Bibliographies thématiques / RecQ4 helicases

Littérature scientifique sur le sujet « RecQ4 helicases »

Auteur : Grafiati
Publié le 11 mars 2023

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Articles de revues sur le sujet "RecQ4 helicases"

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Thangavel, Saravanabhavan, Ramiro Mendoza-Maldonado, Erika Tissino, Julia M. Sidorova, Jinhu Yin, Weidong Wang, Raymond J. Monnat, Arturo Falaschi et Alessandro Vindigni. « Human RECQ1 and RECQ4 Helicases Play Distinct Roles in DNA Replication Initiation ». Molecular and Cellular Biology 30, no 6 (11 janvier 2010) : 1382–96. http://dx.doi.org/10.1128/mcb.01290-09.

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ABSTRACT Cellular and biochemical studies support a role for all five human RecQ helicases in DNA replication; however, their specific functions during this process are unclear. Here we investigate the in vivo association of the five human RecQ helicases with three well-characterized human replication origins. We show that only RECQ1 (also called RECQL or RECQL1) and RECQ4 (also called RECQL4) associate with replication origins in a cell cycle-regulated fashion in unperturbed cells. RECQ4 is recruited to origins at late G1, after ORC and MCM complex assembly, while RECQ1 and additional RECQ4 are loaded at origins at the onset of S phase, when licensed origins begin firing. Both proteins are lost from origins after DNA replication initiation, indicating either disassembly or tracking with the newly formed replisome. Nascent-origin DNA synthesis and the frequency of origin firing are reduced after RECQ1 depletion and, to a greater extent, after RECQ4 depletion. Depletion of RECQ1, though not that of RECQ4, also suppresses replication fork rates in otherwise unperturbed cells. These results indicate that RECQ1 and RECQ4 are integral components of the human replication complex and play distinct roles in DNA replication initiation and replication fork progression in vivo.
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BACHRATI, Csanád Z., et Ian D. HICKSON. « RecQ helicases : suppressors of tumorigenesis and premature aging ». Biochemical Journal 374, no 3 (15 septembre 2003) : 577–606. http://dx.doi.org/10.1042/bj20030491.

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The RecQ helicases represent a subfamily of DNA helicases that are highly conserved in evolution. Loss of RecQ helicase function leads to a breakdown in the maintenance of genome integrity, in particular hyper-recombination. Germ-line defects in three of the five known human RecQ helicases give rise to defined genetic disorders associated with cancer predisposition and/or premature aging. These are Bloom's syndrome, Werner's syndrome and Rothmund–Thomson syndrome, which are caused by defects in the genes BLM, WRN and RECQ4 respectively. Here we review the properties of RecQ helicases in organisms from bacteria to humans, with an emphasis on the biochemical functions of these enzymes and the range of protein partners that they operate with. We will discuss models in which RecQ helicases are required to protect against replication fork demise, either through prevention of fork breakdown or restoration of productive DNA synthesis.
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Rogers, Cody M., Elsbeth Sanders, Phoebe A. Nguyen, Whitney Smith-Kinnaman, Amber L. Mosley et Matthew L. Bochman. « The Genetic and Physical Interactomes of the Saccharomyces cerevisiae Hrq1 Helicase ». G3&#58 ; Genes|Genomes|Genetics 10, no 12 (28 octobre 2020) : 4347–57. http://dx.doi.org/10.1534/g3.120.401864.

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The human genome encodes five RecQ helicases (RECQL1, BLM, WRN, RECQL4, and RECQL5) that participate in various processes underpinning genomic stability. Of these enzymes, the disease-associated RECQL4 is comparatively understudied due to a variety of technical challenges. However, Saccharomyces cerevisiae encodes a functional homolog of RECQL4 called Hrq1, which is more amenable to experimentation and has recently been shown to be involved in DNA inter-strand crosslink (ICL) repair and telomere maintenance. To expand our understanding of Hrq1 and the RecQ4 subfamily of helicases in general, we took a multi-omics approach to define the Hrq1 interactome in yeast. Using synthetic genetic array analysis, we found that mutations of genes involved in processes such as DNA repair, chromosome segregation, and transcription synthetically interact with deletion of HRQ1 and the catalytically inactive hrq1-K318A allele. Pull-down of tagged Hrq1 and mass spectrometry identification of interacting partners similarly underscored links to these processes and others. Focusing on transcription, we found that hrq1 mutant cells are sensitive to caffeine and that mutation of HRQ1 alters the expression levels of hundreds of genes. In the case of hrq1-K318A, several of the most highly upregulated genes encode proteins of unknown function whose expression levels are also increased by DNA ICL damage. Together, our results suggest a heretofore unrecognized role for Hrq1 in transcription, as well as novel members of the Hrq1 ICL repair pathway. These data expand our understanding of RecQ4 subfamily helicase biology and help to explain why mutations in human RECQL4 cause diseases of genomic instability.
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Rogers, Cody M., Chun-Ying Lee, Samuel Parkins, Nicholas J. Buehler, Sabine Wenzel, Francisco Martínez-Márquez, Yuichiro Takagi, Sua Myong et Matthew L. Bochman. « The yeast Hrq1 helicase stimulates Pso2 translesion nuclease activity and thereby promotes DNA interstrand crosslink repair ». Journal of Biological Chemistry 295, no 27 (5 mai 2020) : 8945–57. http://dx.doi.org/10.1074/jbc.ra120.013626.

