Project 171295

Maintenance of genomic stability is a challenge to every cell in the presence of genotoxic agents. Translesion DNA replication or translesion synthesis (TLS), the replication of DNA across damaged DNA, is essential for a cell to survive DNA damage. Numerous cellular and environmental agents continuously damage DNA. DNA damage or lesions blocks or slows down DNA replication, threatening the survival of cells. DNA polymerases (pol) are the molecules responsible to replicate DNA in cells. Only specialized DNA polymerases are able to replicate through damaged DNA. These translesional polymerases (pol) are mutational, introducing errors as they replicate DNA. Consequently, the specialized DNA polymerases mainly determine the mutagenic potential of DNA lesions. These errors in DNA are associated with aging and human diseases, including various forms of cancer. Due to their mutagenic potential, Y-family polymerase activities must be tightly regulated. The regulation is carried by certain protein cofactors. One of these protein-partners is the sliding clamp protein, named PCNAs. This study focuses on structure-function studies of translesion and error-prone DNA polymerases, and their functionally related proteins PCNAs. The goal is to understand why the specialized DNA polymerases make errors and how their function being controlled by the protein-partners. The main technique we use is X-ray crystallography to determine 3-dimensional structures of Y-polymerases, PCNAs and Pol-PCNA complexes. The studies will help us to learn how DNA damage can result in mutations in the human genes, and the role of these events in the onset of diseases.

using X-ray crystallography to study the structure-function of Y-family DNA polymerases and their co-factors in translesion synthesis