Molecular architecture of the Ub-PCNA/Pol ? complex bound to DNA.

ABSTRACT: Translesion synthesis (TLS) is the mechanism by which DNA polymerases replicate through unrepaired DNA lesions. TLS is activated by monoubiquitination of the homotrimeric proliferating cell nuclear antigen (PCNA) at lysine-164, followed by the switch from replicative to specialized polymerases at DNA damage sites. Pol ? belongs to the Y-Family of specialized polymerases that can efficiently bypass UV-induced lesions. Like other members of the Y-Family polymerases, its recruitment to the damaged sites is mediated by the interaction with monoubiquitinated PCNA (Ub-PCNA) via its ubiquitin-binding domain and non-canonical PCNA-interacting motif in the C-terminal region. The structural determinants underlying the direct recognition of Ub-PCNA by Pol ?, or Y-Family polymerases in general, remain largely unknown. Here we report a structure of the Ub-PCNA/Pol ? complex bound to DNA determined by single-particle electron microscopy (EM). The overall obtained structure resembles that of the editing PCNA/PolB complex. Analysis of the map revealed the conformation of ubiquitin that binds the C-terminal domain of Pol ?. Our present study suggests that the Ub-PCNA/Pol ? interaction requires the formation of a structured binding interface, which is dictated by the inherent flexibility of Ub-PCNA.

SUBMITTER: Lau WC 

PROVIDER: S-EPMC4621508 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature