Critical findings on the activation cascade of yeast plasma membrane H +-ATPase

• Published in: FEMS microbiology letters 2003-09, Vol.226 (1), p.175-180
• Main Authors: Kotyk, Arnošt, Lapathitis, Georgios, Horák, Jaroslav
• Format: Article
• Language: English
• Subjects: Activation cascade; Adenosine Triphosphate - metabolism; Biological and medical sciences; Cell Fractionation; Cell Membrane - metabolism; Enzyme Activation; Fundamental and applied biological sciences. Psychology; G-protein; Galactose - metabolism; Gene Expression Regulation, Fungal; Genes, Fungal; Glucose - metabolism; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; GTP-Binding Protein alpha Subunits - genetics; GTP-Binding Protein alpha Subunits - metabolism; GTP-Binding Protein alpha Subunits, Gq-G11; Hexokinase - genetics; Hexokinase - metabolism; Hydrogen-Ion Concentration; Membrane Proteins - genetics; Membrane Proteins - metabolism; Microbiology; Monosaccharide Transport Proteins - genetics; Monosaccharide Transport Proteins - metabolism; Morphology, structure, chemical composition; Mutation; Mycology; Proton-Translocating ATPases - genetics; Proton-Translocating ATPases - metabolism; Receptors, G-Protein-Coupled - genetics; Receptors, G-Protein-Coupled - metabolism; Role of sensors and receptors; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Yeast H +-ATPase
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1016/S0378-1097(03)00591-3

Strains of the yeast Saccharomyces cerevisiae, deficient in either of its two G-proteins, in the Snf3 and Rgt2 sensors, in the Gpr1 receptor and in various hexokinases were tested for their ability to start the activation cascade with a metabolizable monosaccharide that leads eventually to activation of plasma membrane H +-ATPase. The acidification rate after addition of glucose to glucose-grown cells and of galactose to galactose-grown ones, and the rate of ATP hydrolysis by purified plasma membranes in both types of cells were studied. It appears unequivocally that phosphorylation of the monosaccharide is essential for the activation; the role of the Gpa2 protein (possibly in combination with the Gpr1 receptor) is very probable while the two sensors appear to play somewhat ambiguous roles – in the absence of both the activation was actually higher than in the parent strain. The Gpa1 G-protein is not involved in acidification but may function in ATPase activity where, in addition to the phosphorylation step, other factors can play a role. There appear to be alternative pathways leading to the ultimate activation of the H +-ATPase, not necessarily involving G-proteins.