Double strand breaks (DSBs) are a common occurrence in the Eukaryotic genome. Such DNA damage may result in chromosomal rearrangement and/or chromosome loss which pose a great threat to genome stability and cell viability. Mechanisms through which Saccharomyces cerevisiae repair DSBs include homology dependent repair (HDR), non-homologous end joining (NHEJ), and on rare occasions, telomere healing. Telomere healing is a rare mutagenic process in which the cell employs telomerase to repair DSBs. Though the addition of a telomere to the site of a DSB results in the loss of the chromosome end, de novo telomere addition may stabilize the genome for continuation of the cell cycle (McClintock, 1941). Previous studies have identified specific sequences within the yeast genome that exhibit an increased probability for de novo telomere addition. These sites have been termed Sites of Internal Repair-associated Telomere Addition (SiRTAs). One goal of the Friedman Lab is to develop a methodology for the identification of SiRTAs throughout the yeast genome. Using galactose inducible CRISPR-Cas9 mediated cleavage, various selection criteria and deep sequencing, the current focus of my research is the identification of SiRTAs throughout the non-essential regions of Chromosome VII.
PI: Katherine Friedman, Ph.D.