Influence of carbon source on pyrimidine synthesis in Pseudomonas mendocina

Abstract

The effect of carbon source on the regulation of the de novo pyrimidine biosynthetic enzymes in the bacterium Pseudomonas mendocina was studied. When glucose was the carbon source, orotic acid supplementation of P. mendocina cells produced the greatest depression of aspartate transcarbamoylase, dihydroorotate dehydrogenase and orotate phosphoribosyltransferase activities while P. mendocina cells grown in the presence of uracil caused the maximal decrease in dihydroorotase and OMP decarboxylase activities. After the pyrimidine starvation of an orotate phosphoribosyltransferase mutant strain of P. mendocina grown on glucose, the pyrimidine biosynthetic pathway enzyme activities were generally diminished. With respect to pyrimidine starvation studies, the carbon source glucose appeared to lessen regulation at the level of enzyme synthesis compared to what has been observed when succinate served as the carbon source. The regulation of the pyrimidine biosynthetic pathway by carbon source in P. mendocina appeared to differ from how carbon source influenced the control of pyrimidine biosynthesis in the closely-related species Pseudomonas stutzeri.

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

“…The same pattern of repression and derepression has been reported in P. oleovorans ATCC 8062 (Lee and Chandler 1941) when grown in glucose minimal medium with uracil (Haugaard and West 2002). Also, P. mendocina cells grown in PsMM with glucose/uracil and glucose/orotate caused decreased pyrimidine enzyme specific activities (Santiago and West 2003).…”

Regulation of pyrimidine biosynthesis in Acidovorax delafieldii

“…Since transcriptional regulation of the pyrimidine biosynthetic pathway in species of Acidovorax has not been previously studied, A. delafieldii ATCC 17505 T was compared to what is known regarding control of pyrimidine biosynthesis in species classified within the close-related genus Pseudomonas. After comparing the regulation of pyrimidine biosynthesis in A. delafieldii ATCC 17505 T with that observed for Pseudomonas putida ATCC 17536, Pseudomonas stutzeri ATCC 17588 T , Pseudomonas mendocina ATCC 25411 T , Pseudomonas pseudoalcaligenes ATCC 17440 T and Pseudomonas alcaligenes ATCC 14909 T (WEST 1997, SANTIAGO and WEST 2002, 2003a, 2003, the transcriptional regulation of pyrimidine biosynthesis in P. alcaligenes appeared to be the most similar. With respect to carbon source, the pyrimidine biosynthetic enzyme activities in succinate-grown P. alcaligenes cells were higher than in glucose-grown-cells (SANTIAGO and WEST 2003b).…”

“…Since Acidovorax delafieldii is a nutritionally versatile species frequently present in wastewater treatment plants (ZHAO and WARD 1999, SCHULZE et al 1999, KHAN et al 2002, it was of interest to learn whether pyrimidine nucleotide biosynthesis in this bacterium is highly controlled to ensure its survival under harsh environmental conditions. As regulation of pyrimidine biosynthesis has been indicated by prior studies investigating species of the related genus Pseudomonas (CHU and WEST 1990, WEST 1994, 1997, SANTIAGO and WEST 2002, 2003a, 2003b, it seemed plausible that pyrimidine biosynthesis in A. delafieldii ATCC 17505 T could also be regulated. The de novo pyrimidine biosynthetic pathway consists of five enzymes that culminates with the formation of uridine 5′-monophosphate (UMP).…”

Pyrimidine Biosynthesis and Ribonucleoside Metabolism in Species of Pseudomonas

“…When the succinate-grown ATCC 25411 cells were supplemented with uracil, dihydroorotase or decarboxylase activity was observed to be greatly diminished relative to the unsupplemented cells [88]. If the ATCC 25411 cells were grown on glucose as a carbon source and supplemented with orotic acid or uracil, the pyrimidine biosynthetic enzyme activity appeared to be repressed by their metabolites, compared to their enzyme activity in the unsupplemented cells [89]. A mutant strain deficient in orotate phosphoribosyltransferase activity was utilized to determine the effect of pyrimidine limitation upon the pyrimidine biosynthetic pathway enzymes' activity.…”

“…The pyrimidine biosynthetic pathway enzymes in pseudomonads include aspartate transcarbamoylase, dihydroorotase, dihydroorotate dehydrogenase, orotate phosphoribosyltransferase and orotidine 5′-monophosphate (OMP) decarboxylase (Figure 1). The species taxonomically assigned to the Pseudomonas aeruginosa group where the regulation of pyrimidine biosynthesis has been investigated previously include P. aeruginosa, Pseudomonas alcaligenes, Pseudomonas citronellolis, Pseudomonas mendocina, Pseudomonas nitroreducens, Pseudomonas oleovorans, Pseudomonas pseudoalcaligenes and Pseudomonas resinovorans [84][85][86][87][88][89][90][91][92][93][94][95][96]. In Table 1, the regulation of pyrimidine biosynthesis in species assigned to the P. aeruginosa homology group is compared relative to enzyme repression by a uracil-related metabolite and the level of enzyme synthesis following pyrimidine limitation of a pyrimi-dine auxotroph.…”