Regulation of pyrimidine nucleotide formation in Pseudomonas reptilivora

Abstract

Aims: To study the regulation of de novo pyrimidine biosynthesis in the pathogenic bacterium Pseudomonas reptilivora ATCC 14836. Methods and Results: The pyrimidine biosynthetic pathway enzymes were assayed in extracts of Ps. reptilivora ATCC 14836 cells and of cells from an auxotroph lacking aspartate transcarbamoylase activity. Pyrimidine biosynthetic pathway enzyme activities in ATCC 14836 were influenced by the addition of pyrimidine bases to the culture medium with orotic acid addition inducing dihydroorotase activity. Pyrimidine starvation of the transcarbamoylase mutant strain increased its de novo enzyme activities suggesting that the de novo pathway was also subject to repression by a pyrimidine-related compound. Aspartate transcarbamoylase activity in ATCC 14836 was inhibited in vitro by pyrophosphate and ATP. Conclusions: Regulation of pyrimidine biosynthesis in Ps. reptilivora was observed at the level of enzyme synthesis and at the level of activity for aspartate transcarbamoylase. Its regulation of enzyme synthesis seemed to be more highly controlled than what was observed in the related species Ps. fluorescens. Significance and Impact of the Study: This investigation found that pyrimidine biosynthesis is controlled in Ps. reptilivora. This could prove helpful to future studies exploring its pathogenicity.

Regulation of the pyrimidine biosynthetic pathway in a pyrD knockout mutant of Pseudomonas aeruginosa

“…In this study pyrimidine starvation experiments have demonstrated that the pyrimidine biosynthetic enzymes can be influenced, suggesting that regulation is occurring at the transcriptional level. This finding for P. aeruginosa is supported by the basic research of West and collaborators who have reported transcriptional regulation in a number of other Pseudomonas species (West 2004a, 2004c, West 2005a, 2005b.…”

NMR Metabolic Profiling of Aspergillus nidulans to Monitor Drug and Protein Activity

“…OMP is an exhaustively studied metabolic enzyme that includes numerous X-ray structures . Since pyrimidines are generally important for a variety of cell function and highly regulated, − inhibition of the pyrimidine biosynthetic pathway tends to stimulate or up-regulate pyrimidine salvage pathways. , Thus, pyrimidine biosynthetic pathways are a common target for drug discovery. − The A. nidulans pyrG89 mutant eliminates the normal function of OMP and is similar to uaZ14 , where both are recessive, loss-of-function mutations. The pyrG89 mutant has not been characterized at the DNA or the protein level.…”

“…OMP is an exhaustively studied metabolic enzyme that includes numerous X-ray structures. 60 Since pyrimidines are generally important for a variety of cell function and highly regulated, [61][62][63][64] inhibition of the pyrimidine biosynthetic pathway tends to stimulate or up-regulate pyrimidine salvage pathways. 65,66 Thus, pyrimidine biosynthetic pathways are a common target for drug discovery.…”

Pyrimidine Biosynthesis and Ribonucleoside Metabolism in Species of Pseudomonas

“…The regulation of pyrimidine biosynthesis has been investigated in certain species taxonomically assigned to the Pseudomonas fluorescens chlororaphis group, including P. fluorescens, Pseudomonas mucidolens, Pseudomonas reptilivora, Pseudomonas synxantha and Pseudomonas veronii [102][103][104][105][106][107][108][109]. The regulation of pyrimidine biosynthesis in the P. fluorescens homology group species was compared by examining uracil-related metabolite repression or the influence of pyrimidine auxotroph limitation on the biosynthetic enzyme levels (Table 3).…”

“…Pyrimidine biosynthesis was shown to be regulated by pyrimidines in P. reptilivora ATCC 14836 [107]. In succinate-grown ATCC 14836 cells, uracil supplementation lowered transcarbamoylase, dehydrogenase, phosphoribosyltransferase or decarboxylase activity, while orotic acid supplementation was less effective in repressing the pathway enzymes' activity relative to each one's activity in unsupplemented cells [107].…”