Identification and characterization of thiamin repressible acid phosphatase in yeast.

We have identified a genetic locus, pho4, in Schizosaccharomyces pombe which encodes a minor expressed cell surface acid phosphatase that is repressed by low concentrations (0.5 microM) of thiamin. The enzyme was purified from a strain that overproduces the enzyme.

The all2 gene is required for the induction of the purine deamination pathway in Schizosaccharomyces pombe.

Five mutants were isolated at the all2 gene on the basis of their inability to utilize hypoxanthine as a sole source of nitrogen. These mutants failed to utilize the purines adenine, hypoxanthine, xanthine, uric acid, allantoin and allantoic acid, although they could utilize urea and ammonium. The all2 mutants appeared to be defective in purine induction of uricase, allantoinase, allantoicase and ureidoglycollase activities but retained wild-type activity of the constitutively synthesized urease.

Genetic studies of purine breakdown in the fission yeast Schizosaccharomyces pombe.

Purines such as hypoxanthine, xanthine, uric acid, allantoin and allantoic acid serve as sole nitrogen sources for the yeast Schizosaccharomyces pombe. A number of classes of mutants unable to use purines have been isolated and genetically analysed. Mutants in the urol gene lack uricase, all1 lack allantoinase, ala1 lack allantoicase whilst in ure1, ure2, ure3 and ure4 genes lack urease activity.