Distinct Albino3-dependent and -independent Pathways for Thylakoid Membrane Protein Insertion*
Distinct Albino3-dependent and -independent Pathways for Thylakoid Membrane Protein Insertion*
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类囊体膜蛋白插入的独特 Albino3 依赖和独立途径*
DOI：
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发表时间：
2001
影响因子：
4.8
通讯作者：
C. Robinson
中科院分区：
文献类型：
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作者：
C. Woolhead;S. Thompson;Misty J. Moore;Christophe Tissier;A. Mant;A. Rodger;R. Henry;C. Robinson
同源蛋白Oxa1、YidC和Alb3分别介导线粒体、细菌和叶绿体类囊体中膜蛋白的插入。YidC在大肠杆菌中的耗尽影响了所研究的每个膜蛋白的整合，并且先前已经证明Alb3是在类囊体中插入信号识别颗粒（SRP）依赖性蛋白Lhcb 1所需的。在这项研究中，我们分析了“全球”的作用，Alb3在插入类囊体膜蛋白。我们发现，插入的两个叶绿素结合蛋白，Lhcb4.1和Lhcb5，几乎完全阻断预孵育的类囊体与抗Alb3抗体，这表明在插入途径中需要Alb3。另一方面，相关PsbS蛋白的插入不受Alb3抗体的影响，并且一组不依赖于SRP的信号肽携带蛋白PsbX、PsbW和PsbY的插入同样完全不受影响。此外，蛋白酶K能够完全降解Alb3，但这种处理不影响这些蛋白质的插入。在这里研究的类囊体蛋白，白蛋白3的要求严格相关的基质因子和核苷三磷酸的要求。然而，大多数测试的蛋白质不需要Alb3或任何其他已知形式的易位装置。
The homologous proteins Oxa1, YidC, and Alb3 mediate the insertion of membrane proteins in mitochondria, bacteria, and chloroplast thylakoids, respectively. Depletion of YidC inEscherichia coli affects the integration of every membrane protein studied, and Alb3 has been shown previously to be required for the insertion of a signal recognition particle (SRP)-dependent protein, Lhcb1, in thylakoids. In this study we have analyzed the “global” role of Alb3 in the insertion of thylakoid membrane proteins. We show that insertion of two chlorophyll-binding proteins, Lhcb4.1 and Lhcb5, is almost totally blocked by preincubation of thylakoids with anti-Alb3 antibodies, indicating a requirement for Alb3 in the insertion pathway. Insertion of the related PsbS protein, on the other hand, is unaffected by Alb3 antibodies, and insertion of a group of SRP-independent, signal peptide-bearing proteins, PsbX, PsbW, and PsbY, is likewise completely unaffected. Proteinase K is furthermore able to completely degrade Alb3, but this treatment does not affect the insertion of these proteins. Among the thylakoid proteins studied here, Alb3 requirement correlates strictly with a requirement for stromal factors and nucleoside triphosphates. However, the majority of proteins tested do not require Alb3 or any other known form of translocation apparatus.