Elucidation of novel components of the response to genotoxic stress in Saccharomyces cerevisiae.

摘要

Faithful maintenance of genome integrity is essential for cellular viability. Failure to efficiently recognize and repair DNA damage or respond to replication stress can lead to genomic instability and, in higher eukaryotes, cancer. The cellular response to genotoxic stress has been particularly well characterized in Saccharomyces cerevisiae through the isolation of mutants that are hypersensitive to specific agents that cause DNA damage and/or replication stress. However, there is still much about this response that is not yet known, including many of the actual components. The work described in this dissertation was driven by a desire to improve our knowledge of this area. We used high-throughput genomic and proteomic screening approaches to identify novel genes and proteins that mediate the genotoxic stress response. From these experiments, we isolated Wss1, which is required for an efficient response to UV irradiation and replication stress. We believe Wss1 may contribute to survival by stabilizing or processing stalled or collapsed replication forks. As a result of the investigation of WSS1, we also isolated PSY2 as a gene required for viability following treatment with the DNA damaging agent MMS. Further study revealed that Psy2 partners with the phosphatase Pph3 to regulate the cell cycle checkpoint response. In addition to our efforts into the general response, we also pursued the identification of genes that when inactivated, attenuate the cells ability to mutate. From this effort, we identified two genes, FYV6 and RNR4, that function in novel pathways that induce mutagenesis in response to UV irradiation. Together, these studies illustrate that the tools available in the post-genomic era provide opportunities for novel insights into the response to genotoxic stress at a rapid pace.