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Watson AJ, Shaffer ML, Bouley RA, Petreaca RC. F-box DNA Helicase 1 (FBH1) Contributes to the Destabilization of DNA Damage Repair Machinery in Human Cancers. Cancers (Basel) 2023; 15:4439. [PMID: 37760409 PMCID: PMC10526855 DOI: 10.3390/cancers15184439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/01/2023] [Accepted: 09/03/2023] [Indexed: 09/29/2023] Open
Abstract
Homologous recombination (HR) is the major mechanism of rescue of stalled replication forks or repair of DNA double-strand breaks (DSBs) during S phase or mitosis. In human cells, HR is facilitated by the BRCA2-BRCA1-PALB2 module, which loads the RAD51 recombinase onto a resected single-stranded DNA end to initiate repair. Although the process is essential for error-free repair, unrestrained HR can cause chromosomal rearrangements and genome instability. F-box DNA Helicase 1 (FBH1) antagonizes the role of BRCA2-BRCA1-PALB2 to restrict hyper-recombination and prevent genome instability. Here, we analyzed reported FBH1 mutations in cancer cells using the Catalogue of Somatic Mutations in Cancers (COSMIC) to understand how they interact with the BRCA2-BRCA1-PALB2. Consistent with previous results from yeast, we find that FBH1 mutations co-occur with BRCA2 mutations and to some degree BRCA1 and PALB2. We also describe some co-occurring mutations with RAD52, the accessory RAD51 loader and facilitator of single-strand annealing, which is independent of RAD51. In silico modeling was used to investigate the role of key FBH1 mutations on protein function, and a Q650K mutation was found to destabilize the protein structure. Taken together, this work highlights how mutations in several DNA damage repair genes contribute to cellular transformation and immortalization.
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Affiliation(s)
- Alizhah J. Watson
- Biology Program, The Ohio State University, Marion, OH 433023, USA; (A.J.W.); (M.L.S.)
| | - Michaela L. Shaffer
- Biology Program, The Ohio State University, Marion, OH 433023, USA; (A.J.W.); (M.L.S.)
| | - Renee A. Bouley
- Department of Chemistry and Biochemistry, The Ohio State University, Marion, OH 43302, USA
| | - Ruben C. Petreaca
- Department of Molecular Genetics, The Ohio State University, Marion, OH 43302, USA
- Cancer Biology Program, James Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
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2
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Liu D, Sonalkar J, Prasanth SG. ORChestra coordinates the replication and repair music. Bioessays 2023; 45:e2200229. [PMID: 36811379 PMCID: PMC10023367 DOI: 10.1002/bies.202200229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/24/2023]
Abstract
Error-free genome duplication and accurate cell division are critical for cell survival. In all three domains of life, bacteria, archaea, and eukaryotes, initiator proteins bind replication origins in an ATP-dependent manner, play critical roles in replisome assembly, and coordinate cell-cycle regulation. We discuss how the eukaryotic initiator, Origin recognition complex (ORC), coordinates different events during the cell cycle. We propose that ORC is the maestro driving the orchestra to coordinately perform the musical pieces of replication, chromatin organization, and repair.
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Affiliation(s)
- Dazhen Liu
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801 USA
| | - Jay Sonalkar
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801 USA
| | - Supriya G. Prasanth
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801 USA
- Cancer center at Illinois, UIUC
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3
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Bloh K, Rivera-Torres N. A Consensus Model of Homology-Directed Repair Initiated by CRISPR/Cas Activity. Int J Mol Sci 2021; 22:3834. [PMID: 33917142 PMCID: PMC8067812 DOI: 10.3390/ijms22083834] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 03/31/2021] [Accepted: 04/05/2021] [Indexed: 12/26/2022] Open
Abstract
The mechanism of action of ssODN-directed gene editing has been a topic of discussion within the field of CRISPR gene editing since its inception. Multiple comparable, but distinct, pathways have been discovered for DNA repair both with and without a repair template oligonucleotide. We have previously described the ExACT pathway for oligo-driven DNA repair, which consisted of a two-step DNA synthesis-driven repair catalyzed by the simultaneous binding of the repair oligonucleotide (ssODN) upstream and downstream of the double-strand break. In order to better elucidate the mechanism of ExACT-based repair, we have challenged the assumptions of the pathway with those outlines in other similar non-ssODN-based DNA repair mechanisms. This more comprehensive iteration of the ExACT pathway better described the many different ways where DNA repair can occur in the presence of a repair oligonucleotide after CRISPR cleavage, as well as how these previously distinct pathways can overlap and lead to even more unique repair outcomes.
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Affiliation(s)
- Kevin Bloh
- Gene Editing Institute, Helen F. Graham Cancer Center & Research Institute, ChristianaCare, 4701 Ogletown-Stanton Road, Newark, DE 19710, USA;
- Department of Medical and Molecular Sciences, University of Delaware, Newark, DE 19710, USA
| | - Natalia Rivera-Torres
- Gene Editing Institute, Helen F. Graham Cancer Center & Research Institute, ChristianaCare, 4701 Ogletown-Stanton Road, Newark, DE 19710, USA;
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4
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Murdocca M, Spitalieri P, De Masi C, Udroiu I, Marinaccio J, Sanchez M, Talarico RV, Fiorillo C, D'Adamo M, Sbraccia P, D'Apice MR, Novelli G, Sgura A, Sangiuolo F. Functional analysis of POLD1 p.ser605del variant: the aging phenotype of MDPL syndrome is associated with an impaired DNA repair capacity. Aging (Albany NY) 2021; 13:4926-4945. [PMID: 33618333 PMCID: PMC7950258 DOI: 10.18632/aging.202680] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 01/04/2021] [Indexed: 01/31/2023]
Abstract
Mandibular hypoplasia, Deafness and Progeroid features with concomitant Lipodystrophy define a rare systemic disorder, named MDPL Syndrome, due to almost always a de novo variant in POLD1 gene, encoding the DNA polymerase δ. We report a MDPL female heterozygote for the recurrent p.Ser605del variant. In order to deepen the functional role of the in frame deletion affecting the polymerase catalytic site of the protein, cellular phenotype has been characterised. MDPL fibroblasts exhibit in vitro nuclear envelope anomalies, accumulation of prelamin A and presence of micronuclei. A decline of cell growth, cellular senescence and a blockage of proliferation in G0/G1 phase complete the aged cellular picture. The evaluation of the genomic instability reveals a delayed recovery from DNA induced-damage. Moreover, the rate of telomere shortening was greater in pathological cells, suggesting the telomere dysfunction as an emerging key feature in MDPL. Our results suggest an alteration in DNA replication/repair function of POLD1 as a primary pathogenetic cause of MDPL. The understanding of the mechanisms linking these cellular characteristics to the accelerated aging and to the wide spectrum of affected tissues and clinical symptoms in the MDPL patients may provide opportunities to develop therapeutic treatments for progeroid syndromes.
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Affiliation(s)
- Michela Murdocca
- Department of Biomedicine and Prevention, Tor Vergata University, Rome 00133, Italy
| | - Paola Spitalieri
- Department of Biomedicine and Prevention, Tor Vergata University, Rome 00133, Italy
| | - Claudia De Masi
- Department of Biomedicine and Prevention, Tor Vergata University, Rome 00133, Italy
| | - Ion Udroiu
- Department of Science, "Roma Tre" University, Rome 00154, Italy
| | | | - Massimo Sanchez
- Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome 00161, Italy
| | | | - Chiara Fiorillo
- Paediatric Neurology and Neuromuscular Disorders, University of Genoa and Istituto Gaslini, Genoa 16147, Italy
| | - Monica D'Adamo
- Department of Systems Medicine, Tor Vergata University, Rome 00133, Italy
| | - Paolo Sbraccia
- Department of Systems Medicine, Tor Vergata University, Rome 00133, Italy
| | | | - Giuseppe Novelli
- Department of Biomedicine and Prevention, Tor Vergata University, Rome 00133, Italy.,Laboratory of Medical Genetics, Tor Vergata Hospital, Rome 00133, Italy
| | - Antonella Sgura
- Department of Science, "Roma Tre" University, Rome 00154, Italy
| | - Federica Sangiuolo
- Department of Biomedicine and Prevention, Tor Vergata University, Rome 00133, Italy.,Laboratory of Medical Genetics, Tor Vergata Hospital, Rome 00133, Italy
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5
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Zabolotnaya E, Mela I, Henderson RM, Robinson NP. Turning the Mre11/Rad50 DNA repair complex on its head: lessons from SMC protein hinges, dynamic coiled-coil movements and DNA loop-extrusion? Biochem Soc Trans 2020; 48:2359-2376. [PMID: 33300987 PMCID: PMC7752040 DOI: 10.1042/bst20170168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 10/19/2020] [Accepted: 10/22/2020] [Indexed: 12/12/2022]
Abstract
The bacterial SbcC/SbcD DNA repair proteins were identified over a quarter of a century ago. Following the subsequent identification of the homologous Mre11/Rad50 complex in the eukaryotes and archaea, it has become clear that this conserved chromosomal processing machinery is central to DNA repair pathways and the maintenance of genomic stability in all forms of life. A number of experimental studies have explored this intriguing genome surveillance machinery, yielding significant insights and providing conceptual advances towards our understanding of how this complex operates to mediate DNA repair. However, the inherent complexity and dynamic nature of this chromosome-manipulating machinery continue to obfuscate experimental interrogations, and details regarding the precise mechanisms that underpin the critical repair events remain unanswered. This review will summarize our current understanding of the dramatic structural changes that occur in Mre11/Rad50 complex to mediate chromosomal tethering and accomplish the associated DNA processing events. In addition, undetermined mechanistic aspects of the DNA enzymatic pathways driven by this vital yet enigmatic chromosomal surveillance and repair apparatus will be discussed. In particular, novel and putative models of DNA damage recognition will be considered and comparisons will be made between the modes of action of the Rad50 protein and other related ATPases of the overarching SMC superfamily.