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DNA interstrand crosslink (ICL) repair requires a complex network of DNA damage response pathways. Removal of the ICL lesions is vital, as they are physical barriers to essential DNA processes that require the separation of duplex DNA, such as replication and transcription. The Fanconi anemia (FA) pathway is the principal mechanism for ICL repair in metazoans and is coupled to DNA replication. In Saccharomyces cerevisiae, a vestigial FA pathway is present, but ICLs are predominantly repaired by a pathway involving the Pso2 nuclease, which is hypothesized to use its exonuclease activity to digest through the lesion to provide access for translesion polymerases. However, Pso2 lacks translesion nuclease activity in vitro, and mechanistic details of this pathway are lacking, especially relative to FA. We recently identified the Hrq1 helicase, a homolog of the disease-linked enzyme RecQ-like helicase 4 (RECQL4), as a component of Pso2-mediated ICL repair. Here, using genetic, biochemical, and biophysical approaches, including single-molecule FRET (smFRET)– and gel-based nuclease assays, we show that Hrq1 stimulates the Pso2 nuclease through a mechanism that requires Hrq1 catalytic activity. Importantly, Hrq1 also stimulated Pso2 translesion nuclease activity through a site-specific ICL in vitro. We noted that stimulation of Pso2 nuclease activity is specific to eukaryotic RecQ4 subfamily helicases, and genetic and biochemical data suggest that Hrq1 likely interacts with Pso2 through their N-terminal domains. These results advance our understanding of FA-independent ICL repair and establish a role for the RecQ4 helicases in the repair of these detrimental DNA lesions.
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Séguéla-Arnaud, Mathilde, Wayne Crismani, Cécile Larchevêque, Julien Mazel, Nicole Froger, Sandrine Choinard, Afef Lemhemdi et al. « Multiple mechanisms limit meiotic crossovers : TOP3α and two BLM homologs antagonize crossovers in parallel to FANCM ». Proceedings of the National Academy of Sciences 112, no 15 (30 mars 2015) : 4713–18. http://dx.doi.org/10.1073/pnas.1423107112.

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Meiotic crossovers (COs) have two important roles, shuffling genetic information and ensuring proper chromosome segregation. Despite their importance and a large excess of precursors (i.e., DNA double-strand breaks, DSBs), the number of COs is tightly regulated, typically one to three per chromosome pair. The mechanisms ensuring that most DSBs are repaired as non-COs and the evolutionary forces imposing this constraint are poorly understood. Here we identified Topoisomerase3α (TOP3α) and the RECQ4 helicases—the Arabidopsis slow growth suppressor 1 (Sgs1)/Bloom syndrome protein (BLM) homologs—as major barriers to meiotic CO formation. First, the characterization of a specific TOP3α mutant allele revealed that, in addition to its role in DNA repair, this topoisomerase antagonizes CO formation. Further, we found that RECQ4A and RECQ4B constitute the strongest meiotic anti-CO activity identified to date, their concomitant depletion leading to a sixfold increase in CO frequency. In both top3α and recq4ab mutants, DSB number is unaffected, and extra COs arise from a normally minor pathway. Finally, both TOP3α and RECQ4A/B act independently of the previously identified anti-CO Fanconi anemia of complementation group M (FANCM) helicase. This finding shows that several parallel pathways actively limit CO formation and suggests that the RECQA/B and FANCM helicases prevent COs by processing different substrates. Despite a ninefold increase in CO frequency, chromosome segregation was unaffected. This finding supports the idea that CO number is restricted not because of mechanical constraints but likely because of the long-term costs of recombination. Furthermore, this work demonstrates how manipulating a few genes holds great promise for increasing recombination frequency in plant-breeding programs.
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Park, Youngji, Guangbin Luo et Stanton Gerson. « Repopulation Advantage of Blm−/− Cells in the Primary Recipients Can Be Reversed by Cisplatin Treatment. » Blood 104, no 11 (16 novembre 2004) : 2683. http://dx.doi.org/10.1182/blood.v104.11.2683.2683.

