Acetate-nonutilizing mutants of Neurospora rassa. II. Biochemical deficiencies and the roles of certain enzymes.
The levels of Krebs cycle, glyoxylate cycle, and certain other enzymes were measured in a wild-type strain and in seven groups of acetate-nonutilizing (acu) mutants of Neurospora crassa, both after growth on a medium containing sucrose and after a subsequent 6-hr incubation in a similar medium, containing acetate as the sole source of carbon. In the wild strain, incubation in acetate medium caused a rise in the levels of isocitrate lyase, malate synthase, phosphoenolpyruvate carboxykinase, acetyl-coenzyme A synthetase, nicotinamide adenine dinucleotide phosphate-linked isocitrate dehydrogenase, citrate synthase, and fumarate hydratase. Isocitrate lyase activity was absent in acu-3 mutants; acu-5 mutants lacked acetyl-coenzyme A synthetase activity; and no oxoglutarate dehydrogenase activity (or only low levels) could be detected in acu-2 and acu-7 mutants. In acu-6 mutants, phosphoenolpyruvate carboxykinase activity was either very low or absent. No specific biochemical deficiencies could be attributed to the acu-1 and acu-4 mutations. The role of several of these enzymes during growth on acetate is discussed.
D000085:Acetates / Q000378:metabolism*; D002952:Citric Acid Cycle; D003470:Culture Media; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D006038:Glyoxylates / Q000378:metabolism; D006836:Hydro-Lyases / Q000378:metabolism; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D008025:Ligases / Q000378:metabolism; D008190:Lyases / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000378:metabolism; D009154:Mutation; D009491:Neurospora / Q000201:enzymology* / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D011770:Pyruvate Kinase / Q000378:metabolism; D013385:Succinate Dehydrogenase; D013395:Sucrose / Q000378:metabolism
D000085:Acetates; D003470:Culture Media; D006038:Glyoxylates; D013395:Sucrose; D010088:Oxidoreductases; D008291:Malate Dehydrogenase; D007521:Isocitrate Dehydrogenase; D013385:Succinate Dehydrogenase; D005969:Glutamate Dehydrogenase; D011770:Pyruvate Kinase; D008190:Lyases; D006836:Hydro-Lyases; D008025:Ligases