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Affiliation(s)
| | - Ioanna Mela
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, U.K
| | | | - Nicholas P. Robinson
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YG, U.K
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Time origin and structural analysis of the induced CRISPR/cas9 megabase-sized deletions and duplications involving the Cntn6 gene in mice. Sci Rep 2019; 9:14161. [PMID: 31578377 PMCID: PMC6775113 DOI: 10.1038/s41598-019-50649-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 09/13/2019] [Indexed: 01/23/2023] Open
Abstract
In a previous study using one-step CRISPR/Cas9 genome editing in mouse zygotes, we created five founders carrying a 1,137 kb deletion and two founders carrying the same deletion, plus a 2,274 kb duplication involving the Cntn6 gene (encoding contactin-6). Using these mice, the present study had the following aims: (i) to establish stage of origin of these rearrangements; (ii) to determine the fate of the deleted DNA fragments; and (iii) to estimate the scale of unpredicted DNA changes accompanying the rearrangements. The present study demonstrated that all targeted deletions and duplications occurred at the one-cell stage and more often in one pronucleus only. FISH analysis revealed that there were no traces of the deleted DNA fragments either within chromosome 6 or on other chromosomes. These data were consistent with the Southern blot analysis showing that chromosomes with deletion often had close to expected sizes of removed DNA fragments. High-throughput DNA sequencing of two homozygotes for duplication demonstrated that there were no unexpected significant or scale DNA changes either at the gRNA and joint sites or other genome sites. Thus, our data suggested that CRISPR/Cas9 technology could generate megabase-sized deletions and duplications in mouse gametes at a reasonably specific level.
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7
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Yang W, Seidman MM, Rupp WD, Gao Y. Replisome structure suggests mechanism for continuous fork progression and post-replication repair. DNA Repair (Amst) 2019; 81:102658. [PMID: 31303546 DOI: 10.1016/j.dnarep.2019.102658] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
What happens to DNA replication when it encounters a damaged or nicked DNA template has been under investigation for five decades. Initially it was thought that DNA polymerase, and thus the replication-fork progression, would stall at road blocks. After the discovery of replication-fork helicase and replication re-initiation factors by the 1990s, it became clear that the replisome can "skip" impasses and finish replication with single-stranded gaps and double-strand breaks in the product DNA. But the mechanism for continuous fork progression after encountering roadblocks is entangled with translesion synthesis, replication fork reversal and recombination repair. The recently determined structure of the bacteriophage T7 replisome offers the first glimpse of how helicase, primase, leading-and lagging-strand DNA polymerases are organized around a DNA replication fork. The tightly coupled leading-strand polymerase and lagging-strand helicase provides a scaffold to consolidate data accumulated over the past five decades and offers a fresh perspective on how the replisome may skip lesions and complete discontinuous DNA synthesis. Comparison of the independently evolved bacterial and eukaryotic replisomes suggests that repair of discontinuous DNA synthesis occurs post replication in both.
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Affiliation(s)
- Wei Yang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA.
| | - Michael M Seidman
- Laboratory of Molecular Gerontology, National Institute of Aging, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD, 21224, USA
| | - W Dean Rupp
- Department of Therapeutic Radiology, Yale University, New Haven, CT, 06520-8040, USA
| | - Yang Gao
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
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8
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Aksoz M, Albayrak E, Aslan GS, Turan RD, Alyazici LY, Siyah P, Tuysuz EC, Canikyan S, Yucel D, Meric N, Gulbas Z, Sahin F, Kocabas F. c-Myc Inhibitor 10074-G5 Induces Murine and Human Hematopoietic Stem and Progenitor Cell Expansion and HDR Modulator Rad51 Expression. Curr Cancer Drug Targets 2019; 19:479-494. [DOI: 10.2174/1568009618666180905100608] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 04/24/2018] [Accepted: 08/25/2018] [Indexed: 12/29/2022]
Abstract
Background:c-Myc plays a major role in the maintenance of glycolytic metabolism and hematopoietic stem cell (HSC) quiescence.Objective:Targeting modulators of HSC quiescence and metabolism could lead to HSC cell cycle entry with concomitant expansion.Methods and Results:Here we show that c-Myc inhibitor 10074-G5 treatment leads to 2-fold increase in murine LSKCD34low HSC compartment post 7 days. In addition, c-Myc inhibition increases CD34+ and CD133+ human HSC number. c-Myc inhibition leads to downregulation of glycolytic and cyclindependent kinase inhibitor (CDKI) gene expression ex vivo and in vivo. In addition, c-Myc inhibition upregulates major HDR modulator Rad51 expression in hematopoietic cells. Besides, c-Myc inhibition does not alter proliferation kinetics of endothelial cells, fibroblasts or adipose-derived mesenchymal stem cells, however, it limits bone marrow derived mesenchymal stem cell proliferation. We further demonstrate that a cocktail of c-Myc inhibitor 10074-G5 along with tauroursodeoxycholic acid (TUDCA) and i-NOS inhibitor L-NIL provides a robust HSC maintenance and expansion ex vivo as evident by induction of all stem cell antigens analyzed. Intriguingly, the cocktail of c-Myc inhibitor 10074-G5, TUDCA and L-NIL improves HDR related gene expression.Conclusion:These findings provide tools to improve ex vivo HSC maintenance and expansion, autologous HSC transplantation and gene editing through modulation of HSC glycolytic and HDR pathways.
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Affiliation(s)
- Merve Aksoz
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, Istanbul, Turkey
| | - Esra Albayrak
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, Istanbul, Turkey
| | - Galip Servet Aslan
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, Istanbul, Turkey
| | - Raife Dilek Turan
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, Istanbul, Turkey
| | - Lamia Yazgi Alyazici
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, Istanbul, Turkey
| | - Pınar Siyah
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, Istanbul, Turkey
| | - Emre Can Tuysuz
- Biotechnology Program, Graduate School of Natural and Applied Sciences, Yeditepe University, 34755, Istanbul, Turkey
| | - Serli Canikyan
- Onkim Stem Cell Technologies, Istanbul Technical University - KOSGEB, Istanbul, Turkey
| | - Dogacan Yucel
- Faculty of Medicine, University of Minnesota, Minneapolis, MN, United States
| | - Neslihan Meric
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, Istanbul, Turkey
| | - Zafer Gulbas
- Bone Marrow Transplantation Center, Anadolu Medical Center, Kocaeli, Turkey
| | - Fikrettin Sahin
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, Istanbul, Turkey
| | - Fatih Kocabas
- Regenerative Biology Research Laboratory, Department of Genetics and Bioengineering, Faculty of Engineering, Yeditepe University, Istanbul, Turkey
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The deubiquitylating enzyme USP15 regulates homologous recombination repair and cancer cell response to PARP inhibitors. Nat Commun 2019; 10:1224. [PMID: 30874560 PMCID: PMC6420636 DOI: 10.1038/s41467-019-09232-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 02/26/2019] [Indexed: 02/07/2023] Open
Abstract
Poly-(ADP-ribose) polymerase inhibitors (PARPi) selectively kill breast and ovarian cancers with defects in homologous recombination (HR) caused by BRCA1/2 mutations. There is also clinical evidence for the utility of PARPi in breast and ovarian cancers without BRCA mutations, but the underlying mechanism is not clear. Here, we report that the deubiquitylating enzyme USP15 affects cancer cell response to PARPi by regulating HR. Mechanistically, USP15 is recruited to DNA double-strand breaks (DSBs) by MDC1, which requires the FHA domain of MDC1 and phosphorylated Ser678 of USP15. Subsequently, USP15 deubiquitinates BARD1 BRCT domain, and promotes BARD1-HP1γ interaction, resulting in BRCA1/BARD1 retention at DSBs. USP15 knockout mice exhibit genomic instability in vivo. Furthermore, cancer-associated USP15 mutations, with decreased USP15-BARD1 interaction, increases PARP inhibitor sensitivity in cancer cells. Thus, our results identify a novel regulator of HR, which is a potential biomarker for therapeutic treatment using PARP inhibitors in cancers. Deubiquitinases have been shown to be involved in double strand break repair pathways. Here the authors reveal that USP15 deybiquitinase plays a role in homologues recombination repair by targeting BARD1 and affecting cells response to PARP inhibitors.