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Abstract Deficiencies in DNA repair-related genes such RecQ DNA helicases lead to human genetic disorders such as Bloom’s syndrome, Werner’s syndrome, and Rothmund-Thomson syndrome characterized by premature aging and cancer predisposition. We hypothesized that deficiency in RecQ DNA helicases may lead to drug hypersensitivity and/or stem cell failure after serial transplantation. Several genotoxic agents were tested on the bone marrow cells isolated from Bloom (Blm)−/− and RecQ4−/− knockout mice and compared to wildtype bone marrow cells. RecQ4−/− bone marrow showed mild sensitivity to γ-ray irradiation and very mild sensitivity to cisplatin. RecQ4−/− bone marrow did not show sensitivity to etoposide. However, Blm−/− bone marrow cells did not show hypersensitivity to either γ-ray irradiation or etoposide treatment, implying each RecQ DNA helicase may have different roles for DNA repair and/or proliferation in bone marrow cells. To assess how deficiency in RecQ DNA helicase affects hematopoietic stem cell function, serial transplantation capacity into lethally irradiated recipients was compared between bone marrow cells isolated from Blm−/− (Ly5.2) and wildtype (Ly5.1) mice. Competitive repopulating capacity was monitored by Ly5.1 / Ly5.2 marker analysis of peripheral blood every three weeks. There was no difference in early repopulating capacity between Blm−/− and wildtype in primary transplants at 3, 6 and 9 weeks post-transplantation (wt 46.6% ± 11.9% vs. Blm−/− 53.5% ± 11.9%, n=6, p=0.33 at 9 weeks post-transplantation). However, at 15 weeks post-transplantation, Blm−/− cells showed higher repopulation than wildtype bone marrow cells (wt 30.7 % ± 7.1 % vs. Blm−/− 69.3% ± 7.1%, n=3, p=0.003), implying Blm−/− cells might gradually accumulate a proliferative advantage over wildtype cells. To assess whether drug treatment may cause sensitivity in Blm−/− cells after transplantation, primary recipients of an equal mixture of Blm−/− and wildtype bone marrow were treated with 1 mg/kg cisplatin biweekly i.p. between 9 to 15 weeks post-transplantation and repopulation capacity was monitored. The repopulation advantage of Blm−/− cells in primary transplants was abolished by cisplatin treatment (wt 61.3 % ± 17.3 % vs. Blm−/− 38.7% ± 17.3%, n=3, p=0.19, in the cisplatin-treated cohort compared to wt 30.7 % ± 7.1 % vs. Blm−/− 69.3% ± 7.1%, n=3, p=0.003, in the control cohort). Thus, a proliferative advantage of progenitors is apparent in Blm−/− bone marrow, but lost after cisplatin-mediated DNA damage. This suggests that defective DNA repair of Blm−/− cell may promote deregulated proliferation of hematopoietic progenitors.
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Cheok, C. F., C. Z. Bachrati, K. L. Chan, C. Ralf, L. Wu et I. D. Hickson. « Roles of the Bloom's syndrome helicase in the maintenance of genome stability ». Biochemical Society Transactions 33, no 6 (26 octobre 2005) : 1456–59. http://dx.doi.org/10.1042/bst0331456.

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The RecQ family of DNA helicases is highly conserved in evolution from bacteria to humans. Of the five known human RecQ family members, three (BLM, WRN and RECQ4, which cause Bloom's syndrome, Werner's syndrome and Rothmund–Thomson syndrome respectively) are mutated in distinct clinical disorders associated with cancer predisposition and/or premature aging. BLM forms part of a multienzyme complex including topoisomerase IIIα, replication protein A and a newly identified factor called BLAP75. Together, these proteins play a role in the resolution of DNA structures that arise during the process of homologous recombination repair. In the absence of BLM, cells show genomic instability and a high incidence of sister-chromatid exchanges. In addition to a DNA structure-specific helicase activity, BLM also catalyses Holliday-junction branch migration and the annealing of complementary single-stranded DNA molecules.
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Garige, Mamatha, et Sudha Sharma. « Cellular Deficiency of Werner Syndrome Protein or RECQ1 Promotes Genotoxic Potential of Hydroquinone and Benzo[a]pyrene Exposure ». International Journal of Toxicology 33, no 5 (septembre 2014) : 373–81. http://dx.doi.org/10.1177/1091581814547422.

