Effect of 3-O-methyl-D-glucose on the production of glycosidases by Cryptococcus laurentii and Saccharomyces cerevisiae.

3-O-Methyl-D-glucose (3-O-MeGlc) or a mixture of 3-O-MeGlc and glucose stimulate invertase, beta-glucosidase, alpha-glucosidase, and alpha-galactosidase production by Cryptococcus laurentii. They also increase invertase and alpha-glucosidase production by Saccharomyces cerevisiae. The stimulatory effect of 3-O-MeGlc is not caused by competition with glucose for transport nor by a direct action on glycosidases. It is proposed that 3-O-MeGlc acts as a structural rather than as a functional analogue of glucose displacing it from regulatory sites to relieve catabolite repression. Evidence is presented suggesting that intracellular cAMP levels may be related to the effect of 3-O-MeGlc.