Biochemical parameters of glutamine synthetase from Klebsiella aerogenes.
AUTOR(ES)
Bender, R A
RESUMO
The glutamine synthetase (GS) from Klebsiella aerogenes is similar to that from Escherichia coli in several respects: (i) it is repressed by high levels of ammonia in the growth medium; (ii) its biosynthetic activity is greatly reduced by adenylylation; and (iii) adenylylation lowers the pH optimum and alters the response of the enzymes to various inhibitors in the gamma-glutamyl transferase (gammaGT) assay. There are, however, several important differences: (i) the isoactivity point for the adenylylated and non-adenylylated forms in the gammaGT assay occurs at pH 7.55 in K. aerogenes and at pH 7.15 in E. coli; (ii) the non-adenylylated form of the GS from K. aerogenes is stimulated by 60 mM MgCl2 in the gammaGT assay at pH 7.15. A biosynthetic reaction assay that correlates well with number of non-adenylylated enzyme subunits, as determined by the method of Mg2+ inhibition of the gammaGT assay, is described. Finally, we have found that it is necessary to use special methods to harvest growing cells to prevent changes in the adenylylation state of GS from occurring during harvesting.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=235040Documentos Relacionados
- Autogenous regulation of the synthesis of glutamine synthetase in Klebsiella aerogenes.
- Identification of the structural gene for glutamine synthetase in Klebsiella aerogenes.
- Regulation of the synthesis of glutamine synthetase by the PII protein in Klebsiella aerogenes.
- Genetic control of glutamine synthetase in Klebiella aerogenes.
- Role of glnA-linked genes in regulation of glutamine synthetase and histidase formation in Klebsiella aerogenes.
