From genomics to proteomics

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All living organisms are constantly exposed to environmental agents that cause DNA damage, including UV from sunlight, radiation and the vast majority (>90%) of chemical carcinogens, which pose a great danger to the survival of species and public health. Our research focuses on how these agents cause genomic instability, cell death and cancer, and how living organisms respond to these assaults and protect themselves. The major focus of research in my laboratory is to study a recently described pathway called DNA damage tolerance (DDT) in eukaryotes, from simple yeast to human. We contributed to the initial discovery of key genes involved in this pathway, which does not remove DNA damage, but instead allows the replication machinery to bypass the roadblock with or without causing mutations. Due to its short history and complexity in operation, little was known about how this pathway operated until recently. In essence, DDT in eukaryotes is regulated through covalent modifications of a replication clamp called PCNA. In particular, attachment by a single ubiquitin (Ub) leads to a mutagenic bypass, whereas further attachment with a Ub chain leads to non-mutagenic bypass; how the latter is achieved remains unclear. My laboratory recently discovered that a PCNA-like clamp called 9-1-1, which is dedicated to sensing and responding to DNA damage, can also be modified by Ub and that this modification plays a key role in cellular tolerance to DNA damage. Our central objective is to investigate how cells coordinate the DDT process by ubiquitinating two DNA clamps in the model yeast, in cultured human cells, as well as in an animal model. Recently, we began to shift our attention from genetic to biochemical approaches aiming at understanding detailed molecular events governing various DDT signaling pathways.  In each of our proposed research projects, a significant portion is dedicated to biochemical characterization of proteins.  Hence, the requested chromatographic system will play a vital role in ensuring the success of our research programs.