RUI: Evolution of the Phosphate Starvation Response in Yeast

Villanova University, Villanova PA

Investigators

Abstract

Intellectual Merit This project investigates the phosphate signal transduction (PHO) pathway in the Ascomycota fungal lineage. Ascomycetes diverged from a common fungal ancestor hundreds of millions of years ago and many aspects of the PHO pathway from Saccharomyces cerevisiae are conserved in the lineage, providing a rare opportunity to perform detailed comparative genomic analyses. The two aims of this project are (1) to define the phosphate starvation response and PHO pathway in Candida glabrata and (2) to define the PHO pathway in Schizosaccharomyces pombe. C. glabrata is a model species closely related to S. cerevisiae and Sz. pombe is a distantly related model organism. Comparing the S. cerevisiae and C. glabrata PHO pathways allows for an analysis of how a signal transduction pathway alters transcriptional output in closely related species and how these alterations impact niche specificity. The upstream signaling components and downstream transcriptional output of the PHO pathway will be characterized. Because Sz. pombe does not share orthologous components with the PHO signaling pathway of S. cerevisiae, but generates a similar output (transcriptional up-regulation of phosphate starvation genes), this research will provide the context for how a divergent organism in a similar niche has evolved a phosphate-starvation response, and adopted a similar gene expression program with a different signaling pathway. Eight mutants aberrant in their expression of the phosphate-regulated gene PHO1 will be characterized and the genes required for the phosphate starvation response will be cloned. The transcriptional response of these mutants (and wild-type) will be measured with DNA microarrays and rt-qPCR. These studies are accessible to relatively new scientists such as undergraduate students and Master's level students. These systematic comparative genomic analyses will help to explain the evolutionary steps required to tailor a pathway for growth in different niches. Broader Impact Most of the techniques utilized in this project are accessible to beginning scientists. Many experiments utilize basic genetic and molecular biology techniques and are self-contained projects designed for undergraduate and Master's level students. The self-contained projects are ideal for students in that they encourage student ownership of an aspect of the total project. This work will create the resources for numerous undergraduates and Master's students at Villanova University to gain practical experience with the scientific method for a future in biomedical or scientific research. Students will also be strongly encouraged to attend scientific meetings to interact with other scientists. Finally, students from disadvantaged backgrounds and underrepresented minority groups will be actively recruited and encouraged to stay in scientific fields through a positive undergraduate/Masters experience.