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Assimilation of nicotinamide mononucleotide requires periplasmic AphA phosphatase in Salmonella enterica.

Grose JH, Bergthorsson U, Xu Y, Sterneckert J, Khodaverdian B, Roth JR

Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.

Salmonella enterica can obtain pyridine from exogenous nicotinamide mononucleotide (NMN) by three routes. In route 1, nicotinamide is removed from NMN in the periplasm and enters the cell as the free base. In route 2, described here, phosphate is removed from NMN in the periplasm by acid phosphatase (AphA), and the produced nicotinamide ribonucleoside (NmR) enters the cell via the PnuC transporter. Internal NmR is then converted back to NMN by the NmR kinase activity of NadR. Route 3 is seen only in pnuC* transporter mutants, which import NMN intact and can therefore grow on lower levels of NMN. Internal NMN produced by either route 2 or route 3 is deamidated to nicotinic acid mononucleotide and converted to NAD by the biosynthetic enzymes NadD and NadE.

Published 21 June 2005 in J Bacteriol, 187(13): 4521-30.
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