Evidence that feedback inhibition of NAD kinase controls responses to oxidative stress.

ABSTRACT: 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 (KD = 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 variatio

SUBMITTER: Grose JH 

PROVIDER: S-EPMC1472491 | biostudies-literature | 2006 May

REPOSITORIES: biostudies-literature