1
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Calabrese A, von Arx C, Tafuti AA, Pensabene M, De Laurentiis M. Prevention, diagnosis and clinical management of hereditary breast cancer beyond BRCA1/2 genes. Cancer Treat Rev 2024; 129:102785. [PMID: 38870570 DOI: 10.1016/j.ctrv.2024.102785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 05/18/2024] [Accepted: 06/09/2024] [Indexed: 06/15/2024]
Abstract
The detection of germline pathogenic variants (gPVs) in BRCA1/2 and other breast cancer (BC) genes is rising exponentially thanks to the advent of multi-gene panel testing. This promising technology, coupled with the availability of specific therapies for BC BRCA-related, has increased the number of patients eligible for genetic testing. Implementing multi-gene panel testing for hereditary BC screening holds promise to maximise benefits for patients at hereditary risk of BC. These benefits range from prevention programs to antineoplastic-targeted therapies. However, the clinical management of these patients is complex and requires guidelines based on recent evidence. Furthermore, applying multi-gene panel testing into clinical practice increases the detection of variants of uncertain significance (VUSs). This augments the complexity of patients' clinical management, becoming an unmet need for medical oncologists. This review aims to collect updated evidence on the most common BC-related genes besides BRCA1/2, from their biological role in BC development to their potential impact in tailoring prevention and treatment strategies.
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Affiliation(s)
- A Calabrese
- Department Breast and Thoracic Oncology, Istituto Nazionale Tumori - IRCCS, 'Fondazione G. Pascale', Via Mariano Semmola, 53, 80131 Napoli, NA, Italy
| | - C von Arx
- Department Breast and Thoracic Oncology, Istituto Nazionale Tumori - IRCCS, 'Fondazione G. Pascale', Via Mariano Semmola, 53, 80131 Napoli, NA, Italy.
| | - A A Tafuti
- Department Breast and Thoracic Oncology, Istituto Nazionale Tumori - IRCCS, 'Fondazione G. Pascale', Via Mariano Semmola, 53, 80131 Napoli, NA, Italy
| | - M Pensabene
- Department Breast and Thoracic Oncology, Istituto Nazionale Tumori - IRCCS, 'Fondazione G. Pascale', Via Mariano Semmola, 53, 80131 Napoli, NA, Italy
| | - M De Laurentiis
- Department Breast and Thoracic Oncology, Istituto Nazionale Tumori - IRCCS, 'Fondazione G. Pascale', Via Mariano Semmola, 53, 80131 Napoli, NA, Italy
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2
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Torrance EL, Diop A, Bobay LM. Homologous Recombination Shapes the Architecture and Evolution of Bacterial Genomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.31.596828. [PMID: 38895235 PMCID: PMC11185547 DOI: 10.1101/2024.05.31.596828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Homologous recombination is a key evolutionary force that varies considerably across bacterial species. However, how the landscape of homologous recombination varies across genes and within individual genomes has only been studied in a few species. Here, we used Approximate Bayesian Computation to estimate the recombination rate along the genomes of 145 bacterial species. Our results show that homologous recombination varies greatly along bacterial genomes and shapes many aspects of genome architecture and evolution. The genomic landscape of recombination presents several key signatures: rates are highest near the origin of replication in most species, patterns of recombination generally appear symmetrical in both replichores ( i.e. replicational halves of circular chromosomes) and most species have genomic hotpots of recombination. Furthermore, many closely related species share conserved landscapes of recombination across orthologs indicating that recombination landscapes are conserved over significant evolutionary distances. We show evidence that recombination drives the evolution of GC-content through increasing the effectiveness of selection and not through biased gene conversion, thereby contributing to an ongoing debate. Finally, we demonstrate that the rate of recombination varies across gene function and that many hotspots of recombination are associated with adaptive and mobile regions often encoding genes involved in pathogenicity.
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3
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Boyd BM, James I, Johnson KP, Weiss RB, Bush SE, Clayton DH, Dale C. Stochasticity, determinism, and contingency shape genome evolution of endosymbiotic bacteria. Nat Commun 2024; 15:4571. [PMID: 38811551 PMCID: PMC11137140 DOI: 10.1038/s41467-024-48784-2] [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: 07/06/2023] [Accepted: 05/10/2024] [Indexed: 05/31/2024] Open
Abstract
Evolution results from the interaction of stochastic and deterministic processes that create a web of historical contingency, shaping gene content and organismal function. To understand the scope of this interaction, we examine the relative contributions of stochasticity, determinism, and contingency in shaping gene inactivation in 34 lineages of endosymbiotic bacteria, Sodalis, found in parasitic lice, Columbicola, that are independently undergoing genome degeneration. Here we show that the process of genome degeneration in this system is largely deterministic: genes involved in amino acid biosynthesis are lost while those involved in providing B-vitamins to the host are retained. In contrast, many genes encoding redundant functions, including components of the respiratory chain and DNA repair pathways, are subject to stochastic loss, yielding historical contingencies that constrain subsequent losses. Thus, while selection results in functional convergence between symbiont lineages, stochastic mutations initiate distinct evolutionary trajectories, generating diverse gene inventories that lack the functional redundancy typically found in free-living relatives.
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Affiliation(s)
- Bret M Boyd
- Center for Biological Data Science, Virginia Commonwealth University, Richmond, VA, US.
| | - Ian James
- School of Biological Sciences, University of Utah, Salt Lake City, UT, US
| | - Kevin P Johnson
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois, Champaign, IL, US
| | - Robert B Weiss
- Department of Human Genetics, University of Utah, Salt Lake City, UT, US
| | - Sarah E Bush
- School of Biological Sciences, University of Utah, Salt Lake City, UT, US
| | - Dale H Clayton
- School of Biological Sciences, University of Utah, Salt Lake City, UT, US
| | - Colin Dale
- School of Biological Sciences, University of Utah, Salt Lake City, UT, US
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4
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Liljegren MM, Gama JA, Johnsen PJ, Harms K. The recombination initiation functions DprA and RecFOR suppress microindel mutations in Acinetobacter baylyi ADP1. Mol Microbiol 2024. [PMID: 38760330 DOI: 10.1111/mmi.15277] [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: 11/22/2023] [Revised: 04/24/2024] [Accepted: 04/26/2024] [Indexed: 05/19/2024]
Abstract
Short-Patch Double Illegitimate Recombination (SPDIR) has been recently identified as a rare mutation mechanism. During SPDIR, ectopic DNA single-strands anneal with genomic DNA at microhomologies and get integrated during DNA replication, presumably acting as primers for Okazaki fragments. The resulting microindel mutations are highly variable in size and sequence. In the soil bacterium Acinetobacter baylyi, SPDIR is tightly controlled by genome maintenance functions including RecA. It is thought that RecA scavenges DNA single-strands and renders them unable to anneal. To further elucidate the role of RecA in this process, we investigate the roles of the upstream functions DprA, RecFOR, and RecBCD, all of which load DNA single-strands with RecA. Here we show that all three functions suppress SPDIR mutations in the wildtype to levels below the detection limit. While SPDIR mutations are slightly elevated in the absence of DprA, they are strongly increased in the absence of both DprA and RecA. This SPDIR-avoiding function of DprA is not related to its role in natural transformation. These results suggest a function for DprA in combination with RecA to avoid potentially harmful microindel mutations, and offer an explanation for the ubiquity of dprA in the genomes of naturally non-transformable bacteria.
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Affiliation(s)
- Mikkel M Liljegren
- Microbial Pharmacology and Population Biology Research Group, Department of Pharmacy, UiT The Arctic University of Norway, Tromsø, Norway
| | - João A Gama
- Microbial Pharmacology and Population Biology Research Group, Department of Pharmacy, UiT The Arctic University of Norway, Tromsø, Norway
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), Madrid, Spain
| | - Pål J Johnsen
- Microbial Pharmacology and Population Biology Research Group, Department of Pharmacy, UiT The Arctic University of Norway, Tromsø, Norway
| | - Klaus Harms
- Microbial Pharmacology and Population Biology Research Group, Department of Pharmacy, UiT The Arctic University of Norway, Tromsø, Norway
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5
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Bonde NJ, Wood EA, Myers KS, Place M, Keck JL, Cox MM. Identification of recG genetic interactions in Escherichia coli by transposon sequencing. J Bacteriol 2023; 205:e0018423. [PMID: 38019006 PMCID: PMC10870727 DOI: 10.1128/jb.00184-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 08/07/2023] [Indexed: 11/30/2023] Open
Abstract
IMPORTANCE DNA damage and subsequent DNA repair processes are mutagenic in nature and an important driver of evolution in prokaryotes, including antibiotic resistance development. Genetic screening approaches, such as transposon sequencing (Tn-seq), have provided important new insights into gene function and genetic relationships. Here, we employed Tn-seq to gain insight into the function of the recG gene, which renders Escherichia coli cells moderately sensitive to a variety of DNA-damaging agents when they are absent. The reported recG genetic interactions can be used in combination with future screens to aid in a more complete reconstruction of DNA repair pathways in bacteria.
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Affiliation(s)
- Nina J. Bonde
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Elizabeth A. Wood
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kevin S. Myers
- Great Lakes Bioenergy Research Center and the Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Michael Place
- Great Lakes Bioenergy Research Center and the Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - James L. Keck
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Michael M. Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
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6
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Rao TVP, Kuzminov A. Robust linear DNA degradation supports replication-initiation-defective mutants in Escherichia coli. G3 (BETHESDA, MD.) 2022; 12:jkac228. [PMID: 36165702 PMCID: PMC9635670 DOI: 10.1093/g3journal/jkac228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Accepted: 08/22/2022] [Indexed: 06/16/2023]
Abstract
RecBCD helicase/nuclease supports replication fork progress via recombinational repair or linear DNA degradation, explaining recBC mutant synthetic lethality with replication elongation defects. Since replication initiation defects leave chromosomes without replication forks, these should be insensitive to the recBCD status. Surprisingly, we found that both Escherichia coli dnaA46(Ts) and dnaC2(Ts) initiation mutants at semi-permissive temperatures are also recBC-colethal. Interestingly, dnaA46 recBC lethality suppressors suggest underinitiation as the problem, while dnaC2 recBC suppressors signal overintiation. Using genetic and physical approaches, we studied the dnaA46 recBC synthetic lethality, for the possibility that RecBCD participates in replication initiation. Overproduced DnaA46 mutant protein interferes with growth of dnaA+ cells, while the residual viability of the dnaA46 recBC mutant depends on the auxiliary replicative helicase Rep, suggesting replication fork inhibition by the DnaA46 mutant protein. The dnaA46 mutant depends on linear DNA degradation by RecBCD, rather than on recombinational repair. At the same time, the dnaA46 defect also interacts with Holliday junction-moving defects, suggesting reversal of inhibited forks. However, in contrast to all known recBC-colethals, which fragment their chromosomes, the dnaA46 recBC mutant develops no chromosome fragmentation, indicating that its inhibited replication forks are stable. Physical measurements confirm replication inhibition in the dnaA46 mutant shifted to semi-permissive temperatures, both at the level of elongation and initiation, while RecBCD gradually restores elongation and then initiation. We propose that RecBCD-catalyzed resetting of inhibited replication forks allows replication to displace the "sticky" DnaA46(Ts) protein from the chromosomal DNA, mustering enough DnaA for new initiations.
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Affiliation(s)
| | - Andrei Kuzminov
- Corresponding author: Department of Microbiology, University of Illinois at Urbana-Champaign, B103 C&LSL, 601 South Goodwin Avenue, Urbana, IL 61801-3709, USA.
