ISOLATION AND CHARACTERIZATION OF AN INVERTASE AND ITS REPRESSOR GENES FROM SCHIZOSACCHAROMYCES-POMBE

PCR was used to isolate an invertase homolog gene from the fission yea st Schizosaccharomyces pombe. The cloned inv1(+) gene encodes a protei n of 581 amino acids with 16 potential asparagine-linked glycosylation sites, and has 39% and 38% identity to the Schwanniomyces occidentali s and Saccharomyces cerevisiae SUC2 invertases. When the inv1(+) gene was disrupted, S. pombe strains lacked detectable invertase activity. This result showed that the inv1(+) gene encodes only one active inver tase in S. pombe cells. The transcription of inv1(+) is repressed in t he presence of glucose. The transcription of inv1(+) was not affected in cyr1 Delta strain which lacks adenylate cyclase activity, unlike tr anscription of S. pombe fbp1(+) gene. We have identified an S. pombe g ene (scr1(+)) that encodes a homolog of the Aspergillus nidulans CREA which is required for glucose repression of the glyconeogenic pathway. Although the deletion of scr1(+) did not influence the transcription of fbp1(+) gene, glucose repression of the inv1(+) gene was severely a ffected. These results showed that glucose repression of inv1(+) gene is dependent on scr1(+) gene, and S. pombe CAMP signalling pathway may not be essential for glucose repression of inv1(+) gene. (C) 1998 Aca demic Press.