Regulation of pyrimidine formation in Pseudomonas lundensis.
The regulation of pyrimidine formation in the food spoilage agent Pseudomonas lundensis ATCC 49968 by pyrimidines was examined. In P. lundensis cells grown on glucose as a carbon source, the enzymes aspartate transcarbamoylase, dihydroorotase, and orotidine 5'-monophosphate decarboxylase were induced by orotic acid. Pyrimidine auxotrophs containing reduced transcarbamoylase or orotate phosphoribosyltransferase activity were isolated using chemical mutagenesis and selection procedures. Independent of carbon source, the maximum derepression of enzyme activity was observed for orotidine 5'-monophosphate decarboxylase after pyrimidine limitation of either auxotroph. In the glucose-grown cells of the transcarbamoylase mutant strain, orotic acid induced dihydroorotase and decarboxylase activities. Aspartate transcarbamoylase activity in succinate-grown P. lundensis cells was highly regulated by pyrophosphate as well as by pyrimidine and purine ribonucleotides. It was concluded that pyrimidine formation in P. lundensis was controlled both at the level of de novo pyrimidine biosynthetic enzyme synthesis and at the level of transcarbamoylase activity.
Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA. Thomas.West@sdstate.edu
Thomas P
TP
West
D001221:Aspartate Carbamoyltransferase / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003470:Culture Media; D004790:Enzyme Induction; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D009963:Orotic Acid / Q000378:metabolism; D011549:Pseudomonas / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D011743:Pyrimidines / Q000096:biosynthesis*; D013386:Succinates / Q000378:metabolism
D001426:Bacterial Proteins; D003470:Culture Media; D011743:Pyrimidines; D013386:Succinates; D009963:Orotic Acid; D001221:Aspartate Carbamoyltransferase; D005947:Glucose