Albany 2015:Book of Abstracts
June 9-13 2015
©Adenine Press (2012)
Structural insights into the RAD51 paralog complexes reveal molecular details of disease causing mutations
Homologous recombinational repair (HRR) is essential for the maintenance of genome stability, repairing highly deleterious double-stranded DNA breaks. Key to this process is the recombinase RAD51, which forms a nucleoprotein filament and catalyzes the search for homology. Five RAD51 paralogs have been identified in humans that mediate HRR: RAD51B, RAD51C, RAD51D, XRCC2 and XRCC3. Interactions between these proteins, and complexes of these proteins with RAD51, are important for HRR. Furthermore, mutations in the RAD51 paralogs have been linked to cancer predisposition in humans, such as RAD51C (FANCO) mutations that predispose to ovarian and breast cancer (Gly125Val and Leu138Phe), as well as a Fanconi anemia-like disorder (Arg258His). Yet, due to difficulties working with the Rad51 paralogs, we have very little knowledge about their functions and how their mutations result in disease phenotypes.
To address the lack of structural information for the RAD51 paralogs I have studied the RAD51C (FANCO) homolog from the hyperthermophilic eukaryote Alvinella pompejana (Alvi). Here I present recent high-resolution crystal structures of Alvi RAD51C domains. These structures provide a molecular framework for understanding how human point mutations may disrupt RAD51C functions to result in either an increased risk of ovarian and breast cancer, or a Fanconi anemia-like disorder. Recently, I have also developed purification schemes for the human RAD51 paralog complexes, which is paving the way for structural analyses of RAD51 paralog assemblies. Combining small-angle X-ray scattering and crystallography will allow molecular models of RAD51 paralog complexes to be built, which will be subsequently tested by the design of separation-of-function mutations to block key protein-protein and protein-DNA interfaces. Collectively, these results will provide a molecular basis from which to understand the biological functions of the RAD51 paralogs.
Gareth J. Williams
Life Science Division