title: Regulation of glutaminase levels in Escherichia coli.
abstract: Nitrogenous metabolites, cyclic adenosine 3':5'-monophosphate (cAMP), and the stage of culture growth all influence the levels of glutaminase A in Escherichia coli, but no variables in culture conditions alter the levels of glutaminase B. Growth of E. coli on culture media containing glucose and excess ammonia results in a rise in the level of glutaminase A as the cultures enter stationary phase; this rise is abolished by ammonia limitation. cAMP or glycerol reduce the level of glutaminase A. In mutants deficient in cAMP receptor protein, glutaminase A levels are unchanged by cAMP, but they are still susceptible to regulation by ammonia. We consider glutaminase B to be a constitutive enzyme, since its levels appear independent of nutritional conditions.
mesh_terms: D000332:Aerobiosis; D000643:Ammonium Chloride / Q000378:metabolism; D000693:Anaerobiosis; D003470:Culture Media; D000242:Cyclic AMP / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology* / Q000254:growth & development; D005971:Glutamates / Q000378:metabolism; D005972:Glutaminase / Q000096:biosynthesis*; D005973:Glutamine / Q000378:metabolism; D005990:Glycerol / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000096:biosynthesis*; D009154:Mutation; D013696:Temperature
chemical_list: D003470:Culture Media; D005971:Glutamates; D007527:Isoenzymes; D000643:Ammonium Chloride; D005973:Glutamine; D000242:Cyclic AMP; D005972:Glutaminase; D005990:Glycerol