Dissecting the role of HOG mitogen-activated protein kinase signaling in the regulation of Yeast Flocculation

Abstract

AbstractThe living organisms are frequently exposed to multiple biotic and abiotic stress forms during their lifetime. Organisms cope with stress conditions by regulating their gene expression programs. In response to different environmental stress conditions, yeast cells activate different tolerance mechanisms. Many of these mechanisms share common signaling pathways. Flocculation of yeast is one of the key mechanisms to survive under unfavorable environmental conditions. The Tup1-Cyc8 corepressor complex is a major regulator of yeast flocculation. In addition, yeast cells also utilize different MAPK pathways to regulate the expression of genes during stress conditions. Here we present the pieces of evidence that the HOG MAPK pathway is involved in the regulation of yeast flocculation phenotype. We observed constitutive activation of the HOG MAPK pathway in flocculating cells. The binding of phosphorylated Hog1 at theFLOgenes promoter increases significantly upon sodium chloride exposure. We found that the treatment of cells with cantharidin reduces the Hog1 phosphorylation, causing a sharp reduction in the expression ofFLOgenes and flocculation phenotype. Similarly, deletion of theHOG1in flocculating cells, resulted in the reduction of flocculation. Altogether our results suggest the involvement of HOG MAPK in the regulation ofFLOgenes and flocculation of yeast.