NAD biosynthesis

Araki T, Sasaki Y, Milbrandt J (2004) Increased nuclear NAD biosynthesis and SIRTl activation prevent axonal degeneration. Science 305(5686) 1010-1013... 

The NAD biosynthesis pathway mediated by nicotinamide phosphoribosyltransferase regulates Srr2 activity in mammalian cells. The Journal of Biological Chemistry, 279, 50754—50763. 

Table 1 Enzymes involved in NAD biosynthesis and examples of their occurrence in various species...

Figure 2 NAD biosynthesis subsystem diagram. Major functional roles are shown by 4-6 letter abbreviations (explained in Table 1) over the colored background reflecting the key aspects or modules (pathways) that comprise NAD biosynthesis in various species. Catalyzed reactions are shown by solid straight arrows, and corresponding intermediate metabolites are shown as abbreviations within ovals Asp, L-aspartate lA, Iminoaspartate Qa, quinolinic acid Nm, nicotinamide Na, nicotinic acid NaMN, nicotinic acid mononucleotide NMN, nicotinamide mononucleotide RNm, N-ribosyInicotinamide NaAD, nicotinate adenine dinucleotide NAD, nicotinamide adenine dinucleotide NADP, NAD-phosphate Trp, tryptophan FKyn, N-formylkynurenine Kyn, kynurenine HKyn, 3-hydroxykynurenine HAnt, 3-hydroxyanthranilate and ACMS, a-amino-/3-carboxymuconic semialdehyde. Unspecified reactions (including spontaneous transformation and transport) are shown by dashed arrows.

The NMNAT activity was originally inferred by bioinformatics analysis and experimentally identified for the central domain (aa 64—234) of the multifunctional NadR protein from E. coli. The three-domain version of the NadR protein that exists only in Enterobacteriaceae contains an N-terminal HTH domain, which is involved in DNA binding, mediating its role as a transcriptional regulator of NAD biosynthesis (see Section... 

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