Program Faculty

Our lab uses the budding yeast S. cerevisiae as a model system to study DNA replication and genome stability in eukaryotic cells. Our approach is to apply genetics, biochemistry and molecular biology to analyze highly-conserved genes involved in this process. The main project focuses on a DNA helicase-topoisomerase complex that is known to control genome stability in humans. The yeast gene SGS1 is the homolog of the genes responsible for both Bloom's Syndrome and Werner's Syndrome in humans. We have shown that Sgs1 is a 3' - 5' DNA helicase that interacts with Top3 and is composed of two functional domains. In the absence of either domain the yeast genome undergoes hyper-recombination and rearrangement. A second project involves the use of genetic screens to identify and characterize new genes required for genome stability. Here we are focused on determining the function of six conserved but poorly characterized "SLX" genes that were identified based on their genetic interaction with SGS1. Enzymatically, we have shown that four of these these genes encode two heterodimeric structure-specific endonucleases while a third pair appears to encode a novel protein-modifying activity. The long-term goal of this project is to determine the mechanism by which these enzymes maintain genome stability. A third project involves Replication Protein A (RPA) which is a ssDNA binding protein required for DNA replication, repair, and recombination. RPA is a three-subunit ssDNA binding protein that is found in all eukaryotes from yeast to humans. Using a combination of biochemistry and molecular biology we have shown that RPA contains at least four non-identical ssDNA binding domains. Genetically. we have determined which of these domains are required for cell viability. and have identified other essential regions of the protein that interact directly with the DNA replication machinery. Our current focus is to determine the role of RPA in the DNA damage response.

Publications