scholarly journals Genetic Recombination in Bacillus subtilis 168: Effect of ΔhelD on DNA Repair and Homologous Recombination

2001 ◽  
Vol 183 (19) ◽  
pp. 5772-5777 ◽  
Author(s):  
Begoña Carrasco ◽  
Silvia Fernández ◽  
Marie-Agnes Petit ◽  
Juan C. Alonso
Keyword(s):  
Dna Repair ◽  
Bacillus Subtilis ◽  
Homologous Recombination ◽  
Genetic Recombination ◽  
Methyl Methanesulfonate ◽  
Plasmid Transformation ◽  
Dna Damaging Agents ◽  
Bacillus Subtilis 168 ◽  
Recombination Repair ◽  
Helicase Iv

ABSTRACT The B. subtilis ΔhelD allele rendered cells proficient in transformational recombination and moderately sensitive to methyl methanesulfonate when present in an otherwise Rec+ strain. The ΔhelD allele was introduced into rec-deficient strains representative of the α (recF strain), β (addA addB), γ (recH), ɛ (ΔrecU), and ζ (ΔrecS) epistatic groups. The ΔhelDmutation increased the sensitivity to DNA-damaging agents ofaddAB, ΔrecU, and ΔrecS cells, did not affect the survival ofrecH cells, and decreased the sensitivity ofrecF cells. ΔhelD also partially suppressed the DNA repair phenotype of other mutations classified within the α epistatic group, namely the recL, ΔrecO, and recR mutations. The ΔhelD allele marginally reduced plasmid transformation (three- to sevenfold) of mutations classified within the α, β, and γ epistatic groups. Altogether, these data indicate that the loss of helicase IV might stabilize recombination repair intermediates formed in the absence of recFLOR and renderrecFLOR, addAB, andrecH cells impaired in plasmid transformation.

scholarly journals Genetic Recombination in Bacillus subtilis 168: Contribution of Holliday Junction Processing Functions in Chromosome Segregation

2004 ◽  
Vol 186 (17) ◽  
pp. 5557-5566 ◽  
Author(s):  
Begoña Carrasco ◽  
M. Castillo Cozar ◽  
Rudi Lurz ◽  
Juan C. Alonso ◽  
Silvia Ayora
Keyword(s):  
Dna Repair ◽  
Bacillus Subtilis ◽  
Genetic Recombination ◽  
Holliday Junction ◽  
Dna Helicases ◽  
Chromosomal Segregation ◽  
Dna Damaging Agents ◽  
Bacillus Subtilis 168 ◽  
Repair Deficiency ◽  
Repair Defect

ABSTRACT Bacillus subtilis mutants classified within the ε (ruvA, ΔruvB, ΔrecU, and recD) and η (ΔrecG) epistatic groups, in an otherwise rec+ background, render cells impaired in chromosomal segregation. A less-pronounced segregation defect in ΔrecA and Δsms (ΔradA) cells was observed. The repair deficiency of addAB, ΔrecO, ΔrecR, recH, ΔrecS, and ΔsubA cells did not correlate with a chromosomal segregation defect. The sensitivity of ε epistatic group mutants to DNA-damaging agents correlates with ongoing DNA replication at the time of exposure to the agents. The Δsms (ΔradA) and ΔsubA mutations partially suppress the DNA repair defect in ruvA and recD cells and the segregation defect in ruvA and ΔrecG cells. The Δsms (ΔradA) and ΔsubA mutations partially suppress the DNA repair defect of ΔrecU cells but do not suppress the segregation defect in these cells. The ΔrecA mutation suppresses the segregation defect but does not suppress the DNA repair defect in ΔrecU cells. These results result suggest that (i) the RuvAB and RecG branch migrating DNA helicases, the RecU Holliday junction (HJ) resolvase, and RecD bias HJ resolution towards noncrossovers and that (ii) Sms (RadA) and SubA proteins might play a role in the stabilization and or processing of HJ intermediates.

scholarly journals Genetic Recombination in Bacillus subtilis 168: Effects of recU and recSMutations on DNA Repair and Homologous Recombination

1998 ◽  
Vol 180 (13) ◽  
pp. 3405-3409 ◽  
Author(s):  
Silvia Fernández ◽  
Alexei Sorokin ◽  
Juan C. Alonso
Keyword(s):  
Dna Repair ◽  
Bacillus Subtilis ◽  
Selectable Marker ◽  
Genetic Recombination ◽  
Null Alleles ◽  
Single Mutation ◽  
Coding Regions ◽  
Dna Damaging Agents ◽  
Bacillus Subtilis 168 ◽  
Intramolecular Recombination

