivation activity in accordance with the arrangement of cis -acting GATA motifs. While GATA1 binds to Single-GATA in a monovalent way via C-finger without the influence of N-finger, the N-finger appears to contribute to specific bivalent binding of GATA1 to Pal-GATA, i.e., the N- and C-fingers in a single GATA1 molecule individually bind to two GATA motifs aligned in a palindromic orientation. Showing very good agreement with the human case analyses, the transgenic expression of G1R216Q that lacks N-finger-DNA interaction potential hardly rescues the GATA1-deficient mice due to defects in definitive erythropoiesis, indicating that roles owed by R216 residue are vital for the GATA1 activity in vivo. The N-finger also contributes to GATA1 homodimer formation, which is a prerequisite for two GATA1 binding to two GATA motifs aligned in a tandem orientation. Each GATA1 C-finger in the dimeric GATA1 protein binds to each GATA motif in Tandem-GATA. In this regard, we previously found in a transgenic complementation rescue assay that mutant GATA1 molecule G13KA, which lacks the dimerization potential but possesses most of the other N- and C-finger functions, hardly rescues the GATA1-deficient mice from embryonic lethality, indicating that the GATA1 dimerization is important to attain full GATA1 activity. We surmise based on these observations that the configuration of cis -acting GATA motifs located in the regulatory regions of the GATA1 target genes critically influences the DNA-binding of GATA1 and controls transcription of the genes. Disclosures No relevant conflicts of interest to declare.
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Parraga, G., L. Young i R. E. Klevit. "Zinc-finger motifs and DNA binding". Trends in Biochemical Sciences 14, nr 10 (październik 1989): 398. http://dx.doi.org/10.1016/0968-0004(89)90283-1.
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Gao, Xiang, Daniel J. Rowley, Xiaowu Gai i Daniel F. Voytas. "Ty5 gag Mutations Increase Retrotransposition and Suggest a Role for Hydrogen Bonding in the Function of the Nucleocapsid Zinc Finger". Journal of Virology 76, nr 7 (1.04.2002): 3240–47. http://dx.doi.org/10.1128/jvi.76.7.3240-3247.2002.
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ABSTRACT The Ty5 retrotransposon of Saccharomyces paradoxus transposes in Saccharomyces cerevisiae at frequencies 1,000-fold lower than do the native Ty1 elements. The low transposition activity of Ty5 could be due to differences in cellular environments between these yeast species or to naturally occurring mutations in Ty5. By screening of a Ty5 mutant library, two single mutants (D252N and Y68C) were each found to increase transposition approximately sixfold. When combined, transposition increased 36-fold, implying that the two mutations act independently. Neither mutation affected Ty5 protein synthesis, processing, cDNA recombination, or target site choice. However, cDNA levels in both single mutants and the double mutant were significantly higher than in the wild type. The D252N mutation resides in the zinc finger of nucleocapsid and increases the potential for hydrogen bonding with nucleic acids. We generated other mutations that increase the hydrogen bonding potential (i.e., D252R and D252K) and found that they similarly increased transposition. This suggests that hydrogen bonding within the zinc finger motif is important for cDNA production and builds upon previous studies implicating basic amino acids flanking the zinc finger as important for zinc finger function. Although NCp zinc fingers differ from the zinc finger motifs of cellular enzymes, the requirement for efficient hydrogen bonding is likely universal.
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Bowzard, J. Bradford, Robert P. Bennett, Neel K. Krishna, Sandra M. Ernst, Alan Rein i John W. Wills. "Importance of Basic Residues in the Nucleocapsid Sequence for Retrovirus Gag Assembly and Complementation Rescue". Journal of Virology 72, nr 11 (1.11.1998): 9034–44. http://dx.doi.org/10.1128/jvi.72.11.9034-9044.1998.
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ABSTRACT The Gag proteins of Rous sarcoma virus (RSV) and human immunodeficiency virus (HIV) contain small interaction (I) domains within their nucleocapsid (NC) sequences. These overlap the zinc finger motifs and function to provide the proper density to viral particles. There are two zinc fingers and at least two I domains within these Gag proteins. To more thoroughly characterize the important sequence features and properties of I domains, we analyzed Gag proteins that contain one or no zinc finger motifs. Chimeric proteins containing the amino-terminal half of RSV Gag and various portions of the carboxy terminus of murine leukemia virus (MLV) (containing one zinc finger) Gag had only one I domain, whereas similar chimeras with human foamy virus (HFV) (containing no zinc fingers) Gag had at least two. Mutational analysis of the MLV NC sequence and inspection of I domain sequences within the zinc-fingerless C terminus of HFV Gag suggested that clusters of basic residues, but not the zinc finger motif residues themselves, are required for the formation of particles of proper density. In support of this, a simple string of strongly basic residues was found to be able to substitute for the RSV I domains. We also explored the possibility that differences in I domains (e.g., their number) account for differences in the ability of Gag proteins to be rescued into particles when they are unable to bind to membranes. Previously published experiments have shown that such membrane-binding mutants of RSV and HIV (two I domains) can be rescued but that those of MLV (one I domain) cannot. Complementation rescue experiments with RSV-MLV chimeras now map this difference to the NC sequence of MLV. Importantly, the same RSV-MLV chimeras could be rescued by complementation when the block to budding was after, rather than before, transport to the membrane. These results suggest that MLV Gag molecules begin to interact at a much later time after synthesis than those of RSV and HIV.
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Guo, Jianhui, Tiyun Wu, Bradley F. Kane, Donald G. Johnson, Louis E. Henderson, Robert J. Gorelick i Judith G. Levin. "Subtle Alterations of the Native Zinc Finger Structures Have Dramatic Effects on the Nucleic Acid Chaperone Activity of Human Immunodeficiency Virus Type 1 Nucleocapsid Protein". Journal of Virology 76, nr 9 (1.05.2002): 4370–78. http://dx.doi.org/10.1128/jvi.76.9.4370-4378.2002.
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ABSTRACT The nucleocapsid protein (NC) of human immunodeficiency virus type 1 has two zinc fingers, each containing the invariant CCHC zinc-binding motif; however, the surrounding amino acid context is not identical in the two fingers. Recently, we demonstrated that zinc coordination is required when NC unfolds complex secondary structures in RNA and DNA minus- and plus-strand transfer intermediates; this property of NC reflects its nucleic acid chaperone activity. Here we have analyzed the chaperone activities of mutants having substitutions of alternative zinc-coordinating residues, i.e., CCHH or CCCC, for the wild-type CCHC motif. We also investigated the activities of mutants that retain the CCHC motifs but have mutations that exchange or duplicate the zinc fingers (mutants 1-1, 2-1, and 2-2); these changes affect amino acid context. Our results indicate that in general, for optimal activity in an assay that measures stimulation of minus-strand transfer and inhibition of nonspecific self-priming, the CCHC motif in the zinc fingers cannot be replaced by CCHH or CCCC and the amino acid context of the fingers must be conserved. Context changes also reduce the ability of NC to facilitate primer removal in plus-strand transfer. In addition, we found that the first finger is a more crucial determinant of nucleic acid chaperone activity than the second finger. Interestingly, comparison of the in vitro results with earlier in vivo replication data raises the possibility that NC may adopt multiple conformations that are responsible for different NC functions during virus replication.
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Guo, Xuemin, John-William N. Carroll, Margaret R. MacDonald, Stephen P. Goff i Guangxia Gao. "The Zinc Finger Antiviral Protein Directly Binds to Specific Viral mRNAs through the CCCH Zinc Finger Motifs". Journal of Virology 78, nr 23 (1.12.2004): 12781–87. http://dx.doi.org/10.1128/jvi.78.23.12781-12787.2004.
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ABSTRACT The zinc finger antiviral protein (ZAP) is a recently isolated host antiviral factor. It specifically inhibits the replication of Moloney murine leukemia virus (MLV) and Sindbis virus (SIN) by preventing the accumulation of viral RNA in the cytoplasm. For this report, we mapped the viral sequences that are sensitive to ZAP inhibition. The viral sequences were cloned into a luciferase reporter and analyzed for the ability to mediate ZAP-dependent destabilization of the reporter. The sensitive sequence in MLV was mapped to the 3′ long terminal repeat; the sensitive sequences in SIN were mapped to multiple fragments. The fragment of SIN that displayed the highest destabilizing activity was further analyzed by deletion mutagenesis for the minimal sequence that retained the activity. This led to the identification of a fragment of 653 nucleotides. Any further deletion of this fragment resulted in significantly lower activity. We provide evidence that ZAP directly binds to the active but not the inactive fragments. The CCCH zinc finger motifs of ZAP play important roles in RNA binding and antiviral activity. Disruption of the second and fourth zinc fingers abolished ZAP's activity, whereas disruption of the first and third fingers just slightly lowered its activity.
