Pyridine nucleotide cycle and NAD⁺ biosynthetic routes.

<p>The routes known to be functional across diverse bacterial species are shown by solid lines. Preiss-Handler pathway is shadowed. Dashed and hollow arrows relate to uptake and <i>de </i><i>novo</i> NaMN synthesis, respectively. Blue arrow corresponds to nicotinamidase activity (PncA), Red arrow corresponds to nicotinamide mononucleotide deamidase activity (PncC) and green arrow corresponds to NAD⁺-dependent DNA ligase. Enzymes are indicated as the acronym used to identify the corresponding gene locus: NadA, quinolinate synthetase; NadB, L-aspartate oxidase; NadC, quinolinate phosphoribosyl transferase; NadD, NaMN adenylyltransferase; NadE, NAD synthetase; NadM, NMN adenyltransferase; NadR^C, NmR kinase; NadR^N, NMN adenylyltransferase; NadV, Nm phosphoribosyltransferase; PncA, Nam deamidase; PncB, Na phosphoribosyltransferase; PncC, nicotinamide mononucleotide deamidase; PncU, nucleoside permease. The gene name of the enzymes existing in <i>O. iheyensis</i> is highlighted in brown. Abbreviations: NAD, nicotinamide adenine dinucleotide; IA, α-iminosuccinate; Qa, quinolonic acid; Asp, aspartate; Trp, tryptophan; NAM, nicotinamide; NA: nicotinic acid; NMN, nicotinic acid mononucleotide; NaAD, nicotinic acid adenine dinucleotide; NmR, nicotinamide riboside; DNA, deoxyribonucleic acid.