The product of a newly identified gene, gInF, is required for synthesis of glutamine synthetase in Salmonella.

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Abstract
The product of a newly identified gene, glnF, which is distinct from the glutamine synthetase structural gene (glnA), is required for synthesis of glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] in S. typhimurium and probably in Escherichia coli. Salmonella strains with ICR (2-chloro-6-methyoxy-9-[3-(2-chloroethyl)aminopropylamino]acridine dihydrochloride)-induced (frameshift) mutations in glnF are glutamine auxotrophs; they have < 10% of wild-type glutamine synthetase activity or antigen and are unable to derepress the synthesis of the enzyme. The mutant allele is recessive to the wild-type allele, indicating that the glnF gene encodes a diffusible product. Mutant glnF strains have normal activities of all proteins involved in covalent modification of glutamine synthetase: adenylyltransferase (EC 2.7.7.42), PII, uridylyltransferase and uridylyl removing enzyme. In addition they have glutamate synthase (EC 1.4.1.13) and glutamate dehydrogenase (EC 1.4.1.4) activities. Thus, glnF does not encode the structure of any of these proteins. Apparently, the product of the glnF gene is (or produces) a positive regulatory factor required for synthesis of glutamine synthetase, and autoregulation cannot account for control of the synthesis of glutamine synthetase in Salmonella.