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The 5 known RecQ helicases in humans (RECQ1, BLM, WRN, RECQL4, and RECQ5) have demonstrated roles in diverse genome maintenance mechanisms but their functions in safeguarding the genome from environmental toxicants are poorly understood. Here, we have evaluated a potential role of WRN (mutated in Werner syndrome) and RECQ1 (the most abundant homolog of WRN) in hydroquinone (HQ)- and benzo[a]pyrene (BaP)-induced genotoxicity. Silencing of WRN or RECQ1 expression in HeLa cells increased their sensitivity to HQ and BaP but elicited distinct DNA damage response. The RECQ1-depleted cells exhibited increased replication protein A phosphorylation, Chk1 activation, and DNA double-strand breaks (DSBs) as compared to control or WRN-depleted cells following exposure to BaP treatment. The BaP-induced DSBs in RECQ1-depleted cells were dependent on DNA-dependent protein kinase activity. Notably, loss of WRN in RECQ1-depleted cells ameliorated BaP toxicity. Collectively, our results provide first indication of nonredundant participation of WRN and RECQ1 in protection from the potentially carcinogenic effects of BaP and HQ.
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Gupta, Sonia Vidushi, et Kristina Hildegard Schmidt. « Maintenance of Yeast Genome Integrity by RecQ Family DNA Helicases ». Genes 11, no 2 (18 février 2020) : 205. http://dx.doi.org/10.3390/genes11020205.

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With roles in DNA repair, recombination, replication and transcription, members of the RecQ DNA helicase family maintain genome integrity from bacteria to mammals. Mutations in human RecQ helicases BLM, WRN and RecQL4 cause incurable disorders characterized by genome instability, increased cancer predisposition and premature adult-onset aging. Yeast cells lacking the RecQ helicase Sgs1 share many of the cellular defects of human cells lacking BLM, including hypersensitivity to DNA damaging agents and replication stress, shortened lifespan, genome instability and mitotic hyper-recombination, making them invaluable model systems for elucidating eukaryotic RecQ helicase function. Yeast and human RecQ helicases have common DNA substrates and domain structures and share similar physical interaction partners. Here, we review the major cellular functions of the yeast RecQ helicases Sgs1 of Saccharomyces cerevisiae and Rqh1 of Schizosaccharomyces pombe and provide an outlook on some of the outstanding questions in the field.
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Pike, Ashley C. W., Shivasankari Gomathinayagam, Paolo Swuec, Matteo Berti, Ying Zhang, Christina Schnecke, Francesca Marino et al. « Human RECQ1 helicase-driven DNA unwinding, annealing, and branch migration : Insights from DNA complex structures ». Proceedings of the National Academy of Sciences 112, no 14 (23 mars 2015) : 4286–91. http://dx.doi.org/10.1073/pnas.1417594112.

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RecQ helicases are a widely conserved family of ATP-dependent motors with diverse roles in nearly every aspect of bacterial and eukaryotic genome maintenance. However, the physical mechanisms by which RecQ helicases recognize and process specific DNA replication and repair intermediates are largely unknown. Here, we solved crystal structures of the human RECQ1 helicase in complexes with tailed-duplex DNA and ssDNA. The structures map the interactions of the ssDNA tail and the branch point along the helicase and Zn-binding domains, which, together with reported structures of other helicases, define the catalytic stages of helicase action. We also identify a strand-separating pin, which (uniquely in RECQ1) is buttressed by the protein dimer interface. A duplex DNA-binding surface on the C-terminal domain is shown to play a role in DNA unwinding, strand annealing, and Holliday junction (HJ) branch migration. We have combined EM and analytical ultracentrifugation approaches to show that RECQ1 can form what appears to be a flat, homotetrameric complex and propose that RECQ1 tetramers are involved in HJ recognition. This tetrameric arrangement suggests a platform for coordinated activity at the advancing and receding duplexes of an HJ during branch migration.
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Thèses sur le sujet "RecQ4 helicases"

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THANGAVEL, SARAVANA BHAVAN. « Characterization of the Role of RecQ helicases in human DNA replication ». Doctoral thesis, Scuola Normale Superiore, 2010. http://hdl.handle.net/11384/85963.

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Cellular and biochemical studies support a role for all five human RecQ helicases in DNA replication, however their specific functions during this process are unclear. In my thesis, I investigated the in vivo association of the five human RecQ helicases with three well-characterized human replication origins. I showed that only RECQ1 and RECQ4 associate with replication origins in a cell cycle-regulated fashion in unperturbed cells, while other RecQ helicases interact with replication origins only under replication perturbed conditions. Under endogenous conditions, RECQ4 is recruited to origins at late G1 after ORC and MCM complex assembly, while RECQ1 and additional RECQ4 are loaded at origins at the onset of S phase when licensed origins begin firing. Both proteins are lost from origins after DNA replication initiation, indicating either disassembly or tracking with the newly formed replisome. Cell proliferation, DNA synthesis, nascent origin DNA synthesis and the frequency of origin firing are reduced after RECQ1 depletion, and to a greater extent after RECQ4 depletion. Depletion of RECQ1, though not RECQ4, also suppresses replication fork rates in otherwise unperturbed cells. Loading of PCNA during S phase is affected by RECQ1 depletion while the RECQ4 depleted cells show defect in RPA and PCNA loading during S phase of the cell cycle. These results indicate that RECQ1 and RECQ4 are integral components of the human replication complex, and play distinct roles in DNA replication initiation and replication fork progression in vivo.
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Mojumdar, Aditya. « Structural and Biochemical study of human RECQ4 ». Doctoral thesis, Università degli studi di Trieste, 2015. http://hdl.handle.net/10077/11141.

