GenePage for the pncC gene of Escherichia coli K-12

Primary Gene Name: pncC
EcoGene Accession Number: EG12698
K-12 Gene Accession Number: ECK2695
MG1655 Gene Identifier: b2700
Gene Name Mnemonic: Pyridine nucleotide cycle
Alternate Gene Symbols: ygaD
Description: Nicotinamide-nucleotide amidohydrolase; NMN amidohydrolase
  # bp Upstream # bp Downstream
MW: 17581.72 ---------165 aa Pre-Run BlastP UniProt
Pre-Run BlastP NR+Env
Left End: 2823849
Left Intergenic Region

Name: recA_pncC

Length: 79 bp gap

Orientation: Codirectional-

Left_end: 2823770

Right_end: 2823848

Centisome: 60.84

Genomic Address
Minute or Centisome (%) = 60.84
Right End: 2824346
Right Intergenic Region

Name: pncC_mltB

Length: 144 bp gap

Orientation: Codirectional-

Left_end: 2824347

Right_end: 2824490

Centisome: 60.85

NMN amidohydrolase is also known as NMN deamidase. PncC(YgaD) is the only one of three PncC(CinA) domain (PF02464) proteins that has NMN amidohydrolase activity; YdeJ and YfaY are inactive PncC homologs (Galeazzi, 2011). E. coli NMN amidohydrolase is required for the recycling of NAD (via PNC IV) catalyzing the deamidation of NMN to NaMN; unpublished results of S. Sirilan and B. Olivera were cited for the initial report of an NMN amidohydrolase activity in crude extracts of E. coli (Manlapaz-Fernandez, 1973). NMN amidohydrolase was partially purified, but the gene was not identified; NMN amidohydrolase has a native MW of 33K (and an observed pI of 5.3) indicating PncC dimerization; NMN amidohydrolase exhibits a pH optimum of approximately 9 (Hillyard, 1981). PncC is is part of the most active pathway, PNC IV, for recycling NAD in E. coli; a second pathway PNC VI is also present. The assignment of the gene name pncC was originally suggested for the NMN amidohydrolase structural gene in Salmonella (Foster, 1979). The pncC gene was mismapped twice in Salmonella. The initial mapping of pncC in Salmonella was based on a penicillin selection against wildtype that could catabolize NMN; mutants with a pnuA allele of nadR, whose enzymatic activity is required for NMN uptake by assisting in the nicotinamide riboside substrate conversion to NMN and release from the PnuC transporter (Foster, 1979; Kinney, 1979; Foster, 1987; Foster, 1990). A second misidentification of the Salmonella pncC gene occurred when a selection for NMN catabolism mutants identified a gene (aphA) with a metabolic activity required for NMN uptake, not the catabolic enzyme NMN amidohydrolase; the periplasmic AphA is required for the de-phosphorylation of NMN to form nicotinamide riboside, the PnuC transporter substrate (Cheng, 1995; Grose, 2005).

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