ABSTRACT Bacillus subtilis recombination-deficient mutants were constructed by inserting a selectable marker (cat gene) into the yppB and ypbC coding regions. TheyppB:cat and ypbC:catnull alleles rendered cells sensitive to DNA-damaging agents, impaired plasmid transformation (25- and 100-fold), and moderately affected chromosomal transformation when present in an otherwise Rec+ B. subtilis strain. The yppBgene complemented the defect of the recG40 strain.yppB and ypbC and their respective null alleles were termed “recU” and “recU1” (recU:cat) and “recS” and “recS1” (recS:cat), respectively. The recU and recS mutations were introduced into rec-deficient strains representative of the α (recF), β (addA5 addB72), γ (recH342), and ɛ (recG40) epistatic groups. The recU mutation did not modify the sensitivity ofrecH cells to DNA-damaging agents, but it did affect inter- and intramolecular recombination in recH cells. TherecS mutation did not modify the sensitivity ofaddAB cells to DNA-damaging agents, and it marginally affected recF, recH, and recUcells. The recS mutation markedly reduced (about 250-fold) intermolecular recombination in recH cells, and there were reductions of 10- to 20-fold in recF, addAB, and recU cells. Intramolecular recombination was blocked inrecS recF, recS addAB, and recS recU cells. RecU and RecS have no functional counterparts inEscherichia coli. Altogether, these data indicate that therecU and recS proteins are required for DNA repair and intramolecular recombination and that the recF(α epistatic group), addAB (β), recH (γ),recU (ɛ), and recS genes provide overlapping activities that compensate for the effects of single mutation. We tentatively placed recS within a new group, termed “ζ.”

scholarly journals Recombinogenic Effects of DNA-Damaging Agents Are Synergistically Increased by Transcription inSaccharomyces cerevisiae: New Insights Into Transcription-Associated Recombination

Genetics ◽  
2003 ◽  
Vol 165 (2) ◽  
pp. 457-466 ◽  
Author(s):  
M García-Rubio ◽  
P Huertas ◽  
S González-Barrera ◽  
A Aguilera
Keyword(s):  
Dna Damage ◽  
Homologous Recombination ◽  
Dna Sequence ◽  
Direct Repeat ◽  
Methyl Methanesulfonate ◽  
Immunoglobulin Genes ◽  
Developmentally Regulated ◽  
Dna Damaging Agents ◽  
Regulated Promoters ◽  
Synergistic Increase

AbstractHomologous recombination of a particular DNA sequence is strongly stimulated by transcription, a phenomenon observed from bacteria to mammals, which we refer to as transcription-associated recombination (TAR). TAR might be an accidental feature of DNA chemistry with important consequences for genetic stability. However, it is also essential for developmentally regulated processes such as class switching of immunoglobulin genes. Consequently, it is likely that TAR embraces more than one mechanism. In this study we tested the possibility that transcription induces recombination by making DNA more susceptible to recombinogenic DNA damage. Using different plasmid-chromosome and direct-repeat recombination constructs in which transcription is driven from either the PGAL1- or the Ptet-regulated promoters, we haveshown that either 4-nitroquinoline-N-oxide (4-NQO) or methyl methanesulfonate (MMS) produces a synergistic increase of recombination when combined with transcription. 4-NQO and MMS stimulated recombination of a transcriptionally active DNA sequence up to 12,800- and 130-fold above the spontaneous levels observed in the absence of transcription, whereas 4-NQO and MMS alone increased recombination 193- and 4.5-fold, respectively. Our results provide evidence that TAR is due, at least in part, to the ability of transcription to enhance the accessibility of DNA to exogenous chemicals and internal metabolites responsible for recombinogenic lesions. We discuss possible parallelisms between the mechanisms of induction of recombination and mutation by transcription.