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Tsai, Robert Y. L., i Randall R. Reed. "Identification of DNA Recognition Sequences and Protein Interaction Domains of the Multiple-Zn-Finger Protein Roaz". Molecular and Cellular Biology 18, nr 11 (1.11.1998): 6447–56. http://dx.doi.org/10.1128/mcb.18.11.6447.
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ABSTRACT Roaz, a rat C2H2 zinc finger protein, plays a role in the regulation of olfactory neuronal differentiation through its interaction with the Olf-1/EBF transcription factor family. An additional role for the Roaz/Olf-1/EBF heterodimeric protein is suggested by its ability to regulate gene activation at a distinct promoter lacking Olf-1/EBF-binding sites. Using an in vitro binding-site selection assay (Selex), we demonstrate that Roaz protein binds to novel inverted perfect or imperfect repeats of GCACCC separated by 2 bp. We show that Roaz is capable of binding to a canonical consensus recognition sequence with high affinity (Kd = 3 nM). Analysis of the structural requirement for protein dimerization and DNA binding by Roaz reveals the role of specific zinc finger motifs in the Roaz protein for homodimerization and heterodimerization with the Olf-1/EBF transcription factor. The DNA-binding domain of Roaz is mapped to the N-terminal 277 amino acids, containing the first seven zinc finger motifs, which confers weak monomeric binding to a single half site and a stronger dimeric binding to the inverted repeat in a binding-site-dependent manner. Full-length protein can form dimers on both the inverted repeat and direct repeat but not on a single half site. These findings support the role of the TFIIIA-type Zn fingers in both protein-protein interaction and protein-DNA interaction and suggest distinct functions for specific motifs in proteins with a large number of zinc finger structures.
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Zhang, Jun-Wu, Han Peng i Zhan-Wen Du. "Identification, Characterization of a Novel Zinc Finger Protein (HZF1) Gene and Its Roles in Erythroid Differentiation and Megakaryocyte Differentiation." Blood 106, nr 11 (16.11.2005): 4237. http://dx.doi.org/10.1182/blood.v106.11.4237.4237.
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Abstract A significant number of transcription factors contain evolutionarily conserved zinc finger motifs. The classical C2H2 zinc finger motif, which employs two cysteine and two histidine residues to coordinate a single zinc ion, is a maim type of the zinc finger proteins. Many of the identified C2H2 type zinc protein have been demonstrated to be transcription factors that play important roles in differentiation and development of cells and tissues of higher organisms. In this study, we obtained some novel expression sequence tags (ESTs) containing C2H2 type motifs by reverse transcription-polymerase chain reaction (RT-PCR) using RNAs derived from hemin-induced K562 cells. A cDNA encoding novel zinc finger protein (designed as HZF1) was obtained by screening the human bone marrow cDNA library using one of the ESTs as the probe. The cDNA sequences (2013 nucleotides) have been submitted to the GenBank databases under accession No. AF244088.1). Three transcripts of HZF1 gene were explored by PCR amplification of cDNAs derived from hemin-induced K562 cells. The cDNA sequences (2632 nucleotides) of the longest transcript have been submitted to the GenBank databases under accession No. DQ117529). These transcripts may result from different splicing of the pre-mRNA of HZF1 but the differences between them are only involved in 5′ non-translation region of HZF1 mRNA. BLASTN analysis revealed that HZF1 gene has four exons and three introns. The putative protein consists of 670 amino acid residues including continuous 15 C2H2 and 2 C2RH zinc finger motifs. This structure characterization and the nuclear location of the protein suggest that HZF1 may function as a transcription factor. HZF1 mRNA was detected in ubiquitous tissues and various hematopoietic cell lines. Increased HZF1 mRNA expression was observed following hemin-induction or phorbol myristate acetate (PMA)-induction of K562 cells. Both of the antisence method and RNA interference assay revealed that repression of the intrinsic expression of HZF1 blocked the hemin-induced erythroid differentiation and reduced the PMA-induced megakaryocytic differentiation of K562 cells, which suggested that HZF1 play an important part in erythroid differentiation and megakaryocytic differentiation.
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Su, Dan, Zhiyong Lou, Fei Sun, Yujia Zhai, Haitao Yang, Rongguang Zhang, Andrzej Joachimiak, Xuejun C. Zhang, Mark Bartlam i Zihe Rao. "Dodecamer Structure of Severe Acute Respiratory Syndrome Coronavirus Nonstructural Protein nsp10". Journal of Virology 80, nr 16 (15.08.2006): 7902–8. http://dx.doi.org/10.1128/jvi.00483-06.
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ABSTRACT The severe acute respiratory syndrome coronavirus (SARS-CoV) nonstructural proteins nsp1 to nsp16 have been implicated by genetic analysis in the assembly of a functional replication/transcription complex. We report the crystal structure of nsp10 from SARS-CoV at 2.1-Å resolution. The nsp10 structure has a novel fold, and 12 identical subunits assemble to form a unique spherical dodecameric architecture. Two zinc fingers have been identified from the nsp10 monomer structure with the sequence motifs C-(X)2-C-(X)5-H-(X)6-C and C-(X)2-C-(X)7-C-(X)-C. The nsp10 crystal structure is the first of a new class of zinc finger protein three-dimensional structures to be revealed experimentally. The zinc finger sequence motifs are conserved among all three coronavirus antigenic groups, implicating an essential function for nsp10 in all coronaviruses. Based on the structure, we propose that nsp10 is a transcription factor for coronavirus replication/transcription.
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Rollins, M. B., S. Del Rio, A. L. Galey, D. R. Setzer i M. T. Andrews. "Role of TFIIIA zinc fingers in vivo: analysis of single-finger function in developing Xenopus embryos". Molecular and Cellular Biology 13, nr 8 (sierpień 1993): 4776–83. http://dx.doi.org/10.1128/mcb.13.8.4776-4783.1993.
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The Xenopus 5S RNA gene-specific transcription factor IIIA (TFIIIA) has nine consecutive Cys2His2 zinc finger motifs. Studies were conducted in vivo to determine the contribution of each of the nine zinc fingers to the activity of TFIIIA in living cells. Nine separate TFIIIA mutants were expressed in Xenopus embryos following microinjection of their respective in vitro-derived mRNAs. Each mutant contained a single histidine-to-asparagine substitution in the third zinc ligand position of an individual zinc finger. These mutations result in structural disruption of the mutated finger with little or no effect on the other fingers. The activity of mutant proteins in vivo was assessed by measuring transcriptional activation of the endogenous 5S RNA genes. Mutants containing a substitution in zinc finger 1, 2, or 3 activate 5S RNA genes at a level which is reduced relative to that in embryos injected with the message for wild-type TFIIIA. Proteins with a histidine-to-asparagine substitution in zinc finger 5 or 7 activate 5S RNA genes at a level that is roughly equivalent to that of the wild-type protein. Zinc fingers 8 and 9 appear to be critical for the normal function of TFIIIA, since mutations in these fingers result in little or no activation of the endogenous 5S RNA genes. Surprisingly, proteins with a mutation in zinc finger 4 or 6 stimulate 5S RNA transcription at a level that is significantly higher than that mediated by similar concentrations of wild-type TFIIIA. Differences in the amount of newly synthesized 5S RNA in embryos containing the various mutant forms of TFIIIA result from differences in the relative number and/or activity of transcription complexes assembled on the endogenous 5S RNA genes and, in the case of the finger 4 and finger 6 mutants, result from increased transcriptional activation of the normally inactive oocyte-type 5S RNA genes. The remarkably high activity of the finger 6 mutant can be reproduced in vitro when transcription is carried out in the presence of 5S RNA. Disruption of zinc finger 6 results in a form of TFIIIA that exhibits reduced susceptibility to feedback inhibition by 5S RNA and therefore increases the availability of the transcription factor for transcription complex formation.
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Rollins, M. B., S. Del Rio, A. L. Galey, D. R. Setzer i M. T. Andrews. "Role of TFIIIA zinc fingers in vivo: analysis of single-finger function in developing Xenopus embryos." Molecular and Cellular Biology 13, nr 8 (sierpień 1993): 4776–83. http://dx.doi.org/10.1128/mcb.13.8.4776.
