A second thylakoid membrane-localized Alb3/Oxal/YidC homologue is involved in proper chloroplast biogenesis in Arabidopsis thaliana
A second thylakoid membrane-localized Alb3/Oxal/YidC homologue is involved in proper chloroplast biogenesis in Arabidopsis thaliana
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DOI：
10.1074/jbc.m513623200
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发表时间：
2006-06-16
影响因子：
4.8
通讯作者：
Schuenemann, Danja
中科院分区：
文献类型：
--
作者：
Gerdes, Lars;Bals, Thomas;Schuenemann, Danja
整合膜蛋白Alb 3、Oxygenase和YidC属于进化上保守的蛋白质家族，分别介导蛋白质插入叶绿体的类囊体膜、线粒体的内膜和细菌中。虽然Oxygenase和YidC参与了广泛的膜蛋白的插入，但Alb 3的功能似乎仅限于插入捕光叶绿素结合蛋白的一个子集。在这项研究中，我们确定了第二个叶绿体同系物的Alb 3/Oxidase/YidC家族，命名为Alb 4。Alb 4与先前描述的110-kDa内包膜蛋白Artemis的Alb 3/Oxygenase/YidC结构域几乎相同。我们发现，Alb 4是作为一个单独的55 kDa的蛋白质和Artemis被错误地识别。Alb 4位于拟南芥叶绿体的类囊体膜上。对拟南芥突变体（Salk_ 136199）和具有降低的Alb 4水平的RNA干扰系的分析揭示了具有改变的超微结构的叶绿体。突变体质体更大，外观上更呈球形，并且突变体系内的基粒堆叠比野生型叶绿体中的贴壁更少。这些数据表明，Alb 4是所需的适当的叶绿体生物发生。
The integral membrane proteins Alb3, OxaI, and YidC belong to an evolutionary conserved protein family mediating protein insertion into the thylakoid membrane of chloroplasts, the inner membrane of mitochondria, and bacteria, respectively. Whereas OxaI and YidC are involved in the insertion of a wide range of membrane proteins, the function of Alb3 seems to be limited to the insertion of a subset of the light-harvesting chlorophyll-binding proteins. In this study, we identified a second chloroplast homologue of the Alb3/OxaI/YidC family, named Alb4. Alb4 is almost identical to the Alb3/OxaI/YidC domain of the previously described 110-kDa inner envelope protein Artemis. We show that Alb4 is expressed as a separate 55-kDa protein and that Artemis was identified mistakenly. Alb4 is located in the thylakoid membrane of Arabidopsis thaliana chloroplasts. Analysis of an Arabidopsis mutant ( Salk_ 136199) and RNA interference lines with a reduced level of Alb4 revealed chloroplasts with an altered ultrastructure. Mutant plastids are larger and more spherical in appearance, and the grana stacks within the mutant lines are less appressed than in the wild-type chloroplasts. These data indicate that Alb4 is required for proper chloroplast biogenesis.