ISSN:
1432-072X
Keywords:
Nitrogenase regulation
;
Glutamine synthetase
;
Ammonia switch-off
;
Rhodopseudomonas palustris
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Nitrogenase activity in Rhodopseudomonas palustris is subject to a rapid switch-off in response to exogenous ammonia. When cells were grown on limiting nitrogen and eventually became nitrogen deficient, nitrogenase synthesis was fully derepressed but the enzyme was insensitive to ammonia. The transformation of ammonia-sensitive to ammonia-insensitive cells was a slow, but fully reversible process. The switch-off effect in ammonia-sensitive cells paralleled changes in the adenylylation state of glutamine synthetase. Ammonia-insensitive cells, however, showed similar changes in glutamine synthetase activity although nitrogenase activity was unaffected. We conclude that nitrogenase regulation and adenylylation of glutamine synthetase are independent processes, at least under conditions of nitrogen deficiency.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00411066