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7
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Jain K, Stanage TH, Wood EA, Cox MM. The Escherichia coli serS gene promoter region overlaps with the rarA gene. PLoS One 2022; 17:e0260282. [PMID: 35427362 PMCID: PMC9012371 DOI: 10.1371/journal.pone.0260282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 04/05/2022] [Indexed: 11/25/2022] Open
Abstract
Deletion of the entire gene encoding the RarA protein of Escherichia coli results in a growth defect and additional deficiencies that were initially ascribed to a lack of RarA function. Further work revealed that most of the effects reflected the presence of sequences in the rarA gene that affect expression of the downstream gene, serS. The serS gene encodes the seryl aminoacyl-tRNA synthetase. Decreases in the expression of serS can trigger the stringent response. The sequences that affect serS expression are located in the last 15 nucleotides of the rarA gene.
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Affiliation(s)
- Kanika Jain
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
| | - Tyler H. Stanage
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Elizabeth A. Wood
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Michael M. Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
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Courcelle J, Worley TK, Courcelle CT. Recombination Mediator Proteins: Misnomers That Are Key to Understanding the Genomic Instabilities in Cancer. Genes (Basel) 2022; 13:genes13030437. [PMID: 35327990 PMCID: PMC8950967 DOI: 10.3390/genes13030437] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/24/2022] [Accepted: 02/24/2022] [Indexed: 02/06/2023] Open
Abstract
Recombination mediator proteins have come into focus as promising targets for cancer therapy, with synthetic lethal approaches now clinically validated by the efficacy of PARP inhibitors in treating BRCA2 cancers and RECQ inhibitors in treating cancers with microsatellite instabilities. Thus, understanding the cellular role of recombination mediators is critically important, both to improve current therapies and develop new ones that target these pathways. Our mechanistic understanding of BRCA2 and RECQ began in Escherichia coli. Here, we review the cellular roles of RecF and RecQ, often considered functional homologs of these proteins in bacteria. Although these proteins were originally isolated as genes that were required during replication in sexual cell cycles that produce recombinant products, we now know that their function is similarly required during replication in asexual or mitotic-like cell cycles, where recombination is detrimental and generally not observed. Cells mutated in these gene products are unable to protect and process replication forks blocked at DNA damage, resulting in high rates of cell lethality and recombination events that compromise genome integrity during replication.
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9
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Jain K, Wood EA, Romero ZJ, Cox MM. RecA-independent recombination: Dependence on the Escherichia coli RarA protein. Mol Microbiol 2021; 115:1122-1137. [PMID: 33247976 PMCID: PMC8160026 DOI: 10.1111/mmi.14655] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/29/2020] [Accepted: 11/20/2020] [Indexed: 11/30/2022]
Abstract
Most, but not all, homologous genetic recombination in bacteria is mediated by the RecA recombinase. The mechanistic origin of RecA-independent recombination has remained enigmatic. Here, we demonstrate that the RarA protein makes a major enzymatic contribution to RecA-independent recombination. In particular, RarA makes substantial contributions to intermolecular recombination and to recombination events involving relatively short (<200 bp) homologous sequences, where RecA-mediated recombination is inefficient. The effects are seen here in plasmid-based recombination assays and in vivo cloning processes. Vestigial levels of recombination remain even when both RecA and RarA are absent. Additional pathways for RecA-independent recombination, possibly mediated by helicases, are suppressed by exonucleases ExoI and RecJ. Translesion DNA polymerases may also contribute. Our results provide additional substance to a previous report of a functional overlap between RecA and RarA.
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Affiliation(s)
- Kanika Jain
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Elizabeth A Wood
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Zachary J Romero
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Michael M Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
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10
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Zhou X, Chen X, An Y, Lu H, Wang L, Xu H, Tian B, Zhao Y, Hua Y. Biochemical characterization of a unique DNA polymerase A from the extreme radioresistant organism Deinococcus radiodurans. Biochimie 2021; 185:22-32. [PMID: 33727139 DOI: 10.1016/j.biochi.2021.02.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/30/2021] [Accepted: 02/19/2021] [Indexed: 01/07/2023]
Abstract
Deinococcus radiodurans survives extraordinary doses of ionizing radiation and desiccation that cause numerous DNA strand breaks. D. radiodurans DNA polymerase A (DrPolA) is essential for reassembling the shattered genome, while its biochemical property has not been fully demonstrated. In this study, we systematically examined the enzymatic activities of DrPolA and characterized its unique features. DrPolA contains an N-terminal nuclease domain (DrPolA-NTD) and a C-terminal Klenow fragment (KlenDr). Compared with the Klenow fragment of E. coli Pol I, KlenDr shows higher fidelity despite the lacking of 3'-5' exonuclease proofreading activity and prefers double-strand DNA rather than Primer-Template substrates. Apart from the well-annotated 5'-3' exonuclease and flap endonuclease activities, DrPolA-NTD displays approximately 140-fold higher gap endonuclease activity than its homolog in E. coli and Human FEN1. Its 5'-3' exonuclease activity on ssDNA, gap endonuclease, and Holliday junction cleavage activities are greatly enhanced by Mn2+. The DrPolA-NTD deficient strain shows increased sensitivity to UV and gamma-ray radiation. Collectively, our results reveal distinct biochemical characteristics of DrPolA during DNA degradation and re-synthesis, which provide new insight into the outstanding DNA repair capacity of D. radiodurans.
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Affiliation(s)
- Xingru Zhou
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, China
| | - Xuanyi Chen
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, China
| | - Ying An
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, China
| | - Huizhi Lu
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, China
| | - Liangyan Wang
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, China
| | - Hong Xu
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, China
| | - Bing Tian
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, China
| | - Ye Zhao
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, China
| | - Yuejin Hua
- The MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, China.
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11
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Kim DS, Camacho CV, Kraus WL. Alternate therapeutic pathways for PARP inhibitors and potential mechanisms of resistance. Exp Mol Med 2021; 53:42-51. [PMID: 33487630 PMCID: PMC8080675 DOI: 10.1038/s12276-021-00557-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 10/12/2020] [Indexed: 01/29/2023] Open
Abstract
Homologous recombination (HR) repair deficiency impairs the proper maintenance of genomic stability, thus rendering cancer cells vulnerable to loss or inhibition of DNA repair proteins, such as poly(ADP-ribose) polymerase-1 (PARP-1). Inhibitors of nuclear PARPs are effective therapeutics for a number of different types of cancers. Here we review key concepts and current progress on the therapeutic use of PARP inhibitors (PARPi). PARPi selectively induce synthetic lethality in cancer cells with homologous recombination deficiencies (HRDs), the most notable being cancer cells harboring mutations in the BRCA1 and BRCA2 genes. Recent clinical evidence, however, shows that PARPi can be effective as cancer therapeutics regardless of BRCA1/2 or HRD status, suggesting that a broader population of patients might benefit from PARPi therapy. Currently, four PARPi have been approved by the Food and Drug Administration (FDA) for the treatment of advanced ovarian and breast cancer with deleterious BRCA mutations. Although PARPi have been shown to improve progression-free survival, cancer cells inevitably develop resistance, which poses a significant obstacle to the prolonged use of PARP inhibitors. For example, somatic BRCA1/2 reversion mutations are often identified in patients with BRCA1/2-mutated cancers after treatment with platinum-based therapy, causing restoration of HR capacity and thus conferring PARPi resistance. Accordingly, PARPi have been studied in combination with other targeted therapies to overcome PARPi resistance, enhance PARPi efficacy, and sensitize tumors to PARP inhibition. Moreover, multiple clinical trials are now actively underway to evaluate novel combinations of PARPi with other anticancer therapies for the treatment of PARPi-resistant cancer. In this review, we highlight the mechanisms of action of PARP inhibitors with or without BRCA1/2 defects and provide an overview of the ongoing clinical trials of PARPi. We also review the current progress on PARPi-based combination strategies and PARP inhibitor resistance.
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Affiliation(s)
- Dae-Seok Kim
- grid.267313.20000 0000 9482 7121Laboratory of Signaling and Gene Regulation, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA ,grid.267313.20000 0000 9482 7121Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA ,grid.267313.20000 0000 9482 7121Present Address: Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Cristel V. Camacho
- grid.267313.20000 0000 9482 7121Laboratory of Signaling and Gene Regulation, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA ,grid.267313.20000 0000 9482 7121Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - W. Lee Kraus
- grid.267313.20000 0000 9482 7121Laboratory of Signaling and Gene Regulation, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA ,grid.267313.20000 0000 9482 7121Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
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12
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Zhang H, Schaub JM, Finkelstein IJ. RADX condenses single-stranded DNA to antagonize RAD51 loading. Nucleic Acids Res 2020; 48:7834-7843. [PMID: 32621611 PMCID: PMC7430644 DOI: 10.1093/nar/gkaa559] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 06/15/2020] [Accepted: 06/18/2020] [Indexed: 12/31/2022] Open
Abstract
RADX is a mammalian single-stranded DNA-binding protein that stabilizes telomeres and stalled replication forks. Cellular biology studies have shown that the balance between RADX and Replication Protein A (RPA) is critical for DNA replication integrity. RADX is also a negative regulator of RAD51-mediated homologous recombination at stalled forks. However, the mechanism of RADX acting on DNA and its interactions with RPA and RAD51 are enigmatic. Using single-molecule imaging of the key proteins in vitro, we reveal that RADX condenses ssDNA filaments, even when the ssDNA is coated with RPA at physiological protein ratios. RADX compacts RPA-coated ssDNA filaments via higher-order assemblies that can capture ssDNA in trans. Furthermore, RADX blocks RPA displacement by RAD51 and prevents RAD51 loading on ssDNA. Our results indicate that RADX is an ssDNA condensation protein that inhibits RAD51 filament formation and may antagonize other ssDNA-binding proteins on RPA-coated ssDNA.
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Affiliation(s)
- Hongshan Zhang
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Jeffrey M Schaub
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.,Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA
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13
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Jolly SM, Gainetdinov I, Jouravleva K, Zhang H, Strittmatter L, Bailey SM, Hendricks GM, Dhabaria A, Ueberheide B, Zamore PD. Thermus thermophilus Argonaute Functions in the Completion of DNA Replication. Cell 2020; 182:1545-1559.e18. [PMID: 32846159 PMCID: PMC7502556 DOI: 10.1016/j.cell.2020.07.036] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/25/2020] [Accepted: 07/24/2020] [Indexed: 01/06/2023]
Abstract
In many eukaryotes, Argonaute proteins, guided by short RNA sequences, defend cells against transposons and viruses. In the eubacterium Thermus thermophilus, the DNA-guided Argonaute TtAgo defends against transformation by DNA plasmids. Here, we report that TtAgo also participates in DNA replication. In vivo, TtAgo binds 15- to 18-nt DNA guides derived from the chromosomal region where replication terminates and associates with proteins known to act in DNA replication. When gyrase, the sole T. thermophilus type II topoisomerase, is inhibited, TtAgo allows the bacterium to finish replicating its circular genome. In contrast, loss of gyrase and TtAgo activity slows growth and produces long sausage-like filaments in which the individual bacteria are linked by DNA. Finally, wild-type T. thermophilus outcompetes an otherwise isogenic strain lacking TtAgo. We propose that the primary role of TtAgo is to help T. thermophilus disentangle the catenated circular chromosomes generated by DNA replication.
