title: Microbial NAD metabolism: lessons from comparative genomics.
abstract: NAD is a coenzyme for redox reactions and a substrate of NAD-consuming enzymes, including ADP-ribose transferases, Sir2-related protein lysine deacetylases, and bacterial DNA ligases. Microorganisms that synthesize NAD from as few as one to as many as five of the six identified biosynthetic precursors have been identified. De novo NAD synthesis from aspartate or tryptophan is neither universal nor strictly aerobic. Salvage NAD synthesis from nicotinamide, nicotinic acid, nicotinamide riboside, and nicotinic acid riboside occurs via modules of different genes. Nicotinamide salvage genes nadV and pncA, found in distinct bacteria, appear to have spread throughout the tree of life via horizontal gene transfer. Biochemical, genetic, and genomic analyses have advanced to the point at which the precursors and pathways utilized by a microorganism can be predicted. Challenges remain in dissecting regulation of pathways.
authors.affiliation: Department of Genetics and Norris Cotton Cancer Center, Dartmouth Medical School, Lebanon, New Hampshire 03756, USA.
authors.forename: Francesca
authors.initials: F
authors.lastname: Gazzaniga
authors.forename: Rebecca
authors.initials: R
authors.lastname: Stebbins
authors.forename: Sheila Z
authors.initials: SZ
authors.lastname: Chang
authors.forename: Mark A
authors.initials: MA
authors.lastname: McPeek
authors.forename: Charles
authors.initials: C
authors.lastname: Brenner
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D053898:Biosynthetic Pathways; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D016680:Genome, Bacterial; D023281:Genomics; D009243:NAD / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D009243:NAD