NdhM Subunit Is Required for the Stability and the Function of NAD(P)H Dehydrogenase Complexes Involved in CO2 Uptake in Synechocystis sp. Strain PCC 6803.
NdhM Subunit Is Required for the Stability and the Function of NAD(P)H Dehydrogenase Complexes Involved in CO2 Uptake in Synechocystis sp. Strain PCC 6803.
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DOI：
10.1074/jbc.m115.698084
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发表时间：
2016-03-11
期刊：
影响因子：
--
通讯作者：
Mi H
中科院分区：
文献类型：
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作者：
He Z;Xu M;Wu Y;Lv J;Fu P;Mi H
蓝藻I型NAD（P）H脱氢酶（NDH-1）复合物在呼吸、CO2吸收和光系统I周围的循环电子传递等多种生物能反应中起着至关重要的作用。NDH-1 MS和NDH-1 MS ′两种类型的NDH-1复合物参与CO2吸收系统。然而，复合物的组成和功能仍然在很大程度上未知。在这里，我们发现ndhM的缺失导致NDH-1依赖的光系统I周围的循环电子传递的失活和CO2吸收的废除，导致在空气CO2条件下的致死表型。NdhM突变后，NDH-1的亲水性亚基如NdhH、NdhI、NdhJ和NdhK在类囊体膜上的积累消失，导致NDH-1 MS、NDH-1 MS ′和NDH-1 L解体。相反，在NdhM的情况下，疏水亚基的积累不受影响。在细胞质中，NDH-1亚复合体组装中间体包括NdhH和NdhK在ΔndhM突变体中受到严重影响，而在NdhI缺失突变体ΔndhI中没有受到影响。体外蛋白质相互作用分析表明，NdhM与NdhK，NdhH，NdhI和NdhJ相互作用，但不与NDH-1复合物的其他亲水性亚基相互作用。这些结果表明，NdhM定位在NDH-1复合物的亲水亚复合物中作为核心亚基，并且对于参与集胞藻PCC 6803菌株CO2吸收的NDH-1 MS和NDH-1 MS ′的功能是必需的。
The cyanobacterial type I NAD(P)H dehydrogenase (NDH-1) complexes play a crucial role in a variety of bioenergetic reactions such as respiration, CO2 uptake, and cyclic electron transport around photosystem I. Two types of NDH-1 complexes, NDH-1MS and NDH-1MS′, are involved in the CO2 uptake system. However, the composition and function of the complexes still remain largely unknown. Here, we found that deletion of ndhM caused inactivation of NDH-1-dependent cyclic electron transport around photosystem I and abolishment of CO2 uptake, resulting in a lethal phenotype under air CO2 condition. The mutation of NdhM abolished the accumulation of the hydrophilic subunits of the NDH-1, such as NdhH, NdhI, NdhJ, and NdhK, in the thylakoid membrane, resulting in disassembly of NDH-1MS and NDH-1MS′ as well as NDH-1L. In contrast, the accumulation of the hydrophobic subunits was not affected in the absence of NdhM. In the cytoplasm, the NDH-1 subcomplex assembly intermediates including NdhH and NdhK were seriously affected in the ΔndhM mutant but not in the NdhI-deleted mutant ΔndhI. In vitro protein interaction analysis demonstrated that NdhM interacts with NdhK, NdhH, NdhI, and NdhJ but not with other hydrophilic subunits of the NDH-1 complex. These results suggest that NdhM localizes in the hydrophilic subcomplex of NDH-1 complexes as a core subunit and is essential for the function of NDH-1MS and NDH-1MS′ involved in CO2 uptake in Synechocystis sp. strain PCC 6803.