Open AccessBRCT Domain Interactions with Phospho-Histone H2A Target Crb2 to Chromatin at Double-Strand Breaks and Maintain the DNA Damage Checkpoint
Author(s) -
Sevil Sofueva,
Li-Lin Du,
Oliver Limbo,
Jessica S. Williams,
Paul Russell
Publication year - 2010
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.00413-10
Subject(s) - g2 m dna damage checkpoint , biology , chromatin , schizosaccharomyces pombe , chek1 , histone , histone h3 , microbiology and biotechnology , schizosaccharomyces , histone h2a , dna repair , cell cycle checkpoint , genetics , dna , saccharomyces cerevisiae , cell cycle , cell , gene
Relocalization of checkpoint proteins to chromatin flanking DNA double-strand breaks (DSBs) is critical for cellular responses to DNA damage.Schizosaccharomyces pombe Crb2, which mediates Chk1 activation by Rad3ATR , forms ionizing radiation-induced nuclear foci (IRIF). Crb2 C-terminal BRCT domains (BRCT2 ) bind histone H2A phosphorylated at a C-terminal SQ motif by Tel1ATM and Rad3ATR , although the functional significance of this interaction is controversial. Here, we show that polar interactions of Crb2 serine-548 and lysine-619 with the phosphate group of phospho-H2A (γ-H2A) are critical for Crb2 IRIF formation and checkpoint function. Mutations of these BRCT2 domain residues have additive effects when combined in a single allele. Combining either mutation with an allele that eliminates the threonine-215 cyclin-dependent kinase phosphorylation site completely abrogates Crb2 IRIF and function. We propose that cooperative phosphate interactions in the BRCT2 γ-H2A-binding pocket of Crb2, coupled with tudor domain interactions with lysine-20 dimethylation of histone H4, facilitate stable recruitment of Crb2 to chromatin surrounding DSBs, which in turn mediates efficient phosphorylation of Chk1 that is required for a sustained checkpoint response. This mechanism of cooperative interactions with the γ-H2A/X phosphate is likely conserved inS. pombe Brc1 and human Mdc1 genome maintenance proteins.