An extreme creA mutation in Aspergillus nidulans has severe effects on D-glucose utilization

Abstract

AspergWus nidulans wild-type and the extreme carbon catabolite derepressed mutant creAd-30 were characterized with respect to enzyme activities, metabolite Concentrations and POlyol p o l s all related to glYCOlYSiS, after growth on mglucose. In the creAd-30 strain the enzymes hexokinase and fructose-6-phosphate reductase showed a two-and threefold increase in activity, respectively, whereas phosphofructokinase and pyruvate kinase activity decreased two-and threefold, respectively, in comparison with the wild-type strain. The most notable changes in metabolite concentrations were that fructose 2,C-bisphosphate and fructose 1,6=bisphosphate showed a 2.5-fold increase, whereas both pyruvate and citrate decreased in the creAd-30. Striking differences were found for the polyol concentrations measured for the two strains tested. lntracellular glycerol and arabitol concentrations were 10-fold higher and erythritol fivefold higher in creAd-30, whereas intracellular trehalose and mannitol were both decreased. The total internal polyol concentration appears to be constant at -700 pmol (g dry wt)? All polyols were also detected in high amounts in the culture filtrate of the creAd-30 mutant strain but no extracellular trehalose was found. The overall production of polyols in this strain was therefore much higher than in the wild-type. The high level of polyols produced and the changes in metabolite concentrations in the creAd-30 strain suggest that the differences in enzyme activities result in an altered flow through glycolysis leading to a more rapid formation of polyols which are subsequently secreted.

Principles of Carbon Catabolite Repression in the Rice Blast Fungus: Tps1, Nmr1-3, and a MATE–Family Pump Regulate Glucose Metabolism during Infection

“…Conversely, FBP1 was expressed most highly in Δ tps1 strains on glucose-minimal media. These results are consistant with a previous study which showed phosphofructokinase activity was decreased, and fructose-1,6-bisphosphate activity was increased, in an Aspergillus strain carrying an extreme creA d mutation, compared to wild type, during growth on glucose [33]. We also looked at the expression of a second important gluconeogenic gene, ICL1 , encoding isocitrate lyase.…”

Cleanup and Analysis of Sugar Phosphates in Biological Extracts by Using Solid-Phase Extraction and Anion-Exchange Chromatography with Pulsed Amperometric Detection

“…Concentrations of sugar phosphates found in microorganisms such as S. cerevisiae (31)(32)(33) and Aspergillus nidulans (7) are typically between 0.1 and 20 mol g Ϫ1 cdw. The combination of AEC-PAD and the sample enrichment which can be obtained by SPE enables the determination of very low quantities of sugar phosphates.…”

Physiology of Aspergillus niger in oxygen‐limited continuous cultures: Influence of aeration, carbon source concentration and dilution rate

“…In presence of D-glucose or other rapidly metabolized carbon sources, CreA inhibits the transcription of specific target genes involved in the catabolism of less preferred carbon sources (Felenbok and Kelly, 1996;Mogensen et al, 2006;Ruijter and Visser, 1997). CreA is thereby involved in a network of reactions and its deletion has several effects both on fungal morphology (Dowzer and Kelly, 1991;Ruijter et al, 1997b;Shroff et al, 1997) and physiology (David et al, 2005;van der Veen et al, 1995). It has been reported that a deletion of creA leads to an accumulation of erythritol and mannitol (David et al, 2005).…”