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10
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Krol K, Antoniuk-Majchrzak J, Skoneczny M, Sienko M, Jendrysek J, Rumienczyk I, Halas A, Kurlandzka A, Skoneczna A. Lack of G1/S control destabilizes the yeast genome via replication stress-induced DSBs and illegitimate recombination. J Cell Sci 2018; 131:jcs.226480. [PMID: 30463853 DOI: 10.1242/jcs.226480] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 11/05/2018] [Indexed: 12/13/2022] Open
Abstract
The protein Swi6 in Saccharomyces cerevisiae is a cofactor in two complexes that regulate the transcription of the genes controlling the G1/S transition. It also ensures proper oxidative and cell wall stress responses. Previously, we found that Swi6 was crucial for the survival of genotoxic stress. Here, we show that a lack of Swi6 causes replication stress leading to double-strand break (DSB) formation, inefficient DNA repair and DNA content alterations, resulting in high cell mortality. Comparative genome hybridization experiments revealed that there was a random genome rearrangement in swi6Δ cells, whereas in diploid swi6Δ/swi6Δ cells, chromosome V is duplicated. SWI4 and PAB1, which are located on chromosome V and are known multicopy suppressors of swi6Δ phenotypes, partially reverse swi6Δ genome instability when overexpressed. Another gene on chromosome V, RAD51, also supports swi6Δ survival, but at a high cost; Rad51-dependent illegitimate recombination in swi6Δ cells appears to connect DSBs, leading to genome rearrangement and preventing cell death.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Kamil Krol
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | | | - Marek Skoneczny
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Marzena Sienko
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Justyna Jendrysek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Izabela Rumienczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Agnieszka Halas
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Anna Kurlandzka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Adrianna Skoneczna
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
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11
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Yang ZK, Luo H, Zhang Y, Wang B, Gao F. Recombinational DSBs-intersected genes converge on specific disease- and adaptability-related pathways. Bioinformatics 2018; 34:3421-3426. [PMID: 29726921 DOI: 10.1093/bioinformatics/bty376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 05/01/2018] [Indexed: 11/13/2022] Open
Abstract
Motivation The budding yeast Saccharomyces cerevisiae is a model species powerful for studying the recombination of eukaryotes. Although many recombination studies have been performed for this species by experimental methods, the population genomic study based on bioinformatics analyses is urgently needed to greatly increase the range and accuracy of recombination detection. Here, we carry out the population genomic analysis of recombination in S.cerevisiae to reveal the potential rules between recombination and evolution in eukaryotes. Results By population genomic analysis, we discover significantly more and longer recombination events in clinical strains, which indicates that adverse environmental conditions create an obviously wider range of genetic combination in response to the selective pressure. Based on the analysis of recombinational double strand breaks (DSBs)-intersected genes (RDIGs), we find that RDIGs significantly converge on specific disease- and adaptability-related pathways, indicating that recombination plays a biologically key role in the repair of DSBs related to diseases and environmental adaptability, especially the human neurological disorders. By evolutionary analysis of RDIGs, we find that the RDIGs highly prevailing in populations of yeast tend to be more evolutionarily conserved, indicating the accurate repair of DSBs in these RDIGs is critical to ensure the eukaryotic survival or fitness. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Zhi-Kai Yang
- Department of Physics, School of Science, Tianjin University, Tianjin, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, China.,SinoGenoMax Co., Ltd./Chinese National Human Genome Center, Beijing, China
| | - Hao Luo
- Department of Physics, School of Science, Tianjin University, Tianjin, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, China
| | - Yanming Zhang
- SinoGenoMax Co., Ltd./Chinese National Human Genome Center, Beijing, China
| | - Baijing Wang
- SinoGenoMax Co., Ltd./Chinese National Human Genome Center, Beijing, China
| | - Feng Gao
- Department of Physics, School of Science, Tianjin University, Tianjin, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, China.,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, China
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12
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Li YC, Naveen V, Lin MG, Hsiao CD. Structural analyses of the bacterial primosomal protein DnaB reveal that it is a tetramer and forms a complex with a primosomal re-initiation protein. J Biol Chem 2017; 292:15744-15757. [PMID: 28808061 PMCID: PMC5612107 DOI: 10.1074/jbc.m117.792002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 08/08/2017] [Indexed: 11/06/2022] Open
Abstract
The DnaB primosomal protein from Gram-positive bacteria plays a key role in DNA replication and restart as a loader protein for the recruitment of replisome cascade proteins. Previous investigations have established that DnaB is composed of an N-terminal domain, a middle domain, and a C-terminal domain. However, structural evidence for how DnaB functions at the atomic level is lacking. Here, we report the crystal structure of DnaB, encompassing the N-terminal and middle domains (residues 1-300), from Geobacillus stearothermophilus (GstDnaB1-300) at 2.8 Å resolution. Our structure revealed that GstDnaB1-300 forms a tetramer with two basket-like architectures, a finding consistent with those from solution studies using analytical ultracentrifugation. Furthermore, our results from both GST pulldown assays and analytical ultracentrifugation show that GstDnaB1-300 is sufficient to form a complex with PriA, the primosomal reinitiation protein. Moreover, with the aid of small angle X-ray scattering experiments, we also determined the structural envelope of full-length DnaB (GstDnaBFL) in solution. These small angle X-ray scattering studies indicated that GstDnaBFL has an elongated conformation and that the protruding density envelopes originating from GstDnaB1-300 could completely accommodate the GstDnaB C-terminal domain (residues 301-461). Taken together with biochemical assays, our results suggest that GstDnaB uses different domains to distinguish the PriA interaction and single-stranded DNA binding. These findings can further extend our understanding of primosomal assembly in replication restart.
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Affiliation(s)
- Yi-Ching Li
- From the Institute of Molecular Biology, Academia Sinica, Taipei, 115, Taiwan and
| | - Vankadari Naveen
- From the Institute of Molecular Biology, Academia Sinica, Taipei, 115, Taiwan and
| | - Min-Guan Lin
- From the Institute of Molecular Biology, Academia Sinica, Taipei, 115, Taiwan and
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Chwan-Deng Hsiao
- From the Institute of Molecular Biology, Academia Sinica, Taipei, 115, Taiwan and
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13
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Martínez-Miguel RM, Sandoval-Cabrera A, Bazán-Tejeda ML, Torres-Huerta AL, Martínez-Reyes DA, Bermúdez-Cruz RM. Giardia duodenalis Rad52 protein: biochemical characterization and response upon DNA damage. J Biochem 2017; 162:123-135. [DOI: 10.1093/jb/mvx009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 01/10/2017] [Indexed: 11/13/2022] Open
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14
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Zadrag-Tecza R, Skoneczna A. Reproductive potential and instability of the rDNA region of the Saccharomyces cerevisiae yeast: Common or separate mechanisms of regulation? Exp Gerontol 2016; 84:29-39. [DOI: 10.1016/j.exger.2016.08.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 08/17/2016] [Indexed: 12/15/2022]
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15
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Lin YC, Naveen V, Hsiao CD. EM structure of a helicase-loader complex depicting a 6:2 binding sub-stoichiometry from Geobacillus kaustophilus HTA426. Biochem Biophys Res Commun 2016; 473:243-248. [PMID: 27005821 DOI: 10.1016/j.bbrc.2016.03.086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 10/22/2022]
Abstract
During DNA replication, bacterial helicase is recruited as a complex in association with loader proteins to unwind the parental duplex. Previous structural studies have reported saturated 6:6 helicase-loader complexes with different conformations. However, structural information on the sub-stoichiometric conformations of these previously-documented helicase-loader complexes remains elusive. Here, with the aid of single particle electron-microscopy (EM) image reconstruction, we present the Geobacillus kaustophilus HTA426 helicase-loader (DnaC-DnaI) complex with a 6:2 binding stoichiometry in the presence of ATPγS. In the 19 Å resolution EM map, the undistorted and unopened helicase ring holds a robust loader density above the C-terminal RecA-like domain. Meanwhile, the path of the central DNA binding channel appears to be obstructed by the reconstructed loader density, implying its potential role as a checkpoint conformation to prevent the loading of immature complex onto DNA. Our data also reveals that the bound nucleotides and the consequently induced conformational changes in the helicase hexamer are essential for active association with loader proteins. These observations provide fundamental insights into the formation of the helicase-loader complex in bacteria that regulates the DNA replication process.
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Affiliation(s)
- Yen-Chen Lin
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Vankadari Naveen
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; Molecular Cell Biology, Taiwan International Graduate Program, Institute of Molecular Biology, Academia Sinica, and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Chwan-Deng Hsiao
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan; Molecular Cell Biology, Taiwan International Graduate Program, Institute of Molecular Biology, Academia Sinica, and Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
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16
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Azeroglu B, Mawer JSP, Cockram CA, White MA, Hasan AMM, Filatenkova M, Leach DRF. RecG Directs DNA Synthesis during Double-Strand Break Repair. PLoS Genet 2016; 12:e1005799. [PMID: 26872352 PMCID: PMC4752480 DOI: 10.1371/journal.pgen.1005799] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 12/19/2015] [Indexed: 11/19/2022] Open
Abstract
Homologous recombination provides a mechanism of DNA double-strand break repair (DSBR) that requires an intact, homologous template for DNA synthesis. When DNA synthesis associated with DSBR is convergent, the broken DNA strands are replaced and repair is accurate. However, if divergent DNA synthesis is established, over-replication of flanking DNA may occur with deleterious consequences. The RecG protein of Escherichia coli is a helicase and translocase that can re-model 3-way and 4-way DNA structures such as replication forks and Holliday junctions. However, the primary role of RecG in live cells has remained elusive. Here we show that, in the absence of RecG, attempted DSBR is accompanied by divergent DNA replication at the site of an induced chromosomal DNA double-strand break. Furthermore, DNA double-stand ends are generated in a recG mutant at sites known to block replication forks. These double-strand ends, also trigger DSBR and the divergent DNA replication characteristic of this mutant, which can explain over-replication of the terminus region of the chromosome. The loss of DNA associated with unwinding joint molecules previously observed in the absence of RuvAB and RecG, is suppressed by a helicase deficient PriA mutation (priA300), arguing that the action of RecG ensures that PriA is bound correctly on D-loops to direct DNA replication rather than to unwind joint molecules. This has led us to put forward a revised model of homologous recombination in which the re-modelling of branched intermediates by RecG plays a fundamental role in directing DNA synthesis and thus maintaining genomic stability.
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Affiliation(s)
- Benura Azeroglu
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Julia S. P. Mawer
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Charlotte A. Cockram
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Martin A. White
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - A. M. Mahedi Hasan
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Milana Filatenkova
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - David R. F. Leach
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
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17
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Abstract
On December 18, 2014, a yellow female fly quietly emerged from her pupal case. What made her unique was that she had only one parent carrying a mutant allele of this classic recessive locus. Then, one generation later, after mating with a wild-type male, all her offspring displayed the same recessive yellow phenotype. Further analysis of other such yellow females revealed that the construct causing the mutation was converting the opposing chromosome with 95% efficiency. These simple results, seen also in mosquitoes and yeast, open the door to a new era of genetics wherein the laws of traditional Mendelian inheritance can be bypassed for a broad variety of purposes. Here, we consider the implications of this fundamentally new form of "active genetics," its applications for gene drives, reversal and amplification strategies, its potential for contributing to cell and gene therapy strategies, and ethical/biosafety considerations associated with such active genetic elements. Also watch the Video Abstract.
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Affiliation(s)
- Valentino M Gantz
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
| | - Ethan Bier
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA
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18
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Halgasova N, Solteszova B, Pevala V, Košťan J, Kutejová E, Bukovska G. A RepA-like protein from bacteriophage BFK20 is a multifunctional protein with primase, polymerase, NTPase and helicase activities. Virus Res 2015; 210:178-87. [DOI: 10.1016/j.virusres.2015.08.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 08/06/2015] [Accepted: 08/10/2015] [Indexed: 11/17/2022]
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19
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Liu H, Zhang H, Wang X, Tian Q, Hu Z, Peng C, Jiang P, Wang T, Guo W, Chen Y, Li X, Zhang P, Pei H. The Deubiquitylating Enzyme USP4 Cooperates with CtIP in DNA Double-Strand Break End Resection. Cell Rep 2015; 13:93-107. [PMID: 26387952 DOI: 10.1016/j.celrep.2015.08.056] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 07/11/2015] [Accepted: 08/19/2015] [Indexed: 12/27/2022] Open
Abstract
DNA end resection is a highly regulated and critical step in DNA double-stranded break (DSB) repair. In higher eukaryotes, DSB resection is initiated by the collaborative action of CtIP and the MRE11-RAD50-NBS1 (MRN) complex. Here, we find that the deubiquitylating enzyme USP4 directly participates in DSB resection and homologous recombination (HR). USP4 confers resistance to DNA damage-inducing agents. Mechanistically, USP4 interacts with CtIP and MRN via a specific, conserved region and the catalytic domain of USP4, respectively, and regulates CtIP recruitment to sites of DNA damage. We also find that USP4 autodeubiquitylation is essential for its HR functions. Collectively, our findings identify USP4 as a key regulator of DNA DSB end resection.