Intramolecular homologous recombination in Bacillus subtilis 168

1992 ◽  
Vol 236 (1) ◽  
pp. 60-64 ◽  
Author(s):  
Juan C. Alonso ◽  
Gerhild Lüder ◽  
Thomas A. Trautner
Keyword(s):  
Bacillus Subtilis ◽  
Homologous Recombination ◽  
Bacillus Subtilis 168

141 INDICATIONS FOR DNA DOUBLE-STRAND BREAK REPAIR IN EARLY BOVINE EMBRYOS

2007 ◽  
Vol 19 (1) ◽  
pp. 188
Author(s):  
A. Brero ◽  
D. Koehler ◽  
T. Cremer ◽  
E. Wolf ◽  
V. Zakhartchenko
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Strand Break ◽  
Dna Lesions ◽  
Homologous Recombination Repair ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Male And Female ◽  
Γh2ax Foci ◽  
Recombination Repair

DNA double-strand breaks (DSBs) are considered the most severe type of DNA lesions, because such lesions, if unrepaired, lead to a loss of genome integrity. Soon after induction of DSBs, chromatin surrounding the damage is modified by phosphorylation of the histone variant H2AX, generating so-called γH2AX, which is a hallmark of DSBs (Takahashi et al. 2005 Cancer Lett. 229, 171–179). γH2AX appears to be a signal for the recruitment of proteins constituting the DNA repair machinery. Depending on the type of damage and the cell cycle stage of the affected cell, DSBs are repaired either by nonhomologous end joining or by homologous recombination using the sister chromatid DNA as template (Hoeijmakers 2001 Nature 411, 366–374). We used immunofluorescence to analyze chromatin composition during bovine development and found γH2AX foci in both male and female pronuclei of IVF embryos. The number and size of foci varied considerably between embryos and between the male and female pronuclei. To test whether the observed γH2AX foci represented sites of active DNA repair, we co-stained IVF zygotes for γH2AX and 3 different proteins involved in homologous recombination repair of DSBs: NBS1 (phosphorylated at amino acid serine 343), 53BP1, and Rad51. We found co-localization of γH2AX foci with phosphorylated NBS1 as well as with Rad51 but did not observe the presence of 53BP1 at γH2AX foci in IVF zygotes. Our finding shows the presence of DSBs in IVF zygotes and suggests the capability of homologous recombination repair. The lack of 53BP1, a component of homologous recombination repair, which usually co-localizes with γH2AX foci at exogenously induced DSBs (Schultz et al. 2000 J. Cell. Biol. 151, 1381–1390) poses the possibility that the mechanism present in early embryos differs substantially from that involved in DNA repair of DSBs in somatic cells.

scholarly journals Homologous Recombination Repair Polymorphisms and the Risk for Osteosarcoma / Polimorfizam Gena Odgovornih Za Reparaciju Dnk Homolognom Rekombinacijom I Rizikza Pojavu Osteosarkoma

2015 ◽  
Vol 34 (2) ◽  
pp. 200-206 ◽  
Author(s):  
Katja Goričar ◽  
Viljem Kovač ◽  
Janez Jazbec ◽  
Janez Lamovec ◽  
Vita Dolžan
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Genome Stability ◽  
Cancer Susceptibility ◽  
Homologous Recombination Repair ◽  
Nucleotide Polymorphisms ◽  
Dna Repair Mechanisms ◽  
Recombination Repair ◽  
Repair Mechanisms ◽  
Repair Genes

Summary Background: DNA repair mechanisms are essential for maintaining genome stability, and genetic variability in DNA repair genes may contribute to cancer susceptibility. Our aim was to evaluate the influence of polymorphisms in the homologous recombination repair genes XRCC3, RAD51, and NBN on the risk for osteosarcoma. Methods: In total, 79 osteosarcoma cases and 373 controls were genotyped for eight single nucleotide polymorphisms (SNPs) in XRCC3, RAD51, and NBN. Logistic regression was used to determine the association of these SNPs with risk for osteosarcoma. Results: None of the investigated SNPs was associated with risk for osteosarcoma in the whole cohort of patients, however, in patients diagnosed before the age of thirty years XRCC3 rs861539 C>T and NBN rs1805794 G>C were associated with significantly decreased risk for osteosarcoma (P=0.047, OR=0.54, 95% CI=0.30-0.99 and P=0.036, OR=0.42, 95% CI=0.19-0.94, respectively). Moreover, in the carriers of a combination of polymorphic alleles in both SNPs risk for osteosarcoma was decreased even more significantly (Ptrend=0.007). The risk for developing osteosarcoma was the lowest in patients with no wild-type alleles for both SNPs (P=0.039, OR=0.31, 95% CI=0.10-0.94). Conclusions: Our results suggest that polymorphisms in homologous recombination repair genes might contribute to risk for osteosarcoma in patients diagnosed below the age of thirty years.

scholarly journals NUCKS1 promotes RAD54 activity in homologous recombination DNA repair

