Glutamate dehydrogenase: genetic mapping and isolation of regulatory mutants of Klebsiella aerogenes

Abstract

The gene for glutamate dehydrogenase (gdhD) has been mapped in Klebsiella aerogenes by P1 transduction. It is linked to pyrF and trp with the order pyrF-trp-gdh. Complementation analysis using F' episomes from Escherichia coli suggests an analogous location in E. coli. Two mutants able to produce glutamate dehydrogenase in the presence of high levels of glutamine synthetase have been isolated. One, tightly linked to gdhD, shows normal repression control by glutamine synthetase but produces four times as much glutamate dehydrogenase activity as does the wild type under all conditions tested. The other revertant is not linked to gdhD or glnA.

Genetic mapping of tyramine oxidase and arylsulfatase genes and their regulation in intergeneric hybrids of enteric bacteria

“…cotransducible with the tyramine oxidase gene (tynA) (10). There are some reports that the map positions of genes in E. coli are similar to those of analogous genes in K. aerogenes (5,17). Complementation of a mutation in K. aerogenes by an episome derived from the E. coli chromosome ought, therefore, to be a useful method for locating the mutation on the K. aerogenes chromosome, although no genetic study on arylsulfatase and tyramine oxidase in E. coli has been reported.…”

“…Scoring of the Ats and Tyn phenotypes was done as described previously (10), except that, when the transductants re(juired glutamine, the Tyn phenotype was scored by assay of tvramine oxidase in test tubes. Gdh and Pvr phenotypes were scored as described by Bender et al (5).…”

“…These findings confirm that the ats gene is located near trp and txn on the chromosome of E. coli and that the arylsulfatase protein has lost enzyme function for the usual substrate. DISCUSSION Recently, the transfers to K. aerogenes of chromosomal genes from E. coli using F factor and P1 phage have been reported (5,6,17). However, there have been no reports about the tyn gene in enteric bacteria other than K. aerogenes.…”

Cloning and characterization of gdhA, the structural gene for glutamate dehydrogenase of Salmonella typhimurium

“…The analysis of several strains with mutations in the structural gene for GDH, gdhA, has demonstrated that the enzyme activity is not essential as long as glutamate synthase is functional (14,15,30). The regulation of ghdA in S. typhimurium differs from that in K. aerogenes, in which growth with a limiting nitrogen source causes a decrease in GDH activity (2,7), and from that in E. coli, where nitrogen limitation has no effect and only the supplementation of glucose-ammonia medium with glutamate causes a decrease in GDH activity (17,25,38). Thus, although similar biosynthetic routes to glutamate exist in a number of organisms, the pattern of gdhA regulation is unique for each.…”

Temperature-sensitive glutamate dehydrogenase mutants of Salmonella typhimurium

“…Mutants of E. coli (2, 20), K. aerogenes (1,13) and S. typhimurium (10) lacking glutamate synthase or glutamate dehydrogenase activity or both have been isolated, but it is not known whether these mutations identify structural genes or regulatory genes. The control of GDH in S. typhimurium is of particular interest because there is substantial expression of this enzyme activity in cells grown in a variety ofmedia, yet the enzyme appears to be unnecessary for growth (4,10).…”