Gratuitous Catabolite Repression by Glucosamine of Maltose Utilization in Saccharomyces cerevisiae

Abstract

Glucosamine acted as a gratuitous catabolite repressor of maltose utilization in Saccharomyces cerevisiae. This repression was relieved in a linear manner as the maltose concentration was increased. Three mutants were isolated in which maltose utilization was no longer repressed by glucosamine. One of these mutants may be generally deficient in catabolite repression since it was not defective in glucosamine transport but was insensitive to glucosamine repression on all catabolite repressible carbon sources tested. Each mutant possessed a maltose uptake system which was notably less sensitive to glucose repression than that of the wild-type strain. These results are discussed in terms of a proposed model for regulation of maltose utilization in S. cerevisiae.

The relationship of growth rate and catabolite repression with WHI2 expression and cell size in Saccharomyces cerevisiae

“…Our results suggest that the whi2 mutant has become resistant at one or more of these stages but remains sensitive at others. Resistance to glucosamine is a method of obtaining catabolite-derepressed mutants (Elliott & Ball, 1973;Hockney & Freeman, 1980). Similar mutants obtained using 2-deoxyglucose have an altered hexokinase PI1 (Entian et al, 1984), one of the potential targets for glucosamine inhibition.…”

“…Furst & Michels (1977) showed that in Saccharomyces carlsbergensis 0-1 5 % glucosamine was sufficient to repress a range of glucose-repressible functions such as O2 uptake, cytochrome c oxidase and maltase levels. Hockney & Freeman (1980) showed that S . cerevisiae responded in a closely similar fashion.…”

“…(Furst & Michels, 1977), probably due to the competitive inhibition of glucosamine uptake. Glucosamine is also a gratuitous inducer of catabolite repression (Elliott & Ball, 1973;Furst & Michels, 1977;Hockney & Freeman, 1980), preventing growth on non-fermentable carbon sources at low concentrations. It can be used to isolate catabolite-derepressed mutants (Elliott & Ball, 1973 ;Hockney & Freeman, 1980).…”

“…Glucosamine is also a gratuitous inducer of catabolite repression (Elliott & Ball, 1973;Furst & Michels, 1977;Hockney & Freeman, 1980), preventing growth on non-fermentable carbon sources at low concentrations. It can be used to isolate catabolite-derepressed mutants (Elliott & Ball, 1973 ;Hockney & Freeman, 1980). The properties of glucosamine, therefore, allow it to be used to regulate cell growth, through adjustment of the glucose : glucosamine ratio, whilst maintaining a constant level of catabolite repression.…”

A heritable switch in carbon source utilization driven by an unusual yeast prion

“…Glucosamine, a nonmetabolizable glucose mimetic, induces a similar repression. Therefore, yeast cells cannot use glycerol as a carbon source if even small amounts of glucosamine are present (Hockney and Freeman 1980;Nevado and Heredia 1996). Some cells spontaneously acquire the ability to use glycerol in the presence of glucosamine, presumably due to defects in glucose repression.…”