THE EFFECT OF THE NITROGEN-SOURCE AND NTRC ON THE ADENYLYLATION OF GLUTAMINE-SYNTHETASE-I IN RHIZOBIUM-ETLI

Regulation of the adenylylation of glutamine synthetase I in Rhizobium etli was found to be different from that in enteric bacteria. Adenyly lation was high in cells growing in low concentrations of ammonia and was not affected by an excess of ammonia. Adenylylation was dependent on NtrC, since strain CFN2012 carrying a ntrC::Tn5 insertion mutation showed low levels of adenylylation. This effect was not due to the lac k of glutamine synthetase II caused by the ntrC mutation, because stra in SM88, which lacks glutamine synthetase II activity owing to a glnII mutation, showed levels of adenylylation similar to those of the wild type.