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The Xenopus 5S RNA gene-specific transcription factor IIIA (TFIIIA) has nine consecutive Cys2His2 zinc finger motifs. Studies were conducted in vivo to determine the contribution of each of the nine zinc fingers to the activity of TFIIIA in living cells. Nine separate TFIIIA mutants were expressed in Xenopus embryos following microinjection of their respective in vitro-derived mRNAs. Each mutant contained a single histidine-to-asparagine substitution in the third zinc ligand position of an individual zinc finger. These mutations result in structural disruption of the mutated finger with little or no effect on the other fingers. The activity of mutant proteins in vivo was assessed by measuring transcriptional activation of the endogenous 5S RNA genes. Mutants containing a substitution in zinc finger 1, 2, or 3 activate 5S RNA genes at a level which is reduced relative to that in embryos injected with the message for wild-type TFIIIA. Proteins with a histidine-to-asparagine substitution in zinc finger 5 or 7 activate 5S RNA genes at a level that is roughly equivalent to that of the wild-type protein. Zinc fingers 8 and 9 appear to be critical for the normal function of TFIIIA, since mutations in these fingers result in little or no activation of the endogenous 5S RNA genes. Surprisingly, proteins with a mutation in zinc finger 4 or 6 stimulate 5S RNA transcription at a level that is significantly higher than that mediated by similar concentrations of wild-type TFIIIA. Differences in the amount of newly synthesized 5S RNA in embryos containing the various mutant forms of TFIIIA result from differences in the relative number and/or activity of transcription complexes assembled on the endogenous 5S RNA genes and, in the case of the finger 4 and finger 6 mutants, result from increased transcriptional activation of the normally inactive oocyte-type 5S RNA genes. The remarkably high activity of the finger 6 mutant can be reproduced in vitro when transcription is carried out in the presence of 5S RNA. Disruption of zinc finger 6 results in a form of TFIIIA that exhibits reduced susceptibility to feedback inhibition by 5S RNA and therefore increases the availability of the transcription factor for transcription complex formation.
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Chen, Yan, Stacy D. Carrington-Lawrence, Ping Bai i Sandra K. Weller. "Mutations in the Putative Zinc-Binding Motif of UL52 Demonstrate a Complex Interdependence between the UL5 and UL52 Subunits of the Human Herpes Simplex Virus Type 1 Helicase/Primase Complex". Journal of Virology 79, nr 14 (lipiec 2005): 9088–96. http://dx.doi.org/10.1128/jvi.79.14.9088-9096.2005.
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ABSTRACT Herpes simplex virus type 1 (HSV-1) encodes a heterotrimeric helicase-primase (UL5/8/52) complex. UL5 contains seven motifs found in helicase superfamily 1, and UL52 contains conserved motifs found in primases. The contributions of each subunit to the biochemical activities of the complex, however, remain unclear. We have previously demonstrated that a mutation in the putative zinc finger at UL52 C terminus abrogates not only primase but also ATPase, helicase, and DNA-binding activities of a UL5/UL52 subcomplex, indicating a complex interdependence between the two subunits. To test this hypothesis and to further investigate the role of the zinc finger in the enzymatic activities of the helicase-primase, a series of mutations were constructed in this motif. They differed in their ability to complement a UL52 null virus: totally defective, partial complementation, and potentiating. In this study, four of these mutants were studied biochemically after expression and purification from insect cells infected with recombinant baculoviruses. All mutants show greatly reduced primase activity. Complementation-defective mutants exhibited severe defects in ATPase, helicase, and DNA-binding activities. Partially complementing mutants displayed intermediate levels of these activities, except that one showed a wild-type level of helicase activity. These data suggest that the UL52 zinc finger motif plays an important role in the activities of the helicase-primase complex. The observation that mutations in UL52 affected helicase, ATPase, and DNA-binding activities indicates that UL52 binding to DNA via the zinc finger may be necessary for loading UL5. Alternatively, UL5 and UL52 may share a DNA-binding interface.
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Shastry, B. S. "Transcription factor IIIA (TFIIIA) in the second decade". Journal of Cell Science 109, nr 3 (1.03.1996): 535–39. http://dx.doi.org/10.1242/jcs.109.3.535.
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Transcription factor IIIA is a very extensively studied eukaryotic gene specific factor. It is a special member of the zinc finger family of nucleic acid binding proteins with multiple functions. Its N-terminal polypeptide (280 amino acid residue containing peptide; finger containing region) carries out sequence specific DNA and RNA binding and the C-terminal peptide (65 amino acid residue containing peptide; non-finger region) is involved in the transactivation process possibly by interacting with other general factors. It is a unique factor in the sense that it binds to two structurally different nucleic acids, DNA and RNA. It accomplishes this function through its zinc fingers, which are arranged into a cluster of nine motifs. Over the past three years there has been considerable interest in determining the structural features of zinc fingers, identifying the fingers that preferentially recognize DNA and RNA, defining the role of metal binding ligands and the linker region in promotor recognition and the role of C-terminal amino acid sequence in the gene activation. This article briefly reviews our current knowledge on this special protein in these areas.
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Nakamura, Takuro, Yukari Yamazaki, Yuriko Saiki, Masatsugu Moriyama, David A. Largaespada, Nancy A. Jenkins i Neal G. Copeland. "Evi9 Encodes a Novel Zinc Finger Protein That Physically Interacts with BCL6, a Known Human B-Cell Proto-Oncogene Product". Molecular and Cellular Biology 20, nr 9 (1.05.2000): 3178–86. http://dx.doi.org/10.1128/mcb.20.9.3178-3186.2000.
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ABSTRACT Evi9 is a common site of retroviral integration in BXH2 murine myeloid leukemias. Here we show that Evi9 encodes a novel zinc finger protein with three tissue-specific isoforms: Evi9a (773 amino acids [aa]) contains two C2H2-type zinc finger motifs, a proline-rich region, and an acidic domain; Evi9b (486 aa) lacks the first zinc finger motif and part of the proline-rich region; Evi9c (239 aa) lacks all but the first zinc finger motif. Proviral integration sites are located in the first intron of the gene and lead to increased gene expression. Evi9a and Evi9c, but not Evi9b, show transforming activity for NIH 3T3 cells, suggesting thatEvi9 is a dominantly acting proto-oncogene. Immunolocalization studies show that Evi9c is restricted to the cytoplasm whereas Evi9a and Evi9b are located in the nucleus, where they form a speckled localization pattern identical to that observed for BCL6, a human B-cell proto-oncogene product. Coimmunoprecipitation and glutathione S-transferase pull-down experiments show that Evi9a and Evi9b, but not Evi9c, physically interact with BCL6, while deletion mutagenesis localized the interaction domains in or near the second zinc finger and POZ domains of Evi9 and BCL6, respectively. These results suggest that Evi9 is a leukemia disease gene that functions, in part, through its interaction with BCL6.
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Franklin, A. J., T. L. Jetton, K. D. Shelton i M. A. Magnuson. "BZP, a novel serum-responsive zinc finger protein that inhibits gene transcription". Molecular and Cellular Biology 14, nr 10 (październik 1994): 6773–88. http://dx.doi.org/10.1128/mcb.14.10.6773-6788.1994.
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We report the fortuitous isolation of cDNA clones encoding a novel zinc finger DNA-binding protein termed BZP. The protein encoded is 114 kDa and contains eight zinc finger motifs, seven of which are present in two clusters at opposite ends of the molecule. Both finger clusters bound to the 9-bp sequence AAAGGTGCA with apparent Kds of approximately 2.5 nM. Two of the finger motifs within the amino- and carboxy-terminal finger clusters share 63% amino acid identity. BZP inhibited transcription of the herpes simplex virus thymidine kinase promoter when copies of the 9-bp target motif were linked in cis, suggesting that it functions as a transcriptional repressor. BZP mRNA and immunoreactivity were detected in several established cell lines but were most abundant in hamster insulinoma (HIT) cells, the parental source of the cDNAs. In mouse tissues, BZP mRNA and immunoreactivity were identified in cells of the endocrine pancreas, anterior pituitary, and central nervous system. Interestingly, in HIT cells proliferating in culture, BZP immunoreactivity was predominately nuclear in location, whereas it was usually located in the cytoplasm in most neural and neuroendocrine tissues. Serum deprivation of HIT cells caused BZP immunoreactivity to become predominantly cytoplasmic in location and attenuated its inhibitory effect on transcription, thereby suggesting that the both the subcellular location and the function of this protein are modulated by factors in serum.
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Franklin, A. J., T. L. Jetton, K. D. Shelton i M. A. Magnuson. "BZP, a novel serum-responsive zinc finger protein that inhibits gene transcription." Molecular and Cellular Biology 14, nr 10 (październik 1994): 6773–88. http://dx.doi.org/10.1128/mcb.14.10.6773.
