Examination of growth phenotypes and protein stability in a Saccharomyces cerevisiae model for TPI deficiency (578.2)

Abstract

Triose Phosphate Isomerase (TPI) is a glycolytic enzyme that catalyzes the inter‐conversion of DHAP to G3P. Mutations in TPI have been identified that are associated with a neurodegenerative disease in humans known as TPI deficiency. To study the cause of TPI deficiency pathogenesis, we constructed Saccharomyces cerevisiae yeast strains expressing various TPI alleles that are associated with the development of TPI deficiency in humans and Drosophila melanogaster. In this study, we examined the cell growth rates of multiple mutant TPI strains by growth curve analysis and spot plate analysis. In addition, we examined the stability of the TPI proteins by cycloheximide chase at high temperature. Interestingly, not all of the mutations resulted in significant changes in growth rates. However, the mutation M80T was associated with the most severe growth defects at all temperatures and the M80T protein exhibited the highest degree of instability at high temperature. Furthermore, the mutation E104D exhibited growth defect and protein instability only at high temperature, suggesting that it is a temperature sensitive allele. Other TPI mutant proteins exhibited varying levels of instability, but no effect on growth. This suggests that protein instability is not the only mechanism of pathogenesis in TPI deficiency.