Regulation of pyrimidine nucleotide formation in Pseudomonas taetrolens ATCC 4683

The regulation of the de novo pyrimidine biosynthetic enzymes in the food spoilage agent Pseudomonas taetrolens ATCC 4683 was investigated. The de novo pyrimidine biosynthetic enzyme activities were determined in P. taetrolens ATCC 4683 cells and in cells from an auxotroph deficient for orotidine 5'-monophosphate decarboxylase activity. Pyrimidine supplementation to the culture medium affected the biosynthetic enzyme activities in ATCC 4683 cells. Transcriptional regulation of the biosynthetic pathway by pyrimidines was indicated after the auxotroph was subjected to pyrimidine limitation. At the level of enzyme activity, aspartate transcarbamoylase activity was strongly inhibited by pyrophosphate, ADP, ATP, UDP, UTP and GTP. Transcriptional regulation of pyrimidine synthesis in P. taetrolens was not as highly controlled as in the taxonomically-related species Pseudomonas fragi although both species contained transcarbamoylase activities subject to significant nucleotide inhibition.