Glycolipozyme MPIase is essential for topology inversion of SecG during preprotein translocation
Glycolipozyme MPIase is essential for topology inversion of SecG during preprotein translocation
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糖脂酶 MPIase 对于前蛋白易位过程中 SecG 的拓扑反转至关重要
DOI：
10.1073/pnas.1303160110
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
K.
中科院分区：
文献类型：
--
作者：
Moser;M.;Nagamori;S.;Huber;M.;Tokuda;H.;Nishiyama;K.
分泌前蛋白通过蛋白传导通道如Sec61（真核生物）和SecYEG（细菌）跨生物膜转运。SecA是一种转位ATP酶，通过SecYEG将前蛋白推出并产生动态结构变化。SecG是SecYEG通道的一个亚基，具有两个跨膜段（transmembrane stretches，TM），经历拓扑结构反转和SecA依赖性易位。最近，我们的特点膜蛋白整合酶（MPIase），糖脂酶不仅参与蛋白质整合到膜，但也前蛋白易位。我们在这里报告说，SecG反转发生时，只有MPIase协会与SecYEG。我们还发现MPIase调节SecYEG的二聚体取向。半胱氨酸扫描诱变映射SecG TM 2相对亲水的环境。SecG的二聚体的形成，交联在TM 2，没有观察到SecG倒置，表明SecYEG经历了一个动态的结构变化，在前蛋白易位。
Presecretory proteins are translocated across biological membranes through protein-conducting channels such as Sec61 (eukaryotes) and SecYEG (bacteria). SecA, a translocation ATPase, pushes preproteins out with dynamic structural changes through SecYEG. SecG, a subunit of the SecYEG channel possessing two transmembrane stretches (TMs), undergoes topology inversion coupled with SecA-dependent translocation. Recently, we characterized membrane protein integrase (MPIase), a glycolipozyme involved in not only protein integration into membranes but also preprotein translocation. We report here that SecG inversion occurs only when MPIase associates with SecYEG. We also found that MPIase modulates the dimer orientation of SecYEG. Cysteine-scanning mutagenesis mapped SecG TM 2 to a relatively hydrophilic environment. The dimer formation of SecG, crosslinked at TM 2, was not observed on SecG inversion, indicating that SecYEG undergoes a dynamic structural change during preprotein translocation.