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Affiliation(s)
- Samson M Jolly
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Howard Hughes Medical Institute and RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Ildar Gainetdinov
- Howard Hughes Medical Institute and RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Karina Jouravleva
- Howard Hughes Medical Institute and RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Han Zhang
- Howard Hughes Medical Institute and RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Lara Strittmatter
- Department of Radiology, Division of Cell Biology and Imaging, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Shannon M Bailey
- Howard Hughes Medical Institute and RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Gregory M Hendricks
- Department of Radiology, Division of Cell Biology and Imaging, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Avantika Dhabaria
- Proteomics Laboratory, Division of Advanced Research Technologies, New York University School of Medicine, New York, NY 10016, USA
| | - Beatrix Ueberheide
- Proteomics Laboratory, Division of Advanced Research Technologies, New York University School of Medicine, New York, NY 10016, USA; Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; Center for Cognitive Neurology, Department of Neurology, New York University School of Medicine, New York, NY 10016, USA
| | - Phillip D Zamore
- Howard Hughes Medical Institute and RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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14
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Krais JJ, Johnson N. BRCA1 Mutations in Cancer: Coordinating Deficiencies in Homologous Recombination with Tumorigenesis. Cancer Res 2020; 80:4601-4609. [PMID: 32747362 PMCID: PMC7641968 DOI: 10.1158/0008-5472.can-20-1830] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/15/2020] [Accepted: 07/29/2020] [Indexed: 01/08/2023]
Abstract
Cancers that arise from BRCA1 germline mutations are deficient for homologous recombination (HR) DNA repair and are sensitive to DNA-damaging agents such as platinum and PARP inhibitors. In vertebrate organisms, knockout of critical HR genes including BRCA1 and BRCA2 is lethal because HR is required for genome replication. Thus, cancers must develop strategies to cope with loss of HR activity. Furthermore, as established tumors respond to chemotherapy selection pressure, additional genetic adaptations transition cancers to an HR-proficient state. In this review, we discuss biological mechanisms that influence the ability of BRCA1-mutant cancers to perform HR. Furthermore, we consider how the HR status fluctuates throughout the cancer life course, from tumor initiation to the development of therapy refractory disease.
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Affiliation(s)
- John J Krais
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Neil Johnson
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania.
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15
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Huang Y, Yang S, Chen W, Li F, Xia A, Ni L, Yang G, Jin F. A Synthetic Genetic Circuit Enables Precise Quantification of Direct Repeat Deletion in Bacteria. ACS Synth Biol 2020; 9:1041-1050. [PMID: 32298577 DOI: 10.1021/acssynbio.9b00256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Quantification of the rate of direct repeat deletion (DRD) is an important aspect in the research of DNA rearrangement. The widely used tetracycline selection method usually introduces antibiotic pressure to the tested organism, which may interfere with the DRD process. Also the length of repeat arm (LRA) is limited by the length of the TetR coding sequence. On the basis of the fluorescent microscopy and high-throughput imaging processing, here we developed a two-module genetic circuit, termed TFDEC (which stands for three-color fluorescence-based deletion event counter), to quantify the DRD rate under neutral conditions. DRD events were determined from the state of a three-state fluorescent logic gate constructed through coupling of an OR gate and an AND gate. TFDEC was applied in Pseudomonas aeruginosa, and we found that the DRD rate was RecA-dependent for long repeat arms (>500 bp) and RecA-independent for short repeat arms (<500 bp), which was consistent with the case in Escherichia coli. In addition, the increase of DRD rate followed an S-shaped curve with the increase of LRA, while treating cells with ciprofloxacin did not change the LRA-dependence of DRD. We also detected a significant increased DRD rate for long repeat arms in the uvrD (8-fold) and radA (4-fold) mutants. Our results show that the TFDEC method could be used as a complement tool for quantification of the DRD rate in the future.
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Affiliation(s)
- Yajia Huang
- Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
- Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences; Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Shuai Yang
- Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences; Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Wenhui Chen
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Feixuan Li
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Aiguo Xia
- Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences; Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Lei Ni
- Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences; Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Guang Yang
- Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Fan Jin
- Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences; Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, P. R. China
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16
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Palmer N, Kaldis P. Less-well known functions of cyclin/CDK complexes. Semin Cell Dev Biol 2020; 107:54-62. [PMID: 32386818 DOI: 10.1016/j.semcdb.2020.04.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 12/31/2022]
Abstract
Cyclin-dependent kinases (CDKs) are activated by cyclins, which play important roles in dictating the actions of CDK/cyclin complexes. Cyclin binding influences the substrate specificity of these complexes in addition to their susceptibility to inhibition or degradation. CDK/cyclin complexes are best known to promote cell cycle progression in the mitotic cell cycle but are also crucial for important cellular processes not strictly associated with cellular division. This chapter primarily explores the understudied topic of CDK/cyclin complex functionality during the DNA damage response. We detail how CDK/cyclin complexes perform dual roles both as targets of DNA damage checkpoint signaling as well as effectors of DNA repair. Additionally, we discuss the potential CDK-independent roles of cyclins in these processes and the impact of such roles in human diseases such as cancer. Our goal is to place the spotlight on these important functions of cyclins either acting as independent entities or within CDK/cyclin complexes which have attracted less attention in the past. We consider that this will be important for a more complete understanding of the intricate functions of cell cycle proteins in the DNA damage response.
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Affiliation(s)
- Nathan Palmer
- Institute of Molecular and Cell Biology (IMCB), A⁎STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore; National University of Singapore (NUS), Department of Biochemistry, Singapore, 117597, Republic of Singapore
| | - Philipp Kaldis
- Institute of Molecular and Cell Biology (IMCB), A⁎STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore; National University of Singapore (NUS), Department of Biochemistry, Singapore, 117597, Republic of Singapore; Department of Clinical Sciences, Lund University, Clinical Research Centre (CRC), Box 50332, SE-202 13, Malmö, Sweden.
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17
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Wu Z, Li S, Tang X, Wang Y, Guo W, Cao G, Chen K, Zhang M, Guan M, Yang D. Copy Number Amplification of DNA Damage Repair Pathways Potentiates Therapeutic Resistance in Cancer. Am J Cancer Res 2020; 10:3939-3951. [PMID: 32226530 PMCID: PMC7086350 DOI: 10.7150/thno.39341] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/22/2019] [Indexed: 01/10/2023] Open
Abstract
Rationale: Loss of DNA damage repair (DDR) in the tumor is an established hallmark of sensitivity to DNA damaging agents such as chemotherapy. However, there has been scant investigation into gain-of-function alterations of DDR genes in cancer. This study aims to investigate to what extent copy number amplification of DDR genes occurs in cancer, and what are their impacts on tumor genome instability, patient prognosis and therapy outcome. Methods: Retrospective analysis was performed on the clinical, genomics, and pharmacogenomics data from 10,489 tumors, matched peripheral blood samples, and 1,005 cancer cell lines. The key discoveries were verified by an independent patient cohort and experimental validations. Results: This study revealed that 13 of the 80 core DDR genes were significantly amplified and overexpressed across the pan-cancer scale. Tumors harboring DDR gene amplification exhibited decreased global mutation load and mechanism-specific mutation signature scores, suggesting an increased DDR proficiency in the DDR amplified tumors. Clinically, patients with DDR gene amplification showed poor prognosis in multiple cancer types. The most frequent Nibrin (NBN) gene amplification in ovarian cancer tumors was observed in 15 out of 31 independent ovarian cancer patients. NBN overexpression in breast and ovarian cancer cells leads to BRCA1-dependent olaparib resistance by promoting the phosphorylation of ATM-S1981 and homology-dependent recombination efficiency. Finally, integration of the cancer pharmacogenomics database of 37 genome-instability targeting drugs across 505 cancer cell lines revealed significant correlations between DDR gene copy number amplification and DDR drug resistance, suggesting candidate targets for increasing patient treatment response. Principal Conclusions: DDR gene amplification can lead to chemotherapy resistance and poor overall survival by augmenting DDR. These amplified DDR genes may serve as actionable clinical biomarkers for cancer management.
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18
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Romero H, Serrano E, Hernández-Tamayo R, Carrasco B, Cárdenas PP, Ayora S, Graumann PL, Alonso JC. Bacillus subtilis RarA Acts as a Positive RecA Accessory Protein. Front Microbiol 2020; 11:92. [PMID: 32117122 PMCID: PMC7031210 DOI: 10.3389/fmicb.2020.00092] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 01/16/2020] [Indexed: 01/15/2023] Open
Abstract
Ubiquitous RarA AAA+ ATPases play crucial roles in the cellular response to blocked replication forks in pro- and eukaryotes. Here, we provide evidence that absence of RarA reduced the viability of ΔrecA, ΔrecO, and recF15 cells during unperturbed growth. The rarA gene was epistatic to recO and recF genes in response to H2O2- or MMS-induced DNA damage. Conversely, the inactivation of rarA partially suppressed the HR defect of mutants lacking end-resection (ΔaddAB, ΔrecJ, ΔrecQ, ΔrecS) or branch migration (ΔruvAB, ΔrecG, ΔradA) activity. RarA contributes to RecA thread formation, that are thought to be the active forms of RecA during homology search. The absence of RarA reduced RecA accumulation, and the formation of visible RecA threads in vivo upon DNA damage. When ΔrarA was combined with mutations in genuine RecA accessory genes, RecA accumulation was further reduced in ΔrarA ΔrecU and ΔrarA ΔrecX double mutant cells, and was blocked in ΔrarA recF15 cells. These results suggest that RarA contributes to the assembly of RecA nucleoprotein filaments onto single-stranded DNA, and possibly antagonizes RecA filament disassembly.
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Affiliation(s)
- Hector Romero
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
- SYNMIKRO, LOEWE-Zentrum für Synthetische Mikrobiologie, Marburg, Germany
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | - Ester Serrano
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
| | - Rogelio Hernández-Tamayo
- SYNMIKRO, LOEWE-Zentrum für Synthetische Mikrobiologie, Marburg, Germany
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | - Begoña Carrasco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
| | - Paula P. Cárdenas
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
| | - Silvia Ayora
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
| | - Peter L. Graumann
- SYNMIKRO, LOEWE-Zentrum für Synthetische Mikrobiologie, Marburg, Germany
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | - Juan C. Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
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19
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Wimmer F, Beisel CL. CRISPR-Cas Systems and the Paradox of Self-Targeting Spacers. Front Microbiol 2020; 10:3078. [PMID: 32038537 PMCID: PMC6990116 DOI: 10.3389/fmicb.2019.03078] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 12/19/2019] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas immune systems in bacteria and archaea record prior infections as spacers within each system’s CRISPR arrays. Spacers are normally derived from invasive genetic material and direct the immune system to complementary targets as part of future infections. However, not all spacers appear to be derived from foreign genetic material and instead can originate from the host genome. Their presence poses a paradox, as self-targeting spacers would be expected to induce an autoimmune response and cell death. In this review, we discuss the known frequency of self-targeting spacers in natural CRISPR-Cas systems, how these spacers can be incorporated into CRISPR arrays, and how the host can evade lethal attack. We also discuss how self-targeting spacers can become the basis for alternative functions performed by CRISPR-Cas systems that extend beyond adaptive immunity. Overall, the acquisition of genome-targeting spacers poses a substantial risk but can aid in the host’s evolution and potentially lead to or support new functionalities.
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Affiliation(s)
- Franziska Wimmer
- Helmholtz Institute for RNA-Based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany
| | - Chase L Beisel
- Helmholtz Institute for RNA-Based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany.,Medical Faculty, University of Würzburg, Würzburg, Germany
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20
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Torres R, Carrasco B, Gándara C, Baidya AK, Ben-Yehuda S, Alonso JC. Bacillus subtilis DisA regulates RecA-mediated DNA strand exchange. Nucleic Acids Res 2019; 47:5141-5154. [PMID: 30916351 PMCID: PMC6547438 DOI: 10.1093/nar/gkz219] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/15/2019] [Accepted: 03/19/2019] [Indexed: 01/12/2023] Open
Abstract
Bacillus subtilis diadenylate cyclase DisA converts two ATPs into c-di-AMP, but this activity is suppressed upon interaction with sites of DNA damage. DisA forms a rapid moving focus that pauses upon induction of DNA damage during spore development. We report that DisA pausing, however, was not observed in the absence of the RecO mediator or of the RecA recombinase, suggesting that DisA binds to recombination intermediates formed by RecA in concert with RecO. DisA, which physically interacts with RecA, was found to reduce its ATPase activity without competing for nucleotides or ssDNA. Furthermore, increasing DisA concentrations inhibit RecA-mediated DNA strand exchange, but this inhibition failed to occur when RecA was added prior to DisA, and was independent of RecA-mediated nucleotide hydrolysis or increasing concentrations of c-di-AMP. We propose that DisA may preserve genome integrity by downregulating RecA activities at several steps of the DNA damage tolerance pathway, allowing time for the repair machineries to restore genome stability. DisA might reduce RecA-mediated template switching by binding to a stalled or reversed fork.
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Affiliation(s)
- Rubén Torres
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin St, 28049 Madrid, Spain
| | - Begoña Carrasco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin St, 28049 Madrid, Spain
| | - Carolina Gándara
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin St, 28049 Madrid, Spain
| | - Amit K Baidya
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, POB 12272, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Sigal Ben-Yehuda
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, POB 12272, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin St, 28049 Madrid, Spain
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21
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Ojha D, Patil KN. Molecular and functional characterization of the Listeria monocytogenes RecA protein: Insights into the homologous recombination process. Int J Biochem Cell Biol 2019; 119:105642. [PMID: 31698090 DOI: 10.1016/j.biocel.2019.105642] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Revised: 10/20/2019] [Accepted: 10/31/2019] [Indexed: 12/28/2022]
Abstract
The recombinases present in the all kingdoms in nature play a crucial role in DNA metabolism processes such as replication, repair, recombination and transcription. However, till date, the role of RecA in the deadly foodborne pathogen Listeria monocytogenes remains unknown. In this study, the authors show that L. monocytogenes expresses recA more than two-fold in vivo upon exposure to the DNA damaging agents, methyl methanesulfonate and ultraviolet radiation. The purified L. monocytogenes RecA protein show robust binding to single stranded DNA. The RecA is capable of forming displacement loop and hydrolyzes ATP, whereas the mutant LmRecAK70A fails to hydrolyze ATP, showing conserved walker A and B motifs. Interestingly, L. monocytogenes RecA and LmRecAK70A perform the DNA strand transfer activity, which is the hallmark feature of RecA protein with an oligonucleotide-based substrate. Notably, L. monocytogenes RecA readily cleaves L. monocytogenes LexA, the SOS regulon and protects the presynaptic filament from the exonuclease I activity. Altogether, this study provides the first detailed characterization of L. monocytogenes RecA and presents important insights into the process of homologous recombination in the gram-positive foodborne bacteria L. monocytogenes.
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Affiliation(s)
- Debika Ojha
- Department of Protein Chemistry and Technology, Council of Scientific & Industrial Research-Central Food Technological Research Institute (CSIR-CFTRI), Mysuru, 570 020, Karnataka, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, Uttar Pradesh, India
| | - K Neelakanteshwar Patil
- Department of Protein Chemistry and Technology, Council of Scientific & Industrial Research-Central Food Technological Research Institute (CSIR-CFTRI), Mysuru, 570 020, Karnataka, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, Uttar Pradesh, India.
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22
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Kim R, Kanamaru S, Mikawa T, Prévost C, Ishii K, Ito K, Uchiyama S, Oda M, Iwasaki H, Kim SK, Takahashi M. RecA requires two molecules of Mg2+ ions for its optimal strand exchange activity in vitro. Nucleic Acids Res 2019; 46:2548-2559. [PMID: 29390145 PMCID: PMC5861410 DOI: 10.1093/nar/gky048] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 01/23/2018] [Indexed: 11/15/2022] Open
Abstract
Mg2+ ion stimulates the DNA strand exchange reaction catalyzed by RecA, a key step in homologous recombination. To elucidate the molecular mechanisms underlying the role of Mg2+ and the strand exchange reaction itself, we investigated the interaction of RecA with Mg2+ and sought to determine which step of the reaction is affected. Thermal stability, intrinsic fluorescence, and native mass spectrometric analyses of RecA revealed that RecA binds at least two Mg2+ ions with KD ≈ 2 mM and 5 mM. Deletion of the C-terminal acidic tail of RecA made its thermal stability and fluorescence characteristics insensitive to Mg2+ and similar to those of full-length RecA in the presence of saturating Mg2+. These observations, together with the results of a molecular dynamics simulation, support the idea that the acidic tail hampers the strand exchange reaction by interacting with other parts of RecA, and that binding of Mg2+ to the tail prevents these interactions and releases RecA from inhibition. We observed that binding of the first Mg2+ stimulated joint molecule formation, whereas binding of the second stimulated progression of the reaction. Thus, RecA is actively involved in the strand exchange step as well as bringing the two DNAs close to each other.
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Affiliation(s)
- Raeyeong Kim
- Department of Chemistry, Yeungnam University, Gyeonsan-city 38541, Republic of Korea
| | - Shuji Kanamaru
- School of Life Science and Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Tsutomu Mikawa
- RIKEN Quantitative Biology Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Chantal Prévost
- Laboratoire de Biochimie Théorique, UPR9080 CNRS Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Kentaro Ishii
- Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan
| | - Kentaro Ito
- School of Life Science and Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Susumu Uchiyama
- Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan.,Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Masayuki Oda
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, 1-5 Hangi-cho, Shimogamo, Sakyo-ku, Kyoto 606-8522, Japan
| | - Hiroshi Iwasaki
- School of Life Science and Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Seog K Kim
- Department of Chemistry, Yeungnam University, Gyeonsan-city 38541, Republic of Korea
| | - Masayuki Takahashi
- School of Life Science and Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
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23
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Abstract
CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against invasion by bacteriophages and other mobile genetic elements. Short fragments of invader DNA are stored as immunological memories within CRISPR (clustered regularly interspaced short palindromic repeat) arrays in the host chromosome. These arrays provide a template for RNA molecules that can guide CRISPR-associated (Cas) proteins to specifically neutralize viruses upon subsequent infection. Over the past 10 years, our understanding of CRISPR-Cas systems has benefited greatly from a number of model organisms. In particular, the study of several members of the Gram-negative Enterobacteriaceae family, especially Escherichia coli and Pectobacterium atrosepticum, have provided significant insights into the mechanisms of CRISPR-Cas immunity. In this review, we provide an overview of CRISPR-Cas systems present in members of the Enterobacteriaceae. We also detail the current mechanistic understanding of the type I-E and type I-F CRISPR-Cas systems that are commonly found in enterobacteria. Finally, we discuss how phages can escape or inactivate CRISPR-Cas systems and the measures bacteria can enact to counter these types of events.
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24
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Thymineless Death in Escherichia coli Is Unaffected by Chromosomal Replication Complexity. J Bacteriol 2019; 201:JB.00797-18. [PMID: 30745374 DOI: 10.1128/jb.00797-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 02/06/2019] [Indexed: 11/20/2022] Open
Abstract
Thymineless death (TLD) is a rapid loss of viability of unclear mechanism in cultures of thyA mutants starved for thymine/thymidine (T starvation). It is accepted that T starvation repeatedly breaks replication forks, while recombinational repair restores them, but when the resulting futile breakage-repair cycle affects the small replication bubbles at oriC, the origin is degraded, killing the cell. Indeed, cells with increased chromosomal replication complexity (CRC), expressed as an elevated origin/terminus (ori/ter) ratio, die more extensively during TLD. Here we tested this logic by elevating the CRC in Escherichia coli thyA mutants before T starvation, anticipating exaggerated TLD. Unexpectedly, TLD remained unaffected by a CRC increase to either the natural limit (ori/ter ratio, ∼6) or the functional limit (ori/ter ratio, ∼16). Moreover, when we forced the CRC over the functional limit (ori/ter ratio, ∼30), TLD lessened. Thus, prior overinitiation does not sensitize cells to TLD. In contradiction with the published results, even blocking new replication initiations by the dnaA(Ts) defect at 42°C fails to prevent TLD. Using the thyA dnaA(Ts) mutant in a new T starvation protocol that excludes new initiations, we show that at 42°C, the same degree of TLD still occurs when chromosomes are demonstrably nonreplicating. Remarkably, 80% of the chromosomal DNA in these nonreplicating T-starved cells is still lost, by an unclear mechanism.IMPORTANCE Thymineless death kills cells of any type and is used in anticancer and antimicrobial treatments. We tested the idea that the more replication forks there are in the chromosome during growth, the more extensive the resulting thymineless death. We varied the number of replication forks in the Escherichia coli chromosome, as measured by the origin-to-terminus ratio, ranging it from the normal 2 to 60, and even completely eliminated replication forks in the nonreplicating chromosomes (ori/ter ratio = 1). Unexpectedly, we found that thymineless death is unaffected by the intensity of replication or by its complete absence; we also found that even nonreplicating chromosomes still disappear during thymine starvation. We conclude that thymineless death can kill E. coli independently of chromosomal replication.
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25
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Nouri H, Monnier AF, Fossum-Raunehaug S, Maciag-Dorszynska M, Cabin-Flaman A, Képès F, Wegrzyn G, Szalewska-Palasz A, Norris V, Skarstad K, Janniere L. Multiple links connect central carbon metabolism to DNA replication initiation and elongation in Bacillus subtilis. DNA Res 2019; 25:641-653. [PMID: 30256918 PMCID: PMC6289782 DOI: 10.1093/dnares/dsy031] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 08/17/2018] [Indexed: 12/27/2022] Open
Abstract
DNA replication is coupled to growth by an unknown mechanism. Here, we investigated this coupling by analyzing growth and replication in 15 mutants of central carbon metabolism (CCM) cultivated in three rich media. In about one-fourth of the condition tested, defects in replication resulting from changes in initiation or elongation were detected. This uncovered 11 CCM genes important for replication and showed that some of these genes have an effect in one, two or three media. Additional results presented here and elsewhere (Jannière, L., Canceill, D., Suski, C., et al. (2007), PLoS One, 2, e447.) showed that, in the LB medium, the CCM genes important for DNA elongation (gapA and ackA) are genetically linked to the lagging strand polymerase DnaE while those important for initiation (pgk and pykA) are genetically linked to the replication enzymes DnaC (helicase), DnaG (primase) and DnaE. Our work thus shows that the coupling between growth and replication involves multiple, medium-dependent links between CCM and replication. They also suggest that changes in CCM may affect initiation by altering the functional recruitment of DnaC, DnaG and DnaE at the chromosomal origin, and may affect elongation by altering the activity of DnaE at the replication fork. The underlying mechanism is discussed.
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Affiliation(s)
- Hamid Nouri
- iSSB, Génopole, CNRS, UEVE, Université Paris-Saclay, Evry France.,MICALIS, INRA, Jouy en Josas, France
| | | | | | | | | | - François Képès
- iSSB, Génopole, CNRS, UEVE, Université Paris-Saclay, Evry France
| | - Grzegorz Wegrzyn
- Department of Molecular Biology, University of Gdansk, Gdansk, Poland
| | | | - Vic Norris
- Laboratoire MERCI, AMMIS, Faculté des Sciences, Mont-Saint-Aignan, France
| | - Kirsten Skarstad
- Department of Cell Biology, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Laurent Janniere
- iSSB, Génopole, CNRS, UEVE, Université Paris-Saclay, Evry France.,MICALIS, INRA, Jouy en Josas, France
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26
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The in vivo and in vitro roles of Trypanosoma cruzi Rad51 in the repair of DNA double strand breaks and oxidative lesions. PLoS Negl Trop Dis 2018; 12:e0006875. [PMID: 30422982 PMCID: PMC6258567 DOI: 10.1371/journal.pntd.0006875] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 11/27/2018] [Accepted: 09/26/2018] [Indexed: 11/22/2022] Open
Abstract
In Trypanosoma cruzi, the etiologic agent of Chagas disease, Rad51 (TcRad51) is a central enzyme for homologous recombination. Here we describe the different roles of TcRad51 in DNA repair. Epimastigotes of T. cruzi overexpressing TcRAD51 presented abundant TcRad51-labeled foci before gamma irradiation treatment, and a faster growth recovery when compared to single-knockout epimastigotes for RAD51. Overexpression of RAD51 also promoted increased resistance against hydrogen peroxide treatment, while the single-knockout epimastigotes for RAD51 exhibited increased sensitivity to this oxidant agent, which indicates a role for this gene in the repair of DNA oxidative lesions. In contrast, TcRad51 was not involved in the repair of crosslink lesions promoted by UV light and cisplatin treatment. Also, RAD51 single-knockout epimastigotes showed a similar growth rate to that exhibited by wild-type ones after treatment with hydroxyurea, but an increased sensitivity to methyl methane sulfonate. Besides its role in epimastigotes, TcRad51 is also important during mammalian infection, as shown by increased detection of T. cruzi cells overexpressing RAD51, and decreased detection of single-knockout cells for RAD51, in both fibroblasts and macrophages infected with amastigotes. Besides that, RAD51-overexpressing parasites infecting mice also presented increased infectivity and higher resistance against benznidazole. We thus show that TcRad51 is involved in the repair of DNA double strands breaks and oxidative lesions in two different T. cruzi developmental stages, possibly playing an important role in the infectivity of this parasite. Trypanosoma cruzi is the causative agent of Chagas disease, a tropical neglected illness that affects 6 million people worldwide, mostly in Latin America. Our research group focuses on the elucidation of DNA repair and metabolism of T. cruzi, and on the possible implications of those mechanisms in both parasite genetic diversity and Chagas disease development. In this work, we investigated the involvement of homologous recombination in the oxidation-induced damage response, and in DNA repair, in T. cruzi cells after gamma radiation exposure. We also examined whether TcRad51 –a key protein for homologous recombination–could be an important factor for T. cruzi’s infectivity. We generated genetically-modified T. cruzi cells for RAD51 and studied the in vitro and in vivo infectivity of these mutant cells. Our results indicate that TcRad51 is a key protein involved in the repair of oxidative and DNA double-strand breaks lesions in two crucial developmental forms of T. cruzi.
