[Studies on regulation of glutamine synthetase activity from Streptomyces lincolnensis].
Glutamine synthetase in crude extracts from Streptomyces lincolnensis growing under different nitrogen sources were studied. The results showed that NH4+ in high concentration repressed the biosynthesis of the enzyme. To determine whether Streptomyces lincolnensis has undergone covalent modification, a comparison of the glutamine synthetase isolated from cells grown on different nitrogen sources was made. No significant difference was observed in specific activity, pH optima, divalent cation response, and ultraviolet absorption spectra. Glutamine synthetase activity was not influenced by ammonia shock or snake venom phosphodiesterase treatment. Under these conditions, the activity of glutamine synthetase from K. aerogenes was markedly changed. There was therefore no evidence for enzymatic adenylylation of glutamine synthetase from Streptomyces lincolnensis. Glutamine synthetase was subject to feedback inhibition by end products of glutamine metabolism. Cumulative feedback inhibition of the Mn(2+)-dependent glutamine synthetase activity was demonstrated. These results suggest that glutamine synthetase from Streptomyces lincolnensis is an allosteric enzyme.
Jin
Z
Z
Shanghai Institute of Plant Physiology, Chinese Academy of Sciences, Shanghai 200032, China.
Jiao
R
R
Mao
Y
Y
D000641:Ammonia / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics
D001426:Bacterial Proteins; D005973:Glutamine; D000641:Ammonia; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen