Biology subjects

Teixeira-Silva, A.

Publications and source records attributed to Teixeira-Silva, A..

2 recordsLinked to original sources

bioRxiv2018

Histone deposition plays an active role in recombination-dependent replication to balance genome2 stability upon replication stress

Replication stress poses a serious threat to genome and epigenome stability. Recombination-Dependent-Replication (RDR) ensures DNA synthesis resumption from arrested forks. Despite the identification of chromatin restoration pathways during DNA repair processes, crosstalk coupling RDR and chromatin assembly is largely unexplored. Here, we addressed the contribution of chromatin assembly to replication stress in fission yeast. We expressed a mutated histone (H3-H113D) to genetically impair replication-dependent chromatin assembly by destabilizing (H3-H4)2 tetramer. We established that DNA synthesis-dependent histone deposition is required for the completion of RDR. Histone deposition prevents joint-molecules from Rqh1-dependent disassembly, a crosstalk contributing to cell survival upon replication stress but channeling RDR towards deleterious events. Asf1 and CAF-1 act in RDR and CAF-1 recruitment to DNA synthesis associated to RDR requires the HR factor Rad52. Our data establish that CAF-1 counteracts Rqh1 activity at sites of replication stress by promoting repair synthesis-coupled histone deposition. These results demonstrate that histone deposition plays an active role in fine-tuning RDR, a benefit counterbalanced by stabilizing at-risk joint molecules for genome stability.

genetics↗

bioRxiv2017

The non-homologous end joining factor Ku orchestrates replication fork resection and fine-tunes Rad51-mediated fork restart

Replication requires Homologous Recombination (HR) to stabilize and restart terminally-arrested forks. HR-mediated fork processing requires single stranded DNA (ssDNA) gaps and not necessarily Double Strand Breaks. We used genetic and molecular assays to investigate fork-resection and restart at dysfunctional, unbroken forks in Schizosaccharomyces pombe. We found that fork-resection is a two-step process coordinated by the non-homologous end joining factor Ku. An initial resection mediated by MRN/Ctp1 removes Ku from terminally-arrested forks, generating ~ 110 bp sized gaps obligatory for subsequent Exo1-mediated long-range resection and replication restart. The lack of Ku results in slower fork restart, excessive resection, and impaired RPA recruitment. We propose that terminally-arrested forks undergo fork reversal, providing a single DNA end for Ku binding which primes RPA-coated ssDNA. We uncover an unprecedented role for Ku in orchestrating resection of unbroken forks and in fine-tuning HR-mediated replication restart.\n\nO_LIKu orchestrates a two-steps DNA end-resection of terminally-arrested and unbroken forks\nC_LIO_LIMRN/Ctp1 removes Ku from terminally-arrested forks to initiate fork-resection\nC_LIO_LIa ~110 bp sized ssDNA gap is sufficient and necessary to promote fork restart.\nC_LIO_LIThe lack of Ku decreases ssDNA RPA-coating, and slows down replication fork restart.\nC_LI

genetics↗