The 9-1-1 checkpoint clamp stimulates DNA resection by Dna2-Sgs1 and Exo1. Issue 16 (13th August 2014)

• Record Type: Journal Article
• Authors: Ngo, Greg H.P.; Balakrishnan, Lata; Dubarry, Marion; Campbell, Judith L.; Lydall, David
• Is Part Of: Nucleic acids research. Volume 42:Issue 16(2014)
• Page Start: 10516
• Page End: 10528
• Publication Date: 2014-08-13
• Subjects: Nucleic acids -- Periodicals; Molecular biology -- Periodicals; 572.805
• DOI: 10.1093/nar/gku746
• Languages: English
• ISSNs: 0305-1048

Abstract

Abstract: Single-stranded DNA (ssDNA) at DNA ends is an important regulator of the DNA damage response. Resection, the generation of ssDNA, affects DNA damage checkpoint activation, DNA repair pathway choice, ssDNA-associated mutation and replication fork stability. In eukaryotes, extensive DNA resection requires the nuclease Exo1 and nuclease/helicase pair: Dna2 and Sgs1 BLM . How Exo1 and Dna2-Sgs1 BLM coordinate during resection remains poorly understood. The DNA damage checkpoint clamp (the 9-1-1 complex) has been reported to play an important role in stimulating resection but the exact mechanism remains unclear. Here we show that the human 9-1-1 complex enhances the cleavage of DNA by both DNA2 and EXO1 in vitro, showing that the resection-stimulatory role of the 9-1-1 complex is direct. We also show that in Saccharomyces cerevisiae, the 9-1-1 complex promotes both Dna2-Sgs1 and Exo1-dependent resection in response to uncapped telomeres. Our results suggest that the 9-1-1 complex facilitates resection by recruiting both Dna2-Sgs1 and Exo1 to sites of resection. This activity of the 9-1-1 complex in supporting resection is strongly inhibited by the checkpoint adaptor Rad9 53BP1 . Our results provide important mechanistic insights into how DNA resection is regulated by checkpoint proteins and have implications for genome stability in eukaryotes.