Identification of Novel Ssl0352 Protein (NdhS), Essential for Efficient Operation of Cyclic Electron Transport around Photosystem I, in NADPH:plastoquinone Oxidoreductase (NDH-1) Complexes of Synechocystis sp. PCC 6803
Identification of Novel Ssl0352 Protein (NdhS), Essential for Efficient Operation of Cyclic Electron Transport around Photosystem I, in NADPH:plastoquinone Oxidoreductase (NDH-1) Complexes of Synechocystis sp. PCC 6803
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DOI：
10.1074/jbc.m111.263780
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发表时间：
2011-10-21
影响因子：
4.8
通讯作者：
Ma, Weimin
中科院分区：
文献类型：
--
作者：
Battchikova, Natalia;Wei, Lanzhen;Ma, Weimin
蓝藻NADPH：质体醌氧化还原酶，或I型NAD(P)H脱氢酶，或NDH-1复合体参与光系统I周围的质体醌还原和循环电子转移（CET），而CET又产生额外的ATP用于细胞代谢，特别是在应激条件下。尽管过去几年蓝藻NDH-1复合物的研究取得了重大成就，但整个亚基组成仍然难以捉摸。为了鉴定缺失的亚基，我们筛选了在强光下生长的Synechocystis 6803细胞的转座子标记文库。两个ndh -1介导的CET （NDH-CET）缺陷突变体被标记在同一个ssl0352基因上，该基因编码一种短的未知蛋白。为了明确Ssl0352的功能，我们构建了Ssl0352缺失突变体和另一个Ssl0352与黄色荧光蛋白（YFP）和His(6)标签融合的突变体。免疫印迹、质谱和共聚焦显微镜分析显示，Ssl0352蛋白存在于类囊体膜中，并与NDH-1L和NDH-1M复合物结合。我们认为Ssl0352是蓝藻NDH-1复合物的一个新的亚基，并将其命名为NdhS。ssl0352基因的缺失严重损害了NDH-CET的活性，并且在强光条件下延缓了细胞的生长，这表明NdhS对于NDH-CET的有效运行至关重要。然而，突变体中NDH-1L和NDH-1M复合物的组装及其在细胞中的含量不受影响。NdhS含有Src同源3-like结构域，可能参与了NdhS -1复合物与电子供体的相互作用。
Cyanobacterial NADPH:plastoquinone oxidoreductase, or type I NAD(P)H dehydrogenase, or the NDH-1 complex is involved in plastoquinone reduction and cyclic electron transfer (CET) around photosystem I. CET, in turn, produces extra ATP for cell metabolism particularly under stressful conditions. Despite significant achievements in the study of cyanobacterial NDH-1 complexes during the past few years, the entire subunit composition still remains elusive. To identify missing subunits, we screened a transposon-tagged library of Synechocystis 6803 cells grown under high light. Two NDH-1-mediated CET (NDH-CET)-defective mutants were tagged in the same ssl0352 gene encoding a short unknown protein. To clarify the function of Ssl0352, the ssl0352 deletion mutant and another mutant with Ssl0352 fused to yellow fluorescent protein (YFP) and the His(6) tag were constructed. Immunoblotting, mass spectrometry, and confocal microscopy analyses revealed that the Ssl0352 protein resides in the thylakoid membrane and associates with the NDH-1L and NDH-1M complexes. We conclude that Ssl0352 is a novel subunit of cyanobacterial NDH-1 complexes and designate it NdhS. Deletion of the ssl0352 gene considerably impaired the NDH-CET activity and also retarded cell growth under high light conditions, indicating that NdhS is essential for efficient operation of NDH-CET. However, the assembly of the NDH-1L and NDH-1M complexes and their content in the cells were not affected in the mutant. NdhS contains a Src homology 3-like domain and might be involved in interaction of the NDH-1 complex with an electron donor.