Analysis of theSchwanniomyces occidentalis SWA2gene promoter inSaccharomyces cerevisiae

Abstract

The effect of different carbon sources on the expression in Saccharomyces cerevisiae of the SWA2 alpha-amylase gene from Schwanniomyces occidentalis was studied from constructs containing its 5' region (-223 to +15), which were fused in-frame to the lacZ gene coding sequence. Maximal expression was achieved with the non-fermentable substrates ethanol and/or glycerol, whereas lower levels were found with maltose or galactose. In contrast, glucose repressed it, even in the presence of any of these other carbon sources. Deletion analyses of the -233 to -85 SWA2 promoter region permitted the identification of two fragments involved in both glucose repression and ethanol activation. A possible region required for cAMP regulation was localised. The SWA2 promoter contains a MIG1-binding GC box whose deletion caused a five-fold increase in the glucose-repressed reporter expression. Despite this, expression of the SWA2 promoter was not MIG1-dependent.

Respiro-fermentative metabolism in yeast cultivated in solid-state culture: The Crabtree effect and ethanol production

“…Glucose presence in the medium can induce genes related to glycolysis and fermentative metabolism. However, the presence of another substrate (ethanol) can stimulate genes related to secondary metabolism and repress the use of glucose to obtain hydrolytic enzymes (Carmona et al, 2002). De Deken (1966) indicated that respiratory metabolism after fermentative metabolism is due to energy compensation necessary for cellular growth.…”