Department of Biological Chemistry, College of Agriculture, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yoshida, Japan.
Laboratory of Regulation of Biological Reactions, Division of Protein Chemistry, Institute for Protein Research, Osaka University, Suita, Japan.
FEBS Open Bio. 2019 Dec;9(12):2126-2136. doi: 10.1002/2211-5463.12752. Epub 2019 Nov 15.
Ferredoxin-NADP reductase (FNR) in plants receives electrons from ferredoxin (Fd) at the end of the photosynthetic electron transfer chain and converts NADP to NADPH. The interaction between Fd and FNR in plants was previously shown to be attenuated by NADP(H). Here, we investigated the molecular mechanism of this phenomenon using maize FNR and Fd, as the three-dimensional structure of this complex is available. NADPH, NADP , and 2'5'-ADP differentially affected the interaction, as revealed through kinetic and physical binding analyses. Site-directed mutations of FNR which change the affinity for NADPH altered the affinity for Fd in the opposite direction to that for NADPH. We propose that the binding of NADP(H) causes a conformational change of FNR which is transferred to the Fd-binding region through different domains of FNR, resulting in allosteric changes in the affinity for Fd.
植物中的铁氧还蛋白-NADP 还原酶（FNR）从光合作用电子传递链末端的铁氧还蛋白（Fd）接收电子，并将 NADP 转化为 NADPH。先前的研究表明，植物中 Fd 与 FNR 的相互作用会被 NADP（H）减弱。在这里，我们使用玉米 FNR 和 Fd 研究了这种现象的分子机制，因为该复合物的三维结构是可用的。通过动力学和物理结合分析，揭示了 NADPH、NADP 和 2'5'-ADP 对相互作用的不同影响。FNR 的定点突变改变了 NADPH 的亲和力，使 Fd 的亲和力朝着与 NADPH 相反的方向改变。我们提出，NADP（H）的结合导致 FNR 的构象发生变化，这种变化通过 FNR 的不同结构域传递到 Fd 结合区域，导致 Fd 亲和力的变构变化。
