期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 103, 期 20, 页码 7601-7606出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0602494103
关键词
NAD metabolism; pyridine nucleoticles; metabolic control; NADP synthesis; sedimentation equilibrium
资金
- NIGMS NIH HHS [GM23408] Funding Source: Medline
Formation of NADP(+) from NAD(+) is catalyzed by NAD kinase (NadK; EC 2.7.1.23). Evidence is presented that NadK is the only NAD kinase of Salmonella enterica and is essential for growth. NadK is inhibited allosterically by NADPH and NADH. Without effectors, NadK exists as an equilibrium mixture of dimers and tetramers (K-D = 1.0 +/- 0.8 mM) but is converted entirely to tetramers in the presence of the inhibitor NADPH. Comparison of NadK kinetic parameters with pool sizes of NADH and NADPH suggests that NadK is substantially inhibited during normal growth and, thus, can increase its activity greatly in response to temporary drops in the pools of inhibitory NADH and NADPH. The primary inhibitor is NADPH during aerobic growth and NADH during anaerobic growth. A model is proposed in which variation of NadK activity is central to the adjustment of pyridine nucleotide pools in response to changes in aeration, oxidative stress, and UV irradiation. It is suggested that each of these environmental factors causes a decrease in the level of reduced pyridine nucleotides, activates NadK, and increases production of NADF(H) at the expense of NAD(H). Activation of NadK may constitute a defensive response that resists loss of protective NADPH.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据