CHARACTERIZATION OF SALMONELLA TYPHIMURIUM MUTANTS WITH ALTERED GLUTAMINE SYNTHETASE ACTIVITY

Characterization of Salmonella typhimurium mutants with altered glutamine synthetase activity.

A number of glutamine auxotrophs of Salmonella typhimurium were isolated and characterized genetically. Three of the mutations appear to be closely linked and are complemented by episomes carrying the glnA region of Escherichia coli. The lesions in these strains are approximately 20% linked by P1 transduction with a mutation in the rha gene, but are unlinked to ilv. Another mutation causing glu...

Histidine regulatory mutants in Salmonella typhimurium II. Histidine regulatory mutants having altered histidyl-tRNA synthetase.

(1) The hid’ gene of Salmonelb ty(phinzurium is the structural gene for histidyltRNA synthetase. Mutants in the hid gene have an altered histidyl-tRNA synthetase and constitute one of the four classes of histidine regulatory mutants. (2) Mutant hisS1520 has a synthetase with a 60.fold decreased affinity for histidine. This mutant has a markedly decreased growth rate on minimal medium and is de-...

L-Methionine SR-sulfoximine-resistant glutamine synthetase from mutants of Salmonella typhimurium.

Two mutants of Salmonella typhimurium resistant to growth inhibition by the glutamine synthetase transition state analog, L-methionine SR-sulfoximine, were isolated and characterized. These mutants are glutamine bradytrophs and cannot use growth rate-limiting nitrogen sources. Although this phenotype resembles that of mutants with lesions in the regulatory gene for glutamine synthetase, glnG, t...

Selection of Salmonella typhimurium mutants with altered serine transhydroxymethylase regulation.

In Salmonella typhimurium the glyA gene product, serine transhydroxymethylase (E.C. 2.1.2.1.; L-serine:tetrahydrofolate-5,10-hydroxymethyltransferase) is responsible for the interconversion of serine and glycine. This reaction also provides the cell with one-carbon units from the 5,10-methylene-tetrahydrofolate formed during glycine synthesis. Despite the importance of this enzyme, however, no ...

Salmonella typhimurium proline mutants.