title: Regulation of fructose 2,6-bisphosphate levels in Neurospora crassa.
abstract: Both wild type and cr-1 mutant (adenylate cyclase and cyclic AMP-deficient) strains of Neurospora crassa contain fructose 2,6-bisphosphate at levels of 27 nmol/g dry tissue weight. This level decreases by about 50% in both strains upon depriving the cells of carbon or nitrogen sources for 3 h. An increase in cyclic AMP levels produced by addition of lysine to nitrogen-starved cells produced no increase in fructose 2,6-bisphosphate levels. Both strains respond to short-term addition of salicylate, acetate, or 2,4-dinitrophenol with an increase in fructose 2,6-bisphosphate. Thus, the above-described regulation of fructose 2,6-bisphosphate levels is cyclic AMP-independent. A suspension of the wild type produces a transient increase of fructose 2,6-bisphosphate in response to administration of glucose, whereas the mutant strain does not respond unless it is fed exogenous cyclic AMP. Substitution of acetate for sucrose as a sole carbon source for growth leads to a differential decrease in fructose 2,6-bisphosphate levels between the two strains: the wild type strain has 63% and the cr-1 mutant strain has 37% of the levels of fructose 2,6-bisphosphate on acetate as compared to sucrose-grown controls. This may be the basis for an advantage of cr-1 over wild type in growth on acetate. Thus, although most regulation of fructose 2,6-bisphosphate is cyclic AMP-independent, the levels can be regulated by a combination of carbon source and cyclic AMP levels.
mesh_terms: D000085:Acetates / Q000378:metabolism; D000242:Cyclic AMP / Q000502:physiology; D005635:Fructosediphosphates / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006598:Hexosediphosphates / Q000378:metabolism*; D009154:Mutation; D009491:Neurospora / Q000378:metabolism*; D009492:Neurospora crassa / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism
chemical_list: D000085:Acetates; D005635:Fructosediphosphates; D006598:Hexosediphosphates; C027652:fructose 2,6-diphosphate; D000242:Cyclic AMP; D005947:Glucose; D009584:Nitrogen