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Publication Abstract from PubMed

Rtt107 (regulator of Ty1 transposition 107; Esc4) is a DNA repair protein from Saccharomyces cerevisiae that can restore stalled replication forks following DNA damage. There are six BRCT (BRCA1 C-terminal) domains in Rtt107 that act as binding sites for other recruited proteins during DNA repair. Several Rtt107 binding partners have been identified, including Slx4, Rtt101, Rad55, and the Smc5/6 (structural maintenance of chromosome) protein complex. Rtt107 can reportedly be recruited to chromatin in the presence of Rtt101 and Rtt109 upon DNA damage, but the chromatin-binding site of Rtt107 has not been identified. Here, we report our investigation of the interaction between phosphorylated histone H2A (gammaH2A) and the C-terminal tandem BRCT repeats (BRCT(5)-BRCT(6)) of Rtt107. The crystal structures of BRCT(5)-BRCT(6) alone and in a complex with gammaH2A reveal the molecular basis of the Rtt107-gammaH2A interaction. We used in vitro mutagenesis and a fluorescence polarization assay to confirm the location of the Rtt107 motif that is crucial for this interaction. In addition, these assays indicated that this interaction requires the phosphorylation of H2A. An in vivo phenotypic analysis in yeast demonstrated the critical role of BRCT(5)-BRCT(6) and its interaction with gammaH2A during the DNA damage response. Our results shed new light on the molecular mechanism by which Rtt107 is recruited to chromatin in response to stalled DNA replication forks.

Structure of C-terminal tandem BRCT repeats of Rtt107 protein reveals critical role in interaction with phosphorylated histone H2A during DNA damage repair.,Li X, Liu K, Li F, Wang J, Huang H, Wu J, Shi Y J Biol Chem. 2012 Mar 16;287(12):9137-46. Epub 2012 Jan 19. PMID:22262834^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.