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We report the fortuitous isolation of cDNA clones encoding a novel zinc finger DNA-binding protein termed BZP. The protein encoded is 114 kDa and contains eight zinc finger motifs, seven of which are present in two clusters at opposite ends of the molecule. Both finger clusters bound to the 9-bp sequence AAAGGTGCA with apparent Kds of approximately 2.5 nM. Two of the finger motifs within the amino- and carboxy-terminal finger clusters share 63% amino acid identity. BZP inhibited transcription of the herpes simplex virus thymidine kinase promoter when copies of the 9-bp target motif were linked in cis, suggesting that it functions as a transcriptional repressor. BZP mRNA and immunoreactivity were detected in several established cell lines but were most abundant in hamster insulinoma (HIT) cells, the parental source of the cDNAs. In mouse tissues, BZP mRNA and immunoreactivity were identified in cells of the endocrine pancreas, anterior pituitary, and central nervous system. Interestingly, in HIT cells proliferating in culture, BZP immunoreactivity was predominately nuclear in location, whereas it was usually located in the cytoplasm in most neural and neuroendocrine tissues. Serum deprivation of HIT cells caused BZP immunoreactivity to become predominantly cytoplasmic in location and attenuated its inhibitory effect on transcription, thereby suggesting that the both the subcellular location and the function of this protein are modulated by factors in serum.
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Kanakoglou, Dimitrios S., Andromachi Pampalou, Lina S. Malakou, Eleftheria Lakiotaki, Theodoros Loupis, Dimitrios M. Vrachnos, Panayiotis D. Glekas i in. "Central Role of C2H2-Type Zinc Finger-Containing Genes in Pediatric Brain Tumors". DNA 2, nr 1 (3.01.2022): 1–21. http://dx.doi.org/10.3390/dna2010001.
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Zinc fingers consist of one of the most abundant motifs in transcription factors and DNA-binding proteins. Recent studies provide evidence on the pathological implication of zinc finger proteins in various neurodevelopmental disorders and malignancies but their role in pediatric brain tumors is largely unexplored. To this end, we investigated the differential expression of zinc finger-containing genes along with relevant biological processes and pathways among four main brain tumor categories (pilocytic astrocytomas, ependymomas, medulloblastomas and glioblastomas). By employing an extended bioinformatic toolset, we performed a preliminary in silico study in order to identify the expression of zinc finger-containing genes and associated functions in pediatric brain tumors. Our data analysis reveals the prominent role of C2H2-type zinc finger-containing genes in the molecular mechanisms underlying pediatric brain tumors followed by the Ring and PHD finger types. Significant dysregulation of ABLIM2 and UHFR1 genes was detected in all tumor types drawing attention to the dysregulation of cell polarization process and Ubiquitin-Proteasome System (UPS) in the pathogenesis of pediatric brain tumors. Moreover, significant gene clustering was observed in multiple locations with two highly visible clusters revealing a contrast in gene regulation between medulloblastomas and the other three brain tumor types, indicating a promising area of future research.
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Bragg, Jennifer N., Diane M. Lawrence i Andrew O. Jackson. "The N-Terminal 85 Amino Acids of the Barley Stripe Mosaic Virus γb Pathogenesis Protein Contain Three Zinc-Binding Motifs". Journal of Virology 78, nr 14 (15.07.2004): 7379–91. http://dx.doi.org/10.1128/jvi.78.14.7379-7391.2004.
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ABSTRACT Barley stripe mosaic virus RNAγ encodes γb, a cysteine-rich protein that affects pathogenesis. Nine of the eleven cysteines are concentrated in two clusters, designated C1 (residues 1 to 23) and C2 (residues 60 to 85), that are arranged in zinc finger-like motifs. A basic motif (BM) rich in lysine and arginine (residues 19 to 47) resides between the C1 and C2 clusters. We have demonstrated that γb binds zinc and that the C1, BM, and C2 motifs have independent zinc-binding activities. To evaluate the requirements for binding, mutations were introduced into each region. Cysteine residues at positions 7, 9, 10, 19, and 23 in the C1 motif were replaced with serines. In the BM, asparagines were substituted for lysines at positions 26 and 35, glutamine for arginine at position 25, and glycines for arginines at positions 33 and 36. The C2 mutations included cysteine replacements with serines at positions 60, 64, 71, and 81, and a histidine-to-leucine change at position 85. These mutations destroyed zinc-binding activity in each of the isolated motifs. γb derivatives containing mutations in only two of the motifs retained the ability to bind zinc, whereas a γb derivative containing mutations inactivating all three motifs destroyed the ability to bind zinc. Plants inoculated with transcripts containing combinations of the C1, BM, and C2 mutations elicited a “null” phenotype in barley characteristic of γb deletion mutants and also delayed the appearance and reduced the size of local lesions in Chenopodium amaranticolor. These results show that zinc binding of each of the motifs is critical for the biological activity of γb.
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Popov, Sergei, Elena Popova, Michio Inoue i Heinrich G. Göttlinger. "Human Immunodeficiency Virus Type 1 Gag Engages the Bro1 Domain of ALIX/AIP1 through the Nucleocapsid". Journal of Virology 82, nr 3 (21.11.2007): 1389–98. http://dx.doi.org/10.1128/jvi.01912-07.
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ABSTRACT Human immunodeficiency virus type 1 (HIV-1) and other retroviruses harbor short peptide motifs in Gag that promote the release of infectious virions. These motifs, known as late assembly (L) domains, recruit a cellular budding machinery that is required for the formation of multivesicular bodies (MVBs). The primary L domain of HIV-1 maps to a PTAP motif in the p6 region of Gag and engages the MVB pathway by binding to Tsg101. Additionally, HIV-1 p6 harbors an auxiliary L domain that binds to the V domain of ALIX, another component of the MVB pathway. We now show that ALIX also binds to the nucleocapsid (NC) domain of HIV-1 Gag and that ALIX and its isolated Bro1 domain can be specifically packaged into viral particles via NC. The interaction with ALIX depended on the zinc fingers of NC, which mediate the specific packaging of genomic viral RNA, but was not disrupted by nuclease treatment. We also observed that HIV-1 zinc finger mutants were defective for particle production and exhibited a similar defect in Gag processing as a PTAP deletion mutant. The effects of the zinc finger and PTAP mutations were not additive, suggesting a functional relationship between NC and p6. However, in contrast to the PTAP deletion mutant, the double mutants could not be rescued by overexpressing ALIX, further supporting the notion that NC plays a role in virus release.
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Smith, Alexander E. F., Farzin Farzaneh i Kevin G. Ford. "Single zinc-finger extension: enhancing transcriptional activity and specificity of three-zinc-finger proteins". Biological Chemistry 386, nr 2 (1.02.2005): 95–99. http://dx.doi.org/10.1515/bc.2005.012.
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AbstractIn order to demonstrate that an existing zinc-finger protein can be simply modified to enhance DNA binding and sequence discrimination in both episomal and chromatin contexts using existing zinc-finger DNA recognition code data, and without recourse to phage display and selection strategies, we have examined the consequences of a single zinc-finger extension to a synthetic three-zinc-finger VP16 fusion protein, on transcriptional activation from model target promoters harbouring the zinc-finger binding sequences. We report a nearly 10-fold enhanced transcriptional activation by the four-zinc-finger VP16 fusion protein relative to the progenitor three-finger VP16 protein in transient assays and a greater than five-fold enhancement in stable reporter-gene expression assays. A marked decrease in transcriptional activation was evident for the four-zinc-finger derivative from mutated regulatory regions compared to the progenitor protein, as a result of recognition site-size extension. This discriminatory effect was shown to be protein concentration-dependent. These observations suggest that four-zinc-finger proteins are stable functional motifs that can be a significant improvement over the progenitor three-zinc-finger protein, both in terms of specificity and the ability to target transcriptional function to promoters, and that single zinc-finger extension can therefore have a significant impact on DNA zinc-finger protein interactions. This is a simple route for modifying or enhancing the binding properties of existing synthetic zinc-finger-based transcription factors and may be particularly suited for the modification of endogenous zinc-finger transcription factors for promoter biasing applications.
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Huang, Shih-Ming, Sheng-Ping Huang, Sung-Ling Wang i Pei-Yao Liu. "Importin α1 is involved in the nuclear localization of Zac1 and the induction of p21WAF1/CIP1 by Zac1". Biochemical Journal 402, nr 2 (12.02.2007): 359–66. http://dx.doi.org/10.1042/bj20061295.
