Characterization of a possible regulatory role of post-translational modifications in Dpb11 function during the DNA damage response in Saccharomyces cerevisiae

Abstract

The Dpb11 protein (ortholog of human TopBP1) is an essential protein acting in several aspects of the cellular program such as replication, DNA damage signaling/repair and recombination. As part of the DNA damage response, Dpb11 has a key regulatory role in DNA damage checkpoint through the interaction between its BRCT domains (BRCA1 C-terminal domain) and phosphorylated residues in proteins, establishing transient protein complexes that are recruited to DNA lesion sites. The DNA damage checkpoint signaling is a sophisticated mechanism of DNA damage surveillance that is capable of recognizing lesions to the DNA molecule and promote a signaling cascade, thus preventing genomic instability. Phosphoproteomic data have shown that the DNA damage checkpoint kinase Rad53 (CHK1/CHK2 in humans) extensively phosphorylate Dpb11 during replication stress induced by MMS. However, it is still unknown if this phosphorylation affects Dpb11 function such as its interaction with different ligands during the DNA damage response. Therefore, this project aims to analyze the physiological role of these phosphorylation events in Dpb11 function during replication stress.