Interstrand Crosslink Repair in Drosophila Melanogaster

University Of California-Davis, Davis CA

Investigators

Abstract

The objective of this project is to understand the mechanism by which Drosophila and other multicellular eukaryotes repair covalent interstrand crosslinks between the two strands of the DNA duplex. This type of damage, which can occur as a result of exposure to a number of compounds, has catastrophic implications for the ability of a cell to replicate its genome. It is unique in that crosslinking simultaneously damages sequences on both strands of the duplex, preventing use of either strand as a template for repair. From genetic screens for mutants uniquely hypersensitive to crosslinking agents, a small group of genes has been identified that appear to be play essential roles in crosslink repair, but to have no essential role in other repair pathways. This phenotype distinguishes these genes from the majority of genes involved in crosslink repair, which are essential components of other major repair pathways. The specific roles in crosslink repair of the four crosslink-specific genes are unknown. The crosslink-sensitive genes, which include mus308, snm1 and two novel mutations, will be studied at the genetic, molecular and biochemical levels to deduce their functional characteristics. The novel mutations will be genetically and molecularly characterized. The snm1 gene, for which there is no mutant allele in Drosophila, will be subjected to targeted and classical mutagenesis until a mutation is obtained. When clones and mutations are available for each of the four genes, the DNA repair phenotypes of all four will be characterized. Epistatic interactions will be determined to position these genes in repair pathways. Interactions at both the genetic and biochemical level will be determined to test the hypothesis that they function as components of a unique aspect of crosslink repair, and biochemical characterization will be performed to understand the molecular role they serve in this process.