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Zac1, a novel seven-zinc-finger transcription factor, preferentially binds GC-rich DNA elements and has intrinsic transactivation activity. To date, the NLS (nuclear localization signal) of Zac1 has not been empirically determined. We generated a series of EGFP (enhanced green fluorescence protein)-tagged deletion mutants of Zac1 and examined their subcellular localization, from which we defined two NLSs within the DNA-binding (or zinc-finger) domain. Fusion proteins consisting of the two EGFP-tagged zinc-finger clusters (zinc finger motifs 1–3 and 4–7) were located exclusively in the nucleus, demonstrating that each of the zinc-finger clusters is sufficient for nuclear localization. Physical interactions between these two zinc-finger clusters and importin α1 were demonstrated using an in vitro glutathione S-transferase pull-down assay. Finally, our results indicate that the association of Zac1 with importin α1 is also involved in regulating the transactivation activity of Zac1 on the p21WAF1/CIP1 gene and protein expression.
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MORISAKI, Tatsuya, Miki IMANISHI, Shiroh FUTAKI i Yukio SUGIURA. "Artificial Transcription Factors Based on Multi-zinc Finger Motifs". YAKUGAKU ZASSHI 130, nr 1 (1.01.2010): 45–48. http://dx.doi.org/10.1248/yakushi.130.45.
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Guo, Jianhui, Tiyun Wu, Jada Anderson, Bradley F. Kane, Donald G. Johnson, Robert J. Gorelick, Louis E. Henderson i Judith G. Levin. "Zinc Finger Structures in the Human Immunodeficiency Virus Type 1 Nucleocapsid Protein Facilitate Efficient Minus- and Plus-Strand Transfer". Journal of Virology 74, nr 19 (1.10.2000): 8980–88. http://dx.doi.org/10.1128/jvi.74.19.8980-8988.2000.
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ABSTRACT The nucleocapsid protein (NC) of human immunodeficiency virus type 1 (HIV-1) has two zinc fingers, each containing the invariant metal ion binding residues CCHC. Recent reports indicate that mutations in the CCHC motifs are deleterious for reverse transcription in vivo. To identify reverse transcriptase (RT) reactions affected by such changes, we have probed zinc finger functions in NC-dependent RT-catalyzed HIV-1 minus- and plus-strand transfer model systems. Our approach was to examine the activities of wild-type NC and a mutant in which all six cysteine residues were replaced by serine (SSHS NC); this mutation severely disrupts zinc coordination. We find that the zinc fingers contribute to the role of NC in complete tRNA primer removal from minus-strand DNA during plus-strand transfer. Annealing of the primer binding site sequences in plus-strand strong-stop DNA [(+) SSDNA] to its complement in minus-strand acceptor DNA is not dependent on NC zinc fingers. In contrast, the rate of annealing of the complementary R regions in (−) SSDNA and 3′ viral RNA during minus-strand transfer is approximately eightfold lower when SSHS NC is used in place of wild-type NC. Moreover, unlike wild-type NC, SSHS NC has only a small stimulatory effect on minus-strand transfer and is essentially unable to block TAR-induced self-priming from (−) SSDNA. Our results strongly suggest that NC zinc finger structures are needed to unfold highly structured RNA and DNA strand transfer intermediates. Thus, it appears that in these cases, zinc finger interactions are important components of NC nucleic acid chaperone activity.
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Longworth, Michelle S., i Laimonis A. Laimins. "The Binding of Histone Deacetylases and the Integrity of Zinc Finger-Like Motifs of the E7 Protein Are Essential for the Life Cycle of Human Papillomavirus Type 31". Journal of Virology 78, nr 7 (1.04.2004): 3533–41. http://dx.doi.org/10.1128/jvi.78.7.3533-3541.2004.
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ABSTRACT The E7 oncoprotein of high-risk human papillomaviruses (HPVs) binds to and alters the action of cell cycle regulatory proteins such as members of the retinoblastoma (Rb) family of proteins as well as the histone deacetylases (HDACs). To examine the significance of the binding of E7 to HDACs in the viral life cycle, a mutational analysis of the E7 open reading frame was performed in the context of the complete HPV type 31 (HPV-31) genome. Human foreskin keratinocytes were transfected with wild-type HPV-31 genomes or HPV-31 genomes containing mutations in HDAC binding sequences as well as in the C-terminal zinc finger-like domain, and stable cell lines were isolated. All mutant genomes, except those with E7 mutations in the HDAC binding site, were found to be stably maintained extrachromosomally at an early passage following transfection. Upon further passage in culture, genomes containing mutations to the Rb binding domain as well as the zinc finger-like region quickly lost the ability to maintain episomal genomes. Genomes containing mutations abolishing E7 binding to HDACs or to Rb or mutations to the zinc finger-like motifs failed to extend the life span of transfected keratinocytes and caused cells to arrest at the same time as the untransfected keratinocytes. When induced to differentiate by suspension in methylcellulose, cells maintaining genomes with mutations in the Rb binding domain or the zinc finger-like motifs were impaired in their abilities to activate late viral functions. This study demonstrates that the interaction of E7 with HDACs and the integrity of the zinc finger-like motifs are essential for extending the life span of keratinocytes and for stable maintenance of viral genomes.
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Perkins, A. S., R. Fishel, N. A. Jenkins i N. G. Copeland. "Evi-1, a murine zinc finger proto-oncogene, encodes a sequence-specific DNA-binding protein". Molecular and Cellular Biology 11, nr 5 (maj 1991): 2665–74. http://dx.doi.org/10.1128/mcb.11.5.2665-2674.1991.
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Evi-1 was originally identified as a common site of viral integration in murine myeloid tumors. Evi-1 encodes a 120-kDa polypeptide containing 10 zinc finger motifs located in two domains 380 amino acids apart and an acidic domain located carboxy terminal to the second set of zinc fingers. These features suggest that Evi-1 is a site-specific DNA-binding protein involved in the regulation of RNA transcription. We have purified Evi-1 protein from E. coli and have employed a gel shift-polymerase chain reaction method using random oligonucleotides to identify a high-affinity binding site for Evi-1. The consensus sequence for this binding site is TGACAAGATAA. Evi-1 protein specifically protects this motif from DNase I digestion. By searching the nucleotide sequence data bases, we have found this binding site both in sequences 5' to genes in putative or known regulatory regions and within intron sequences.
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Perkins, A. S., R. Fishel, N. A. Jenkins i N. G. Copeland. "Evi-1, a murine zinc finger proto-oncogene, encodes a sequence-specific DNA-binding protein." Molecular and Cellular Biology 11, nr 5 (maj 1991): 2665–74. http://dx.doi.org/10.1128/mcb.11.5.2665.
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Evi-1 was originally identified as a common site of viral integration in murine myeloid tumors. Evi-1 encodes a 120-kDa polypeptide containing 10 zinc finger motifs located in two domains 380 amino acids apart and an acidic domain located carboxy terminal to the second set of zinc fingers. These features suggest that Evi-1 is a site-specific DNA-binding protein involved in the regulation of RNA transcription. We have purified Evi-1 protein from E. coli and have employed a gel shift-polymerase chain reaction method using random oligonucleotides to identify a high-affinity binding site for Evi-1. The consensus sequence for this binding site is TGACAAGATAA. Evi-1 protein specifically protects this motif from DNase I digestion. By searching the nucleotide sequence data bases, we have found this binding site both in sequences 5' to genes in putative or known regulatory regions and within intron sequences.
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Arranz, V., F. Harper, Y. Florentin, E. Puvion, M. Kress i M. Ernoult-Lange. "Human and mouse MOK2 proteins are associated with nuclear ribonucleoprotein components and bind specifically to RNA and DNA through their zinc finger domains." Molecular and Cellular Biology 17, nr 4 (kwiecień 1997): 2116–26. http://dx.doi.org/10.1128/mcb.17.4.2116.
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The human and murine MOK2 ortholog genes that are preferentially expressed in brain and testis tissues encode two different Krüppel-like zinc finger proteins. In this paper, we show that the MOK2 proteins are mainly associated with nuclear ribonucleoprotein components, including the nucleoli and extranucleolar structures, and exhibit specific RNA homopolymer binding activities. Moreover, we have identified an identical 18-bp specific DNA binding sequence for both MOK2 proteins using a pool of random sequence oligonucleotides. The DNA binding domain is localized in the seven adjacent zinc finger motifs, which show 94% identity between human and murine proteins. Taken together, these results establish that the MOK2 proteins are able to recognize both DNA and RNA through their zinc fingers. This dual affinity and the subnuclear localization suggest that MOK2 may play roles in transcription, as well as in the posttranscriptional regulation processes of specific genes.
