Functional Characterization of the Subunits N, H, J, and O of the NAD(P)H Dehydrogenase Complexes in Synechocystis sp Strain PCC 6803
Functional Characterization of the Subunits N, H, J, and O of the NAD(P)H Dehydrogenase Complexes in Synechocystis sp Strain PCC 6803
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集胞藻菌株 PCC 6803 中 NAD(P)H 脱氢酶复合物的 N、H、J 和 O 亚基的功能表征
DOI：
10.1104/pp.16.00458
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发表时间：
2016-06-01
期刊：
影响因子：
7.4
通讯作者：
Mi, Hualing
中科院分区：
文献类型：
--
作者：
He, Zhihui;Mi, Hualing
蓝藻NAD(P)H脱氢酶(NDH-1)复合体在PSI周围的呼吸、二氧化碳吸收和循环电子传递等多种生物能量反应中起着至关重要的作用。最近，在确定NDH-1复合体的亚基组成方面取得了实质性进展。然而，蓝藻中几个亚基的定位和生理作用还不完全清楚。通过构建聚球藻中完全分离的ndhN、ndhO、ndhH和ndhJ缺失突变体。在PCC6803菌株中，我们发现ndhN、ndhH或ndhJ的缺失而不是ndhO的缺失严重损害了NDH-1亲水性亚基在类囊体膜上的积累，导致NDH-1MS、NDH-1MS‘以及NDH-1L的分解，最终导致严重的生长抑制表型。相反，NdhO的缺失影响了在空气中pH为6.5的生长。在细胞质中，NdhH和NdhJ都缺失了突变体，但NdhN和NdhO都没有缺失突变体，未能积累由NdhH、NdhJ、NdhK和NdhM组成的NDH-1组装中间体。根据这些结果，我们认为NdhN、NdhH和NdhJ对NDH-1复合体的稳定性和活性是必需的，而NDH-1的NdhO是在无机碳限制的条件下发挥作用的。菌株PCC 6803。我们讨论了这些亚基的作用，并提出了一个新的NDH-1模型。
The cyanobacterial NAD(P)H dehydrogenase (NDH-1) complexes play crucial roles in variety of bioenergetic reactions such as respiration, CO2 uptake, and cyclic electron transport around PSI. Recently, substantial progress has been made in identifying the composition of subunits of NDH-1 complexes. However, the localization and the physiological roles of several subunits in cyanobacteria are not fully understood. Here, by constructing fully segregated ndhN, ndhO, ndhH, and ndhJ null mutants in Synechocystis sp. strain PCC 6803, we found that deletion of ndhN, ndhH, or ndhJ but not ndhO severely impaired the accumulation of the hydrophilic subunits of the NDH-1 in the thylakoid membrane, resulting in disassembly of NDH-1MS, NDH-1MS', as well as NDH-1L, finally causing the severe growth suppression phenotype. In contrast, deletion of NdhO affected the growth at pH 6.5 in air. In the cytoplasm, either NdhH or NdhJ deleted mutant, but neither NdhN nor NdhO deleted mutant, failed to accumulate the NDH-1 assembly intermediate consisting of NdhH, NdhJ, NdhK, and NdhM. Based on these results, we suggest that NdhN, NdhH, and NdhJ are essential for the stability and the activities of NDH-1 complexes, while NdhO for NDH-1 functions under the condition of inorganic carbon limitation in Synechocystis sp. strain PCC 6803. We discuss the roles of these subunits and propose a new NDH-1 model.