Structural basis of γH2AX recognition by human PTIP BRCT5-BRCT6 domains in the DNA damage response pathway

Human Pax2 transactivation domain-interacting protein (hPTIP), containing six BRCT domains, is an essential protein required for the IR induced DDR process with an unclear role. Here we report that the tandem BRCT5-BRCT6 domain of hPTIP recognizes the gamma H2AX tail, and this interaction depends on the phosphorylation of H2AX Ser139 and binding with the carboxyl ending peptide to the aminoacyl ending peptide. The 2.15 angstrom crystal structure of hPTIP BRCT5/6-gamma H2AX complex and mutation analysis provide molecular evidence for direct interactions between PTIP and gamma H2AX. This interaction proffers a new clue to identify the role of PTIP in DDR pathways. Structured summary of protein interactions: PTIP and gamma H2AX bind by fluorescence polarization spectroscopy (View Interaction: 1, 2, 3, 4, 5, 6). PTIP and gamma H2AX bind by X-ray crystallography (View interaction). (C) 2011 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.