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2013/2014
RecQ helicases belong to a ubiquitous family of DNA unwinding enzymes that are essential to maintain genome stability by acting at the interface between DNA replication, recombination and repair. Humans have five different paralogues of RecQ helicases namely RecQ1, BLM, WRN, RecQ4 and RecQ5. This work focuses on the structural and biochemical study of human RecQ4. Germ-line mutations in the RECQ4 gene give rise to three distinct human genetic disorders (Rothmund-Thomson, RAPADILINO and Baller-Gerold syndromes). Despite the important roles of RecQ4 in various cellular processes, RecQ4 have never been fully characterized. In addition to the helicase domain, RecQ4 has a unique N-terminal part that is essential for viability and is constituted by a region homologous to the yeast Sld2 replication initiation factor, followed by a cysteine-rich region, predicted to fold as a Zn knuckle. A part of this work focuses on the structural and biochemical analysis of both the human and Xenopus RecQ4 cysteine-rich regions, and shows by NMR spectroscopy that the Xenopus fragment does indeed assumes the canonical Zn knuckle fold, whereas the human sequence remains unstructured, consistent with the mutation of one of the Zn ligands. Both the human and Xenopus Zn knuckles bind to a variety of nucleic acid substrates, with a preference for RNA. We also investigated the effect of an additional Sld2 homologous region upstream the Zn knuckle. In both the human and Xenopus system, the presence of this region strongly enhances binding to nucleic acids. These results reveal novel possible roles of RecQ4 in DNA replication and genome stability. Recently the catalytic core of RecQ4 has been predicted to include RecQ-like-C-terminal (RQC) domain at the C-terminus of the helicase domain, similar to other RecQ helicases. This domain is composed of a Zn-binding region and a winged helix (WH) domain. Another part of this thesis centers on the structural and biochemical characterization of the catalytic core of RecQ4 including the helicase and RQC domain. The results provide an insight in the Zn binding ligands present in the RQC domain that plays a role in DNA binding and unwinding activity of the protein. Also the presence of the characteristic aromatic residue at the tip of the WH β hairpin and its role in DNA binding and unwinding has been established. Finally, it provides a low resolution SAXS model of the catalytic core of RecQ4.
Elicasi RecQ appartengono a una famiglia ubiquitaria di DNA svolgimento enzimi che sono essenziali per mantenere la stabilità del genoma agendo all'interfaccia tra replicazione del DNA, ricombinazione e riparazione. Gli esseri umani hanno cinque diversi paralogues di RecQ elicasi cioè RecQ1, BLM, WRN, RecQ4 e RecQ5. Questo lavoro si concentra sullo studio strutturale e biochimica di RecQ4 umana. Mutazioni germinali nel gene RECQ4 danno luogo a tre malattie genetiche umane distinte (Rothmund-Thomson, RAPADILINO e sindromi Baller-Gerold). Nonostante i ruoli importanti di RecQ4 in diversi processi cellulari, RecQ4 non sono mai stati pienamente caratterizzato. In aggiunta al dominio elicasi, RecQ4 ha una parte unica N-terminale che è essenziale per la vitalità ed è costituito da una regione omologa al lievito Sld2 fattore di iniziazione replica, seguita da una regione ricca di cisteina, previsto per piegare come stinco Zn . Una parte di questo lavoro si concentra sull'analisi strutturale e biochimica sia della regioni ricche di cisteina Xenopus RecQ4 umana e, e spettacoli di spettroscopia NMR che il frammento Xenopus effettivamente assume la canonica Zn nocca volte, mentre la sequenza di resti umani non strutturato, coerente con la mutazione di uno dei ligandi Zn. Sia il nocche Xenopus Zn umana e si legano ad una varietà di substrati di acido nucleico, con una preferenza per l'RNA. Abbiamo anche studiato l'effetto di un ulteriore regione omologa Sld2 monte la nocca Zn. Sia il sistema Xenopus umano e, la presenza di questa regione migliora fortemente legame ad acidi nucleici. Questi risultati rivelano possibili ruoli nuovi di RecQ4 nella replicazione del DNA e la stabilità del genoma. Recentemente il nucleo catalitico di RecQ4 stato previsto per includere RecQ-like-C-terminale (RQC) dominio al C-terminale del dominio elicasi, simile ad altri elicasi RecQ. Questo dominio è costituito da una regione-Zn vincolanti e un'elica alato (WH) dominio. Un'altra parte di questa tesi incentrata sulla caratterizzazione strutturale e biochimica del nucleo catalitico della RecQ4 compreso il elicasi e il dominio RQC. I risultati forniscono una descrizione nel Zn ligandi presenti nel dominio RQC che svolge un ruolo nel legame al DNA e l'attività svolgimento della proteina legante. Inoltre è stata stabilita la presenza della caratteristica residuo aromatico sulla punta della forcella WH β e il suo ruolo nel legame al DNA e di svolgimento. Infine, esso fornisce una bassa risoluzione SAXS modello del nucleo catalitico di RecQ4.
XXVII Ciclo
1985
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Ren, Hua. « Aspects moléculaires des hélicases de la famille de RecQ ». Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2009. http://tel.archives-ouvertes.fr/tel-00448084.