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Nakaseko, Yukinobu, David Neuhaus, Aaron Klug i Daniela Rhodes. "Adjacent zinc-finger motifs in multiple zinc-finger peptides from SWI5 form structurally independent, flexibly linked domains". Journal of Molecular Biology 228, nr 2 (listopad 1992): 619–36. http://dx.doi.org/10.1016/0022-2836(92)90845-b.
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Quinlan, Kate G. R., Marco Nardini, Alexis Verger, Pierangelo Francescato, Paul Yaswen, Daniela Corda, Martino Bolognesi i Merlin Crossley. "Specific Recognition of ZNF217 and Other Zinc Finger Proteins at a Surface Groove of C-Terminal Binding Proteins". Molecular and Cellular Biology 26, nr 21 (28.08.2006): 8159–72. http://dx.doi.org/10.1128/mcb.00680-06.
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ABSTRACT Numerous transcription factors recruit C-terminal binding protein (CtBP) corepressors. We show that the large zinc finger protein ZNF217 contacts CtBP. ZNF217 is encoded by an oncogene frequently amplified in tumors. ZNF217 contains a typical Pro-X-Asp-Leu-Ser (PXDLS) motif that binds in CtBP's PXDLS-binding cleft. However, ZNF217 also contains a second motif, Arg-Arg-Thr (RRT), that binds a separate surface on CtBP. The crystal structure of CtBP bound to an RRTGAPPAL peptide shows that it contacts a surface crevice distinct from the PXDLS binding cleft. Interestingly, both PXDLS and RRT motifs are also found in other zinc finger proteins, such as RIZ. Finally, we show that ZNF217 represses several promoters, including one from a known CtBP target gene, and mutations preventing ZNF217's contact with CtBP reduce repression. These results identify a new CtBP interaction motif and establish ZNF217 as a transcriptional repressor protein that functions, at least in part, by associating with CtBP.
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Yang, Chang, Rui Hao, Yong Fei Lan, Ye Jia Chen, Chao Wang, Na Bu, Qian Qian Wang i in. "Integrity of zinc finger motifs in PML protein is necessary for inducing its degradation by antimony". Metallomics 11, nr 8 (2019): 1419–29. http://dx.doi.org/10.1039/c9mt00102f.
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Heras, Sara R., M. Carmen Thomas, Francisco Macias, Manuel E. Patarroyo, Carlos Alonso i Manuel C. López. "Nucleic-acid-binding properties of the C2-L1Tc nucleic acid chaperone encoded by L1Tc retrotransposon". Biochemical Journal 424, nr 3 (10.12.2009): 479–90. http://dx.doi.org/10.1042/bj20090766.
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It has been reported previously that the C2-L1Tc protein located in the Trypanosoma cruzi LINE (long interspersed nuclear element) L1Tc 3′ terminal end has NAC (nucleic acid chaperone) activity, an essential activity for retrotransposition of LINE-1. The C2-L1Tc protein contains two cysteine motifs of a C2H2 type, similar to those present in TFIIIA (transcription factor IIIA). The cysteine motifs are flanked by positively charged amino acid regions. The results of the present study show that the C2-L1Tc recombinant protein has at least a 16-fold higher affinity for single-stranded than for double-stranded nucleic acids, and that it exhibits a clear preference for RNA binding over DNA. The C2-L1Tc binding profile (to RNA and DNA) corresponds to a non-co-operative-binding model. The zinc fingers present in C2-L1Tc have a different binding affinity to nucleic acid molecules and also different NAC activity. The RRR and RRRKEK [NLS (nuclear localization sequence)] sequences, as well as the C2H2 zinc finger located immediately downstream of these basic stretches are the main motifs responsible for the strong affinity of C2-L1Tc to RNA. These domains also contribute to bind single- and double-stranded DNA and have a duplex-stabilizing effect. However, the peptide containing the zinc finger situated towards the C-terminal end of C2-L1Tc protein has a slight destabilization effect on a mismatched DNA duplex and shows a strong preference for single-stranded nucleic acids, such as C2-L1Tc. These results provide further insight into the essential properties of the C2-L1Tc protein as a NAC.
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Okabe, Shinichiro, Tetsuya Fukuda, Kazuki Ishibashi, Satoko Kojima, Seiji Okada, Masahiko Hatano, Masaaki Ebara, Hiromitsu Saisho i Takeshi Tokuhisa. "BAZF, a Novel Bcl6 Homolog, Functions as a Transcriptional Repressor". Molecular and Cellular Biology 18, nr 7 (1.07.1998): 4235–44. http://dx.doi.org/10.1128/mcb.18.7.4235.
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ABSTRACT The BCL6 gene, which has been identified from the chromosomal translocation breakpoint in B-cell lymphomas, functions as a sequence-specific transcriptional repressor. We cloned a novelBcl6-homologous gene, BAZF (encoding Bcl6-associated zinc finger protein). The predicted amino acid sequence of BAZF indicated that the BTB/POZ domain and the five repeats of the Krüppel-like zinc finger motif are located in the NH2-terminal region and the COOH-terminal region, respectively. BAZF associated with Bcl6 at the BTB/POZ domain and localized in the nucleus. Since zinc finger motifs of BAZF were 94% identical to those of Bcl6 at the amino acid level, BAZF bound specifically to the DNA-binding sequence of Bcl6 and functioned as a transcriptional repressor. The repressor activity was associated with both the BTB/POZ domain and the middle portion of BAZF. The 17-amino-acid sequence in the middle portion was completely conserved between BAZF and Bcl6, and the conserved region was critical for the repressor activity. Expression of BAZF mRNA, like that of Bcl6 mRNA, was induced in activated lymphocytes as an immediate-early gene. Therefore, the biochemical character of BAZF is similar to that of Bcl6 although the tissue expression pattern of BAZF differs from that ofBcl6. This is apparently the first report of a gene family whose members encode zinc finger proteins with the BTB/POZ domain.
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MacPherson, Sarah, Marc Larochelle i Bernard Turcotte. "A Fungal Family of Transcriptional Regulators: the Zinc Cluster Proteins". Microbiology and Molecular Biology Reviews 70, nr 3 (wrzesień 2006): 583–604. http://dx.doi.org/10.1128/mmbr.00015-06.
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SUMMARY The trace element zinc is required for proper functioning of a large number of proteins, including various enzymes. However, most zinc-containing proteins are transcription factors capable of binding DNA and are named zinc finger proteins. They form one of the largest families of transcriptional regulators and are categorized into various classes according to zinc-binding motifs. This review focuses on one class of zinc finger proteins called zinc cluster (or binuclear) proteins. Members of this family are exclusively fungal and possess the well-conserved motif CysX2CysX6CysX5-12CysX2CysX6-8Cys. The cysteine residues bind to two zinc atoms, which coordinate folding of the domain involved in DNA recognition. The first- and best-studied zinc cluster protein is Gal4p, a transcriptional activator of genes involved in the catabolism of galactose in the budding yeast Saccharomyces cerevisiae. Since the discovery of Gal4p, many other zinc cluster proteins have been characterized; they function in a wide range of processes, including primary and secondary metabolism and meiosis. Other roles include regulation of genes involved in the stress response as well as pleiotropic drug resistance, as demonstrated in budding yeast and in human fungal pathogens. With the number of characterized zinc cluster proteins growing rapidly, it is becoming more and more apparent that they are important regulators of fungal physiology.
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Kim, Min-Kyu, Lei Zhao, Soyoung Jeong, Jing Zhang, Jong-Hyun Jung, Ho Seong Seo, Jong-il Choi i Sangyong Lim. "Structural and Biochemical Characterization of Thioredoxin-2 from Deinococcus radiodurans". Antioxidants 10, nr 11 (20.11.2021): 1843. http://dx.doi.org/10.3390/antiox10111843.
