Transcript and Proteomic Analyses of Wild-Type and GPA2 Mutant Saccharomyces cerevisiae Strains

In response to limited nitrogen and abundant carbon sources, diploid Saccharomyces cerevisiae strains undergo a filamentous transition in cell growth as part of pseudohyphal differentiation. Use of the disaccharide maltose as the principal carbon source, in contrast to the preferred nutrient monosaccharide glucose, has been shown to induce a hyper-filamentous growth phenotype in a strain deficient for GPA2 which codes for a Galpha protein component that interacts with the glucose-sensing receptor Gpr1p to regulate filamentous growth. In this report, we compare the global transcript and proteomic profiles of wild-type and Gpa2p deficient diploid yeast strains grown on both rich and nitrogen starved maltose media. We find that deletion of GPA2 results in significantly different transcript and protein profiles when switching from rich to nitrogen starvation media. The results are discussed with a focus on the genes associated with carbon utilization, or regulation thereof, and a model for the contribution of carbon sensing/metabolism-based signal transduction to pseudohyphal differentiation is proposed. Keywords: Saccharomyces cerevisiae, nitrogen starvation, maltose, pseudohyphal differentiation, yeast, expression profiling For transcriptome profiling, there were 12 Affymetrix Yeast S98 microarrays total. There were four conditions: wildtype MLY61 and gpa2 deletion mutant MLY132 grown in YPM media or transferred to low nitrogen media SLAM. Each condition was done in triplicate, starting with triplicate yeast cultures. Four conditions done in triplicates resulted in 12 samples that went onto 12 microarrays.