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27
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Singh A, Vijayan M, Nagaraju G. RecG wed : A probable novel regulator in the resolution of branched DNA structures in mycobacteria. IUBMB Life 2018; 70:786-794. [PMID: 30240108 DOI: 10.1002/iub.1881] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 05/02/2018] [Accepted: 05/04/2018] [Indexed: 01/31/2023]
Abstract
Structure-specific helicases, such as RecG, play an important role in the resolution of recombination intermediates. A bioinformatic analysis of mycobacterial genomes led to the identification of a protein (RecGwed ) with a C-terminal "edge" domain, similar to the wedge domain of RecG. RecGwed is predominately found in the phylum Actinobacteria and in few human pathogens. Mycobacterium smegmatis RecGwed was able to bind branched DNA structures in vitro but failed to interact with single- or double-stranded DNA. The expression of recGwed in M. smegmatis cells was up-regulated during stationary phase/UV damage and down-regulated during MMS/H2 O2 treatment. These observations indicate the possible involvement of RecGwed in transactions during recombination events, that proceed though branched DNA intermediates. © 2018 IUBMB Life, 70(8):786-794, 2018.
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Affiliation(s)
- Amandeep Singh
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - M Vijayan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Ganesh Nagaraju
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
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28
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Carrasco B, Seco EM, López-Sanz M, Alonso JC, Ayora S. Bacillus subtilis RarA modulates replication restart. Nucleic Acids Res 2018; 46:7206-7220. [PMID: 29947798 PMCID: PMC6101539 DOI: 10.1093/nar/gky541] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/05/2018] [Indexed: 02/01/2023] Open
Abstract
The ubiquitous RarA/Mgs1/WRNIP protein plays a crucial, but poorly understood role in genome maintenance. We show that Bacillus subtilis RarA, in the apo form, preferentially binds single-stranded (ss) over double-stranded (ds) DNA. SsbA bound to ssDNA loads RarA, and for such recruitment the amphipathic C-terminal domain of SsbA is required. RarA is a DNA-dependent ATPase strongly stimulated by ssDNA–dsDNA junctions and SsbA, or by dsDNA ends. RarA, which may interact with PriA, does not stimulate PriA DNA unwinding. In a reconstituted PriA-dependent DNA replication system, RarA inhibited initiation, but not chain elongation. The RarA effect was not observed in the absence of SsbA, or when the host-encoded preprimosome and the DNA helicase are replaced by proteins from the SPP1 phage with similar function. We propose that RarA assembles at blocked forks to maintain genome integrity. Through its interaction with SsbA and with a preprimosomal component, RarA might impede the assembly of the replicative helicase, to prevent that recombination intermediates contribute to pathological DNA replication restart.
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Affiliation(s)
- Begoña Carrasco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, (CNB-CSIC), Cantoblanco 28049, Madrid, Spain
| | - Elena M Seco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, (CNB-CSIC), Cantoblanco 28049, Madrid, Spain
| | - María López-Sanz
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, (CNB-CSIC), Cantoblanco 28049, Madrid, Spain
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, (CNB-CSIC), Cantoblanco 28049, Madrid, Spain
| | - Silvia Ayora
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, (CNB-CSIC), Cantoblanco 28049, Madrid, Spain
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29
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Liu H, Xie Y, Zhang Z, Mao P, Liu J, Ma W, Zhao Y. Telomeric Recombination Induced by DNA Damage Results in Telomere Extension and Length Heterogeneity. Neoplasia 2018; 20:905-916. [PMID: 30118998 PMCID: PMC6097467 DOI: 10.1016/j.neo.2018.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/20/2018] [Accepted: 07/24/2018] [Indexed: 12/11/2022] Open
Abstract
About 15% of human cancers counteract telomere loss by alternative lengthening of telomeres (ALT), which is attributed to homologous recombination (HR)–mediated events. But how telomeric HR leads to length elongation is poorly understood. Here, we explore telomere clustering and telomeric HR induced by double-stranded breaks (DSBs). We show that telomere clustering could occur at G1 and S phase of cell cycle and that three types of telomeric HR occur based on the manner of telomeric DNA exchange: equivalent telomeric sister chromatin exchange (T-SCE), inequivalent T-SCE, and No-SCE. While inequivalent T-SCE increases telomere length heterogeneity with no net gain of telomere length, No-SCE, which is presumably induced by interchromatid HR and/or break-induced replication, results in telomere elongation. Accordingly, cells subjected to long-term telomeric DSBs display increased heterogeneity of length and longer telomeres. We also demonstrate that DSBs-induced telomere elongation is telomerase independent. Moreover, telomeric recombination induced by DSBs is associated with formation of ALT-associated PML body and C-circle. Thus, DNA damage triggers recombination mediated elongation, leading to the induction of multiple ALT phenotypes.
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Affiliation(s)
- Haiying Liu
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Yujie Xie
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Zepeng Zhang
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Pingsu Mao
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Jingfan Liu
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Wenbin Ma
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China
| | - Yong Zhao
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China.
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30
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Maduro MF. Genetic interaction between DNA replication and the Notch signaling pathway. FEBS J 2018; 285:2586-2589. [PMID: 29956459 DOI: 10.1111/febs.14584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 06/12/2018] [Indexed: 11/28/2022]
Abstract
The Notch pathway is a widely conserved cell signaling system found in most metazoans. In Caenorhabditis elegans, GLP-1/Notch signaling is required for developmental cell fate decisions in multiple contexts. A recent report provides a potential link between DNA replication and Notch-dependent proliferation in the C. elegans germline.
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Affiliation(s)
- Morris F Maduro
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, USA
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31
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Sinha AK, Possoz C, Durand A, Desfontaines JM, Barre FX, Leach DRF, Michel B. Broken replication forks trigger heritable DNA breaks in the terminus of a circular chromosome. PLoS Genet 2018. [PMID: 29522563 PMCID: PMC5862497 DOI: 10.1371/journal.pgen.1007256] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
It was recently reported that the recBC mutants of Escherichia coli, deficient for DNA double-strand break (DSB) repair, have a decreased copy number of their terminus region. We previously showed that this deficit resulted from DNA loss after post-replicative breakage of one of the two sister-chromosome termini at cell division. A viable cell and a dead cell devoid of terminus region were thus produced and, intriguingly, the reaction was transmitted to the following generations. Using genome marker frequency profiling and observation by microscopy of specific DNA loci within the terminus, we reveal here the origin of this phenomenon. We observed that terminus DNA loss was reduced in a recA mutant by the double-strand DNA degradation activity of RecBCD. The terminus-less cell produced at the first cell division was less prone to divide than the one produced at the next generation. DNA loss was not heritable if the chromosome was linearized in the terminus and occurred at chromosome termini that were unable to segregate after replication. We propose that in a recB mutant replication fork breakage results in the persistence of a linear DNA tail attached to a circular chromosome. Segregation of the linear and circular parts of this "σ-replicating chromosome" causes terminus DNA breakage during cell division. One daughter cell inherits a truncated linear chromosome and is not viable. The other inherits a circular chromosome attached to a linear tail ending in the chromosome terminus. Replication extends this tail, while degradation of its extremity results in terminus DNA loss. Repeated generation and segregation of new σ-replicating chromosomes explains the heritability of post-replicative breakage. Our results allow us to determine that in E. coli at each generation, 18% of cells are subject to replication fork breakage at dispersed, potentially random, chromosomal locations.
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Affiliation(s)
- Anurag Kumar Sinha
- Bacterial DNA stability, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
- * E-mail: (AKS); (BM)
| | - Christophe Possoz
- Evolution and maintenance of circular chromosomes, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Adeline Durand
- Bacterial DNA stability, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Jean-Michel Desfontaines
- Evolution and maintenance of circular chromosomes, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - François-Xavier Barre
- Evolution and maintenance of circular chromosomes, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - David R. F. Leach
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Bénédicte Michel
- Bacterial DNA stability, Genome biology department, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
- * E-mail: (AKS); (BM)
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32
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Wlodek A, Kendrew SG, Coates NJ, Hold A, Pogwizd J, Rudder S, Sheehan LS, Higginbotham SJ, Stanley-Smith AE, Warneck T, Nur-E-Alam M, Radzom M, Martin CJ, Overvoorde L, Samborskyy M, Alt S, Heine D, Carter GT, Graziani EI, Koehn FE, McDonald L, Alanine A, Rodríguez Sarmiento RM, Chao SK, Ratni H, Steward L, Norville IH, Sarkar-Tyson M, Moss SJ, Leadlay PF, Wilkinson B, Gregory MA. Diversity oriented biosynthesis via accelerated evolution of modular gene clusters. Nat Commun 2017; 8:1206. [PMID: 29089518 PMCID: PMC5663706 DOI: 10.1038/s41467-017-01344-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 09/08/2017] [Indexed: 11/09/2022] Open
Abstract
Erythromycin, avermectin and rapamycin are clinically useful polyketide natural products produced on modular polyketide synthase multienzymes by an assembly-line process in which each module of enzymes in turn specifies attachment of a particular chemical unit. Although polyketide synthase encoding genes have been successfully engineered to produce novel analogues, the process can be relatively slow, inefficient, and frequently low-yielding. We now describe a method for rapidly recombining polyketide synthase gene clusters to replace, add or remove modules that, with high frequency, generates diverse and highly productive assembly lines. The method is exemplified in the rapamycin biosynthetic gene cluster where, in a single experiment, multiple strains were isolated producing new members of a rapamycin-related family of polyketides. The process mimics, but significantly accelerates, a plausible mechanism of natural evolution for modular polyketide synthases. Detailed sequence analysis of the recombinant genes provides unique insight into the design principles for constructing useful synthetic assembly-line multienzymes. Reengineering polyketide synthase encoding genes to produce analogues of natural products can be slow and low-yielding. Here the authors use accelerated evolution to recombine the gene cluster for rapid production of rapamycin-related products.