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Affiliation(s)
- Hailong Liu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Haoxing Zhang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Xiaohui Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Qingsong Tian
- Department of Orthopedics, Renhe Hospital of Three Gorges University, Yichang 443001, China
| | - Zhaohua Hu
- Department of Orthopedics, Renhe Hospital of Three Gorges University, Yichang 443001, China
| | - Changmin Peng
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Industrial Microbiology Key Lab, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13ST. TEDA, Tianjin 300457, China
| | - Pei Jiang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - TingTing Wang
- Department of General Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Wei Guo
- Department of General Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Yali Chen
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Xinzhi Li
- Department of Orthopedics, Renhe Hospital of Three Gorges University, Yichang 443001, China
| | - Pumin Zhang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China.
| | - Huadong Pei
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, China.
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20
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Cannon B, Kachroo AH, Jarmoskaite I, Jayaram M, Russell R. Hexapeptides that inhibit processing of branched DNA structures induce a dynamic ensemble of Holliday junction conformations. J Biol Chem 2015; 290:22734-46. [PMID: 26209636 PMCID: PMC4566245 DOI: 10.1074/jbc.m115.663930] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 07/23/2015] [Indexed: 11/06/2022] Open
Abstract
Holliday junctions are critical intermediates in DNA recombination, repair, and restart of blocked replication. Hexapeptides have been identified that bind to junctions and inhibit various junction-processing enzymes, and these peptides confer anti-microbial and anti-tumor properties. Earlier studies suggested that inhibition results from stabilization of peptide-bound Holliday junctions in the square planar conformation. Here, we use single molecule fluorescence resonance energy transfer (smFRET) and two model junctions, which are AT- or GC-rich at the branch points, to show that binding of the peptide KWWCRW induces a dynamic ensemble of junction conformations that differs from both the square planar and stacked X conformations. The specific features of the conformational distributions differ for the two peptide-bound junctions, but both junctions display greatly decreased Mg(2+) dependence and increased conformational fluctuations. The smFRET results, complemented by gel mobility shift and small angle x-ray scattering analyses, reveal structural effects of peptides and highlight the sensitivity of smFRET for analyzing complex mixtures of DNA structures. The peptide-induced conformational dynamics suggest multiple stacking arrangements of aromatic amino acids with the nucleobases at the junction core. This conformational heterogeneity may inhibit DNA processing by increasing the population of inactive junction conformations, thereby preventing the binding of processing enzymes and/or resulting in their premature dissociation.
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Affiliation(s)
- Brian Cannon
- From the Department of Molecular Biosciences and the Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
| | - Aashiq H Kachroo
- From the Department of Molecular Biosciences and the Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
| | - Inga Jarmoskaite
- From the Department of Molecular Biosciences and the Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
| | - Makkuni Jayaram
- From the Department of Molecular Biosciences and the Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
| | - Rick Russell
- From the Department of Molecular Biosciences and the Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
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21
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Morrical SW. DNA-pairing and annealing processes in homologous recombination and homology-directed repair. Cold Spring Harb Perspect Biol 2015; 7:a016444. [PMID: 25646379 DOI: 10.1101/cshperspect.a016444] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The formation of heteroduplex DNA is a central step in the exchange of DNA sequences via homologous recombination, and in the accurate repair of broken chromosomes via homology-directed repair pathways. In cells, heteroduplex DNA largely arises through the activities of recombination proteins that promote DNA-pairing and annealing reactions. Classes of proteins involved in pairing and annealing include RecA-family DNA-pairing proteins, single-stranded DNA (ssDNA)-binding proteins, recombination mediator proteins, annealing proteins, and nucleases. This review explores the properties of these pairing and annealing proteins, and highlights their roles in complex recombination processes including the double Holliday junction (DhJ) formation, synthesis-dependent strand annealing, and single-strand annealing pathways--DNA transactions that are critical both for genome stability in individual organisms and for the evolution of species.
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Affiliation(s)
- Scott W Morrical
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, Vermont 05405
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22
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Shinohara T, Ikawa S, Iwasaki W, Hiraki T, Hikima T, Mikawa T, Arai N, Kamiya N, Shibata T. Loop L1 governs the DNA-binding specificity and order for RecA-catalyzed reactions in homologous recombination and DNA repair. Nucleic Acids Res 2015; 43:973-86. [PMID: 25561575 PMCID: PMC4333409 DOI: 10.1093/nar/gku1364] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 12/14/2014] [Accepted: 12/18/2014] [Indexed: 11/16/2022] Open
Abstract
In all organisms, RecA-family recombinases catalyze homologous joint formation in homologous genetic recombination, which is essential for genome stability and diversification. In homologous joint formation, ATP-bound RecA/Rad51-recombinases first bind single-stranded DNA at its primary site and then interact with double-stranded DNA at another site. The underlying reason and the regulatory mechanism for this conserved binding order remain unknown. A comparison of the loop L1 structures in a DNA-free RecA crystal that we originally determined and in the reported DNA-bound active RecA crystals suggested that the aspartate at position 161 in loop L1 in DNA-free RecA prevented double-stranded, but not single-stranded, DNA-binding to the primary site. This was confirmed by the effects of the Ala-replacement of Asp-161 (D161A), analyzed directly by gel-mobility shift assays and indirectly by DNA-dependent ATPase activity and SOS repressor cleavage. When RecA/Rad51-recombinases interact with double-stranded DNA before single-stranded DNA, homologous joint-formation is suppressed, likely by forming a dead-end product. We found that the D161A-replacement reduced this suppression, probably by allowing double-stranded DNA to bind preferentially and reversibly to the primary site. Thus, Asp-161 in the flexible loop L1 of wild-type RecA determines the preference for single-stranded DNA-binding to the primary site and regulates the DNA-binding order in RecA-catalyzed recombinase reactions.
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Affiliation(s)
- Takeshi Shinohara
- Cellular & Molecular Biology Unit, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan Advanced Catalysis Research Group, RIKEN Center for Sustainable Resource Science, Wako-shi, Saitama 351-0198, Japan Department of Supramolecular Biology, Graduate School of Nanobiosciences, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Shukuko Ikawa
- Cellular & Molecular Biology Unit, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan Advanced Catalysis Research Group, RIKEN Center for Sustainable Resource Science, Wako-shi, Saitama 351-0198, Japan
| | - Wakana Iwasaki
- Cellular & Molecular Biology Unit, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Toshiki Hiraki
- Advanced Photon Technology Division, Research Infrastructure Group, RIKEN SPring-8 Center, RIKEN Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Takaaki Hikima
- Advanced Photon Technology Division, Research Infrastructure Group, RIKEN SPring-8 Center, RIKEN Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Tsutomu Mikawa
- Cellular & Molecular Biology Unit, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Naoto Arai
- Department of Applied Biological Science, Nihon University College of Bioresource Sciences, 1866 Kameino, Fujisawa-shi, Kanagawa 252-8510, Japan
| | - Nobuo Kamiya
- Advanced Photon Technology Division, Research Infrastructure Group, RIKEN SPring-8 Center, RIKEN Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Takehiko Shibata
- Cellular & Molecular Biology Unit, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan Advanced Catalysis Research Group, RIKEN Center for Sustainable Resource Science, Wako-shi, Saitama 351-0198, Japan Department of Supramolecular Biology, Graduate School of Nanobiosciences, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
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23
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Richter KS, Ende L, Jeske H. Rad54 is not essential for any geminiviral replication mode in planta. PLANT MOLECULAR BIOLOGY 2015; 87:193-202. [PMID: 25492528 DOI: 10.1007/s11103-014-0270-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 12/02/2014] [Indexed: 06/04/2023]
Abstract
The circular single-stranded DNA of phytopathogenic geminiviruses is propagated by three modes: complementary strand replication (CSR), rolling circle replication (RCR) and recombination-dependent replication (RDR), which need host plant factors to be carried out. In addition to necessary host polymerases, proteins of the homologous recombination repair pathway may be considered essential, since geminiviruses are particularly prone to recombination. Among several others, Rad54 was suggested to be necessary for the RCR of Mungbean yellow mosaic India virus. This enzyme is a double-stranded DNA-dependent ATPase and chromatin remodeller and was found to bind and modulate the viral replication-initiator protein in vitro and in Saccharomyces cerevisiae. In contrast to the previous report, we scrutinized the requirement of Rad54 in planta for two distinct fully infectious geminiviruses with respect to the three replication modes. Euphorbia yellow mosaic virus and Cleome leaf crumple virus were inoculated into Rad54-deficient and wildtype Arabidopsis thaliana plant lines to compare the occurrence of viral DNA forms. Replication intermediates were displayed in the time course of infection by one and two-dimensional agarose gel electrophoresis and Southern hybridization. The experiments showed that Rad54 was neither essential for CSR, RCR nor RDR, and it had no significant influence on virus titers during systemic infection.
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Affiliation(s)
- Kathrin S Richter
- Department of Molecular Biology and Plant Virology, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Pfaffenwaldring 57, 70550, Stuttgart, Germany
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24
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Zhang Y, Okada R, Isaka M, Tatsuno I, Isobe KI, Hasegawa T. Analysis of the roles of NrdR and DnaB from Streptococcus pyogenes in response to host defense. APMIS 2014; 123:252-9. [PMID: 25469586 DOI: 10.1111/apm.12340] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 10/01/2014] [Indexed: 12/01/2022]
Abstract
Toxic shock syndrome caused by Streptococcus pyogenes (S. pyogenes) is a re-emerging infectious disease. Many virulence-associated proteins play important roles in its pathogenesis and the production of these proteins is controlled by many regulatory factors. CovS is one of the most important two-component sensor proteins in S. pyogenes, and it has been analyzed extensively. Our recent analyses revealed the existence of a transposon between covS and nrdR in several strains, and we speculated that this insertion has some importance. Hence, we examined the significances of the NrdR stand-alone regulator and DnaB, which is encoded by the gene located immediately downstream of nrdR in S. pyogenes infection. We established an nrdR-only knockout strain, and both nrdR and partial dnaB knockout strain. These established knockout strains exhibited a deteriorated response to H2 O2 exposure. nrdR and partial dnaB knockout strain was more easily killed by human polynuclear blood cells, but the nrdR-only knockout strain had no significant difference compared to wild type in contrast to the combined knockout strain. In addition, the mouse infection model experiment illustrated that nrdR and partial dnaB knockout strain, but not the nrdR-only knockout strain, was less virulent compared with the parental strain. These results suggest that DnaB is involved in response to host defense.
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Affiliation(s)
- Yan Zhang
- Department of Bacteriology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan; Department of Immunology, Nagoya University Graduate School of Medicine, Nagoya, Japan
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25
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Regulation of the bacteriophage T4 Dda helicase by Gp32 single-stranded DNA-binding protein. DNA Repair (Amst) 2014; 25:41-53. [PMID: 25481875 DOI: 10.1016/j.dnarep.2014.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 09/26/2014] [Accepted: 10/01/2014] [Indexed: 11/20/2022]
Abstract
Dda, one of three helicases encoded by bacteriophage T4, has been well-characterized biochemically but its biological role remains unclear. It is thought to be involved in origin dependent DNA replication, recombination-dependent replication, anti-recombination, and recombination repair. The Gp32 protein of bacteriophage T4 plays critical roles in DNA replication, recombination, and repair by coordinating protein components of the replication fork and by stabilizing ssDNA. Previous work demonstrated that stimulation of DNA synthesis by Dda helicase appears to require direct Gp32-Dda protein-protein interactions and that Gp32 and Dda form a tight complex in the absence of ssDNA. Here we characterize the effects of Gp32-Dda physical and functional interactions through changes in the duplex DNA unwinding and ATPase activities of Dda helicase in the presence of different variants of Gp32 and different DNA repair and replication intermediate structures. Results show that Gp32-Dda interactions can be enhancing or inhibitory, depending on the Gp32 domain seen by Dda. Protein-protein interactions with Gp32 stimulate the unwinding activity of Dda, an effect associated with increased turnover of ATP, suggesting a higher rate of ATPase-driven translocation. Dda-Gp32 interactions also promote the unwinding of DNA substrates at higher salt concentrations and in the presence of substrate-bound DNA polymerase. Conversely, the formation of Gp32 clusters on ssDNA can inhibit unwinding, suggesting that Gp32-ssDNA formation sterically regulates which portions of replication and recombination intermediates are accessible for processing by Dda helicase. The data suggest a mechanism of replication fork restart in which Gp32 promotes Dda activity in template switching while preventing premature fork progression.
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26
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Patterson MN, Maxwell PH. Combining magnetic sorting of mother cells and fluctuation tests to analyze genome instability during mitotic cell aging in Saccharomyces cerevisiae. J Vis Exp 2014:e51850. [PMID: 25350605 PMCID: PMC4436843 DOI: 10.3791/51850] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Saccharomyces cerevisiae has been an excellent model system for examining mechanisms and consequences of genome instability. Information gained from this yeast model is relevant to many organisms, including humans, since DNA repair and DNA damage response factors are well conserved across diverse species. However, S. cerevisiae has not yet been used to fully address whether the rate of accumulating mutations changes with increasing replicative (mitotic) age due to technical constraints. For instance, measurements of yeast replicative lifespan through micromanipulation involve very small populations of cells, which prohibit detection of rare mutations. Genetic methods to enrich for mother cells in populations by inducing death of daughter cells have been developed, but population sizes are still limited by the frequency with which random mutations that compromise the selection systems occur. The current protocol takes advantage of magnetic sorting of surface-labeled yeast mother cells to obtain large enough populations of aging mother cells to quantify rare mutations through phenotypic selections. Mutation rates, measured through fluctuation tests, and mutation frequencies are first established for young cells and used to predict the frequency of mutations in mother cells of various replicative ages. Mutation frequencies are then determined for sorted mother cells, and the age of the mother cells is determined using flow cytometry by staining with a fluorescent reagent that detects bud scars formed on their cell surfaces during cell division. Comparison of predicted mutation frequencies based on the number of cell divisions to the frequencies experimentally observed for mother cells of a given replicative age can then identify whether there are age-related changes in the rate of accumulating mutations. Variations of this basic protocol provide the means to investigate the influence of alterations in specific gene functions or specific environmental conditions on mutation accumulation to address mechanisms underlying genome instability during replicative aging.
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Affiliation(s)
| | - Patrick H Maxwell
- Department of Biological Sciences, Rensselaer Polytechnic Institute;
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27
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Abstract
Homologous DNA pairing and strand exchange are at the core of homologous recombination. These reactions are promoted by a DNA-strand-exchange protein assembled into a nucleoprotein filament comprising the DNA-pairing protein, ATP, and single-stranded DNA. The catalytic activity of this molecular machine depends on control of its dynamic instability by accessory factors. Here we discuss proteins known as recombination mediators that facilitate formation and functional activation of the DNA-strand-exchange protein filament. Although the basics of homologous pairing and DNA-strand exchange are highly conserved in evolution, differences in mediator function are required to cope with differences in how single-stranded DNA is packaged by the single-stranded DNA-binding protein in different species, and the biochemical details of how the different DNA-strand-exchange proteins nucleate and extend into a nucleoprotein filament. The set of (potential) mediator proteins has apparently expanded greatly in evolution, raising interesting questions about the need for additional control and coordination of homologous recombination in more complex organisms.
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Affiliation(s)
- Alex Zelensky
- Department of Genetics, Cancer Genomics Netherlands, Erasmus Medical Center Cancer Institute, 3000 CA, Rotterdam, The Netherlands
| | - Roland Kanaar
- Department of Genetics, Cancer Genomics Netherlands, Erasmus Medical Center Cancer Institute, 3000 CA, Rotterdam, The Netherlands Department of Radiation Oncology, Erasmus Medical Center Cancer Institute, 3000 CA, Rotterdam, The Netherlands
| | - Claire Wyman
- Department of Genetics, Cancer Genomics Netherlands, Erasmus Medical Center Cancer Institute, 3000 CA, Rotterdam, The Netherlands Department of Radiation Oncology, Erasmus Medical Center Cancer Institute, 3000 CA, Rotterdam, The Netherlands
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28
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Structural insight into the DNA-binding mode of the primosomal proteins PriA, PriB, and DnaT. BIOMED RESEARCH INTERNATIONAL 2014; 2014:195162. [PMID: 25136561 PMCID: PMC4129139 DOI: 10.1155/2014/195162] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 06/20/2014] [Accepted: 07/01/2014] [Indexed: 01/31/2023]
Abstract
Replication restart primosome is a complex dynamic system that is essential for bacterial survival. This system uses various proteins to reinitiate chromosomal DNA replication to maintain genetic integrity after DNA damage. The replication restart primosome in Escherichia coli is composed of PriA helicase, PriB, PriC, DnaT, DnaC, DnaB helicase, and DnaG primase. The assembly of the protein complexes within the forked DNA responsible for reloading the replicative DnaB helicase anywhere on the chromosome for genome duplication requires the coordination of transient biomolecular interactions. Over the last decade, investigations on the structure and mechanism of these nucleoproteins have provided considerable insight into primosome assembly. In this review, we summarize and discuss our current knowledge and recent advances on the DNA-binding mode of the primosomal proteins PriA, PriB, and DnaT.
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Harteis S, Schneider S. Making the bend: DNA tertiary structure and protein-DNA interactions. Int J Mol Sci 2014; 15:12335-63. [PMID: 25026169 PMCID: PMC4139847 DOI: 10.3390/ijms150712335] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 07/01/2014] [Accepted: 07/01/2014] [Indexed: 12/11/2022] Open
Abstract
DNA structure functions as an overlapping code to the DNA sequence. Rapid progress in understanding the role of DNA structure in gene regulation, DNA damage recognition and genome stability has been made. The three dimensional structure of both proteins and DNA plays a crucial role for their specific interaction, and proteins can recognise the chemical signature of DNA sequence ("base readout") as well as the intrinsic DNA structure ("shape recognition"). These recognition mechanisms do not exist in isolation but, depending on the individual interaction partners, are combined to various extents. Driving force for the interaction between protein and DNA remain the unique thermodynamics of each individual DNA-protein pair. In this review we focus on the structures and conformations adopted by DNA, both influenced by and influencing the specific interaction with the corresponding protein binding partner, as well as their underlying thermodynamics.
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Affiliation(s)
- Sabrina Harteis
- Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
| | - Sabine Schneider
- Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
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Abstract
Genetic instabilities, including mutations and chromosomal rearrangements, lead to cancer and other diseases in humans and play an important role in evolution. A frequent cause of genetic instabilities is double-strand DNA breaks (DSBs), which may arise from a wide range of exogeneous and endogeneous cellular factors. Although the repair of DSBs is required, some repair pathways are dangerous because they may destabilize the genome. One such pathway, break-induced replication (BIR), is the mechanism for repairing DSBs that possesses only one repairable end. This situation commonly arises as a result of eroded telomeres or collapsed replication forks. Although BIR plays a positive role in repairing DSBs, it can alternatively be a dangerous source of several types of genetic instabilities, including loss of heterozygosity, telomere maintenance in the absence of telomerase, and non-reciprocal translocations. Also, mutation rates in BIR are about 1000 times higher as compared to normal DNA replication. In addition, micro-homology-mediated BIR (MMBIR), which is a mechanism related to BIR, can generate copy-number variations (CNVs) as well as various complex chromosomal rearrangements. Overall, activation of BIR may contribute to genomic destabilization resulting in substantial biological consequences including those affecting human health.
