Pleiotropic mutants of Aspergillus nidulans altered in carbon metabolism

Abstract

Mutants altered in carbon catabolite regulation have been isolated by selecting for mutants of theareA217 strain capable of using acetamide as the sole nitrogen source in the presence of sucrose. In addition tocreA mutants described previously by Arst and Cove, strains with mutations in two new genes,creB andcreC, have been found. ThecreB andcreC mutants grow poorly on some sole carbon sources and have low levels of some enzymes of carbon catabolism e.g. β-galactosidase and D-quinate dehydrogenase. ThecreB andcreC mutants are hypersitive to fluoroacetate, fluoroacetamide and allyl alcohol in the presence of glucose or sucrose but not glycerol; and the enzymes, acetamidase, and alcohol dehydrogenase, are less sensitive to carbon catabolite repression than the wild-type strain. Extracellular protease and α-glucosidase enzyme activities are elevated increB andcreC mutants, while L-proline and L-glutamate uptake capacities are lower in both the presence and absence of glucose. Interactions betweencreA, B and C mutations have been investigated in double mutants, and the dominance properties ofcreB andcreC mutants determined. The results indicate that thecreB andcreC genes may have a regulatory role in the control of carbon catabolism.