Functional interplay of the Mre11 nuclease and Ku in the response to replication-associated DNA damage Journal Article

   

Authors:	Foster, S. S.; Balestrini, A.; Petrini, J. H. J.
Article Title:	Functional interplay of the Mre11 nuclease and Ku in the response to replication-associated DNA damage
Abstract:	The Mre11 complex is a central component of the DNA damage response, with roles in damage sensing, molecular bridging, and end resection. We have previously shown that in Saccharomyces cerevisiae, Ku70 (yKu70) deficiency reduces the ionizing radiation sensitivity of mre11δ mutants. In this study, we show that yKu70 deficiency suppressed the camptothecin (CPT) and methyl methanesulfonate (MMS) sensitivity of nuclease-deficient mre11-3 and sae2δ mutants in an Exo1-dependent manner. CPT-induced G2/M arrest, γ-H2AX persistence, and chromosome breaks were elevated in mre11-3 mutants. These outcomes were reduced by yKu70 deficiency. Given that the genotoxic effects of CPT are manifest during DNA replication, these data suggest that Ku limits Exo1-dependent double-strand break (DSB) resection during DNA replication, inhibiting the initial processing steps required for homology-directed repair. We propose that Mre11 nuclease- and Sae2-dependent DNA end processing, which initiates DSB resection prevents Ku from engaging DSBs, thus promoting Exo1-dependent resection. In agreement with this idea, we show that Ku affinity for binding to short single-stranded overhangs is much lower than for blunt DNA ends. Collectively, the data define a nonhomologous end joining (NHEJ)-independent, S-phase-specific function of the Ku heterodimer. © 2011, American Society for Microbiology.
Keywords:	unclassified drug; mutation; dna-binding proteins; nonhuman; outcome assessment; binding affinity; dna replication; protein function; sensitivity analysis; mre11 protein; dna damage; cell cycle s phase; dna repair; models, biological; camptothecin; saccharomyces cerevisiae; dna breaks, double-stranded; cell cycle arrest; chromosome breakage; double stranded dna break; cell cycle g2 phase; cell cycle m phase; saccharomyces cerevisiae proteins; flap endonucleases; sequence homology; ku antigen; histone h2ax; s phase; genotoxicity; endodeoxyribonucleases; exodeoxyribonucleases; dna, fungal; mesylic acid methyl ester; histone h2ax gamma; genes, fungal; endonucleases; dna end-joining repair
Journal Title:	Molecular and Cellular Biology
Volume:	31
Issue:	21
ISSN:	0270-7306
Publisher:	American Society for Microbiology
Date Published:	2011-11-01
Start Page:	4379
End Page:	4389
Language:	English
DOI:	10.1128/mcb.05854-11
PROVIDER:	scopus
PMCID:	PMC3209331
PUBMED:	21876003
DOI/URL:	http://www.scopus.com/inward/record.url?eid=2-s2.0-83255187901&partnerID=40&md5=dfa1161353c9585b46edb693cdc83169
Notes:	--- - "Export Date: 3 January 2012" - "CODEN: MCEBD" - "Source: Scopus"

https://synapse.mskcc.org/synapse/works/has_related_data_chk/16389