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Thioredoxin (Trx), a ubiquitous protein showing disulfide reductase activity, plays critical roles in cellular redox control and oxidative stress response. Trx is a member of the Trx system, comprising Trx, Trx reductase (TrxR), and a cognate reductant (generally reduced nicotinamide adenine dinucleotide phosphate, NADPH). Bacterial Trx1 contains only the Trx-fold domain, in which the active site CXXC motif that is critical for the disulfide reduction activity is located. Bacterial Trx2 contains an N-terminal extension, which forms a zinc-finger domain, including two additional CXXC motifs. The multi-stress resistant bacterium Deinococcus radiodurans encodes both Trx1 (DrTrx1) and Trx2 (DrTrx2), which act as members of the enzymatic antioxidant systems. In this study, we constructed Δdrtrx1 and Δdrtrx2 mutants and examined their survival rates under H2O2 treated conditions. Both drtrx1 and drtrx2 genes were induced following H2O2 treatment, and the Δdrtrx1 and Δdrtrx2 mutants showed a decrease in resistance toward H2O2, compared to the wild-type. Native DrTrx1 and DrTrx2 clearly displayed insulin and DTNB reduction activity, whereas mutant DrTrx1 and DrTrx2, which harbors the substitution of conserved cysteine to serine in its active site CXXC motif, showed almost no reduction activity. Mutations in the zinc binding cysteines did not fully eliminate the reduction activities of DrTrx2. Furthermore, we solved the crystal structure of full-length DrTrx2 at 1.96 Å resolution. The N-terminal zinc-finger domain of Trx2 is thought to be involved in Trx-target interaction and, from our DrTrx2 structure, the orientation of the zinc-finger domain of DrTrx2 and its interdomain interaction, between the Trx-fold domain and the zinc-finger domain, is clearly distinguished from those of the other Trx2 structures.
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Lee, Sang-Jin, Jae-Rin Lee, Hwa-Sun Hah, Young-Hoon Kim, Jin-Hyun Ahn, Chang-Dae Bae, Jun-Mo Yang i Myong-Joon Hahn. "PIAS1 interacts with the KRAB zinc finger protein, ZNF133, via zinc finger motifs and regulates its transcriptional activity". Experimental & Molecular Medicine 39, nr 4 (sierpień 2007): 450–57. http://dx.doi.org/10.1038/emm.2007.49.
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Chen, Canbin, Fangfang Xie, Kamran Shah, Qingzhu Hua, Jiayi Chen, Zhike Zhang, Jietang Zhao, Guibing Hu i Yonghua Qin. "Genome-Wide Identification of WRKY Gene Family in Pitaya Reveals the Involvement of HmoWRKY42 in Betalain Biosynthesis". International Journal of Molecular Sciences 23, nr 18 (12.09.2022): 10568. http://dx.doi.org/10.3390/ijms231810568.
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The WRKY gene family is a plant-specific transcription factor (TF) that regulates many physiological processes and (a) biotic stress responses. Despite this, little is known about the molecular properties and roles of WRKY TFs in pitaya betalain biosynthesis. Here we report the identification of 70 WRKY in Hylocereus undatus, their gene structure, locations on each chromosome, systematic phylogenetic analysis, conserved motif analysis, and synteny of HuWRKY genes. HmoWRKY42 is a Group IIb WRKY protein and contains a coiled-coil motif, a WRKY domain and a C2H2 zinc-finger motif (CX5CX23HXH). Results from yeast one-hybrid and transient dual-luciferase assays showed that HmoWRKY42 was a transcriptional repressor and could repress HmocDOPA5GT1 expression by binding to its promoter. Yeast two-hybrid assays showed that HmoWRKY42 could interact with itself to form homodimers. Knocking out the coiled-coil motif of HmoWRKY42 prevented its self-interaction and prevented it from binding to the HmocDOPA5GT1 promoter. Knocking out the WRKY domain and C2H2 zinc-finger motif sequence of HmoWRKY42 also prevented it from binding to the HmocDOPA5GT1 promoter. The coiled-coil motif, the WRKY domain and the C2H2 zinc finger motif are key motifs for the binding of HmoWRKY42 to the HmocDOPA5GT1 promoter. HmoWRKY42 is localized in the nucleus and possesses trans-activation ability responsible for pitaya betalain biosynthesis by repressing the transcription of HmocDOPA5GT1. As far as we know, no reports are available on the role of HmoWRKY42 in pitaya betalain biosynthesis. The results provide an important foundation for future analyses of the regulation and functions of the HuWRKY gene family.
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Hudson, Nicholas O., i Bethany A. Buck-Koehntop. "Zinc Finger Readers of Methylated DNA". Molecules 23, nr 10 (7.10.2018): 2555. http://dx.doi.org/10.3390/molecules23102555.
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DNA methylation is a prevalent epigenetic modification involved in regulating a number of essential cellular processes, including genomic accessibility and transcriptional outcomes. As such, aberrant alterations in global DNA methylation patterns have been associated with a growing number of disease conditions. Nevertheless, the full mechanisms by which DNA methylation information is interpreted and translated into genomic responses is not yet fully understood. Methyl-CpG binding proteins (MBPs) function as important mediators of this essential process by selectively reading DNA methylation signals and translating this information into down-stream cellular outcomes. The Cys2His2 zinc finger scaffold is one of the most abundant DNA binding motifs found within human transcription factors, yet only a few zinc finger containing proteins capable of conferring selectivity for mCpG over CpG sites have been characterized. This review summarizes our current structural understanding for the mechanisms by which the zinc finger MBPs evaluated to date read this essential epigenetic mark. Further, some of the biological implications for mCpG readout elicited by this family of MBPs are discussed.
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Kato, N., K. Shimotohno, D. VanLeeuwen i M. Cohen. "Human proviral mRNAs down regulated in choriocarcinoma encode a zinc finger protein related to Krüppel". Molecular and Cellular Biology 10, nr 8 (sierpień 1990): 4401–5. http://dx.doi.org/10.1128/mcb.10.8.4401-4405.1990.
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RNA transcripts of the HERV-R (ERV3) human provirus that are abundant in placenta but absent in choriocarcinoma contain nonproviral genomic sequences at their 3' ends. We report here the isolation of cDNA clones of these genomic sequences. The transcripts encode a Krüppel-related zinc finger protein consisting of a unique leader region and more than 12 28-amino-acid finger motifs.
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Kato, N., K. Shimotohno, D. VanLeeuwen i M. Cohen. "Human proviral mRNAs down regulated in choriocarcinoma encode a zinc finger protein related to Krüppel." Molecular and Cellular Biology 10, nr 8 (sierpień 1990): 4401–5. http://dx.doi.org/10.1128/mcb.10.8.4401.
Pełny tekst źródłaStreszczenie:
RNA transcripts of the HERV-R (ERV3) human provirus that are abundant in placenta but absent in choriocarcinoma contain nonproviral genomic sequences at their 3' ends. We report here the isolation of cDNA clones of these genomic sequences. The transcripts encode a Krüppel-related zinc finger protein consisting of a unique leader region and more than 12 28-amino-acid finger motifs.
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Wang, S. S., D. R. Stanford, C. D. Silvers i A. K. Hopper. "STP1, a gene involved in pre-tRNA processing, encodes a nuclear protein containing zinc finger motifs". Molecular and Cellular Biology 12, nr 6 (czerwiec 1992): 2633–43. http://dx.doi.org/10.1128/mcb.12.6.2633-2643.1992.
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STP1 is an unessential yeast gene involved in the removal of intervening sequences from some, but not all, families of intervening sequence-containing pre-tRNAs. Previously, we proposed that STP1 might encode a product that generates pre-tRNA conformations efficiently recognized by tRNA-splicing endonuclease. To test the predictions of this model, we have undertaken a molecular analysis of the STP1 gene and its products. The STP1 locus is located on chromosome IV close to at least two other genes involved in RNA splicing: PRP3 and SPP41. The STP1 open reading frame (ORF) could encode a peptide of 64,827 Da; however, inspection of putative transcriptional and translational regulatory signals and mapping of the 5' ends of mRNA provide evidence that translation of the STP1 ORF usually initiates at a second AUG to generate a protein of 58,081 Da. The STP1 ORF contains three putative zinc fingers. The first of these closely resembles both the DNA transcription factor consensus and the Xenopus laevis p43 RNA-binding protein consensus. The third motif more closely resembles the fingers found in spliceosomal proteins. Employing antisera to the endogenous STP1 protein and to STP1-LacZ fusion proteins, we show that the STP1 protein is localized to nuclei. The presence of zinc finger motifs and the nuclear location of the STP1 protein support the model that this gene product is involved directly in pre-tRNA splicing.
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Wang, S. S., D. R. Stanford, C. D. Silvers i A. K. Hopper. "STP1, a gene involved in pre-tRNA processing, encodes a nuclear protein containing zinc finger motifs." Molecular and Cellular Biology 12, nr 6 (czerwiec 1992): 2633–43. http://dx.doi.org/10.1128/mcb.12.6.2633.
