Reduced activity of glutamine synthetase in Rhodospirillum rubrum mutants lacking the adenylyltransferase GlnE.
In the nitrogen-fixing bacterium Rhodospirillum rubrum, the GlnE adenylyltransferase (encoded by glnE) catalyzes reversible adenylylation of glutamine synthetase, thereby regulating nitrogen assimilation. We have generated glnE mutant strains that are unable to adenylylate glutamine synthetase (GS). Surprisingly, the activity of GS was lower in the mutants than in the wild type, even when grown in nitrogen-fixing conditions. Our results support the proposal that R. rubrum can only cope with the absence of an adenylylation system in the presence of lowered GS expression or activity. In general terms, this report also provides further support for the central role of GS in bacterial metabolism.
Jonsson
Anders
A
Department of Biochemistry and Biophysics, Stockholm University, SE-10691 Stockholm, Sweden.
Nordlund
Stefan
S
Teixeira
Pedro Filipe
PF
D017353:Gene Deletion; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism*; D009586:Nitrogen Fixation; D009713:Nucleotidyltransferases / Q000235:genetics*; D012247:Rhodospirillum rubrum / Q000201:enzymology* / Q000235:genetics
D009713:Nucleotidyltransferases; C020658:glutamine-synthetase adenylyltransferase; D005974:Glutamate-Ammonia Ligase