scholarly journals The cohesin-like RecN protein stimulates RecA-mediated recombinational repair of DNA double-strand breaks

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Lee A. Uranga ◽  
Emigdio D. Reyes ◽  
Praveen L. Patidar ◽  
Lindsay N. Redman ◽  
Shelley L. Lusetti
Keyword(s):  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Dna Double Strand Breaks ◽  
Strand Breaks

scholarly journals Critical Role of RecN in Recombinational DNA Repair and Survival of Helicobacter pylori

2007 ◽  
Vol 76 (1) ◽  
pp. 153-160 ◽  
Author(s):  
Ge Wang ◽  
Robert J. Maier
Keyword(s):  
Helicobacter Pylori ◽  
Parent Strain ◽  
Dna Recombination ◽  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Wild Type ◽  
Dna Double Strand Breaks ◽  
Air Exposure ◽  
Strand Breaks ◽  
H Pylori

ABSTRACT Homologous recombination is one of the key mechanisms responsible for the repair of DNA double-strand breaks. Recombinational repair normally requires a battery of proteins, each with specific DNA recognition, strand transfer, resolution, or other functions. Helicobacter pylori lacks many of the proteins normally involved in the early stage (presynapsis) of recombinational repair, but it has a RecN homologue with an unclear function. A recN mutant strain of H. pylori was shown to be much more sensitive than its parent to mitomycin C, an agent predominantly causing DNA double-strand breaks. The recN strain was unable to survive exposure to either air or acid as well as the parent strain, and air exposure resulted in no viable recN cells recovered after 8 h. In oxidative stress conditions (i.e., air exposure), a recN strain accumulated significantly more damaged (multiply fragmented) DNA than the parent strain. To assess the DNA recombination abilities of strains, their transformation abilities were compared by separately monitoring transformation using H. pylori DNA fragments containing either a site-specific mutation (conferring rifampin resistance) or a large insertion (kanamycin resistance cassette). The transformation frequencies using the two types of DNA donor were 10- and 50-fold lower, respectively, for the recN strain than for the wild type, indicating that RecN plays an important role in facilitating DNA recombination. In two separate mouse colonization experiments, the recN strain colonized most of the stomachs, but the average number of recovered cells was 10-fold less for the mutant than for the parent strain (a statistically significant difference). Complementation of the recN strain by chromosomal insertion of a functional recN gene restored both the recombination frequency and mouse colonization ability to the wild-type levels. Thus, H. pylori RecN, as a component of DNA recombinational repair, plays a significant role in H. pylori survival in vivo.

scholarly journals RecN protein and transcription factor DksA combine to promote faithful recombinational repair of DNA double-strand breaks

2005 ◽  
Vol 57 (1) ◽  
pp. 97-110 ◽  
Author(s):  
Tom R. Meddows ◽  
Andrew P. Savory ◽  
Jane I. Grove ◽  
Timothy Moore ◽  
Robert G. Lloyd
Keyword(s):  
Transcription Factor ◽  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Dna Double Strand Breaks ◽  
Strand Breaks

scholarly journals RecO impedes RecG-SSB binding to impair the strand annealing recombination pathway in E.coli

2019 ◽  
Author(s):  
Xuefeng Pan ◽  
Li Yang ◽  
Nan Jiang ◽  
Xifang Chen ◽  
Bo Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Repair ◽  
Dna Replication ◽  
Replication Fork ◽  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Homologous Recombinational Repair ◽  
Differential Binding

AbstractFaithful duplication of genomic DNA relies not only on the fidelity of DNA replication itself, but also on fully functional DNA repair and homologous recombination machinery. We report a molecular mechanism responsible for deciding homologous recombinational repair pathways during replication dictated by binding of RecO and RecG to SSB in E.coli. Using a RecG-yfp fusion protein, we found that RecG-yfp foci appeared only in the ΔrecG, ΔrecO and ΔrecA, ΔrecO double mutants. Surprisingly, foci were not observed in wild-type ΔrecG, or double mutants where recG and either recF or, separately recR were deleted. In addition, formation of RecG-yfp foci in the ΔrecO::kanR required wildtype ssb, as ssb-113 could not substitute. This suggests that RecG and RecO binding to SSB is competitive. We also found that the UV resistance of recO alone mutant increased to certain extent by supplementing RecG. In an ssb-113 mutant, RecO and RecG worked following a different pattern. Both RecO and RecG were able to participate in repairing UV damages when grown at permissive temperature, while they could also be involved in making DNA double strand breaks when grown at nonpermissive temperature. So, our results suggested that differential binding of RecG and RecO to SSB in a DNA replication fork in Escherichia coli.may be involved in determining whether the SDSA or DSBR pathway of homologous recombinational repair is used.Author summarySingle strand DNA binding proteins (SSB) stabilize DNA holoenzyme and prevent single strand DNA from folding into non-B DNA structures in a DNA replication fork. It has also been revealed that SSB can also act as a platform for some proteins working in DNA repair and recombination to access DNA molecules when DNA replication fork needs to be reestablished. In Escherichia coli, several proteins working primarily in DNA repair and recombination were found to participate in DNA replication fork resumption by physically interacting with SSB, including RecO and RecG etc. However the hierarchy of these proteins interacting with SSB in Escherichia coli has not been well defined. In this study, we demonstrated a differential binding of RecO and RecG to SSB in DNA replication was used to establish a RecO-dependent pathway of replication fork repair by abolishing a RecG-dependent replication fork repair. We also show that, RecG and RecO could randomly participate in DNA replication repair in the absence of a functional SSB, which may be responsible for the generation of DNA double strand breaks in an ssb-113 mutant in Escherichia coli.