Pełny tekst źródłaStreszczenie:
STP1 is an unessential yeast gene involved in the removal of intervening sequences from some, but not all, families of intervening sequence-containing pre-tRNAs. Previously, we proposed that STP1 might encode a product that generates pre-tRNA conformations efficiently recognized by tRNA-splicing endonuclease. To test the predictions of this model, we have undertaken a molecular analysis of the STP1 gene and its products. The STP1 locus is located on chromosome IV close to at least two other genes involved in RNA splicing: PRP3 and SPP41. The STP1 open reading frame (ORF) could encode a peptide of 64,827 Da; however, inspection of putative transcriptional and translational regulatory signals and mapping of the 5' ends of mRNA provide evidence that translation of the STP1 ORF usually initiates at a second AUG to generate a protein of 58,081 Da. The STP1 ORF contains three putative zinc fingers. The first of these closely resembles both the DNA transcription factor consensus and the Xenopus laevis p43 RNA-binding protein consensus. The third motif more closely resembles the fingers found in spliceosomal proteins. Employing antisera to the endogenous STP1 protein and to STP1-LacZ fusion proteins, we show that the STP1 protein is localized to nuclei. The presence of zinc finger motifs and the nuclear location of the STP1 protein support the model that this gene product is involved directly in pre-tRNA splicing.
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Hasegawa, Atsushi, Hiroshi Kaneko, Daishi Ishihara, Masahiro Nakamura, Akira Watanabe, Masayuki Yamamoto, Cecelia D. Trainor i Ritsuko Shimizu. "GATA1 Binding Kinetics on Conformation-Specific Binding Sites Elicit Differential Transcriptional Regulation". Molecular and Cellular Biology 36, nr 16 (23.05.2016): 2151–67. http://dx.doi.org/10.1128/mcb.00017-16.
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GATA1 organizes erythroid and megakaryocytic differentiation by orchestrating the expression of multiple genes that show diversified expression profiles. Here, we demonstrate that GATA1 monovalently binds to a single GATA motif (Single-GATA) while a monomeric GATA1 and a homodimeric GATA1 bivalently bind to two GATA motifs in palindromic (Pal-GATA) and direct-repeat (Tandem-GATA) arrangements, respectively, and form higher stoichiometric complexes on respective elements. The amino-terminal zinc (N) finger of GATA1 critically contributes to high occupancy of GATA1 on Pal-GATA. GATA1 lacking the N finger-DNA association fails to trigger a rate of target gene expression comparable to that seen with the wild-type GATA1, especially when expressed at low level. This study revealed that Pal-GATA and Tandem-GATA generate transcriptional responses from GATA1 target genes distinct from the response of Single-GATA. Our results support the notion that the distinct alignments in binding motifs are part of a critical regulatory strategy that diversifies and modulates transcriptional regulation by GATA1.
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Diaz, Brenda, Christopher Mederos, Kemin Tan i Yuk-Ching Tse-Dinh. "Microbial Type IA Topoisomerase C-Terminal Domain Sequence Motifs, Distribution and Combination". International Journal of Molecular Sciences 23, nr 15 (5.08.2022): 8709. http://dx.doi.org/10.3390/ijms23158709.
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Type IA topoisomerases have highly conserved catalytic N-terminal domains for the cleaving and rejoining of a single DNA/RNA strand that have been extensively characterized. In contrast, the C-terminal region has been less covered. Two major types of small tandem C-terminal domains, Topo_C_ZnRpt (containing C4 zinc finger) and Topo_C_Rpt (without cysteines) were initially identified in Escherichia coli and Mycobacterium tuberculosis topoisomerase I, respectively. Their structures and interaction with DNA oligonucleotides have been revealed in structural studies. Here, we first present the diverse distribution and combinations of these two structural elements in various bacterial topoisomerase I (TopA). Previously, zinc fingers have not been seen in type IA topoisomerases from well-studied fungal species within the phylum Ascomycota. In our extended studies of C-terminal DNA-binding domains, the presence of zf-GRF and zf-CCHC types of zinc fingers in topoisomerase III (Top3) from fungi species in many phyla other than Ascomycota has drawn our attention. We secondly analyze the distribution and combination of these fungal zf-GRF- and zf-CCHC-containing domains. Their potential structures and DNA-binding mechanism are evaluated. The highly diverse arrangements and combinations of these DNA/RNA-binding domains in microbial type IA topoisomerase C-terminal regions have important implications for their interactions with nucleic acids and protein partners as part of their physiological functions.
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Trainor, C. D., J. G. Omichinski, T. L. Vandergon, A. M. Gronenborn, G. M. Clore i G. Felsenfeld. "A palindromic regulatory site within vertebrate GATA-1 promoters requires both zinc fingers of the GATA-1 DNA-binding domain for high-affinity interaction." Molecular and Cellular Biology 16, nr 5 (maj 1996): 2238–47. http://dx.doi.org/10.1128/mcb.16.5.2238.
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GATA-1, a transcription factor essential for the development of the erythroid lineage, contains two adjacent highly conserved zinc finger motifs. The carboxy-terminal finger is necessary and sufficient for specific binding to the consensus GATA recognition sequence: mutant proteins containing only the amino-terminal finger do not bind. Here we identify a DNA sequence (GATApal) for which the GATA-1 amino-terminal finger makes a critical contribution to the strength of binding. The site occurs in the GATA-1 gene promoters of chickens, mice, and humans but occurs very infrequently in other vertebrate genes known to be regulated by GATA proteins. GATApal is a palindromic site composed of one complete [(A/T)GATA(A/G)] and one partial (GAT) canonical motif. Deletion of the partial motif changes the site to a normal GATA site and also reduces by as much as eightfold the activity of the GATA-1 promoter in an erythroid precursor cell. We propose that GATApal is important for positive regulation of GATA-1 expression in erythroid cells.
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Rodriguez, Alyssa A., Jessica L. Wojtaszek, Briana H. Greer, Tuhin Haldar, Kent S. Gates, R. Scott Williams i Brandt F. Eichman. "An autoinhibitory role for the GRF zinc finger domain of DNA glycosylase NEIL3". Journal of Biological Chemistry 295, nr 46 (2.09.2020): 15566–75. http://dx.doi.org/10.1074/jbc.ra120.015541.
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The NEIL3 DNA glycosylase maintains genome integrity during replication by excising oxidized bases from single-stranded DNA (ssDNA) and unhooking interstrand cross-links (ICLs) at fork structures. In addition to its N-terminal catalytic glycosylase domain, NEIL3 contains two tandem C-terminal GRF-type zinc fingers that are absent in the other NEIL paralogs. ssDNA binding by the GRF–ZF motifs helps recruit NEIL3 to replication forks converged at an ICL, but the nature of DNA binding and the effect of the GRF–ZF domain on catalysis of base excision and ICL unhooking is unknown. Here, we show that the tandem GRF–ZFs of NEIL3 provide affinity and specificity for DNA that is greater than each individual motif alone. The crystal structure of the GRF domain shows that the tandem ZF motifs adopt a flexible head-to-tail configuration well-suited for binding to multiple ssDNA conformations. Functionally, we establish that the NEIL3 GRF domain inhibits glycosylase activity against monoadducts and ICLs. This autoinhibitory activity contrasts GRF–ZF domains of other DNA-processing enzymes, which typically use ssDNA binding to enhance catalytic activity, and suggests that the C-terminal region of NEIL3 is involved in both DNA damage recruitment and enzymatic regulation.
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Bellini, M., J. C. Lacroix i J. G. Gall. "A zinc-binding domain is required for targeting the maternal nuclear protein PwA33 to lampbrush chromosome loops." Journal of Cell Biology 131, nr 3 (1.11.1995): 563–70. http://dx.doi.org/10.1083/jcb.131.3.563.
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In oocytes of the newt Pleurodeles waltl, the maternal nuclear protein PwA33 occurs on the lampbrush chromosomes and in some nucleoplasmic particles of the germinal vesicle. PwA33 is a modular protein and we used site-directed mutagenesis to alter the sequences encoding two metal-binding regions, the C3HC4 (or RING finger) and B-box motifs. Several mutant clones were generated and their synthetic transcripts were injected into Pleurodeles oocytes for in vivo analysis. In the oocyte, all translation products localized in the germinal vesicle. Proteins encoded by RING finger mutant clones were distributed in a pattern identical to that of the wild type protein, but when His266 of the B-box was mutated, PwA33 failed to localize in the lampbrush chromosomes and the nucleoplasmic particles. Using an in vitro colorimetric assay, we demonstrated that PwA33 is a zinc-binding protein and that mutations in the RING finger and B-Box altered its metal-binding properties. The RING finger motif bound two Zn2+ ions and the binding ratios of several mutants were consistent with the tertiary structure recently proposed for this motif. The B-box coordinated one Zn2+ and this binding was inhibited by the His266 mutation. The failure of the His266 mutation to bind zinc and to localize properly within the germinal vesicle suggests that an intact B-box is required for normal functioning of the PwA33 protein in the oocyte.