Abstract: In order to maintain the integrity of chromosomal structure and genetic stability, in addition to those elaborate DNA damage repair mechanisms to remove DNA lesions, cells have also evolved DNA damage tolerance mechanisms to bypass damage. One extensively studied lesion-bypass pathway is translesion synthesis(TLS), an error-prone repair pathway, in which replicative polymerase δ is replaced with a specialized TLS polymerase, a low fidelity enzyme, which is able to by-pass lesions, allowing stalled replication fork in S-phase to proceed. The switching between replicative and TLS polymerases is generally considered to be a core in TLS pathway. However, there remains much controversy on the exact mechanism of polymerase switching. This article briefly reviewed and discussed researches about biological properties of eukaryotic DNA polymerase δ, structure and function of its subunits, and activation mechanisms of polymerase switching in TLS pathway, etc.

Key words: DNA polymerase Pol δ, TLS polymerase, proliferating cell nuclear antigen(PCNA), ubiquitin modification, polymerase switching mechanism