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Affiliation(s)
- Aleksandra Wlodek
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | - Steve G Kendrew
- Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK.,Engineered Biodesign Limited, Cambridge, CB22 3GN, UK
| | - Nigel J Coates
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK.,Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | - Adam Hold
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | - Joanna Pogwizd
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | - Steven Rudder
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | - Lesley S Sheehan
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK.,Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | | | - Anna E Stanley-Smith
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK.,Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | - Tony Warneck
- Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | - Mohammad Nur-E-Alam
- Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK.,Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh, 12372, Saudi Arabia
| | - Markus Radzom
- Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK.,BASF SE, Speyerer Str. 2, Limburgerhof, 67117, Germany
| | - Christine J Martin
- Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | - Lois Overvoorde
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | - Markiyan Samborskyy
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Silke Alt
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Daniel Heine
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Guy T Carter
- Chemical and Screening Sciences, Wyeth Pharmaceuticals, 401 North Middletown Road, Pearl River, NY, 10965, USA
| | - Edmund I Graziani
- Chemical and Screening Sciences, Wyeth Pharmaceuticals, 401 North Middletown Road, Pearl River, NY, 10965, USA.,Medicine Discovery Network-Synthetic Biology, Pfizer Worldwide R&D, 445 Eastern Point Rd., Groton, CT, 06340, USA
| | - Frank E Koehn
- Chemical and Screening Sciences, Wyeth Pharmaceuticals, 401 North Middletown Road, Pearl River, NY, 10965, USA
| | - Leonard McDonald
- Chemical and Screening Sciences, Wyeth Pharmaceuticals, 401 North Middletown Road, Pearl River, NY, 10965, USA
| | - Alexander Alanine
- Roche Innovation Center Basel, Pharmaceutical Research and Early Development (PRED), Basel, CH-4070, Switzerland
| | | | - Suzan Keen Chao
- Roche Innovation Center Basel, Pharmaceutical Research and Early Development (PRED), Basel, CH-4070, Switzerland
| | - Hasane Ratni
- Roche Innovation Center Basel, Pharmaceutical Research and Early Development (PRED), Basel, CH-4070, Switzerland
| | - Lucinda Steward
- Roche Innovation Center Basel, Pharmaceutical Research and Early Development (PRED), Basel, CH-4070, Switzerland
| | - Isobel H Norville
- Defence Science and Technology Laboratory, Porton Down, PO17 6AD, UK
| | - Mitali Sarkar-Tyson
- Defence Science and Technology Laboratory, Porton Down, PO17 6AD, UK.,Marshall Centre for Infectious Diseases, School of Biomedical Sciences, University of Western Australia, Monash Avenue, Nedlands, WA, 6009, Australia
| | - Steven J Moss
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK.,Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK
| | - Peter F Leadlay
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Barrie Wilkinson
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK. .,Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK. .,Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
| | - Matthew A Gregory
- Isomerase Therapeutics Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK. .,Biotica Technology Ltd., Chesterford Research Park, Cambridge, CB10 1XL, UK.
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33
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Zhao L, So CWE. PARPi potentiates with current conventional therapy in MLL leukemia. Cell Cycle 2017; 16:1861-1869. [PMID: 28886273 PMCID: PMC5638355 DOI: 10.1080/15384101.2017.1288325] [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: 12/02/2016] [Accepted: 01/25/2017] [Indexed: 12/11/2022] Open
Abstract
Acute myeloid leukemias driven by MLL fusion proteins are commonly associated with poor prognosis and refractory treatment. Here, we provide evidence that olaparib can potentiate sensitivity of MLL leukemia cells to conventional chemotherapy and DNMT inhibitors offering new potential therapeutic strategies for MLL rearranged leukemias Using the primary mouse leukemia cells and human MLL-AF9 leukemic cell line, we demonstrate that treatment of MLL-AF9 leukemic cells with DNMT inhibitors or chemotherapies in combination with olaparib results in significant reduction in colony formation or cell growth while the single agent treatments had little impacts. Combining olaparib with DNMT inhibitor induce cell cycle block and apoptosis. Furthermore, we observe a significant increase in proportion of cells with >10 γH2AX DNA damage foci and double stranded breaks when treated with DNMT inhibitors or chemotherapy agents in combination with olaparib, thus providing possible mechanistic insights for the synergism.
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Affiliation(s)
- Lu Zhao
- Leukemia and Stem Cell Biology Group, Department of Haematological Medicine, King's College London, Denmark Hill campus, London UK
| | - Chi Wai Eric So
- Leukemia and Stem Cell Biology Group, Department of Haematological Medicine, King's College London, Denmark Hill campus, London UK
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34
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Raguse M, Torres R, Seco EM, Gándara C, Ayora S, Moeller R, Alonso JC. Bacillus subtilis DisA helps to circumvent replicative stress during spore revival. DNA Repair (Amst) 2017; 59:57-68. [PMID: 28961460 DOI: 10.1016/j.dnarep.2017.09.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 08/24/2017] [Accepted: 09/08/2017] [Indexed: 02/06/2023]
Abstract
The mechanisms that allow to circumvent replicative stress, and to resume DNA synthesis are poorly understood in Bacillus subtilis. To study the role of the diadenylate cyclase DisA and branch migration translocase (BMT) RadA/Sms in restarting a stalled replication fork, we nicked and broke the circular chromosome of an inert mature haploid spore, damaged the bases, and measured survival of reviving spores. During undisturbed ripening, nicks and breaks should be repaired by pathways that do not invoke long-range end resection or genetic exchange by homologous recombination, after which DNA replication might be initiated. We found that DNA damage reduced the viability of spores that lacked DisA, BMT (RadA/Sms, RuvAB or RecG), the Holliday junction resolvase RecU, or the translesion synthesis DNA polymerases (PolY1 or PolY2). DisA and RadA/Sms, in concert with RuvAB, RecG, RecU, PolY1 or PolY2, are needed to bypass replication-blocking lesions. DisA, which binds to stalled or reversed forks, did not apparently affect initiation of PriA-dependent DNA replication in vitro. We propose that DisA is necessary to coordinate responses to replicative stress; it could help to circumvent damaged template bases that otherwise impede fork progression.
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Affiliation(s)
- Marina Raguse
- German Aerospace Center (DLReV), Institute of Aerospace Medicine, Radiation Biology Department, Space Microbiology Research Group, Linder Hoehe, D-51147 Cologne (Köln), Germany
| | - Rubén Torres
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Elena M Seco
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Carolina Gándara
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Silvia Ayora
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, Cantoblanco, 28049 Madrid, Spain
| | - Ralf Moeller
- German Aerospace Center (DLReV), Institute of Aerospace Medicine, Radiation Biology Department, Space Microbiology Research Group, Linder Hoehe, D-51147 Cologne (Köln), Germany.
| | - Juan C Alonso
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, Cantoblanco, 28049 Madrid, Spain.
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Pawłowska E, Szczepanska J, Blasiak J. DNA2-An Important Player in DNA Damage Response or Just Another DNA Maintenance Protein? Int J Mol Sci 2017; 18:ijms18071562. [PMID: 28718810 PMCID: PMC5536050 DOI: 10.3390/ijms18071562] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 07/13/2017] [Accepted: 07/17/2017] [Indexed: 02/01/2023] Open
Abstract
The human DNA2 (DNA replication helicase/nuclease 2) protein is expressed in both the nucleus and mitochondria, where it displays ATPase-dependent nuclease and helicase activities. DNA2 plays an important role in the removing of long flaps in DNA replication and long-patch base excision repair (LP-BER), interacting with the replication protein A (RPA) and the flap endonuclease 1 (FEN1). DNA2 can promote the restart of arrested replication fork along with Werner syndrome ATP-dependent helicase (WRN) and Bloom syndrome protein (BLM). In mitochondria, DNA2 can facilitate primer removal during strand-displacement replication. DNA2 is involved in DNA double strand (DSB) repair, in which it is complexed with BLM, RPA and MRN for DNA strand resection required for homologous recombination repair. DNA2 can be a major protein involved in the repair of complex DNA damage containing a DSB and a 5' adduct resulting from a chemical group bound to DNA 5' ends, created by ionizing radiation and several anticancer drugs, including etoposide, mitoxantrone and some anthracyclines. The role of DNA2 in telomere end maintenance and cell cycle regulation suggests its more general role in keeping genomic stability, which is impaired in cancer. Therefore DNA2 can be an attractive target in cancer therapy. This is supported by enhanced expression of DNA2 in many cancer cell lines with oncogene activation and premalignant cells. Therefore, DNA2 can be considered as a potential marker, useful in cancer therapy. DNA2, along with PARP1 inhibition, may be considered as a potential target for inducing synthetic lethality, a concept of killing tumor cells by targeting two essential genes.
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Affiliation(s)
- Elzbieta Pawłowska
- Department of Orthodontics, Medical University of Lodz, 92-216 Lodz, Poland.
| | - Joanna Szczepanska
- Department of Pediatric Dentistry, Medical University of Lodz, 92-216 Lodz, Poland.
| | - Janusz Blasiak
- Department of Molecular Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland.
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Torres R, Romero H, Rodríguez-Cerrato V, Alonso JC. Interplay between Bacillus subtilis RecD2 and the RecG or RuvAB helicase in recombinational repair. DNA Repair (Amst) 2017; 55:40-46. [DOI: 10.1016/j.dnarep.2017.05.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 05/08/2017] [Accepted: 05/10/2017] [Indexed: 10/24/2022]
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Abstract
In bacteria, replication forks assembled at a replication origin travel to the terminus, often a few megabases away. They may encounter obstacles that trigger replisome disassembly, rendering replication restart from abandoned forks crucial for cell viability. During the past 25 years, the genes that encode replication restart proteins have been identified and genetically characterized. In parallel, the enzymes were purified and analyzed in vitro, where they can catalyze replication initiation in a sequence-independent manner from fork-like DNA structures. This work also revealed a close link between replication and homologous recombination, as replication restart from recombination intermediates is an essential step of DNA double-strand break repair in bacteria and, conversely, arrested replication forks can be acted upon by recombination proteins and converted into various recombination substrates. In this review, we summarize this intense period of research that led to the characterization of the ubiquitous replication restart protein PriA and its partners, to the definition of several replication restart pathways in vivo, and to the description of tight links between replication and homologous recombination, responsible for the importance of replication restart in the maintenance of genome stability.
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Activity and in vivo dynamics of Bacillus subtilis DisA are affected by RadA/Sms and by Holliday junction-processing proteins. DNA Repair (Amst) 2017; 55:17-30. [PMID: 28511132 DOI: 10.1016/j.dnarep.2017.05.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 05/03/2017] [Accepted: 05/04/2017] [Indexed: 12/18/2022]
Abstract
Bacillus subtilis c-di-AMP synthase DisA and RecA-related RadA/Sms are involved in the repair of DNA damage in exponentially growing cells. We provide genetic evidence that DisA or RadA/Sms is epistatic to the branch migration translocase (BMT) RecG and the Holliday junction (HJ) resolvase RecU in response to DNA damage. We provide genetic evidence damage. Functional DisA-YFP formed dynamic foci in exponentially growing cells, which moved through the nucleoids at a speed compatible with a DNA-scanning mode. DisA formed more static structures in the absence of RecU or RecG than in wild type cells, while dynamic foci were still observed in cells lacking the BMT RuvAB. Purified DisA synthesizes c-di-AMP, but interaction with RadA/Sms or with HJ DNA decreases DisA-mediated c-di-AMP synthesis. RadA/Sms-YFP also formed dynamic foci in growing cells, but the foci moved throughout the cells rather than just on the nucleoids, and co-localized rarely with DisA-YFP foci, suggesting that RadA/Sms and DisA interact only transiently in unperturbed conditions. Our data suggest a model in which DisA moving along dsDNA indicates absence of DNA damage/replication stress via normal c-di-AMP levels, while interaction with HJ DNA/halted forks leads to reduced c-di-AMP levels and an ensuing block in cell proliferation. RadA/Sms may be involved in modulating DisA activities.
