Regulation and Characterization of Acid and Alkaline Phosphatase in Yeast

Abstract

SUMMARYThe activity of acid and alkaline phosphatase in baker's yeast is derepressed when the organisms are starved of phosphate. Mutants lacking phosphatase activity and mutants with constitutive phosphatase synthesis were isolated. In all of them acid and alkaline phosphatases were affected simultaneously. Nevertheless, characterization of these two enzymes by sensitivity to inhibition by orthophosphate, temperature inactivation, proteolytic digestion and cation dependence showed that they were clearly distinct. It is suggested that these two enzymes share a common genetic and structural component.

Identification of the genetic locus for the structural gene and a new regulatory gene for the synthesis of repressible alkaline phosphatase in Saccharomyces cerevisiae.

“…The repressible alkaline phosphatase (namely, the nonspecific alkaline phosphatase) shows, however, a significant level of activity even under repressed conditions. This basal activity was found to be severely reduced in a pho8 (formerly phoH) mutant, and the enzyme failed to be derepressed.Repression or derepression of the repressible alkaline phosphatase occurs in response to signals of the presence or absence of inorganic phosphate in the medium (16,20,23). The signals are transmitted by the function of a regulatory system specified by the PHO4 (formerly PHOD), PHO80 (PHOR), PHO81 (PHOS), and PHO85 (PHOU) genes.…”

“…Repression or derepression of the repressible alkaline phosphatase occurs in response to signals of the presence or absence of inorganic phosphate in the medium (16,20,23). The signals are transmitted by the function of a regulatory system specified by the PHO4 (formerly PHOD), PHO80 (PHOR), PHO81 (PHOS), and PHO85 (PHOU) genes.…”

RNA and homology mapping of two DNA fragments with repressible acid phosphatase genes from Saccharomyces cerevisiae.

“…The repressible APase is expressed only when the cells are starved for phosphate (14,22), whereas the so-called constitutive enzyme was recently shown to be synthesized only in the presence of phosphate (13). Extensive genetic analysis has revealed unlinked genes for several regulatory elements involved in APase repression and induction (20)(21)(22) …”

“…The yeast Saccharomyces cerevisiae synthesizes several phosphatases involved in phosphorous metabolism (14). Two types of acid phosphatase (APase) (orthophosphoric-monoester phosphohydrolase [acid optimum]; EC 3.1.3.2) have been identified (22), one apparently produced constitutively and one repressed by Pi.…”

Regulation of Yeast Acid Phosphatase by Orthophosphate and Phenylmercuric Acetate

“…It has been recently reported (Schurr & Yagil, 1971) that KH2P04 inhibits competitively yeast acid phosphatase. Kinetic studies performed in our laboratory revealed that KH,PO, is a competitive inhibitor of acid phosphatase in the living cells of commercial baker's yeast and in a cell-free extract, with a Ki value of 2.4 x I O -~ M. In our experiments total inhibition was achieved with 0-I M-KH,PO,.…”