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

Abstract

Two lines of evidence showed that the PH08 gene encodes the structure of repressible, nonspecific alkaline phosphatase in Saccharomyces cerevisiae: (i) the enzyme produced by a temperature-sensitive pho8 mutant at the permissive temperature (25°C) was more thermolabile than that of the wild-type strain, and (ii) the PH08 gene showed a gene dosage effect on the enzyme activity. The pho8 locus has been mapped on chromosome IV, 8 centimorgans distal to rna3. A new mutant carrying the pho9 gene was isolated which lacks repressible alkaline phosphatase, but has the normal phenotype for the synthesis of repressible acid phosphatase. The pho9 gene segregated independently of all known pho-regulatory genes and did not show the gene dosage effect on repressible alkaline phosphatase activity. The pho9/pho9 diploid hardly sporulated and showed no commitment to intragenic recombination when it was inoculated on sporulation medium. Hence the pho9 mutant has a phenotype similar to the pep4 mutant, which was isolated as a pleiotropic mutant with reduced levels of proteinases A and B and carboxypeptidase Y. An allelism test indicated that pho9 and pep4 are allelic.In a previous communication (20), we observed that a cellular extract of Saccharomyces cerevisiae contains two species of alkaline phosphatase: a nonspecific alkaline phosphatase (EC 3.1.3.1) and a specific p-nitrophenylphosphatase. The nonspecific enzyme is repressible by inorganic phosphate in the medium, whereas the specific p-nitrophenylphosphatase is synthesized constitutively. 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. This same regulatory system combined with the PHO2 (PHOB) gene product controls the synthesis of acid phosphatase (EC 3.1.3.2) (23, 25). It was proved that the PHO2 function is not involved in t Present address:

<i>PHO8</i> gene coding alkaline phosphatase of <i>Saccharomyces cerevisiae</i> is involved in polyphosphate metabolism

“…Under the Pi-sufficient conditions, ALP activity by Pho8p was low, but detectable (Fig. 1b), as reported by Kaneko et al (1982). It has been reported that WT cells in the stationary phase subcultured in a fresh YPD medium increase their polyP content during the logarithmic and early stationary phases, but that the polyP content decreases soon afterwards (Werner et al, 2005).…”

“…These strains were grown at 30∞C under aerobic conditions in a YPD medium (1% yeast extract, 2% peptone and 2% glucose) or a low Pi YPD medium (YPD (-Pi)). The YPD (-Pi) medium was made according to a previously established method (Werner et al, 2005), which was based on the method of Kaneko et al (1982). Growth was measured by determining the optical density at 600 nm (OD 600 ).…”

Regulation of Manganese Antioxidants by Nutrient Sensing Pathways in Saccharomyces cerevisiae

“…The Pho80p/Pho85p kinase pair negatively regulates the Pho4p transcription factor for the induction of phosphate uptake and storage genes such as PHO84 (Kaneko et al 1982;Ogawa et al 2000;Wykoff and O'shea 2001;Lee et al 2007;Wykoff et al 2007). We addressed whether hyperactive Pho4p in pho80 mutants accounts for the severe oxygen toxicity of sod1Δ pho80Δ cells.…”

“…Of the strains tested, the most severe oxygen toxicity was observed when phosphate control was disrupted through mutations in the phosphate-sensing kinase complex Pho80p/ Pho85p (Kaneko et al 1982;Ogawa et al 2000;Wykoff and O'shea 2001;Carroll and O'shea 2002;Lee et al 2007;Wykoff et al 2007). Deletion of either pho80 or pho85 rendered sod1Δ mutants lacking Cu/Zn SOD1 inviable in air and cells seemed nearly devoid of Mn antioxidant protection (Reddi et al 2009).…”

Phosphoinositide 3-Kinases and Their FYVE Domain-containing Effectors as Regulators of Vacuolar/Lysosomal Membrane Trafficking Pathways

“…Cellular levels of PtdIns-4-P and PtdIns-4,5-P 2 are not affected in hydrolase-deficient strains (40). Indeed, the vacuole/lysosome contains candidate lipases and phosphatases (41,42), which may function in the turn-* This minireview will be reprinted in the 1999 Minireview Compendium, which will be available in December, 1999. This is the second article of five in "A Thematic Series on Kinases and Phosphatases That Regulate Lipid Signaling."…”