Gazzaniga Francesca, Stebbins Rebecca, Chang Sheila Z, McPeek Mark A, Brenner Charles
Department of Genetics and Norris Cotton Cancer Center, Dartmouth Medical School, Lebanon, New Hampshire 03756, USA.
Microbiol Mol Biol Rev. 2009 Sep;73(3):529-41, Table of Contents. doi: 10.1128/MMBR.00042-08.
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.
NAD是氧化还原反应的辅酶以及NAD消耗酶的底物，这些酶包括ADP-核糖转移酶、Sir2相关的蛋白质赖氨酸脱乙酰酶和细菌DNA连接酶。已鉴定出能从六种已确定的生物合成前体中的少至一种多达五种合成NAD的微生物。从天冬氨酸或色氨酸从头合成NAD既不普遍也并非严格需氧。从烟酰胺、烟酸、烟酰胺核糖和烟酸核糖进行补救性NAD合成是通过不同基因模块发生的。在不同细菌中发现的烟酰胺补救基因nadV和pncA似乎已通过水平基因转移遍布生命之树。生化、遗传和基因组分析已发展到可以预测微生物利用的前体和途径的程度。在剖析途径的调控方面仍存在挑战。