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Affiliation(s)
| | | | - Anna Malkova
- Author to whom correspondence should be addressed; ; Tel.: +1-317-278-5717; Fax: +1-317-274-2946
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31
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Lee M, Lee CH, Demin AA, Munashingha PR, Amangyeld T, Kwon B, Formosa T, Seo YS. Rad52/Rad59-dependent recombination as a means to rectify faulty Okazaki fragment processing. J Biol Chem 2014; 289:15064-79. [PMID: 24711454 DOI: 10.1074/jbc.m114.548388] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The correct removal of 5'-flap structures by Rad27 and Dna2 during Okazaki fragment maturation is crucial for the stable maintenance of genetic materials and cell viability. In this study, we identified RAD52, a key recombination protein, as a multicopy suppressor of dna2-K1080E, a lethal helicase-negative mutant allele of DNA2 in yeasts. In contrast, the overexpression of Rad51, which works conjointly with Rad52 in canonical homologous recombination, failed to suppress the growth defect of the dna2-K1080E mutation, indicating that Rad52 plays a unique and distinct role in Okazaki fragment metabolism. We found that the recombination-defective Rad52-QDDD/AAAA mutant did not rescue dna2-K1080E, suggesting that Rad52-mediated recombination is important for suppression. The Rad52-mediated enzymatic stimulation of Dna2 or Rad27 is not a direct cause of suppression observed in vivo, as both Rad52 and Rad52-QDDD/AAAA proteins stimulated the endonuclease activities of both Dna2 and Rad27 to a similar extent. The recombination mediator activity of Rad52 was dispensable for the suppression, whereas both the DNA annealing activity and its ability to interact with Rad59 were essential. In addition, we found that several cohesion establishment factors, including Rsc2 and Elg1, were required for the Rad52-dependent suppression of dna2-K1080E. Our findings suggest a novel Rad52/Rad59-dependent, but Rad51-independent recombination pathway that could ultimately lead to the removal of faulty flaps in conjunction with cohesion establishment factors.
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Affiliation(s)
- Miju Lee
- From the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea and
| | - Chul-Hwan Lee
- From the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea and
| | - Annie Albert Demin
- From the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea and
| | - Palinda Ruvan Munashingha
- From the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea and
| | - Tamir Amangyeld
- From the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea and
| | - Buki Kwon
- From the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea and
| | - Tim Formosa
- the Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112
| | - Yeon-Soo Seo
- From the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea and
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Choi DH, Min MH, Kim MJ, Lee R, Kwon SH, Bae SH. Hrq1 facilitates nucleotide excision repair of DNA damage induced by 4-nitroquinoline-1-oxide and cisplatin in Saccharomyces cerevisiae. J Microbiol 2014; 52:292-8. [PMID: 24682993 DOI: 10.1007/s12275-014-4018-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 02/12/2014] [Accepted: 02/16/2014] [Indexed: 11/27/2022]
Abstract
Hrq1 helicase is a novel member of the RecQ family. Among the five human RecQ helicases, Hrq1 is most homologous to RECQL4 and is conserved in fungal genomes. Recent genetic and biochemical studies have shown that it is a functional gene, involved in the maintenance of genome stability. To better define the roles of Hrq1 in yeast cells, we investigated genetic interactions between HRQ1 and several DNA repair genes. Based on DNA damage sensitivities induced by 4-nitroquinoline-1-oxide (4-NQO) or cisplatin, RAD4 was found to be epistatic to HRQ1. On the other hand, mutant strains defective in either homologous recombination (HR) or post-replication repair (PRR) became more sensitive by additional deletion of HRQ1, indicating that HRQ1 functions in the RAD4-dependent nucleotide excision repair (NER) pathway independent of HR or PRR. In support of this, yeast two-hybrid analysis showed that Hrq1 interacted with Rad4, which was enhanced by DNA damage. Overexpression of Hrq1K318A helicase-deficient protein rendered mutant cells more sensitive to 4-NQO and cisplatin, suggesting that helicase activity is required for the proper function of Hrq1 in NER.
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Affiliation(s)
- Do-Hee Choi
- Department of Biological Sciences, College of Natural Science, Inha University, Incheon, 402-751, Republic of Korea
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Ju Y, Xu T, Zhang H, Yu A. FOXO1-dependent DNA damage repair is regulated by JNK in lung cancer cells. Int J Oncol 2014; 44:1284-92. [PMID: 24452601 DOI: 10.3892/ijo.2014.2269] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 12/23/2013] [Indexed: 11/06/2022] Open
Abstract
DNA damage or mutation in cells contributes to tumorigenesis. The transcription factor FOXO1 modulates the expression of genes involved in DNA damage repair, cell cycle arrest and apoptosis. The transcriptional activity of FOXO1 is fundamentally regulated by post-translational modification and subcellular localization. H1299 lung cancer cells were treated with the alkylating agent MNNG, and the cell viability and DNA damage were separately determined by MTT and comet assay. Using immunofluorescence and western blotting, we observed the subcellular localization of FOXO1 and measured the relevant protein expression levels, respectively. To examine cell cycle arrest and apoptosis, flow cytometry analysis was preformed. The interaction between FOXO1 and JNK was analyzed through immunoprecipitation. Our results showed that cell viability was reduced at 24 h after MNNG treatment, and appeared to recover to some degree at 48 h. The increased expression and nuclear export of FOXO1 emerged at 4 h after the treatment. Nuclear FOXO1 played a pivotal role in cell cycle arrest, apoptosis and DNA damage repair by upregulating p27(Kip1), Bim and GADD45 gene expression, respectively. AKT-dependent S256 phosphorylation of FOXO1 and the S473 phosphorylation of AKT were both enhanced following DNA damage. Moreover, our studies revealed that FOXO1 directly interacted with JNK, and the inhibition of the JNK activity led to decreased expression of FOXO1 target genes. These findings suggest for the first time that FOXO1 is a promising candidate substrate for JNK, and the FOXO1-dependent DNA damage repair may be regulated positively by the JNK pathway in H1299 lung cancer cells.
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Affiliation(s)
- Yinghua Ju
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, China Medical University, Shenyang 110001, P.R. China
| | - Taojun Xu
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, China Medical University, Shenyang 110001, P.R. China
| | - Hongkai Zhang
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, China Medical University, Shenyang 110001, P.R. China
| | - Aiming Yu
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, China Medical University, Shenyang 110001, P.R. China
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Branagan AM, Klein JA, Jordan CS, Morrical SW. Control of helicase loading in the coupled DNA replication and recombination systems of bacteriophage T4. J Biol Chem 2013; 289:3040-54. [PMID: 24338568 DOI: 10.1074/jbc.m113.505842] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Gp59 protein of bacteriophage T4 promotes DNA replication by loading the replicative helicase, Gp41, onto replication forks and recombination intermediates. Gp59 also blocks DNA synthesis by Gp43 polymerase until Gp41 is loaded, ensuring that synthesis is tightly coupled to unwinding. The distinct polymerase blocking and helicase loading activities of Gp59 likely involve different binding interactions with DNA and protein partners. Here, we investigate how interactions of Gp59 with DNA and Gp32, the T4 single-stranded DNA (ssDNA)-binding protein, are related to these activities. A previously characterized mutant, Gp59-I87A, exhibits markedly reduced affinity for ssDNA and pseudo-fork DNA substrates. We demonstrate that on Gp32-covered ssDNA, the DNA binding defect of Gp59-I87A is not detrimental to helicase loading and translocation. In contrast, on pseudo-fork DNA the I87A mutation is detrimental to helicase loading and unwinding in the presence or absence of Gp32. Other results indicate that Gp32 binding to lagging strand ssDNA relieves the blockage of Gp43 polymerase activity by Gp59, whereas the inhibition of Gp43 exonuclease activity is maintained. Our findings suggest that Gp59-Gp32 and Gp59-DNA interactions perform separate but complementary roles in T4 DNA metabolism; Gp59-Gp32 interactions are needed to load Gp41 onto D-loops, and other nucleoprotein structures containing clusters of Gp32. Gp59-DNA interactions are needed to load Gp41 onto nascent or collapsed replication forks lacking clusters of Gp32 and to coordinate bidirectional replication from T4 origins. The dual functionalities of Gp59 allow it to promote the initiation or re-start of DNA replication from a wide variety of recombination and replication intermediates.
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Affiliation(s)
- Amy M Branagan
- From the Department of Biochemistry, University of Vermont College of Medicine, Burlington, Vermont 05405
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35
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Liu J, Berger CL, Morrical SW. Kinetics of presynaptic filament assembly in the presence of single-stranded DNA binding protein and recombination mediator protein. Biochemistry 2013; 52:7878-89. [PMID: 24124995 DOI: 10.1021/bi401060p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Enzymes of the RecA/Rad51 family catalyze DNA strand exchange reactions that are important for homologous recombination and for the accurate repair of DNA double-strand breaks. RecA/Rad51 recombinases are activated by their assembly into presynaptic filaments on single-stranded DNA (ssDNA), a process that is regulated by ssDNA binding protein (SSB) and mediator proteins. Mediator proteins stimulate strand exchange by accelerating the rate-limiting displacement of SSB from ssDNA by the incoming recombinase. The use of mediators is a highly conserved strategy in recombination, but the precise mechanism of mediator activity is unknown. In this study, the well-defined bacteriophage T4 recombination system (UvsX recombinase, Gp32 SSB, and UvsY mediator) is used to examine the kinetics of presynaptic filament assembly on native ssDNA in vitro. Results indicate that the ATP-dependent assembly of UvsX presynaptic filaments on Gp32-covered ssDNA is limited by a salt-sensitive nucleation step in the absence of mediator. Filament nucleation is selectively enhanced and rendered salt-resistant by mediator protein UvsY, which appears to stabilize a prenucleation complex. This mechanism potentially explains how UvsY promotes presynaptic filament assembly at physiologically relevant ionic strengths and Gp32 concentrations. Other data suggest that presynaptic filament assembly involves multiple nucleation events, resulting in many short UvsX-ssDNA filaments or clusters, which may be the relevant form for recombination in vivo. Together, these findings provide the first detailed kinetic model for presynaptic filament assembly involving all three major protein components (recombinase, mediator, and SSB) on native ssDNA.
