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 PMA2-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.