Mapping of the Saccharomyces cerevisiae Oxa1-Mitochondrial Ribosome Interface and Identification of MrpL40, a Ribosomal Protein in Close Proximity to Oxa1 and Critical for Oxidative Phosphorylation Complex Assembly
Mapping of the Saccharomyces cerevisiae Oxa1-Mitochondrial Ribosome Interface and Identification of MrpL40, a Ribosomal Protein in Close Proximity to Oxa1 and Critical for Oxidative Phosphorylation Complex Assembly
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DOI：
10.1128/ec.00219-09
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发表时间：
2009-11-01
期刊：
影响因子：
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通讯作者：
Stuart, Rosemary A.
中科院分区：
文献类型：
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作者：
Jia, Lixia;Kaur, Jasvinder;Stuart, Rosemary A.
Oxa1蛋白在促进新生多肽链共翻译插入线粒体内膜中起核心作用。线粒体编码的蛋白质是在基质定位的核糖体上合成的，核糖体与内膜相连，并与Oxa1蛋白物理结合。在本研究中，我们使用化学交联方法绘制了酿酒酵母Oxa1-核糖体界面，我们在这里证明了Oxa1和大核糖体亚基蛋白MrpL40的密切关联。也提供了证据表明MrpL40与另一个大型核糖体蛋白Mrp20/L23蛋白之间存在密切的物理和功能关系。MrpL40与细菌核糖体蛋白L24具有相同的序列特征，与Mrp20/L23一样，已知其位于核糖体多肽出口位点附近。因此，我们认为MrpL40代表酿酒酵母L24同源物。MrpL40，像许多线粒体核糖体蛋白一样，包含一个c端延伸区，与细菌的对应物没有相似性。我们发现，这个c端线粒体特异性区域对于MrpL40支持线粒体编码蛋白的正确补体的合成及其随后组装成氧化磷酸化复合物的能力很重要。
The Oxa1 protein plays a central role in facilitating the cotranslational insertion of the nascent polypeptide chains into the mitochondrial inner membrane. Mitochondrially encoded proteins are synthesized on matrix-localized ribosomes which are tethered to the inner membrane and in physical association with the Oxa1 protein. In the present study we used a chemical cross-linking approach to map the Saccharomyces cerevisiae Oxa1-ribosome interface, and we demonstrate here a close association of Oxa1 and the large ribosomal subunit protein, MrpL40. Evidence to indicate that a close physical and functional relationship exists between MrpL40 and another large ribosomal protein, the Mrp20/L23 protein, is also provided. MrpL40 shares sequence features with the bacterial ribosomal protein L24, which like Mrp20/L23 is known to be located adjacent to the ribosomal polypeptide exit site. We propose therefore that MrpL40 represents the Saccharomyces cerevisiae L24 homolog. MrpL40, like many mitochondrial ribosomal proteins, contains a C-terminal extension region that bears no similarity to the bacterial counterpart. We show that this C-terminal mitochondria-specific region is important for MrpL40's ability to support the synthesis of the correct complement of mitochondrially encoded proteins and their subsequent assembly into oxidative phosphorylation complexes.