2020 ◽  
Vol 219 (10) ◽  
Author(s):  
David G. Maranon ◽  
Neelam Sharma ◽  
Yuxin Huang ◽  
Platon Selemenakis ◽  
Meiling Wang ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Human Cells ◽  
Cyclin Dependent Kinase ◽  
Loop Formation ◽  
Multifunctional Protein ◽  
Kinase Substrate ◽  
Dna Damage Signaling ◽  
Dna Damaging Agents

NUCKS1 (nuclear ubiquitous casein kinase and cyclin-dependent kinase substrate 1) is a chromatin-associated, vertebrate-specific, and multifunctional protein with a role in DNA damage signaling and repair. Previously, we have shown that NUCKS1 helps maintain homologous recombination (HR) DNA repair in human cells and functions as a tumor suppressor in mice. However, the mechanisms by which NUCKS1 positively impacts these processes had remained unclear. Here, we show that NUCKS1 physically and functionally interacts with the DNA motor protein RAD54. Upon exposure of human cells to DNA-damaging agents, NUCKS1 controls the resolution of RAD54 foci. In unperturbed cells, NUCKS1 prevents RAD54’s inappropriate engagement with RAD51AP1. In vitro, NUCKS1 stimulates the ATPase activity of RAD54 and the RAD51–RAD54-mediated strand invasion step during displacement loop formation. Taken together, our data demonstrate that the NUCKS1 protein is an important new regulator of the spatiotemporal events in HR.

Homologous recombination deficiency (HRD) scoring in pancreatic ductal adenocarcinoma (PDAC) and response to chemotherapy.

2020 ◽  
Vol 38 (4_suppl) ◽  
pp. 741-741
Author(s):  
Grainne M. O'Kane ◽  
Rob Denroche ◽  
Sarah Louise Picardo ◽  
Amy Zhang ◽  
Spring Holter ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Structural Variation ◽  
Ductal Adenocarcinoma ◽  
Cutoff Score ◽  
Homologous Recombination Repair ◽  
Germline Variants ◽  
Dna Damaging Agents ◽  
Response To Chemotherapy ◽  
Recombination Repair ◽  
Clinical Trial Information

741 Background: Whole genome sequencing (WGS) can reveal patterns of substitution base signatures and structural variation consistent with tumours deficient in homologous recombination repair. We evaluated the published HRDetect score and a novel HRD hallmark score (HS) in patients receiving combination chemotherapy (cCT) on the COMPASS trial for advanced PDAC. Methods: The HRD-HS incorporates 10 genomic characteristics of HRD-PDAC with a score ≥ 4 defining HRD. HRD-HS and an HRDetect score ≥0.7 were applied to WGS data and overall survival (OS) and response (ORR) evaluated. Sensitivity and specificity were ascertained. Results: As of 05/19, 205 eligible patients (pts) were enrolled and 186 received cCT including modified FOLFIRINOX n = 108 (58%) or cisplatin/gemcitabine n = 2 (1%) and gemcitabine/nab-paclitaxel n = 76 (41%). HRD-HS had a sensitivity of 87.5% and specificity of 100% in detecting HRD-PDAC. In contrast, HRDetect (≥0.7) had sensitivity of 51.9% and specificity of 100%; sensitivity increased to 73.7% when using a cutoff score of ≥0.99. 23/186 (12%) pts were classified as HRdetecthi and median OS was 15.3months (mo) vs 8.7mo in HRDetectlo pts (HR 0.44 95% CI 0.27-.70, p = 0.009). In platinum treated pts, median OS was 18.1mo (HRDetecthi) vs 9.3mo (HRDetectlo) (HR 0.38 95%CI 0.21-0.69, p = 0.02). HRD-HS predicted the longest median OS for platinum of 21.0mths. ORR in HRDetecthi was not different to HRDetectlo pts treated with cCT, however in those receiving platinum the ORR was 50% vs 19% respectively (p < 0.001). Of the false positives by HRDetect, 46% had a non-BRCA1 tandem duplicator phenotype (TDP). The TDP group comprised 8% of all patients enrolled. HRD-PDAC was caused by inactivation of BRCA1/2, PALB2, RAD51C and XRCC2; all germline variants were pathogenic. Pathogenic ATM and CHEK2 germline variants were present in 3 pts with evidence of a second somatic hit or LOH, none of these identified as HRD by either classifier nor considered a TDP. Conclusions: HRD-HS most correctly identified HRD-PDAC however the HRDetect score classifies additional patients sensitive to cCT, especially platinum. The TDP cohort may be responsive to DNA damaging agents warranting further evaluation. Clinical trial information: NCT02750657.

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