Pyrimidine nucleotide synthesis in Pseudomonas citronellolis.
Pyrimidine biosynthesis was active in Pseudomonas citronellolis ATCC 13674 and appeared to be regulated by pyrimidines. When wild-type cells were grown on succinate in the presence of uracil, the de novo enzyme activities were depressed while only four enzyme activities were depressed in the glucose-grown cells. On either carbon source, orotic acid-grown cells had diminished aspartate transcarbamoylase, dihydroorotase or OMP decarboxylase activity. Pyrimidine limitation of glucose-grown pyrimidine auxotrophic cells resulted in de novo enzyme activities, except for transcarbamoyolase activity, that were elevated by more than 5-fold compared to their activities in uracil-grown cells. Since pyrimidine limitation of succinate-grown mutant cells produced less enzyme derepression, catabolite repression appeared to be a factor. At the level of enzyme activity, aspartate transcarbamoylase activity in P. citronellolis was strongly inhibited by all effectors tested. Compared to the regulation of pyrimidine biosynthesis in taxonomically-related species, pyrimidine biosynthesis in P. citronellolis appeared more highly regulated.
Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD 57007, USA. Thomas.West@sdstate.edu
Thomas P
TP
West
D001221:Aspartate Carbamoyltransferase / Q000378:metabolism; D004794:Enzyme Repression; D015964:Gene Expression Regulation, Bacterial; D011549:Pseudomonas / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D011742:Pyrimidine Nucleotides / Q000096:biosynthesis*
D011742:Pyrimidine Nucleotides; D001221:Aspartate Carbamoyltransferase