Onset of Carbon Catabolite Repression in Aspergillus nidulans

The role of hexose phosphorylating enzymes in the signaling of carbon catabolite repression was investigated in the filamentous fungus Aspergillus nidulans . A d -fructose non-utilizing, hexokinase-deficient ( hxkA1 , formerly designated frA1 ) strain was utilized to obtain new mutants lacking eithe...

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Bibliographic Details
Published in:The Journal of biological chemistry 2003-04, Vol.278 (14), p.11849-11857
Main Authors: Flipphi, Michel, van de Vondervoort, Peter J.I., Ruijter, George J.G., Visser, Jaap, Arst, Herbert N., Felenbok, Béatrice
Format: Article
Language:English
Subjects:
dna-binding
ethanol regulon
gene-cluster
glucose repression
hexose phosphorylation
metabolite repression
saccharomyces-cerevisiae
sclerotinia-sclerotiorum
xylanase genes
yeast hexokinase
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Summary:The role of hexose phosphorylating enzymes in the signaling of carbon catabolite repression was investigated in the filamentous fungus Aspergillus nidulans . A d -fructose non-utilizing, hexokinase-deficient ( hxkA1 , formerly designated frA1 ) strain was utilized to obtain new mutants lacking either glucokinase ( glkA4 ) or both hexose kinases ( hxkA1/glkA4 ). d -Glucose and d -fructose phosphorylation is completely abolished in the double mutant, which consequently cannot grow on either sugar. The glucokinase single mutant exhibits no nutritional deficiencies. Three repressible diagnostic systems, ethanol utilization ( alcA and alcR genes), xylan degradation ( xlnA ), and acetate catabolism ( facA ), were analyzed in these hexose kinase mutants at the transcript level. Transcriptional repression by d -glucose is fully retained in the two single kinase mutants, whereas the hexokinase mutant is partially derepressed for d -fructose. Thus, hexokinase A and glucokinase A compensate each other for carbon catabolite repression by d -glucose in the single mutants. In contrast, both d -glucose and d -fructose repression are severely impaired for all three diagnostic systems in the double mutant. Unlike the situation in Saccharomyces cerevisiae , the hexose phosphorylating enzymes play parallel roles in glucose repression in A. nidulans.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M209443200