In yeast, the RSF1 gene product functions in the transition from fermentative to glycerol-based respiratory growth

Efficient transition between vastly different growth conditions in single celled organisms requires a suite of ordered gene expression changes. Relatively little is known about gene expression changes that facilitate the transition from fermentative to glycerol-based respiratory growth in yeast. In this work transcriptome analyses of yeast undergoing a transition from fermentative to glycerol-based respiratory growth revealed a suite of metabolic as well as structural changes required for adaptation. Extensive remodeling of membrane transporters and the cortical actin cytoskeleton was apparent at the mRNA level, and was consistent with the needs of actively respiring cells. Transcript level changes of genes encoding several components of TRID, SAGA and SLIK as well as the mediator complex suggest that remodeling of the basal transcriptional apparatus may be an important mechanism for biasing transcription towards respiratory promoters under respiratory conditions. Transition to respiratory growth was accompanied by an oxidative stress response which increased in magnitude through steady-state glycerol-based growth. Unexpected induction of the osmotic stress response was observed as well and appears to be a general feature of respiratory growth. Surprisingly, levels of several transcripts from genes encoding products required for respiration were actually decreased during the shift to glycerol-based respiratory-growth.;Transcriptome profiling of a strain lacking Rsf1p during a shift from fermentative to glycerol-based respiratory growth revealed that Rsf1p plays a major role in both the transition to and steady state growth in glycerol. A Deltarsf1 mutant had elevated stress response transcript levels throughout the glycerol-respiratory shift as well as during steady-state glycerol-based growth. Inappropriately high glycerol anabolism and DAK2 transcript levels in a strain lacking Rsf1p indicate an incomplete transition from glycerol anabolism to glycerol catabolism. Genes encoding F0 F1-ATPase and cytochrome c oxidase subunits failed to be induced during glycerol, but not ethanol-based respiratory growth in strains lacking Rsf1p; indicating the importance of Rsf1p in maintaining appropriate respiration-related transcript levels during glycerol-based respiratory growth. This suggests that there are different transcriptional regulatory networks which are involved in maintaining appropriate transcript levels from genes encoding components of the respiratory chain during glycerol- vs. ethanol-based growth.