PKA regulatory subunit Bcy1 couples growth, lipid metabolism, and fermentation during anaerobic xylose growth in Saccharomyces cerevisiae

ABSTRACT: All organisms have evolved elaborate physiological pathways that regulate growth, proliferation, metabolism, and stress response. These pathways must be properly coordinated to elicit the appropriate response to an ever-changing environment. While individual pathways have been well studied in a variety of model systems, there remains much to uncover about how they are integrated to produce global changes in a cell. Past work from our lab, focused on engineering the budding yeast Saccharomyces cerevisiae for fermentation of the non-native pentose sugar xylose, discovered that hyperactivation of the RAS/Protein Kinase A (PKA) pathway was needed for rapid anaerobic xylose fermentation. Interestingly, the mechanism of PKA hyperactivation has a dramatic impact on growth and metabolism on xylose; deletion of the RAS inhibitor IRA2 permits rapid growth and fermentation, while deletion of the PKA regulatory subunit BCY1 allows for fermentation without growth on xylose. To understand how a single deletion in the PKA pathway can decouple growth and metabolism, we performed transcriptomic analysis of these strains, predicting that altered PKA activity would impact global gene expression and identify pathways important for growth and metabolism coordination. Notably, we found enriched differential expression of lipid metabolism genes, targets of the phospholipid biosynthetic gene transcription factor Ino4, and genes containing the Aft1/2 consensus motif. These results suggested that dysfunctional lipid homeostasis may be responsible for decoupling growth and metabolism in the bcy1∆ strain. In parallel work, we also directly evolved the bcy1∆ strain to grow anaerobically on xylose and found point mutations in TPK1, OPI1, RIM8, and TOA1 permitted growth. Interestingly, Opi1 is the inhibitor of Ino4, further supporting the role of lipid homeostasis in growth and metabolism coordination. This work shows that a single genetic change can have dramatic impacts on multiple aspects of cellular physiology.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE220465 | GEO | 2023/05/01

REPOSITORIES: GEO