Effects of pol zeta, pol eta, and Polymerase delta Mutants on the Genetic Instability of Inverted Repeat InsH during Break-Induced Replication

Break-induced replication (BIR) is a type of DNA repair pathway that specializes in the repair of one ended double-stranded breaks (DSBs). The pathway is necessary to preserve genetic information in the presence of DNA damage. However it is not currently known how BIR proceeds through inverted repeats (IRs) that are capable of forming secondary structures. Not only that, the specific subset of proteins required to assist BIR through IRs is also unknown.Saccharomyces cerevisiae is a suitable organism for the investigation of BIR because it allows for easy investigation into the role of highly conserved proteins. S. cerevisiae mutant experimental strains were generated using transformation techniques and then coupled with a chromosome III disome system containing a LYS2-InsH construct at the 16 kb position. BIR does not appear to require translesion polymerases to assist the bypass of IRs. Polymerase d mutants investigated did not appear to significantly affect the progression of BIR through IRs raising additional questions as to the mechanism through these unstable elements. These results help clarify the mechanism by which BIR proceeds through IRs and eliminates the possibility that translesion polymerases, often recruited to bypass unstable DNA elements, are involved. Polymerase d is supported by numerous studies to be the driver of replication during BIR synthesis and this study elucidates how a few of the mutants of polymerase d did not affect the progression through IRs but raises questions for other polymerase d mutants that could affect the progression of BIR through IRs.