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Affiliation(s)
- Jie Liu
- Department of Biochemistry and ‡Department of Molecular Physiology and Biophysics, University of Vermont College of Medicine , Burlington, Vermont 05405, United States
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36
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Karia B, Martinez JA, Bishop AJR. Induction of homologous recombination following in utero exposure to DNA-damaging agents. DNA Repair (Amst) 2013; 12:912-21. [PMID: 24029142 DOI: 10.1016/j.dnarep.2013.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 07/06/2013] [Accepted: 08/19/2013] [Indexed: 11/19/2022]
Abstract
Much of our understanding of homologous recombination, as well as the development of the working models for these processes, has been derived from extensive work in model organisms, such as yeast and fruit flies, and mammalian systems by studying the repair of induced double strand breaks or repair following exposure to genotoxic agents in vitro. We therefore set out to expand this in vitro work to ask whether DNA-damaging agents with varying modes of action could induce somatic change in an in vivo mouse model of homologous recombination. We exposed pregnant dams to DNA-damaging agents, conferring a variety of lesions at a specific time in embryo development. To monitor homologous recombination frequency, we used the well-established retinal pigment epithelium pink-eyed unstable assay. Homologous recombination resulting in the deletion of a duplicated 70 kb fragment in the coding region of the Oca2 gene renders this gene functional and can be visualized as a pigmented eyespot in the retinal pigment epithelium. We observed an increased frequency of pigmented eyespots in resultant litters following exposure to cisplatin, methyl methanesulfonate, ethyl methanesulfonate, 3-aminobenzamide, bleomycin, and etoposide with a contrasting decrease in the frequency of detectable reversion events following camptothecin and hydroxyurea exposure. The somatic genomic rearrangements that result from such a wide variety of differently acting damaging agents implies long-term potential effects from even short-term in utero exposures.
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Affiliation(s)
- Bijal Karia
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA; Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
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Subramanyam S, Jones WT, Spies M, Spies MA. Contributions of the RAD51 N-terminal domain to BRCA2-RAD51 interaction. Nucleic Acids Res 2013; 41:9020-32. [PMID: 23935068 PMCID: PMC3799448 DOI: 10.1093/nar/gkt691] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
RAD51 DNA strand exchange protein catalyzes the central step in homologous recombination, a cellular process fundamentally important for accurate repair of damaged chromosomes, preservation of the genetic integrity, restart of collapsed replication forks and telomere maintenance. BRCA2 protein, a product of the breast cancer susceptibility gene, is a key recombination mediator that interacts with RAD51 and facilitates RAD51 nucleoprotein filament formation on single-stranded DNA generated at the sites of DNA damage. An accurate atomistic level description of this interaction, however, is limited to a partial crystal structure of the RAD51 core fused to BRC4 peptide. Here, by integrating homology modeling and molecular dynamics, we generated a structure of the full-length RAD51 in complex with BRC4 peptide. Our model predicted previously unknown hydrogen bonding patterns involving the N-terminal domain (NTD) of RAD51. These interactions guide positioning of the BRC4 peptide within a cavity between the core and the NTDs; the peptide binding separates the two domains and restricts internal dynamics of RAD51 protomers. The model’s depiction of the RAD51-BRC4 complex was validated by free energy calculations and in vitro functional analysis of rationally designed mutants. All generated mutants, RAD51E42A, RAD51E59A, RAD51E237A, RAD51E59A/E237A and RAD51E42A/E59A/E237A maintained basic biochemical activities of the wild-type RAD51, but displayed reduced affinities for the BRC4 peptide. Strong correlation between the calculated and experimental binding energies confirmed the predicted structure of the RAD51-BRC4 complex and highlighted the importance of RAD51 NTD in RAD51-BRCA2 interaction.
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Affiliation(s)
- Shyamal Subramanyam
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA, Center for the Physics of Living Cells, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA, Department of Biochemistry, Carver College of Medicine, College of Pharmacy, University of Iowa, Iowa City, IA 52242, USA and Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA 52242, USA
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Sakakibara N, Chen D, McBride AA. Papillomaviruses use recombination-dependent replication to vegetatively amplify their genomes in differentiated cells. PLoS Pathog 2013; 9:e1003321. [PMID: 23853576 PMCID: PMC3701714 DOI: 10.1371/journal.ppat.1003321] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
- Nozomi Sakakibara
- Laboratory of Viral Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
| | - Dan Chen
- Laboratory of Viral Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
| | - Alison A. McBride
- Laboratory of Viral Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
- * E-mail:
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39
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Coordinated Binding of Single-Stranded and Double-Stranded DNA by UvsX Recombinase. PLoS One 2013; 8:e66654. [PMID: 23824136 PMCID: PMC3688935 DOI: 10.1371/journal.pone.0066654] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2012] [Accepted: 05/11/2013] [Indexed: 11/19/2022] Open
Abstract
Homologous recombination is important for the error-free repair of DNA double-strand breaks and for replication fork restart. Recombinases of the RecA/Rad51 family perform the central catalytic role in this process. UvsX recombinase is the RecA/Rad51 ortholog of bacteriophage T4. UvsX and other recombinases form presynaptic filaments on ssDNA that are activated to search for homology in dsDNA and to perform DNA strand exchange. To effectively initiate recombination, UvsX must find and bind to ssDNA within an excess of dsDNA. Here we examine the binding of UvsX to ssDNA and dsDNA in the presence and absence of nucleotide cofactor, ATP. We also examine how the binding of one DNA substrate is affected by simultaneous binding of the other to determine how UvsX might selectively assemble on ssDNA. We show that the two DNA binding sites of UvsX are regulated by the nucleotide cofactor ATP and are coordinated with each other such that in the presence of ssDNA, dsDNA binding is significantly reduced and correlated with its homology to the ssDNA bound to the enzyme. UvsX has high affinity for dsDNA in the absence of ssDNA, which may allow for sequestration of the enzyme in an inactive form prior to ssDNA generation.
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40
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Break-induced replication: functions and molecular mechanism. Curr Opin Genet Dev 2013; 23:271-9. [PMID: 23790415 DOI: 10.1016/j.gde.2013.05.007] [Citation(s) in RCA: 134] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 05/21/2013] [Accepted: 05/22/2013] [Indexed: 02/08/2023]
Abstract
Break-induced replication (BIR) is the pathway of homologous recombination (HR) conserved from phages to eukaryotes that serves to repair DNA breaks that have only one end. BIR contributes to the repair of broken replication forks and allows telomere lengthening in the absence of telomerase. Nonallelic BIR may lead to translocations and other chromosomal rearrangements. In addition, BIR initiated at sites of microhomology can generate copy number variations (CNVs) and complex chromosomal changes. The level of mutagenesis associated with DNA synthesis in BIR is significantly higher than during normal replication. These features make BIR a likely pathway to promote bursts of genetic changes that fuel cancer progression and evolution.
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41
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Currall BB, Chiang C, Talkowski ME, Morton CC. Mechanisms for Structural Variation in the Human Genome. CURRENT GENETIC MEDICINE REPORTS 2013; 1:81-90. [PMID: 23730541 DOI: 10.1007/s40142-013-0012-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
It has been known for several decades that genetic variation involving changes to chromosomal structure (i.e., structural variants) can contribute to disease; however this relationship has been brought into acute focus in recent years largely based on innovative new genomics approaches and technology. Structural variants (SVs) arise from improperly repaired DNA double-strand breaks (DSB). DSBs are a frequent occurrence in all cells and two major pathways are involved in their repair: homologous recombination and non-homologous end joining. Errors during these repair mechanisms can result in SVs that involve losses, gains and rearrangements ranging from a few nucleotides to entire chromosomal arms. Factors such as rearrangements, hotspots and induced DSBs are implicated in the formation of SVs. While de novo SVs are often associated with disease, some SVs are conserved within human subpopulations and may have had a meaningful influence on primate evolution. As the ability to sequence the whole human genome rapidly evolves, the diversity of SVs is illuminated, including very complex rearrangements involving multiple DSBs in a process recently designated as "chromothripsis". Elucidating mechanisms involved in the etiology of SVs informs disease pathogenesis as well as the dynamic function associated with the biology and evolution of human genomes.
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Affiliation(s)
- Benjamin B Currall
- Departments of Obstetrics, Gynecology and Reproductive Biology, Brigham and Women's Hospital and Harvard Medical School, New Research Building, Room 160D, 77 Avenue Louis Pasteur, Boston, MA 02115, USA. Harvard Medical School, Boston, MA, USA
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42
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Timeless-dependent DNA replication-coupled recombination promotes Kaposi's Sarcoma-associated herpesvirus episome maintenance and terminal repeat stability. J Virol 2013; 87:3699-709. [PMID: 23325691 DOI: 10.1128/jvi.02211-12] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Kaposi's Sarcoma-associated herpesvirus (KSHV) is maintained as a stable episome in latently infected pleural effusion lymphoma (PEL) cells. Episome maintenance is conferred by the binding of the KSHV-encoded LANA protein to the viral terminal repeats (TR). Here, we show that DNA replication in the KSHV TR is coupled with DNA recombination and mediated in part through the cellular replication fork protection factors Timeless (Tim) and Tipin. We show by two-dimensional (2D) agarose gel electrophoresis that replication forks naturally stall and form recombination-like structures at the TR during an unperturbed cell cycle. Chromatin immunoprecipitation (ChIP) assays revealed that Tim and Tipin are selectively enriched at the KSHV TR during S phase and in a LANA-dependent manner. Tim depletion inhibited LANA-dependent TR DNA replication and caused the loss of KSHV episomes from latently infected PEL cells. Tim depletion resulted in the aberrant accumulation of recombination structures and arrested MCM helicase at TR. Tim depletion did not induce the KSHV lytic cycle or apoptotic cell death. We propose that KSHV episome maintenance requires Tim-assisted replication fork protection at the viral terminal repeats and that Tim-dependent recombination-like structures form at TR to promote DNA repeat stability and viral genome maintenance.
