Grant: Discovery Grants Program - Individual

Ku is an abundant, ubiquitous factor that has been remarkably conserved throughout evolution as it has been*identified in all organisms from bacteria to man. Ku is a complex of two proteins that plays an essential role in*the repair of double-strand DNA breaks, a form of DNA damage in which both strands of the double helix*break, leading to chromosome rearrangements and, ultimately, genomic instability.*While it is understood that Ku is essential for the proper repair of DNA, its mode of action is still unclear. It is*known that Ku interacts with a number of other factors that play roles in the repair of DNA, however, the*details and the outcome of these interactions are poorly understood.****Using the crystal structure of Ku that was recently made available, we can predict regions of the protein that are*accessible to contact other proteins. Thus we have made mutations in several of these accessible regions to test*if they alter Ku DNA repair functions. We have identified two Ku mutations that alter its ability to function in*response to DNA damage. We found that these mutations result in different defects suggesting that the mutated*regions are involved in distinct functions. We propose to identify the proteins that interact with these Ku motifs****and elucidate how they function together in the repair of DNA.*In the long-term, these analyses will enhance our understanding of the functions of Ku in the mechanisms that*are set in place to deal with double-stranded DNA breaks.**