A Salmonella typhimurium Strain Defective in Uracil Catabolism and  -Alanine Synthesis

Abstract

A selection procedure for uracil catabolism mutant strains involving indicator dye plates was developed. Using this method, a strain defective in uracil catabolism has been isolated in Salmonella typhimurium that was temperature-sensitive at 42 degrees C where it required low concentrations of N-carbamoyl-beta-alanine, beta-alanine or pantothenic acid for growth. An extract of the mutant strain degraded uracil at 37 degrees C at a significantly diminished rate compared to that observed for the wild-type strain under the same growth conditions. The conversion of dihydrouracil to N-carbamoyl-beta-alanine was blocked at all temperatures examined in the mutant strain. By means of genetic analysis, the mutant strain was determined to be defective at two genetic loci. Transduction studies with bacteriophage P22 indicated that the panD gene is mutated in this strain, accounting for its beta-alanine requirement. Episomal transfers between Escherichia coli and the mutant strain provided evidence that the defect in uracil catabolism was located in another region of the S. typhimurium chromosome.

Effect of supplementation of inulin in dietary on lactation performance, rumen fermentation, ruminal microbial profile and metabolites in dairy cows

“…In the present study, the increase of uracil upregulated the nucleic acid metabolism, which might indicate that supplementation of inulin might promote the synthesis of rumen MCP [17]. Additionally, the decomposed product of uracil was β-alanine, which could further synthesize propionate [58]. This might explain the positive correlation between uracil and lactose.…”

Leaky Pantothenate and Thiamin Mutations of Salmonella typhimurium Conferring Sulphometuron Methyl Sensitivity

“…These crossfeeding results and the suppressor mutant's leaky auxotrophy were compatible with strain TV145 containing a mutation in panD, dfp or panE since (a) either of two enzymes, ketopantoic acid reductase (panE) and acetohydroxyacid isomeroreductase (ilvc), is sufficient to catalyse the conversion of ketopantoate to pantoate in vivo (Primerano & Burns, 1983) and ( 21) mutations in either dfp (Spitzer et al, 1988) or panD (West et al, 1985) result in a partial requirement for pantothenate. To demonstrate that the TnlO insertion in strain TV145 did not inactivate panE, the insertion was introduced into the ilvC strain SA2595 by transduction.…”

“…In contrast, the biochemical genetics of the S. typhimurium system had not been investigated. P-Alanine auxotrophic mutations have been mapped to both the pan cluster at minute 5 (Primerano & Burns, 1983;West et al, 1985) and to minute 89 (Ortega et al, 1975). Enzymic analyses of these mutations have not been reported.…”

“…Strains harbouring panD : : TnlO grew, though more slowly than the wild-type, on minimal medium at 30 "C and 37 "C. It is unlikely that such strains would have been scored as auxotrophs by other workers. Indeed, P-alanine-stimulated strains of S. typhimurium and E. coli have only been identified as secondary phenotypes of mutations modulating DNA synthesis (Spitzer et al, 1988), pyrimidine catabolism (West et al, 1985) or sulphometuron methyl sensitivity (this work) ; after extremely harsh, nitrosoguanidine mutagenesis resulting in the formation of multiple auxotrophies (Ortega et al, 1975); or as derivatives of a strain defective in branchedchain amino acid synthesis (Primerano & Burns, 1983).…”

The Biochemistry of Pyrimidine Base Catabolism: Why Understanding the Cellular Recycling of Pyrimidine Bases is Important

“…Pyrimidine base catabolism usually involves either a reductive pathway or an oxidative pathway with the former more prevalent in humans as well as in plants, unicellular eukaryotes and bacteria [1][2][3][4]. The reductive pathway involves three enzymes which include dihydropyrimidine dehydrogenase (EC 1.3.1.2), dihydropyrimidinase (EC 2.5.2.2) and β-ureidopropionase (EC 3.5.1.6) [2][3][4].…”