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Dans les cellules, le déroulement de l'ADN double-brin est catalysé par une famille de protéines appelées hélicases. Ces protéines sont présentes chez tous les organismes des virus jusqu'à l'homme. Parmi ces hélicases, celles de la famille RecQ jouent un rôle essentiel dans le métabolisme de l'ADN en facilitant de nombreux processus cellulaires tels que la réplication, la réparation, la recombinaison, la transcription et la maintenance des télomères. Chez l'homme, il existe cinq membres de la famille RecQ identifiés comme RECQ1, BLM, WRN, RECQ4 et RECQ5. Les mutations dans BLM, WRN et RECQ4 sont associées à une prédisposition au cancer. En plus du domaine hélicase très conservé et contenant sept motifs bien distincts, la plupart des hélicases de la famille RecQ possèdent également un domaine RecQ C-terminal (RecQ-Ct) et un domaine hélicase RNase D (HRDC). Au cours de ce travail, nous nous concentrons sur les mécanismes intrafonctionnels de certains membres de la famille RecQ des hélicases. Tout d'abord, nous avons utilisé deux isoformes naturels de l'hélicase RECQ5 humain comme modèle pour étudier la modulation fonctionnelle du domaine hélicase avec le doigt de zinc. Ici, nous montrons que la variante tronquée RECQ5α de l'hélicase RECQ5β issue d'un épissage alternatif et composée uniquement du domaine hélicase ne possède ni l'activité ATPase ni l'activité de déroulement de l'ADN. A l'inverse, et ce de matière étonnante, cette protéine est dotée d'une forte activité de réhybridation du brin déroulé. Les mesures quantitatives indiquent que l'amélioration de l'affinité de la protéine pour l'ADN que lui confère le doigt de zinc est à l'origine de ses activités ATPase et hélicase. Le plus important est que l'on constate que le doigt de zinc est capable d'agir comme un facteur moléculaire à même de supprimer l'activité de re-synthèse du brin déroulé par le domaine hélicase et de déclencher l'activité de déroulement d'ADN à travers une modulation de la fixation à l'ADN. Ensuite, nous avons analysé les propriétés biochimiques de deux isoformes de l'hélicase RecQ de Bacillus subtilis : SubL et SubS. Parmi elles, SubS ne dispose pas du domaine HRDC. Nos études montrent que le domaine HRDC est crucial pour Bacillus subtilis RecQ hélicases dans la résolution des intermédiaires de réplication et / ou de réparation de l'ADN tels que les jonctions de Holliday et la jonction de kappa. Les activités ATPase, hélicase et l'activité de rehybridation du brin déroulé sont plus importantes en présence du domaine HRDC. Ces résultats nous permettent de spéculer sur l'importance du domaine HRDC des activités de la famille de RecQ hélicase. Nous avons découvert que dans la famille RecQ, le 12 domaine HRDC peut augmenter les activités ATPases et hélicases. De manière intéressante, le domaine HRDC de Bacillus subtilis joue un rôle critique dans la résolution des intermédiaires de réplication ou de réparation de l'ADN et des jonctions de Holliday. Nous suggérons l'hypothèse que le domaine HRDC des hélicases RecQ participe à exposer leurs fonctions dans le processus de réparation de l'ADN. Dans la dernière partie, nous nous sommes intéressés à l'existence et au rôle du doigt d'arginine dans la protéine BLM. Ces études ont été menées afin de démontrer son rôle dans l'hydrolyse d'ATP et dans la conversion en mouvement mécanique permettant à la protéine de progresser le long de l'ADN. Nos études démontrent que le résidu R982, situé à proximité du γ-phosphate de l'ATP, fonctionne comme un doigt d'arginine dans la protéine BLM. Nos conclusions indiquent en outre que ce doigt d'arginine interagit avec d'autres motifs conservés situés autour du γ-phosphate des nucléotides et qu'ils effectuent ensemble les fonctions enzymatiques au sein d'un réseau complexe.
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Kaiser, Sebastian [Verfasser], et Caroline [Gutachter] Kisker. « A RecQ helicase in disguise : Characterization of the unconventional Structure and Function of the human Genome Caretaker RecQ4 / Sebastian Kaiser ; Gutachter : Caroline Kisker ». Würzburg : Universität Würzburg, 2019. http://d-nb.info/1206879246/34.

