A structural hinge in the eukaryotic DNA repair glycosylase, MutY homologue, mediates catalytic activity and interactions with the Rad9‐Rad1‐Hus1 checkpoint complex

The DNA glycosylase MutY homologue (MYH) removes adenines misincorporated opposite 8‐oxoguanine as part of the base excision repair pathway. Importantly, defects in human MYH activity cause the inherited colorectal cancer syndrome MYH‐associated polyposis. A key feature of MYH activity is its coordination with the cell cycle checkpoint via interaction with the Rad9‐Rad1‐Hus1 (9‐1‐1) complex. Here we report the structure of the catalytic domain and interdomain connector (IDC) of hMYH which reveals that the IDC adopts a stabilized conformation projecting away from the catalytic domain to form a docking scaffold for 9‐1‐1. We further examined the role of the IDC using Schizosaccharomyces pombe MYH as a model system. In vitro studies demonstrated that the eukaryotic IDC is required for DNA damage selection and robust enzymatic activity. We additionally identified residues I261 and E262 of S. pombe MYH (equivalent to V315 and E316 of the hMYH IDC) as critical for maintaining the MYH/9‐1‐1 interaction. Our studies also provided the first evidence that disruption of the MYH/9‐1‐1 interaction diminishes the repair of oxidative DNA damage in vivo . Thus, preserving the MYH/9‐1‐1 interaction contributes significantly to minimizing the mutagenic potential of oxidative DNA damage. Research support was provided in part by grant RSG‐09‐058‐01‐GMC from the American Cancer Society.