Regulation of energy metabolism in yeast. Inheritance of a pleiotropic mutation causing defects in metabolism of energy reserves, ethanol utilization and formation of cytochrome a.a3.

The recessive, nuclear gene mutation glc1, which causes glycogen deficiency in Saccharomyces cerevisiae, is highly pleiotropic. Studies of the inheritance of glc1 revealed two classes of phenotypic characteristics: I. Traits invariably associated with the mutant gene and II. Traits whose expressions require the presence of glc1 and one or more additional genes. Class I traits include glycogen deficiency and the loss of capacity to accumulate trehalose in nonproliferating conditions. Traits in the second class include a decreased rate of growth on ethanol medium, a deficiency in cytochrome a.a3 and an enhanced accumulation of pigment, probably a metalloporphyrin. Constructed strains containing both glc1 and the constitutive maltose fermentation gene MAL4c can accumulate trehalose but not glycogen during growth on glucose. However, accumulated trehalose is degraded when cells are exposed to nonproliferating conditions. It is proposed that the glc1 mutation affects a regulatory system, probably involving a protein kinase and/or protein phosphatase, which regulates glycogen synthase and trehalase. Independent regulation of trehalose synthesis by a system controlled by MAL4c is indicated.