Manting E H, van Der Does C, Remigy H, Engel A, Driessen A J
Department of Microbiology, Groningen Biomolecular Sciences, Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
EMBO J. 2000 Mar 1;19(5):852-61. doi: 10.1093/emboj/19.5.852.
Translocase mediates preprotein translocation across the Escherichia coli inner membrane. It consists of the SecYEG integral membrane protein complex and the peripheral ATPase SecA. Here we show by functional assays, negative-stain electron microscopy and mass measurements with the scanning transmission microscope that SecA recruits SecYEG complexes to form the active translocation channel. The active assembly of SecYEG has a side length of 10.5 nm and exhibits an approximately 5 nm central cavity. The mass and structure of this SecYEG as well as the subunit stoichiometry of SecA and SecY in a soluble translocase-precursor complex reveal that translocase consists of the SecA homodimer and four SecYEG complexes.
转位酶介导前体蛋白穿过大肠杆菌内膜进行转位。它由SecYEG整合膜蛋白复合物和外周ATP酶SecA组成。在这里，我们通过功能测定、负染电子显微镜以及扫描透射显微镜的质量测量表明，SecA招募SecYEG复合物以形成活性转位通道。SecYEG的活性组装体边长为10.5纳米，并呈现出一个约5纳米的中央腔。这种SecYEG的质量和结构以及可溶性转位酶 - 前体复合物中SecA和SecY的亚基化学计量比表明，转位酶由SecA同型二聚体和四个SecYEG复合物组成。
