Phosphoribosylpyrophosphate synthetase (PrsA) variants alter cellular pools of ribose 5-phosphate and influence thiamine synthesis in Salmonella enterica.
Phosphoribosylamine (PRA) is the first intermediate in the common purine/thiamine biosynthetic pathway and is primarily synthesized by the product of the purF gene, glutamine phosphoribosylpyrophosphate (PRPP) amidotransferase (E.C. 2.4.2.14). Past genetic and biochemical studies have shown that multiple mechanisms for the synthesis of PRA independent of PurF are present in Salmonella enterica. Here, we describe mutant alleles of the essential prsA gene, which encodes PRPP synthetase (E.C. 2.7.6.1), that allow PurF-independent thiamine synthesis. The mutant alleles resulted in reduced PrsA activity in extracts, caused nutritional requirements indicative of PRPP limitation and allowed non-enzymic formation of PRA due to a build-up of ribose 5-phosphate (R5P). These results emphasize the balance that must be reached between pathways competing for the same substrate to maintain robustness of the metabolic network.
Koenigsknecht
Mark J
MJ
Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Fenlon
Luke A
LA
Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Downs
Diana M
DM
Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
D000483:Alleles; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D009154:Mutation; D012267:Ribosemonophosphates / Q000378:metabolism*; D019779:Salmonella enterica / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D013831:Thiamine / Q000096:biosynthesis*; D000637:Transaminases / Q000378:metabolism*
D001426:Bacterial Proteins; D003470:Culture Media; D008074:Lipoproteins; D008565:Membrane Proteins; D012267:Ribosemonophosphates; C082160:prsA protein, bacteria; C008891:phosphoribosylamine; C031626:ribose-5-phosphate; D000637:Transaminases; C022389:phosphoribosyl pyrophosphate aminotransferase; D013831:Thiamine