Extracellular arabinases in Aspergillus nidulans: the effect of different cre mutations on enzyme levels
| Autor: | P. van der Veen, Herbert N. Arst, M.J.A. Flipphi, Jantien Visser |
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| Rok vydání: | 1994 |
| Předmět: |
Molecular Genetics of Industrial Micro-organisms
Mutant Catabolite repression Reductase Biochemistry Microbiology Gene Expression Regulation Enzymologic Aspergillus nidulans Induction Moleculaire genetica van industriële micro-organismen Genetics Molecular Biology Derepression VLAG Regulator gene biology Structural gene D-Xylulose Reductase General Medicine Carbon catabolite repression biology.organism_classification Arabinose Carbon Fed-batch culture Enzyme Induction Mutation Arabinases Enzyme Repression Sugar Alcohol Dehydrogenases |
| Zdroj: | Archives of Microbiology 162 (1994) Archives of Microbiology, 162, 433-440 |
| ISSN: | 1432-072X 0302-8933 |
| Popis: | The regulation of the syntheses of two arabinan-degrading extracellular enzymes and several intracellular L-arabinose catabolic enzymes was examined in wild-type and carbon catabolite derepressed mutants of Aspergillus nidulans. alpha-L-Arabinofuranosidase B, endoarabinase, L-arabinose reductase, L-arabitol dehydrogenase, xylitol dehydrogenase, and L-xylulose reductase were all inducible to varying degrees by L-arabinose and L-arabitol and subject to carbon catabolite repression by D-glucose. With the exception of L-xylulose reductase, all were clearly under the control of creA, a negative-acting wide domain regulatory gene mediating carbon catabolite repression. Measurements of intracellular enzyme activities and of intracellular concentrations of arabitol and xylitol in mycelia grown on D-glucose in the presence of inducer indicated that carbon catabolite repression diminishes, but does not prevent uptake of inducer. Mutations in creA resulted in an apparently, in some instances very marked, elevated inducibility, perhaps reflecting an element of "self" catabolite repression by the inducing substrate. creA mutations also resulted in carbon catabolite derepression to varying degrees. The regulatory effects of a mutation in creB and in creC, two genes whose roles are unclear, but likely to be indirect, were, when observable, more modest. As with previous data showing the effect of creA mutations on structural gene expression, there were striking instances of phenotypic variation amongst creA mutant alleles and this variation followed no discernible pattern, i.e. it was non-hierarchical. This further supports molecular data obtained elsewhere, indicating a direct role for creA in regulating structural gene expression, and extends the range of activities under creA control. |
| Databáze: | OpenAIRE |
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