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

In research to date, regulation of the pyrimidine biosynthetic pathway at the level of gene expression has not been shown for wild type Pseudomonas aeruginosa. No repression was observed when uracil was added to the growth medium nor was any derepression seen when Pyr(-) auxotrophs were limited for pyrimidines. Here we show that the addition of uracil to Pseudomonas minimal medium influenced the synthesis of pyrimidine enzymes, while starvation of a pyrimidine knockout mutant (pyrD) elicited derepression of the pyrimidine enzymes.

Pseudomonas aeruginosa dihydroorotases: a tale of three pyrCs.

Pseudomonas aeruginosa PAO1 was shown to contain three pyrC sequences. Two of these genes, designated pyrC (PA3527) and pyrC2 (PA5541), encode polypeptides with dihydroorotase (DHOase) activity, while the third, pyrC' (PA0401), encodes a DHOase-like polypeptide that lacks DHOase activity, but is necessary for the structure and function of ATCase. Both pyrC and pyrC2 were cloned and complemented an Escherichia coli pyrC mutant.