Glucose-negative Mutants of Pachysolen tannophilus

Abstract

Mutants of the yeast Pachysolen tannophilus, exhibiting decreased ability to utilize D-glucose as the sole carbon source, were obtained by selecting for resistance to 2-deoxyglucose. Enzyme studies confirmed that these strains are defective in the hexose-phosphorylating enzymes and are unable to phosphorylate D-glucose to D-glucose 6-phosphate. The results confirmed the presence of two hexokinases, A and B, with ratios of D-glUCOSe to D-fructose phosphorylation activity of 1 *3/ 1.0 and 3.0/ 1.0, respectively, and a D-glucose-specific glucokinase. The behaviour of a hexose-negative strain, able to ferment D-XylOSe in the presence of D-glucose, is described.

Characterisation of the Aspergillus nidulans frA1 mutant: hexose phosphorylation and apparent lack of involvement of hexokinase in glucose repression

“…Upon dedpletion of the glucose, either glucose or fructose was added to a final concentration of 50 mM and the cultures were incubated for another 3 h. Mycelia of fructose-utilising transformants of WG212 (nos. 4,5,12,16) were grown in MM containing fructose for 16 h. Phospho rylation of 1 mM glucose or 10 mM fructose was measured as described in Section 2.2. Activities were determined in the absence and presence of 1 mM trehalose 6-phosphate (T6P).…”