Department of Structural Biology, Max-Planck-Institute of Biophysics, Frankfurt 60438, Germany.
Department of Structural Biology, Institute of Physical and Theoretical Chemistry, Goethe University of Frankfurt, Frankfurt 60439, Germany.
Proc Natl Acad Sci U S A. 2023 Aug 22;120(34):e2301447120. doi: 10.1073/pnas.2301447120. Epub 2023 Aug 14.
The TOM complex is the main entry point for precursor proteins (preproteins) into mitochondria. Preproteins containing targeting sequences are recognized by the TOM complex and imported into mitochondria. We have determined the structure of the TOM core complex from by single-particle electron cryomicroscopy at 3.3 Å resolution, showing its interaction with a bound preprotein at 4 Å resolution, and of the TOM holo complex including the Tom20 receptor at 6 to 7 Å resolution. TOM is a transmembrane complex consisting of two β-barrels, three receptor subunits, and three short transmembrane subunits. Tom20 has a transmembrane helix and a receptor domain on the cytoplasmic side. We propose that Tom20 acts as a dynamic gatekeeper, guiding preproteins into the pores of the TOM complex. We analyze the interactions of Tom20 with other TOM subunits, present insights into the structure of the TOM holo complex, and suggest a translocation mechanism.
TOM 复合物是前体蛋白（preprotein）进入线粒体的主要入口。含有靶向序列的前体蛋白被 TOM 复合物识别并导入线粒体。我们通过单颗粒电子 cryomicroscopy 在 3.3 Å 的分辨率下确定了来自 的 TOM 核心复合物的结构，显示了其与结合的前体蛋白在 4 Å 的分辨率下的相互作用，以及包括 Tom20 受体的 TOM 整体复合物在 6 到 7 Å 的分辨率下的结构。TOM 是一个由两个β桶、三个受体亚基和三个短跨膜亚基组成的跨膜复合物。Tom20 在细胞质侧有一个跨膜螺旋和一个受体结构域。我们提出 Tom20 作为一个动态的守门员，引导前体蛋白进入 TOM 复合物的孔道。我们分析了 Tom20 与其他 TOM 亚基的相互作用，深入了解了 TOM 整体复合物的结构，并提出了一种移位机制。
