The SOSS1 single‐stranded DNA binding complex promotes DNA end resection in concert with Exo1. (23rd November 2012)

• Record Type: Journal Article
• Authors: Yang, Soo‐Hyun; Zhou, Ruobo; Campbell, Judith; Chen, Junjie; Ha, Taekjip; Paull, Tanya T
• Is Part Of: EMBO journal. Volume 32:Number 1(2013)
• Page Start: 126
• Page End: 139
• Publication Date: 2012-11-23
• Subjects: DNA repair -- resection -- RPA -- single‐stranded DNA; Molecular biology -- Periodicals; 572.805
• DOI: 10.1038/emboj.2012.314
• Languages: English
• ISSNs: 0261-4189

Abstract

Abstract : The human SSB homologue 1 (hSSB1) has been shown to facilitate homologous recombination and double‐strand break signalling in human cells. Here, we compare the DNA‐binding properties of the SOSS1 complex, containing SSB1, with Replication Protein A (RPA), the primary single‐strand DNA (ssDNA) binding complex in eukaryotes. Ensemble and single‐molecule approaches show that SOSS1 binds ssDNA with lower affinity compared to RPA, and exhibits less stable interactions with DNA substrates. Nevertheless, the SOSS1 complex is uniquely capable of promoting interaction of human Exo1 with double‐strand DNA ends and stimulates its activity independently of the MRN complex in vitro . Both MRN and SOSS1 also act to mitigate the inhibitory action of the Ku70/80 heterodimer on Exo1 activity in vitro . These results may explain why SOSS complexes do not localize with RPA to replication sites in human cells, yet have a strong effect on double‐strand break resection and homologous recombination. Abstract : Distinct functional properties of the two mammalian single‐strand DNA‐binding activities, RPA and the hSSB1‐containing SOSS1 complex, underlie their preferential involvement in replication and in DNA double‐strand break resection, respectively.