NMR Structure and Dynamics of the C-Terminal Domain from Human Revl and Its Complex with Rev1 Interacting Region of DNA Polymerase η

Rev1 is a translesion synthesis (TLS) DNA polymerase essential for DNA damage tolerance in eukaryotes. In the process of TLS stalled high-fidelity replicative DNA polymerases are temporarily replaced by specialized TLS enzymes that can bypass sites of DNA damage (lesions), thus allowing replication to continue or postreplicational gaps to be filled. Despite its limited catalytic activity, human Rev1 plays a key role in TLS by serving as a scaffold that provides an access of Y-family TLS polymerases pol eta, t, and K to their cognate DNA lesions and facilitates their subsequent exchange to pole that extends the distorted DNA primer template. Rev1 interaction with the other major human TLS polymerases, pol eta, I, K, and the regulatory subunit Rev7 of pol zeta, is mediated by Rev1 C-terminal domain (Rev1-CT). We used NMR spectroscopy to determine the spatial structure of the Rev1-CT domain (residues 11S7-1251) and its complex with Rev1 interacting region (RIR) from pol eta (residues 524-539). The domain forms a four-helix bundle with a well-structured N-terminal beta-hairpin docking against helices 1 and 2, creating a binding pocket for the two conserved Phe residues of the RIR motif that upon binding folds into an a-helix. NMR spin-relaxation and NMR relaxation dispersion measurements suggest that free Rev1-CT and Rev1-CT/pol eta-RIR complex exhibit mu s-ms conformational dynamics encompassing the RIR binding site, which might facilitate selection of the molecular configuration optimal for binding. These results offer new insights into the control of TLS in human cells by providing a structural basis for understanding the recognition of the Rev1-CT by Y-family DNA polymerases.