Regulation of the Expression of the H+-atpase Genes Pma1 and Pma2 During Growth and Effects of Octanoic-acid in Saccharomyces-cerevisiae

A peak of plasma membrane H+-ATPase activity during exponential growth is correlated with the expression of the PMA1 gene as monitored by measurements of the beta-galactosidase activity from a PMA1-lacZ fusion. This peak of activity is also correlated to the content of the H+-ATPase protein in yeast plasma membrane as shown by quantitative immunodetection. The PMA(2)-lacZ fusion assay indicates that the expression of the PMA2 gene is activated somewhat later during exponential phase but under all circumstances its activity remains at least 500-fold lower than that of the PMA1-lacZ fusion. A slight but significant stimulation of ATPase activity by low concentrations of octanoic acid coincides with a decrease in the PMA1 gene expression. It is concluded that octanoic acid stimulates de PMA1 ATPase activity by posttranslational mechanisms