Function of the PHO regulatory genes for repressible acid phosphatase synthesis in Saccharomyces cerevisiae

Abstract

Expression of the repressible acid phosphatase (rAPase) gene, PHO5, of Saccharomyces cerevisiae is repressed by a certain level of inorganic phosphate (Pi) in the medium and is derepressed when the Pi concentration is lowered. The Pi signals are conveyed to PHO5 by a regulatory system consisting of proteins coded for by the PHO2, PHO4, PHO80 and PHO81 genes. We have found that the transcription of PHO81 is regulated by Pi through the PHO regulatory system. Increasing the dosage of PHO4 and PHO81 by ligating each gene to YEp13 gives rise to, respectively, considerable and weak synthesis of rAPase by cultivation of the transformants in high-Pi medium; but in low-Pi medium, increased dosage of PHO4 stimulates the rAPase synthesis significantly, whereas PHO81 has no effect. Increased dosage of PHO2 stimulates rAPase synthesis considerably in low-Pi but not in high-Pi. A coordinate increase of PHO80 cancels the dosage effect of PHO4, but not that of PHO81. Coordinate increases of PHO80 and PHO2 give rise to the same phenotype as an increased dosage of PHO80 alone. The level of the PHO4 protein was found to be the limiting factor of the rAPase synthesis and the copy number of the PHO5 gene not to be. These facts accord with the idea that the PHO80 protein transmits the Pi signals to the PHO5 gene via the PHO4 protein, whereas the PHO2 protein does not have a direct function in the signal transmission.

Role of trans-activating proteins in the generation of active chromatin at the PHO5 promoter in S. cerevisiae

“…A similar effect of PH04 overexpression on enzyme activity has been reported by Yoshida et al (1989b (Tschumper and Carbon, 1980). In order to replace the TRPJ gene by the LEU2 gene, a 2.2 kb XhoI-SaII LEU2 fragment was isolated from YEpl3 (Broach et al, 1979) and inserted into the HindIll site of YRp7' after prior attachment of HindIIl linkers.…”

“…It is known that the two positive trans-acting regulatory proteins PH02 and PH04 are required for expression of PH05 (Table I; for review see Yoshida et al, 1987Yoshida et al, , 1989b and that, in vitro, both proteins bind to the PH05 promoter at defined locations : Arndt et al, 1987 Figure onditions. The non-shaded nucleosomes 3A.…”

Inorganic Phosphate Deprivation Causes tRNA Nuclear Accumulation via Retrograde Transport inSaccharomyces cerevisiae

“…The coldsensitive nature of the synthetic slow-growth interaction observed in los1D pho88D cells may explain why PHO88 was found as a SGA candidate when the array was performed at 22°but not at 37°. Tetrad dissection was performed at 23°on YEPD medium, which has low levels of P i (Yoshida et al 1989b). This may have contributed to the absence of los1D pho88D progeny.…”

A positive regulatory gene, THI3, is required for thiamine metabolism in Saccharomyces cerevisiae

“…Accordingly, it was considered that the THI2 (PH06) and THI3 genes are both required for expression of T-rAPase and several enzymes involved in thiamine synthesis, whereas the thiamine transport system was regulated only by the THI3 gene as a positive factor. Two positive regulatory genes, PH02 and PHO4, whose products are indispensable for the transcriptional control of the structural genes for repressible acid phosphatase encoded by PHOS and the Pi transport system encoded by PH084 in S. cerevisiae, have been reported by Oshima and coworkers (20,29,30). The PHO regulatory system in S. cerevisiae appears to be of interest for further study of this thiamine regulatory system.…”