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Prindle MJ, Loeb LA. DNA polymerase delta in DNA replication and genome maintenance. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2012; 53:666-82. [PMID: 23065663 PMCID: PMC3694620 DOI: 10.1002/em.21745] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 09/09/2012] [Accepted: 09/12/2012] [Indexed: 05/12/2023]
Abstract
The eukaryotic genome is in a constant state of modification and repair. Faithful transmission of the genomic information from parent to daughter cells depends upon an extensive system of surveillance, signaling, and DNA repair, as well as accurate synthesis of DNA during replication. Often, replicative synthesis occurs over regions of DNA that have not yet been repaired, presenting further challenges to genomic stability. DNA polymerase δ (pol δ) occupies a central role in all of these processes: catalyzing the accurate replication of a majority of the genome, participating in several DNA repair synthetic pathways, and contributing structurally to the accurate bypass of problematic lesions during translesion synthesis. The concerted actions of pol δ on the lagging strand, pol ϵ on the leading strand, associated replicative factors, and the mismatch repair (MMR) proteins results in a mutation rate of less than one misincorporation per genome per replication cycle. This low mutation rate provides a high level of protection against genetic defects during development and may prevent the initiation of malignancies in somatic cells. This review explores the role of pol δ in replication fidelity and genome maintenance.
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Affiliation(s)
- Marc J Prindle
- Department of Pathology, The Joseph Gottstien Memorial Cancer Research Laboratory, University of Washington, Seattle, WA 98195-7705, USA
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44
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Abstract
Proper repair of DNA double strand breaks (DSBs) is vital for the preservation of genomic integrity. There are two main pathways that repair DSBs, Homologous recombination (HR) and Non-homologous end-joining (NHEJ). HR is restricted to the S and G2 phases of the cell cycle due to the requirement for the sister chromatid as a template, while NHEJ is active throughout the cell cycle and does not rely on a template. The balance between both pathways is essential for genome stability and numerous assays have been developed to measure the efficiency of the two pathways. Several proteins are known to affect the balance between HR and NHEJ and the complexity of the break also plays a role. In this review we describe several repair assays to determine the efficiencies of both pathways. We discuss how disturbance of the balance between HR and NHEJ can lead to disease, but also how it can be exploited for cancer treatment.
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Affiliation(s)
- Inger Brandsma
- Department of Genetics, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.
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Huh MS, Price O'Dea T, Ouazia D, McKay BC, Parise G, Parks RJ, Rudnicki MA, Picketts DJ. Compromised genomic integrity impedes muscle growth after Atrx inactivation. J Clin Invest 2012; 122:4412-23. [PMID: 23114596 DOI: 10.1172/jci63765] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 09/06/2012] [Indexed: 01/23/2023] Open
Abstract
ATR-X syndrome is a severe intellectual disability disorder caused by mutations in the ATRX gene. Many ancillary clinical features are attributed to CNS deficiencies, yet most patients have muscle hypotonia, delayed ambulation, or kyphosis, pointing to an underlying skeletal muscle defect. Here, we identified a cell-intrinsic requirement for Atrx in postnatal muscle growth and regeneration in mice. Mice with skeletal muscle-specific Atrx conditional knockout (Atrx cKO mice) were viable, but by 3 weeks of age presented hallmarks of underdeveloped musculature, including kyphosis, 20% reduction in body mass, and 34% reduction in muscle fiber caliber. Atrx cKO mice also demonstrated a marked regeneration deficit that was not due to fewer resident satellite cells or their inability to terminally differentiate. However, activation of Atrx-null satellite cells from isolated muscle fibers resulted in a 9-fold reduction in myoblast expansion, caused by delayed progression through mid to late S phase. While in S phase, Atrx colocalized specifically to late-replicating chromatin, and its loss resulted in rampant signs of genomic instability. These observations support a model in which Atrx maintains chromatin integrity during the rapid developmental growth of a tissue.
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Affiliation(s)
- Michael S Huh
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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Branagan AM, Maher RL, Morrical SW. Assembly and dynamics of Gp59-Gp32-single-stranded DNA (ssDNA), a DNA helicase loading complex required for recombination-dependent replication in bacteriophage T4. J Biol Chem 2012; 287:19070-81. [PMID: 22500043 DOI: 10.1074/jbc.m112.343830] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Gp59 protein of bacteriophage T4 plays critical roles in recombination-dependent DNA replication and repair by correctly loading the replicative helicase, Gp41, onto recombination intermediates. Previous work demonstrated that Gp59 is required to load helicase onto single-stranded DNA that is saturated with Gp32, the T4 single-stranded DNA (ssDNA)-binding protein. Gp59 and Gp32 bind simultaneously to ssDNA, forming a Gp59-Gp32-ssDNA complex that is a key intermediate in helicase loading. Here we characterize the assembly and dynamics of this helicase loading complex (HLC) through changes in the fluorescent states of Gp32F, a fluorescein-Gp32 conjugate. Results show that HLC formation requires a minimum Gp32-ssDNA cluster size and that Gp59 co-localizes with Gp32-ssDNA clusters in the presence of excess free ssDNA. These and other results indicate that Gp59 targets helicase assembly onto Gp32-ssDNA clusters that form on the displaced strand of D-loops, which suggests a mechanism for the rapid initiation of recombination-dependent DNA replication. Helicase loading at the HLC requires ATP binding (not hydrolysis) by Gp41 and results in local remodeling of Gp32 within the HLC. Subsequent ATPase-driven translocation of Gp41 progressively disrupts Gp32-ssDNA interactions. Evidence suggests that Gp59 from the HLC is recycled to promote multiple rounds of helicase assembly on Gp32-ssDNA, a capability that could be important for the restart of stalled replication forks.
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Affiliation(s)
- Amy M Branagan
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, Vermont 05405, USA
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Byrd AK, Matlock DL, Bagchi D, Aarattuthodiyil S, Harrison D, Croquette V, Raney KD. Dda helicase tightly couples translocation on single-stranded DNA to unwinding of duplex DNA: Dda is an optimally active helicase. J Mol Biol 2012; 420:141-54. [PMID: 22504228 DOI: 10.1016/j.jmb.2012.04.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 03/04/2012] [Accepted: 04/01/2012] [Indexed: 01/06/2023]
Abstract
Helicases utilize the energy of ATP hydrolysis to unwind double-stranded DNA while translocating on the DNA. Mechanisms for melting the duplex have been characterized as active or passive, depending on whether the enzyme actively separates the base pairs or simply sequesters single-stranded DNA (ssDNA) that forms due to thermal fraying. Here, we show that Dda translocates unidirectionally on ssDNA at the same rate at which it unwinds double-stranded DNA in both ensemble and single-molecule experiments. Further, the unwinding rate is largely insensitive to the duplex stability and to the applied force. Thus, Dda transduces all of its translocase activity into DNA unwinding activity so that the rate of unwinding is limited by the rate of translocation and that the enzyme actively separates the duplex. Active and passive helicases have been characterized by dividing the velocity of DNA unwinding in base pairs per second (V(un)) by the velocity of translocation on ssDNA in nucleotides per second (V(trans)). If the resulting fraction is 0.25, then a helicase is considered to be at the lower end of the "active" range. In the case of Dda, the average DNA unwinding velocity was 257±42 bp/s, and the average translocation velocity was 267±15 nt/s. The V(un)/V(trans) value of 0.96 places Dda in a unique category of being an essentially "perfectly" active helicase.
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Affiliation(s)
- Alicia K Byrd
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, 4301 West Markham Street, Slot 516, Little Rock, AR 72205, USA
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Munashingha PR, Lee CH, Kang YH, Shin YK, Nguyen TA, Seo YS. The trans-autostimulatory activity of Rad27 suppresses dna2 defects in Okazaki fragment processing. J Biol Chem 2012; 287:8675-87. [PMID: 22235122 DOI: 10.1074/jbc.m111.326470] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Dna2 and Rad27 (yeast Fen1) are the two endonucleases critical for Okazaki fragment processing during lagging strand DNA synthesis that have been shown to interact genetically and physically. In this study, we addressed the functional consequences of these interactions by examining whether purified Rad27 of Saccharomyces cerevisiae affects the enzymatic activity of Dna2 and vice versa. For this purpose, we constructed Rad27DA (catalytically defective enzyme with an Asp to Ala substitution at amino acid 179) and found that it significantly stimulated the endonuclease activity of wild type Dna2, but failed to do so with Dna2Δ405N that lacks the N-terminal 405 amino acids. This was an unexpected finding because dna2Δ405N cells were still partially suppressed by overexpression of rad27DA in vivo. Further analyses revealed that Rad27 is a trans-autostimulatory enzyme, providing an explanation why overexpression of Rad27, regardless of its catalytic activity, suppressed dna2 mutants as long as an endogenous wild type Rad27 is available. We found that the C-terminal 16-amino acid fragment of Rad27, a highly polybasic region due to the presence of multiple positively charged lysine and arginine residues, was sufficient and necessary for the stimulation of both Rad27 and Dna2. Our findings provide further insight into how Dna2 and Rad27 jointly affect the processing of Okazaki fragments in eukaryotes.
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Affiliation(s)
- Palinda Ruvan Munashingha
- Center for DNA Replication and Genome Instability, Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Korea
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Seeliger K, Dukowic-Schulze S, Wurz-Wildersinn R, Pacher M, Puchta H. BRCA2 is a mediator of RAD51- and DMC1-facilitated homologous recombination in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2012; 193:364-75. [PMID: 22077663 DOI: 10.1111/j.1469-8137.2011.03947.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
• Mutations in the breast cancer susceptibility gene 2 (BRCA2) are correlated with hereditary breast cancer in humans. Studies have revealed that mammalian BRCA2 plays crucial roles in DNA repair. Therefore, we wished to define the role of the BRCA2 homologs in Arabidopsis in detail. • As Arabidopsis contains two functional BRCA2 homologs, an Atbrca2 double mutant was generated and analyzed with respect to hypersensitivity to genotoxic agents and recombination frequencies. Cytological studies addressing male and female meiosis were also conducted, and immunolocalization was performed in male meiotic prophase I. • The Atbrca2 double mutant showed hypersensitivity to the cross-linking agent mitomycin C and displayed a dramatic reduction in somatic homologous recombination frequency, especially after double-strand break induction. The loss of AtBRCA2 also led to severe defects in male meiosis and development of the female gametophyte and impeded proper localization of the synaptonemal complex protein AtZYP1 and the recombinases AtRAD51 and AtDMC1. • The results demonstrate that AtBRCA2 is important for both somatic and meiotic homologous recombination. We further show that AtBRCA2 is required for proper meiotic synapsis and mediates the recruitment of AtRAD51 and AtDMC1. Our results suggest that BRCA2 controls single-strand invasion steps during homologous recombination in plants.
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Affiliation(s)
- Katharina Seeliger
- Botanical Institute II, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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