The Gratuitous Repair on Undamaged DNA Misfold

Pan, Xuefeng; Xiao, Peng; Hong-qun, LI; Zhao, Dongxu; Duan, Fei

doi:10.5772/22441

Cited by 1 publication

(1 citation statement)

References 145 publications

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“…The E.coli SSB forms a homotetrameric protein complex that plays a central role in DNA replication, repair and recombination [60, 61, and 65]. In DNA replication, SSB binds single stranded DNA (ssDNA) of the lagging strand template in a DNA replication fork with no DNA sequence specificity, protecting the ssDNA from misfolding and also from nuclease attack [67,68]. In homologous recombination, SSB prevents recombinase RecA from loading onto ssDNA until recombination mediator proteins (RMPs) come to facilitate the exchange of RecA with SSB for ssDNA.…”

Section: Introductionmentioning

confidence: 99%

RecO impedes RecG-SSB binding to impair the strand annealing recombination pathway inE.coli

Pan

Yang

Jiang

et al. 2019

Preprint

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Faithful 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 Δ recG, Δ recO and Δ recA, Δ recO double mutants. Surprisingly, foci were not observed in wild-type Δ recG, or double mutants where recG and either recF or, separately recR were deleted. In addition, formation of RecG-yfp foci in the Δ recO::kan R required wildtype ssb, as ssb-113 could not substitute. This suggests that RecGand 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.

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Section: Introductionmentioning

confidence: 99%