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El Kafsi H, Loux V, Mariadassou M, Blin C, Chiapello H, Abraham AL, Maguin E, van de Guchte M. Unprecedented large inverted repeats at the replication terminus of circular bacterial chromosomes suggest a novel mode of chromosome rescue. Sci Rep 2017; 7:44331. [PMID: 28281695 PMCID: PMC5345009 DOI: 10.1038/srep44331] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 02/07/2017] [Indexed: 12/29/2022] Open
Abstract
The first Lactobacillus delbrueckii ssp. bulgaricus genome sequence revealed the presence of a very large inverted repeat (IR), a DNA sequence arrangement which thus far seemed inconceivable in a non-manipulated circular bacterial chromosome, at the replication terminus. This intriguing observation prompted us to investigate if similar IRs could be found in other bacteria. IRs with sizes varying from 38 to 76 kbp were found at the replication terminus of all 5 L. delbrueckii ssp. bulgaricus chromosomes analysed, but in none of 1373 other chromosomes. They represent the first naturally occurring very large IRs detected in circular bacterial genomes. A comparison of the L. bulgaricus replication terminus regions and the corresponding regions without IR in 5 L. delbrueckii ssp. lactis genomes leads us to propose a model for the formation and evolution of the IRs. The DNA sequence data are consistent with a novel model of chromosome rescue after premature replication termination or irreversible chromosome damage near the replication terminus, involving mechanisms analogous to those proposed in the formation of very large IRs in human cancer cells. We postulate that the L. delbrueckii ssp. bulgaricus-specific IRs in different strains derive from a single ancestral IR of at least 93 kbp.
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Affiliation(s)
- Hela El Kafsi
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Valentin Loux
- MaIAGE, INRA, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | | | - Camille Blin
- MaIAGE, INRA, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Hélène Chiapello
- MaIAGE, INRA, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Anne-Laure Abraham
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Emmanuelle Maguin
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Maarten van de Guchte
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
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Elevated Rate of Genome Rearrangements in Radiation-Resistant Bacteria. Genetics 2017; 205:1677-1689. [PMID: 28188144 PMCID: PMC5378121 DOI: 10.1534/genetics.116.196154] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 01/30/2017] [Indexed: 01/27/2023] Open
Abstract
A number of bacterial, archaeal, and eukaryotic species are known for their resistance to ionizing radiation. One of the challenges these species face is a potent environmental source of DNA double-strand breaks, potential drivers of genome structure evolution. Efficient and accurate DNA double-strand break repair systems have been demonstrated in several unrelated radiation-resistant species and are putative adaptations to the DNA damaging environment. Such adaptations are expected to compensate for the genome-destabilizing effect of environmental DNA damage and may be expected to result in a more conserved gene order in radiation-resistant species. However, here we show that rates of genome rearrangements, measured as loss of gene order conservation with time, are higher in radiation-resistant species in multiple, phylogenetically independent groups of bacteria. Comparison of indicators of selection for genome organization between radiation-resistant and phylogenetically matched, nonresistant species argues against tolerance to disruption of genome structure as a strategy for radiation resistance. Interestingly, an important mechanism affecting genome rearrangements in prokaryotes, the symmetrical inversions around the origin of DNA replication, shapes genome structure of both radiation-resistant and nonresistant species. In conclusion, the opposing effects of environmental DNA damage and DNA repair result in elevated rates of genome rearrangements in radiation-resistant bacteria.
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Kelso AA, Goodson SD, Chavan S, Say AF, Turchick A, Sharma D, Ledford LL, Ratterman E, Leskoske K, King AV, Attaway CC, Bandera Y, Foulger SH, Mazin AV, Temesvari LA, Sehorn MG. Characterization of the recombination activities of the Entamoeba histolytica Rad51 recombinase. Mol Biochem Parasitol 2016; 210:71-84. [PMID: 27678398 DOI: 10.1016/j.molbiopara.2016.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 08/10/2016] [Accepted: 09/02/2016] [Indexed: 11/29/2022]
Abstract
The protozoan parasite responsible for human amoebiasis is Entamoeba histolytica. An important facet of the life cycle of E. histolytica involves the conversion of the mature trophozoite to a cyst. This transition is thought to involve homologous recombination (HR), which is dependent upon the Rad51 recombinase. Here, a biochemical characterization of highly purified ehRad51 protein is presented. The ehRad51 protein preferentially binds ssDNA, forms a presynaptic filament and possesses ATP hydrolysis activity that is stimulated by the presence of DNA. Evidence is provided that ehRad51 catalyzes robust DNA strand exchange over at least 5.4 kilobase pairs. Although the homologous DNA pairing activity of ehRad51 is weak, it is strongly enhanced by the presence of two HR accessory cofactors, calcium and Hop2-Mnd1. The biochemical system described herein was used to demonstrate the potential for targeting ehRad51 with two small molecule inhibitors of human RAD51. We show that 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) inhibited ehRad51 by interfering with DNA binding and attenuated encystation in Entamoeba invadens, while B02 had no effect on ehRad51 strand exchange activity. These results provide insight into the underlying mechanism of homology-directed DNA repair in E. histolytica.
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Affiliation(s)
- Andrew A Kelso
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA; Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, SC 29634, USA
| | - Steven D Goodson
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA; Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, SC 29634, USA
| | - Suchitra Chavan
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, SC 29634, USA; Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - Amanda F Say
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA
| | - Audrey Turchick
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA
| | - Deepti Sharma
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA
| | - LeAnna L Ledford
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA
| | - Erin Ratterman
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA
| | - Kristin Leskoske
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA
| | - Ada V King
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | | | - Yura Bandera
- Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634, USA; Department of Material Science and Engineering, Clemson University, Clemson, SC 29634, USA
| | - Stephen H Foulger
- Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634, USA; Department of Material Science and Engineering, Clemson University, Clemson, SC 29634, USA
| | - Alexander V Mazin
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
| | - Lesly A Temesvari
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, SC 29634, USA; Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA; Clemson University School of Health Research, Clemson, SC 29634, USA
| | - Michael G Sehorn
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA; Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634, USA; Clemson University School of Health Research, Clemson, SC 29634, USA.
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Getting Ready for the Dance: FANCJ Irons Out DNA Wrinkles. Genes (Basel) 2016; 7:genes7070031. [PMID: 27376332 PMCID: PMC4962001 DOI: 10.3390/genes7070031] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/13/2016] [Accepted: 06/27/2016] [Indexed: 12/21/2022] Open
Abstract
Mounting evidence indicates that alternate DNA structures, which deviate from normal double helical DNA, form in vivo and influence cellular processes such as replication and transcription. However, our understanding of how the cellular machinery deals with unusual DNA structures such as G-quadruplexes (G4), triplexes, or hairpins is only beginning to emerge. New advances in the field implicate a direct role of the Fanconi Anemia Group J (FANCJ) helicase, which is linked to a hereditary chromosomal instability disorder and important for cancer suppression, in replication past unusual DNA obstacles. This work sets the stage for significant progress in dissecting the molecular mechanisms whereby replication perturbation by abnormal DNA structures leads to genomic instability. In this review, we focus on FANCJ and its role to enable efficient DNA replication when the fork encounters vastly abundant naturally occurring DNA obstacles, which may have implications for targeting rapidly dividing cancer cells.
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Abstract
Since the first demonstration that CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against phages and plasmids, numerous studies have yielded key insights into the molecular mechanisms governing how these systems attack and degrade foreign DNA. However, the molecular mechanisms underlying the adaptation stage, in which new immunological memory is formed, have until recently represented a major unresolved question. In this Progress article, we discuss recent discoveries that have shown both how foreign DNA is identified by the CRISPR-Cas adaptation machinery and the molecular basis for its integration into the chromosome to form an immunological memory. Furthermore, we describe the roles of each of the specific CRISPR-Cas components that are involved in memory formation, and consider current models for their evolutionary origin.
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Doerfler L, Schmidt KH. Exo1 phosphorylation status controls the hydroxyurea sensitivity of cells lacking the Pol32 subunit of DNA polymerases delta and zeta. DNA Repair (Amst) 2015; 24:26-36. [PMID: 25457771 DOI: 10.1016/j.dnarep.2014.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 09/29/2014] [Accepted: 10/02/2014] [Indexed: 11/16/2022]
Abstract
Exo1 belongs to the Rad2 family of structure-specific nucleases and possesses 5'-3' exonuclease activity on double-stranded DNA substrates. Exo1 interacts physically with the DNA mismatch repair (MMR) proteins Msh2 and Mlh1 and is involved in the excision of the mispaired nucleotide. Independent of its role in MMR, Exo1 contributes to long-range resection of DNA double-strand break (DSB) ends to facilitate their repair by homologous recombination (HR), and was recently identified as a component of error-free DNA damage tolerance pathways. Here, we show that Exo1 activity increases the hydroxyurea sensitivity of cells lacking Pol32, a subunit of DNA polymerases δ and ζ. Both, phospho-mimicking and dephospho-mimicking exo1 mutants act as hypermorphs, as evidenced by an increase in HU sensitivity of pol32Δ cells, suggesting that they are trapped in an active form and that phosphorylation of Exo1 at residues S372, S567, S587, S692 is necessary, but insufficient, for the accurate regulation of Exo1 activity at stalled replication forks. In contrast, neither phosphorylation status is important for Exo1's role in MMR or in the suppression of genome instability in cells lacking Sgs1 helicase. This ability of an EXO1 deletion to suppress the HU hypersensitivity of pol32Δ cells is in contrast to the negative genetic interaction between deletions of EXO1 and POL32 in MMS-treated cells as well as the role of EXO1 in DNA-damage treated rad53 and mec1 mutants.
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Affiliation(s)
- Lillian Doerfler
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, United States; Graduate Program in Cell and Molecular Biology, University of South Florida, Tampa, FL 33620, United States
| | - Kristina H Schmidt
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, United States; Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, United States.
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Thakur RS, Basavaraju S, Khanduja JS, Muniyappa K, Nagaraju G. Mycobacterium tuberculosis RecG protein but not RuvAB or RecA protein is efficient at remodeling the stalled replication forks: implications for multiple mechanisms of replication restart in mycobacteria. J Biol Chem 2015; 290:24119-39. [PMID: 26276393 DOI: 10.1074/jbc.m115.671164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 11/06/2022] Open
Abstract
Aberrant DNA replication, defects in the protection, and restart of stalled replication forks are major causes of genome instability in all organisms. Replication fork reversal is emerging as an evolutionarily conserved physiological response for restart of stalled forks. Escherichia coli RecG, RuvAB, and RecA proteins have been shown to reverse the model replication fork structures in vitro. However, the pathways and the mechanisms by which Mycobacterium tuberculosis, a slow growing human pathogen, responds to different types of replication stress and DNA damage are unclear. Here, we show that M. tuberculosis RecG rescues E. coli ΔrecG cells from replicative stress. The purified M. tuberculosis RecG (MtRecG) and RuvAB (MtRuvAB) proteins catalyze fork reversal of model replication fork structures with and without a leading strand single-stranded DNA gap. Interestingly, single-stranded DNA-binding protein suppresses the MtRecG- and MtRuvAB-mediated fork reversal with substrates that contain lagging strand gap. Notably, our comparative studies with fork structures containing template damage and template switching mechanism of lesion bypass reveal that MtRecG but not MtRuvAB or MtRecA is proficient in driving the fork reversal. Finally, unlike MtRuvAB, we find that MtRecG drives efficient reversal of forks when fork structures are tightly bound by protein. These results provide direct evidence and valuable insights into the underlying mechanism of MtRecG-catalyzed replication fork remodeling and restart pathways in vivo.
