Identification of Genes that Provide Cellular Protection Against a Thiol Cross-Linking Agent in Saccharomyces cerevisiae
Organic electrophiles represent an important class of xenobiotic and endogenously produced toxins that damage DNA and proteins. The adduction of electrophiles to these macromolecules interrupts biological processes such as DNA replication, protein folding and turnover. We have recently identified an electrophile (diethyl acetylenedicarboxylate, DAD) that is capable of cross-linking proteins by undergoing reaction with two thiol groups. Because of its unique, electrophilic properties, I sought to determine whether the defense mechanisms that provide protection against DAD are similar to those which protect against electrophiles that cannot cross-link thiol groups in proteins. To this end, I have screened a panel of Saccharomyces cerevisiae deletion mutants lacking various detoxification enzymes to determine their survival when exposed to DAD. Several cytoprotective genes were identified, including many in the glutathione transferase family, (e.g. GTTI, GTO1, and GTO3, all of which localize to different cellular compartments) as well as a putative reductase, YPR1. Our results suggest that glutathione metabolic enzymes in multiple cellular compartments protect cells against damage by thiol cross-linking electrophiles. Finally, studies using a monofunctional electrophile, N-ethylmaleimide, revealed that a similar group of genes provide protection against electrophiles not capable of cross-linking. Together, these findings suggest that glutathione conjugation is an important method of protection against thiol-reactive electrophiles.
© Copyright 2011 Chelsea Stamm