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Guo, Rongbing. « Biochemical and structural characterization of BLM Helicase ». Paris 11, 2008. http://www.theses.fr/2008PA112168.

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Les Hélicases sont un sous-ensemble d'enzymes qui couplent l'énergie provenant de l'hydrolyse des nucléosides triphosphates (NTP) à la séparation des duplex d'acides nucléiques. Elles sont essentielles au métabolisme de l'ADN et de l'ARN (réparation, réplication, recombinaison et transcription). Les hélicases de la famille de RecQ sont essentielles et ont été très conservées lors de l'évolution. Chez l'humain, trois hélicases de type RecQ sont liées à de graves désordres autosomiques. Ils s'agissent du syndrome de Bloom (BS), du syndrome de Werner (WS) et du syndrome de Rothmund-Thomson (RTS) liés respectivement aux hélicases BLM, WRN et RecQ4. Cette thèse se focalise sur l'analyse des relations structurales et fonctionnelles de BLM. La formation d'érythèmes après exposition au soleil et le retard de croissance sont les principaux phénotypes du BS. La stérilité (ou l'infertilité), l'immunodéficience, et la prédisposition à un large spectre de cancers sont également les symptômes cliniques des patients BS. Les brèches et cassures de chromatides, les réarrangements structuraux de chromosomes, la configuration quadriradiale symétrique, tout comme les associations télomériques ou la quantité excessive de ponts d'anaphase représentent autant d'autres caractéristiques des patients BS. Mais, la haute fréquence d'échanges entre chromatides sœurs (SCE) détectable sous le microscope dans les lymphocytes du sang reste à l'heure actuelle le moyen le plus efficace de diagnostiquer la maladie. Cette thèse présente des résultats nouveaux, publiés dans trois articles scientifiques dan des journaux internationau x, sur les relations entre structure et fonctions de l'hélicase BLM qui peuvent être utiles dans l'identification de nouvelles stratégies thérapeutiques du syndrome de BLOOM
Bloom's syndrome (BS) is an autosomal recessive disorder, showing high frequency of sister chromatid exchange in lymphocyte of the patients. Since BS is preposition of a wide spectrum of cancer, the syndrome has been studied for understanding of the mechanism of cancer extensively. Ln the first part, we proved the existence of a zinc-binding domain in which a zinc ion is coordinated by four cysteines residues in RecQ-Ct domain of BLM. This conclusion is drawn from our biophysical and biochemical studies. We modeled the 3D structure of BLM protein based on that of E. Coli RecQ helicase, which revealed a similar structural domain in both helicases that coordinate zinc. The results from experiments with three mutants showed that their enzymatic activities were severely reduced or abrogated. The demetalization of zinc from BLM had no influence on the activities of BLM, but it would decrease the themostability of the protein. Ln conclusion, BLM contains a zinc binding domain with one zinc ion in each protein. The second part of our studies includes the work for understanding of causative molecular mechanism of missense mutations which happened in helicase domain of BLM found in BS patients. On the basis of the work inthe fist part, we further modeled the 3D structure of BLM in complex with A TPyS and DNA. With the model, we deduced the possible causative mechanism of mutants. We produced mutant proteins and purified them to homogeneity. The A TPase activity, A TP binding activity, DNA binding activity and helicase activity ofthe mutants were ail checked. Ln conclusion 1 showed that: 1. BLM642-129o possibly employ an "inchworm" model mechanism; 2. Amino acid residues from 861 to 901 are imprtant for DNA binding; 3. DNA binding ofBLM is mainly controlled by lobe2 and lobe3, lobel contribute to a transient ssDNA binding; 4. The annealing activity of RecQ helicase suggests a weak DNA binding activity
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Budhathoki, Jagat B. « Interactions of RecQ-Family Helicases with G-quadruplex Structures at the Single Molecule Level ». Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1467765011.

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Huber, Michael D. « Structure-function analysis and substrate specific inhibition of RecQ helicases / ». Thesis, Connect to this title online ; UW restricted, 2005. http://hdl.handle.net/1773/9253.

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Bajpai, Sailesh. « Analysis of human RECQ1 helicase function in cells ». Thesis, Open University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522223.

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Levitt, Nicola C. « Role of RecQ helicases in maintenance of genome integrity ». Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275469.

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Lucic, Bojana. « Understanding the structural basis of the human RECQ1 helicase function ». Thesis, Open University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536078.

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Livres sur le sujet "RecQ4 helicases"

1

Lombard, David B. Biochemistry and genetics of recq-helicases. Boston, MA : Kluwer Academic Publishers, 2001.

