n nnnIn higher plants, the chloroplast NAD(P)H dehydrogenase (NDH)complex mediates photosystem I (PSI) cyclic and chlororespiratoryelectron transport. We reported previously that NDH interactswith the PSI complex to form a supercomplex (NDH-PSI). In thisstudy, NDH18 and FKBP16-2 (FK506 Binding Protein 16-2), detectedin the NDH-PSI supercomplex by mass spectrometry, were shownto be NDH subunits by the analysis of their knockdown lines.On the basis of extensive mutant characterization, we proposea structural model for chloroplast NDH, whereby NDH is dividedinto four subcomplexes. The subcomplex A and membrane subcomplexare conserved in cyanobacteria, but the subcomplex B and lumensubcomplex are specific to chloroplasts. Two minor light-harvestingcomplex I proteins, Lhca5 and Lhca6, were required for the full-sizeNDH-PSI supercomplex formation. Similar to crr pgr5 double mutantsthat completely lack cyclic electron flow activity around PSI,the lhca6 pgr5 double mutant exhibited a severe defect in growth.Consistent with the impaired NDH activity, photosynthesis wasalso severely affected in mature leaves of lhca6 pgr5. We concludethat chloroplast NDH became equipped with the novel subcomplexesand became associated with PSI during the evolution of landplants, and this process may have facilitated the efficientoperation of NDH.展开▼
机译：ABSTRACTn n
n TOP n <字体颜色= 464c53>抽象 n 介绍 n 结果 n 讨论 n 方法 n 参考文献 n n nnn在高等植物中，叶绿体NAD（P）H脱氢酶（NDH） 完全x介导光系统I（PSI）的循环和氯呼吸 电子传输。我们以前曾报道过NDH与PSI复合物相互作用 形成超复合物（NDH-PSI）。在此 研究中，通过质谱法在NDH-PSI超复杂物中检测到的 显示了NDH18和FKBP16-2（FK506结合蛋白16-2）。 SUP> 在其广泛的突变体表征的基础上，提出了 叶绿体NDH的结构模型，将NDH划分为 SUP> 分为四个子复合体。亚复合物A和膜亚复合物 在蓝细菌中是保守的，但是亚复合物B和管腔 亚复合物是叶绿体特有的。完整的 NDH-PSI超复合物的形成需要两个次要的 复合物I蛋白Lhca5和Lhca6。与 crr pgr5 双重突变体 类似，它们完全缺乏PSI周围的循环电子流动活性， 出现了 lhca6 pgr5 双重突变体。严重的生长缺陷。 与NDH活性受损同时， lhca6 pgr5 的成熟叶片中的光合作用 也受到严重影响。我们得出的结论是， 叶绿体NDH配备了新型的亚复合物 ，并在陆地植物 的进化过程中与PSI相关，这一过程可能有助于NDH的有效 操作。展开▼
