 This finding indicates that XRCC1-mediated base excision repair is important for speedy recovery from stroke.The NMR solution structure of the Xrcc1 N-terminal domain (Xrcc1 NTD) shows that the structural core is a beta-sandwich with beta-strands connected by loops, three helices and two short two-stranded beta-sheets at each connection side.The Xrcc1 NTD specifically binds single-strand break DNA (gapped and nicked) and a gapped DNA-beta-Pol complex.