Biogenesis and Homeostasis of Nicotinamide Adenine Dinucleotide Cofactor.
Biogenesis and Homeostasis of Nicotinamide Adenine Dinucleotide Cofactor.
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DOI：
10.1128/ecosalplus.3.6.3.10
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发表时间：
2009-08
期刊：
影响因子：
--
通讯作者：
Osterman A
中科院分区：
文献类型：
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作者：
Osterman A
普遍和普遍存在的氧化还原辅因子，烟酰胺腺嘌呤二核苷酸（NAD）及其磷酸化类似物（NADP），共同贡献了约12%的所有生化反应包括在代谢模型ofEscherichia coli K-12。由细胞忠实地维持的NAD库的稳态是由NAD生物合成、利用、分解和再循环途径的网络中的动态平衡引起的，所述网络在各个水平受到严格调节。本文简要介绍了NAD的利用过程，包括一些非氧化还原利用的例子。本文主要就NAD在大肠杆菌中的生物合成和利用进行综述。大肠杆菌和沙门氏菌在过去的12年里出现。最初在哺乳动物系统中发现的第一个吡啶核苷酸循环（PNC）被称为Preiss-Handler途径，包括通过烟酸磷酸核糖基转移酶（PncB）将烟酸（Na）一步转化为NaMN。InE。大肠杆菌和许多其他原核生物中，这种酶与烟酰胺脱酰胺酶（PncA）一起构成了以酰胺化（Nm）或脱酰胺化（Na）前体形式利用吡啶环的主要途径。控制NAD生物合成机制的各种调节机制和检查点的存在反映了在各种生长条件下维持NAD稳态的重要性。在单个酶水平上最重要的调节机制之一是NAD对NAD从头生物合成的第一种酶NadB的经典反馈抑制，以及通过还原辅因子对NadK的代谢调节。
Universal and ubiquitous redox cofactors, nicotinamide adenine dinucleotide (NAD) and its phosphorylated analog (NADP), collectively contribute to approximately 12% of all biochemical reactions included in the metabolic model ofEscherichia coliK-12. A homeostasis of the NAD pool faithfully maintained by the cells results from a dynamic balance in a network of NAD biosynthesis, utilization, decomposition, and recycling pathways that is subject to tight regulation at various levels. A brief overview of NAD utilization processes is provided in this review, including some examples of nonredox utilization. The review focuses mostly on those aspects of NAD biogenesis and utilization inE. coliandSalmonellathat emerged within the past 12 years. The first pyridine nucleotide cycle (PNC) originally identified in mammalian systems and termed the Preiss-Handler pathway includes a single-step conversion of niacin (Na) to NaMN by nicotinic acid phosphoribosyltransferase (PncB). InE. coliand many other prokaryotes, this enzyme, together with nicotinamide deamidase (PncA), compose the major pathway for utilization of the pyridine ring in the form of amidated (Nm) or deamidated (Na) precursors. The existence of various regulatory mechanisms and checkpoints that control the NAD biosynthetic machinery reflects the importance of maintaining NAD homeostasis in a variety of growth conditions. Among the most important regulatory mechanisms at the level of individual enzymes are a classic feedback inhibition of NadB, the first enzyme of NAD de novo biosynthesis, by NAD and a metabolic regulation of NadK by reduced cofactors.