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Affiliation(s)
- Roshan Singh Thakur
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - Shivakumar Basavaraju
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - Jasbeer Singh Khanduja
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - K Muniyappa
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - Ganesh Nagaraju
- From the Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
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Courcelle J, Wendel BM, Livingstone DD, Courcelle CT. RecBCD is required to complete chromosomal replication: Implications for double-strand break frequencies and repair mechanisms. DNA Repair (Amst) 2015; 32:86-95. [PMID: 26003632 PMCID: PMC4522357 DOI: 10.1016/j.dnarep.2015.04.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Several aspects of the mechanism of homologous double-strand break repair remain unclear. Although intensive efforts have focused on how recombination reactions initiate, far less is known about the molecular events that follow. Based upon biochemical studies, current models propose that RecBCD processes double-strand ends and loads RecA to initiate recombinational repair. However, recent studies have shown that RecBCD plays a critical role in completing replication events on the chromosome through a mechanism that does not involve RecA or recombination. Here, we examine several studies, both early and recent, that suggest RecBCD also operates late in the recombination process - after initiation, strand invasion, and crossover resolution have occurred. Similar to its role in completing replication, we propose a model in which RecBCD is required to resect and resolve the DNA synthesis associated with homologous recombination at the point where the missing sequences on the broken molecule have been restored. We explain how the impaired ability to complete chromosome replication in recBC and recD mutants is likely to account for the loss of viability and genome instability in these mutants, and conclude that spontaneous double-strand breaks and replication fork collapse occur far less frequently than previously speculated.
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Affiliation(s)
- Justin Courcelle
- Department of Biology, Portland State University, Portland, OR 97201, United States.
| | - Brian M Wendel
- Department of Biology, Portland State University, Portland, OR 97201, United States
| | - Dena D Livingstone
- Department of Biology, Portland State University, Portland, OR 97201, United States
| | - Charmain T Courcelle
- Department of Biology, Portland State University, Portland, OR 97201, United States
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Kumar Y, Yang J, Hu T, Chen L, Xu Z, Xu L, Hu XX, Tang G, Wang JM, Li Y, Poon WS, Wan W, Zhang L, Mat WK, Pun FW, Lee P, Cheong THY, Ding X, Ng SK, Tsang SY, Chen JF, Zhang P, Li S, Wang HY, Xue H. Massive interstitial copy-neutral loss-of-heterozygosity as evidence for cancer being a disease of the DNA-damage response. BMC Med Genomics 2015. [PMID: 26208496 PMCID: PMC4515014 DOI: 10.1186/s12920-015-0104-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Background The presence of loss-of-heterozygosity (LOH) mutations in cancer cell genomes is commonly encountered. Moreover, the occurrences of LOHs in tumor suppressor genes play important roles in oncogenesis. However, because the causative mechanisms underlying LOH mutations in cancer cells yet remain to be elucidated, enquiry into the nature of these mechanisms based on a comprehensive examination of the characteristics of LOHs in multiple types of cancers has become a necessity. Methods We performed next-generation sequencing on inter-Alu sequences of five different types of solid tumors and acute myeloid leukemias, employing the AluScan platform which entailed amplification of such sequences using multiple PCR primers based on the consensus sequences of Alu elements; as well as the whole genome sequences of a lung-to-liver metastatic cancer and a primary liver cancer. Paired-end sequencing reads were aligned to the reference human genome to identify major and minor alleles so that the partition of LOH products between homozygous-major vs. homozygous-minor alleles could be determined at single-base resolution. Strict filtering conditions were employed to avoid false positives. Measurements of LOH occurrences in copy number variation (CNV)-neutral regions were obtained through removal of CNV-associated LOHs. Results We found: (a) average occurrence of copy-neutral LOHs amounting to 6.9 % of heterologous loci in the various cancers; (b) the mainly interstitial nature of the LOHs; and (c) preference for formation of homozygous-major over homozygous-minor, and transitional over transversional, LOHs. Conclusions The characteristics of the cancer LOHs, observed in both AluScan and whole genome sequencings, point to the formation of LOHs through repair of double-strand breaks by interhomolog recombination, or gene conversion, as the consequence of a defective DNA-damage response, leading to a unified mechanism for generating the mutations required for oncogenesis as well as the progression of cancer cells. Electronic supplementary material The online version of this article (doi:10.1186/s12920-015-0104-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yogesh Kumar
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
| | - Jianfeng Yang
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
| | - Taobo Hu
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
| | - Lei Chen
- Eastern Hepatobiliary Surgery Institute, Second Military Medical University, Shanghai, China.
| | - Zhi Xu
- Department of Oncology, Nanjing First Hospital, and Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.
| | - Lin Xu
- Jiangsu Key Laboratory of Cancer Molecular Biology and Translational Medicine, Jiangsu Cancer Hospital, Nanjing, China.
| | - Xiao-Xia Hu
- Department of Hematology, Changhai Hospital, Second Military Medical University, Shanghai, China.
| | - Gusheng Tang
- Department of Hematology, Changhai Hospital, Second Military Medical University, Shanghai, China.
| | - Jian-Min Wang
- Department of Hematology, Changhai Hospital, Second Military Medical University, Shanghai, China.
| | - Yi Li
- Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China.
| | - Wai-Sang Poon
- Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China.
| | - Weiqing Wan
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, 6 Tiantan Xili, Dongcheng District, Beijing, 100050, China.
| | - Liwei Zhang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, 6 Tiantan Xili, Dongcheng District, Beijing, 100050, China.
| | - Wai-Kin Mat
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
| | - Frank W Pun
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
| | - Peggy Lee
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
| | - Timothy H Y Cheong
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
| | - Xiaofan Ding
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
| | - Siu-Kin Ng
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
| | - Shui-Ying Tsang
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
| | - Jin-Fei Chen
- Department of Oncology, Nanjing First Hospital, and Collaborative Innovation Center for Cancer Personalized Medicine, Nanjing Medical University, Nanjing, China.
| | - Peng Zhang
- MOE Key Laboratory of Bioinformatics and Bioinformatics Division, TNLIST, and Department of Automation, Tsinghua University, Beijing, 100084, China.
| | - Shao Li
- MOE Key Laboratory of Bioinformatics and Bioinformatics Division, TNLIST, and Department of Automation, Tsinghua University, Beijing, 100084, China.
| | - Hong-Yang Wang
- Eastern Hepatobiliary Surgery Institute, Second Military Medical University, Shanghai, China.
| | - Hong Xue
- Division of Life Science, Applied Genomics Centre and Centre for Statistical Science, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
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48
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Functional dissection of proliferating-cell nuclear antigens (1 and 2) in human malarial parasite Plasmodium falciparum: possible involvement in DNA replication and DNA damage response. Biochem J 2015; 470:115-29. [PMID: 26251451 DOI: 10.1042/bj20150452] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 06/22/2015] [Indexed: 11/17/2022]
Abstract
Eukaryotic PCNAs (proliferating-cell nuclear antigens) play diverse roles in nucleic acid metabolism in addition to DNA replication. Plasmodium falciparum, which causes human malaria, harbours two PCNA homologues: PfPCNA1 and PfPCNA2. The functional role of two distinct PCNAs in the parasite still eludes us. In the present study, we show that, whereas both PfPCNAs share structural and biochemical properties, only PfPCNA1 functionally complements the ScPCNA mutant and forms distinct replication foci in the parasite, which PfPCNA2 fails to do. Although PfPCNA1 appears to be the primary replicative PCNA, both PfPCNA1 and PfPCNA2 participate in an active DDR (DNA-damage-response) pathway with significant accumulation in the parasite upon DNA damage induction. Interestingly, PfPCNA genes were found to be regulated not at the transcription level, but presumably at the protein stability level upon DNA damage. Such regulation of PCNA has not been shown in eukaryotes before. Moreover, overexpression of PfPCNA1 and PfPCNA2 in the parasite confers a survival edge on the parasite in a genotoxic environment. This is the first evidence of a PfPCNA-mediated DDR in the parasite and gives new insights and rationale for the presence of two PCNAs as a parasite survival strategy and its probable success.
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49
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Levy A, Goren MG, Yosef I, Auster O, Manor M, Amitai G, Edgar R, Qimron U, Sorek R. CRISPR adaptation biases explain preference for acquisition of foreign DNA. Nature 2015; 520:505-510. [PMID: 25874675 PMCID: PMC4561520 DOI: 10.1038/nature14302] [Citation(s) in RCA: 274] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 02/09/2015] [Indexed: 12/21/2022]
Abstract
CRISPR-Cas (clustered, regularly interspaced short palindromic repeats coupled with CRISPR-associated proteins) is a bacterial immunity system that protects against invading phages or plasmids. In the process of CRISPR adaptation, short pieces of DNA ('spacers') are acquired from foreign elements and integrated into the CRISPR array. So far, it has remained a mystery how spacers are preferentially acquired from the foreign DNA while the self chromosome is avoided. Here we show that spacer acquisition is replication-dependent, and that DNA breaks formed at stalled replication forks promote spacer acquisition. Chromosomal hotspots of spacer acquisition were confined by Chi sites, which are sequence octamers highly enriched on the bacterial chromosome, suggesting that these sites limit spacer acquisition from self DNA. We further show that the avoidance of self is mediated by the RecBCD double-stranded DNA break repair complex. Our results suggest that, in Escherichia coli, acquisition of new spacers largely depends on RecBCD-mediated processing of double-stranded DNA breaks occurring primarily at replication forks, and that the preference for foreign DNA is achieved through the higher density of Chi sites on the self chromosome, in combination with the higher number of forks on the foreign DNA. This model explains the strong preference to acquire spacers both from high copy plasmids and from phages.
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Affiliation(s)
- Asaf Levy
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Moran G Goren
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ido Yosef
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Oren Auster
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Miriam Manor
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Gil Amitai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rotem Edgar
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Udi Qimron
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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50
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Uringa EJ, Baldeyron C, Odijk H, Wassenaar E, van Cappellen WA, Maas A, Hoeijmakers JHJ, Baarends WM, Kanaar R, Essers J. A mRad51-GFP antimorphic allele affects homologous recombination and DNA damage sensitivity. DNA Repair (Amst) 2014; 25:27-40. [PMID: 25463395 DOI: 10.1016/j.dnarep.2014.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/05/2014] [Accepted: 11/07/2014] [Indexed: 10/24/2022]
Abstract
Accurate DNA double-strand break repair through homologous recombination is essential for preserving genome integrity. Disruption of the gene encoding RAD51, the protein that catalyzes DNA strand exchange during homologous recombination, results in lethality of mammalian cells. Proteins required for homologous recombination, also play an important role during DNA replication. To explore the role of RAD51 in DNA replication and DSB repair, we used a knock-in strategy to express a carboxy-terminal fusion of green fluorescent protein to mouse RAD51 (mRAD51-GFP) in mouse embryonic stem cells. Compared to wild-type cells, heterozygous mRad51(+/wt-GFP) embryonic stem cells showed increased sensitivity to DNA damage induced by ionizing radiation and mitomycin C. Moreover, gene targeting was found to be severely impaired in mRad51(+/wt-GFP) embryonic stem cells. Furthermore, we found that mRAD51-GFP foci were not stably associated with chromatin. From these experiments we conclude that this mRad51-GFP allele is an antimorphic allele. When this allele is present in a heterozygous condition over wild-type mRad51, embryonic stem cells are proficient in DNA replication but display defects in homologous recombination and DNA damage repair.
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Affiliation(s)
- Evert-Jan Uringa
- Department of Reproduction and Development, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Céline Baldeyron
- Department of Genetics, Cancer Genomics Center, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Hanny Odijk
- Department of Genetics, Cancer Genomics Center, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Evelyne Wassenaar
- Department of Reproduction and Development, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Wiggert A van Cappellen
- Erasmus Optical Imaging Centre, Department of Pathology, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Alex Maas
- Department of Genetics, Cancer Genomics Center, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Jan H J Hoeijmakers
- Department of Genetics, Cancer Genomics Center, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Willy M Baarends
- Department of Reproduction and Development, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Roland Kanaar
- Department of Genetics, Cancer Genomics Center, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands; Department of Radiation Oncology, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Jeroen Essers
- Department of Genetics, Cancer Genomics Center, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands; Department of Radiation Oncology, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands; Department of Surgical Oncology, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands.
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