Genomics and Enzymology of NAD Biosynthesis

Nicotinamide adenine dinucleotides, NAD and NADP, are indispensable cofactors involved in several redox reactions in all forms of cellular life. In addition, NAD is utilized as a co-substrate in a number of nonredox reactions playing an important role in signaling and regulatory pathways. This chapter highlights the recent findings about genes, enzymes, pathways, and transcriptional regulators of NAD biosynthesis. It also illustrates the application of the comparative genomic approach to projecting the acquired knowledge across several diverse species with completely sequenced genomes. This approach also helps to identify novel operational variants of NAD biosynthesis and to predict previously uncharacterized genes involved therein.