Regulation of MAL1+ gene expression encoding maltase in Schizosaccharomyces pombe by added inositol.

In this study, the effects of inositol addition on maltase activity and expression of MAL1+ gene encoding maltase in Schizosaccharomyces pombe were investigated. The maximum specific maltase activity was observed, when the concentration of inositol reached 6.0 microg/ml in the synthetic medium containing 2.0% glucose. At 1.0 microg/ml inositol concentration, the maltase activity continuously decreased, as initial glucose concentration was higher than 0.1%. mRNA encoding maltase and phosphatidylinositol (PI) content were higher in the cells grown in the synthetic medium with 6.0 microg/ml of inositol and 2.0% glucose than those with 1.0 microg/ml of inositol. These results demonstrated that higher inositol concentration in the synthetic medium could derepress MAL1+ gene expression in S. pombe and PI might be involved in derepression of MAL1+ gene expression in S. pombe probably by PI-type signalling pathway.