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Lombard, David B. Biochemistry and Genetics of RecQ-Helicases. Boston, MA : Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1405-3.

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Lombard, David B. Biochemistry and genetics of recq-helicases. Boston, MA : Kluwer Academic Publishers, 2001.

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Lombard, David B. Biochemistry and Genetics of RecQ-Helicases. Springer, 2012.

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Lombard, David B. Biochemistry and Genetics of Recq-Helicases. Springer London, Limited, 2012.

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Lombard, David B. Biochemistry and Genetics of RecQ-Helicases. Springer, 2000.

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Chapitres de livres sur le sujet "RecQ4 helicases"

1

Lombard, David B. « The RecQ-family helicases ». Dans Biochemistry and Genetics of RecQ-Helicases, 3–19. Boston, MA : Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1405-3_1.

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Lu, Linchao, Weidong Jin, Hao Liu et Lisa L. Wang. « RECQ DNA Helicases and Osteosarcoma ». Dans Advances in Experimental Medicine and Biology, 129–45. Cham : Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04843-7_7.

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Lu, Linchao, Weidong Jin et Lisa L. Wang. « RECQ DNA Helicases and Osteosarcoma ». Dans Current Advances in the Science of Osteosarcoma, 37–54. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-43085-6_3.

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Mohaghegh, Payam, et Ian D. Hickson. « Biochemical Roles of RecQ Helicases ». Dans Molecular Mechanisms of Werner’s Syndrome, 12–21. Boston, MA : Springer US, 2004. http://dx.doi.org/10.1007/978-1-4419-9032-7_2.

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Lombard, David B. « Targeting the WRN Locus in the mouse ». Dans Biochemistry and Genetics of RecQ-Helicases, 21–41. Boston, MA : Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1405-3_2.

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Lombard, David B. « Interaction of the BLM protein with Topo III alpha in Somatic and meiotic cells ». Dans Biochemistry and Genetics of RecQ-Helicases, 43–58. Boston, MA : Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1405-3_3.

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Lombard, David B. « Nijmegen Breakage Syndrome disease protein and Mre11 at PML Nuclear Bodies and meiotic telomeres ». Dans Biochemistry and Genetics of RecQ-Helicases, 59–76. Boston, MA : Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1405-3_4.

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Larsen, Nicolai Balle, et Ian D. Hickson. « RecQ Helicases : Conserved Guardians of Genomic Integrity ». Dans Advances in Experimental Medicine and Biology, 161–84. New York, NY : Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-5037-5_8.

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Kobbe, Daniela, Manfred Focke et Holger Puchta. « Purification and Characterization of RecQ Helicases of Plants ». Dans Methods in Molecular Biology, 195–209. Totowa, NJ : Humana Press, 2009. http://dx.doi.org/10.1007/978-1-60327-355-8_14.

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Seki, Masayuki, Shusuke Tada et Takemi Enomoto. « Function of RECQ family helicase in genome stability ». Dans Subcellular Biochemistry, 49–73. Dordrecht : Springer Netherlands, 2006. http://dx.doi.org/10.1007/978-1-4020-4896-8_5.

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Actes de conférences sur le sujet "RecQ4 helicases"

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Zuo, Mingxin, David Maxwell, Basvoju A. Bhanu Prasad, Zhenghong Peng, William Bornmann et Milind M. Javle. « Abstract 5361 : Development of targeted inhibitors against RecQ1 helicase ». Dans Proceedings : AACR Annual Meeting 2014 ; April 5-9, 2014 ; San Diego, CA. American Association for Cancer Research, 2014. http://dx.doi.org/10.1158/1538-7445.am2014-5361.

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Lao, Victoria Valinluck, Kelly T. Carter, Peter S. Rabinovitch, Piri Welcsh et William M. Grady. « Abstract 1157 : Increased expression of RecQ helicases in sporadic primary colorectal cancers ». Dans Proceedings : AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012 ; Chicago, IL. American Association for Cancer Research, 2012. http://dx.doi.org/10.1158/1538-7445.am2012-1157.

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Chun, Stephen G., Nelson S. Yee, Fang Qi, Richard Allsopp, Philip M. Davy, Keith S. Fong, Michele Carbone et Peter K. Bryant-Greenwood. « Abstract 3209 : The WRN RecQ helicase acts as a tumor suppressor in pancreatic adenocarcinoma ». Dans 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.am10-3209.

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Welcsh, Piri, Keffy Kehrli, Paul Lazarchuk et Julia Sidorova. « Abstract POSTER-BIOL-1346 : Growth-suppressive effect of WRN RECQ helicase inactivation in breast and ovarian cancer cells ». Dans Abstracts : 10th Biennial Ovarian Cancer Research Symposium ; September 8-9, 2014 ; Seattle, WA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1557-3265.ovcasymp14-poster-biol-1346.

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