Regulation of pho1-encoded acid phosphatase of Schizosaccharomyces pombe by adenine and phosphate.

Expression of pho1-encoded acid phosphatase of Schizosaccharomyces pombe has been reported to be regulated by phosphate. In this communication we show that it is also regulated by adenine. Starving adenine auxotrophic strains for adenine leads to a drastic increase of the enzymatic activity while adenine represses this activity. Full repression by adenine only occurs when phosphate is not growth limiting and vice versa. Regulation occurs at the level of mRNA. We isolated adenine non-repressible mutants. They define four genes (anr1, anr2, anr3, and anr5) which are involved in adenine-dependent pho1 expression. All anr mutants are also phosphate non-repressible. These results indicate that the generation and/or transduction of the intracellular signal responsible for pho1 repression is simultaneously dependent on both adenine and phosphate.