DNA damage tolerance is a major cellular mechanism in response to unrepaired DNA lesions during replication. It allows replication to completion in the presence of DNA lesions that block replicative polymerases. Damage tolerance consists of two major mechanisms: template switching and translesion DNA synthesis. Translesion synthesis directly copies damaged sites of the DNA template during replication. Consequently, error-prone translesion synthesis constitutes the major mechanism of base damage-induced mutagenesis. In eukaryotes, translesion synthesis is carried out by the Rev1-Polα pathway. Rev1 possesses a dCMP transferase activity, and is a member of the Y family of DNA polymerases. Additionally, it is widely believed that Rev1 plays non-catalytic functions in translesion synthesis. However, the non-catalytic function of Rev1 is not clearly defined. Using the yeast model system, we have investigated non-catalytic functions of Rev1 in translesion synthesis and base damage-induced mutagenesis. Specifically, we examined the role of Rev1-Rad5 interaction in translesion synthesis of UV damage and a site-specific 1, N6-ethenoadenine (a DNA lesion of lipid peroxidation products). Although Rad5 is better known for its role in template switching, it stably interacts with Rev1. Interaction domains in the Rev1 and Rad5 proteins were defined. Translesion synthesis and mutagenesis required Rad5 in cells. Disrupting the Rev1-Rad5 interaction by mutating Rev1 did not affect the dCMP transferase of Rev1, but led to inactivation of the translesion synthesis pathway. These results show that Rad5 is an indispensible component of the Rev1-Pol ≤ pathway for translesion synthesis and base damage-induced mutagenesis, and a non-catalytic function of Rev1 in translesion DNA synthesis is mediated by its stable interaction with Rad5.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2553. doi:1538-7445.AM2012-2553