title: Characterization of a gamma-glutamyl kinase from Escherichia coli that confers proline overproduction and osmotic tolerance.
abstract: Mutation(s) in the proBA operon of Escherichia coli confers proline overproduction and enhanced osmotic tolerance in enteric bacteria (L. N. Csonka, Mol. Gen. Genet. 182:82-86, 1981; M. J. Mahan and L. N. Csonka, J. Bacteriol. 156:1249-1262, 1983). A glutamate-dependent ATPase assay was developed and used to determine proB-encoded gamma-glutamyl kinase activity in the absence of glutamate-gamma-semialdehyde dehydrogenase. This assay indicated that the feedback insensitivity of mutant gamma-glutamyl kinase was independent of glutamate-gamma-semialdehyde dehydrogenase. However, the capacity of glutamate-gamma-semialdehyde dehydrogenase from the osmotolerant mutant to interact with the kinase was altered in thermal stability, suggesting that mutations in both proB and proA may be required for osmotolerance.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D050698:Glutamate-5-Semialdehyde Dehydrogenase; D006358:Hot Temperature; D006877:Hydroxamic Acids / Q000378:metabolism; D009154:Mutation; D009876:Operon; D009996:Osmotic Fragility; D010770:Phosphotransferases / Q000378:metabolism*; D017851:Phosphotransferases (Carboxyl Group Acceptor); D011392:Proline / Q000096:biosynthesis*; D011489:Protein Denaturation; D013696:Temperature
chemical_list: D006877:Hydroxamic Acids; D011392:Proline; D000445:Aldehyde Oxidoreductases; D050698:Glutamate-5-Semialdehyde Dehydrogenase; D010770:Phosphotransferases; D017851:Phosphotransferases (Carboxyl Group Acceptor); C020650:glutamate 5-kinase; D000251:Adenosine Triphosphatases