Activity of the nicotinamide mononucleotide transport system is regulated in Salmonella typhimurium.
Transport of nicotinamide mononucleotide (NMN) requires two functions, NadI(T) and PnuC. The PnuC protein is membrane associated, as judged by isolation of active TnphoA gene fusions and demonstration that the fusion protein is membrane associated. The PnuC function appears to be the major component of the transport system, since mutant alleles of the pnuC gene permit NMN transport in the absence of NadI(T) function. We present evidence that the activity of the NMN transport system varies in response to internal pyridine levels (presumably NAD). This control mechanism requires NadI(T) function, which is provided by a bifunctional protein encoded by the nadI gene (called nadR by Foster and co-workers [J. W. Foster, Y. K. Park, T. Fenger, and M. P. Spector, J. Bacteriol. 172:4187-4196]). The nadI protein regulates transcription of the nadA and nadB biosynthetic genes and modulates activity of the NMN permease; both regulatory activities respond to the internal pyridine nucleotide level.
Zhu
N
N
Department of Biology, University of Utah, Salt Lake City 84112.
Olivera
B M
BM
Roth
J R
JR
D001426:Bacterial Proteins / Q000378:metabolism; D001692:Biological Transport / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008565:Membrane Proteins / Q000378:metabolism*; D009154:Mutation; D009243:NAD / Q000235:genetics / Q000378:metabolism; D009537:Nicotinamide Mononucleotide / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors
D001426:Bacterial Proteins; D008565:Membrane Proteins; D014157:Transcription Factors; C067130:nadI protein, Salmonella typhimurium; D009243:NAD; D009537:Nicotinamide Mononucleotide