scholarly journals A Zip3-like protein plays a role in crossover formation in the SC-less meiosis of the protist Tetrahymena

2017 ◽  
Vol 28 (6) ◽  
pp. 825-833 ◽  
Author(s):  
Anura Shodhan ◽  
Kensuke Kataoka ◽  
Kazufumi Mochizuki ◽  
Maria Novatchkova ◽  
Josef Loidl
Keyword(s):  
Ring Finger ◽  
Specific Protein ◽  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Recombination Proteins ◽  
Evolutionarily Conserved ◽  
Ring Finger Proteins ◽  
Segregation Of Chromosomes

When programmed meiotic DNA double-strand breaks (DSBs) undergo recombinational repair, genetic crossovers (COs) may be formed. A certain level of this is required for the faithful segregation of chromosomes, but the majority of DSBs are processed toward a safer alternative, namely noncrossovers (NCOs), via nonreciprocal DNA exchange. At the crossroads between these two DSB fates is the Msh4-Msh5 (MutSγ) complex, which stabilizes CO-destined recombination intermediates and members of the Zip3/RNF212 family of RING finger proteins, which in turn stabilize MutSγ. These proteins function in the context of the synaptonemal complex (SC) and mainly act on SC-dependent COs. Here we show that in the SC-less ciliate Tetrahymena, Zhp3 (a protein distantly related to Zip3/RNF212), together with MutSγ, is responsible for the majority of COs. This activity of Zhp3 suggests an evolutionarily conserved SC-independent strategy for balancing CO:NCO ratios. Moreover, we report a novel meiosis-specific protein, Sa15, as an interacting partner of Zhp3. Sa15 forms linear structures in meiotic prophase nuclei to which Zhp3 localizes. Sa15 is required for a wild-type level of CO formation. Its linear organization suggests the existence of an underlying chromosomal axis that serves as a scaffold for Zhp3 and other recombination proteins.

scholarly journals DNA-RNA hybrids at DSBs interfere with repair by homologous recombination

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Pedro Ortega ◽  
Jose Antonio Mérida-Cerro ◽  
Ana G Rondón ◽  
Belén Gómez-González ◽  
Andrés Aguilera
Keyword(s):  
Homologous Recombination ◽  
Dna Lesions ◽  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Dna Double Strand Breaks ◽  
Dna Breaks ◽  
Positive Role ◽  
Strand Breaks ◽  
Endonucleolytic Cleavage ◽  
Chromosomal Recombination

DNA double strand breaks (DSBs) are the most harmful DNA lesions and their repair is crucial for cell viability and genome integrity. The readout of DSB repair may depend on whether DSBs occur at transcribed versus non-transcribed regions. Some studies have postulated that DNA-RNA hybrids form at DSBs to promote recombinational repair, but others have challenged this notion. To directly assess whether hybrids formed at DSBs promote or interfere with recombinational repair we have used plasmid and chromosomal-based systems for the analysis of DSB-induced recombination in Saccharomyces cerevisiae. We show that, as expected, DNA-RNA hybrid formation is stimulated at DSBs. In addition, mutations that promote DNA-RNA hybrid accumulation, such as hpr1∆ and rnh1∆ rnh201∆, cause high levels of plasmid loss when DNA breaks are induced at sites that are transcribed. Importantly, we show that high levels or unresolved DNA-RNA hybrids at the breaks interfere with their repair by homologous recombination. This interference is observed for both plasmid and chromosomal recombination and is independent of whether the DSB is generated by endonucleolytic cleavage or by DNA replication. These data support a model in which DNA-RNA hybrids form fortuitously at DNA breaks during transcription, and need to be removed to allow recombinational repair, rather than playing a positive role.

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