Wenz Lena-Sophie, Ellenrieder Lars, Qiu Jian, Bohnert Maria, Zufall Nicole, van der Laan Martin, Pfanner Nikolaus, Wiedemann Nils, Becker Thomas
Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.
Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany Spemann Graduate School of Biology and Medicine, University of Freiburg, 79104 Freiburg, Germany.
J Cell Biol. 2015 Sep 28;210(7):1047-54. doi: 10.1083/jcb.201504119.
Biogenesis of mitochondrial β-barrel proteins requires two preprotein translocases, the general translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM). TOM and SAM form a supercomplex that promotes transfer of β-barrel precursors. The SAM core complex contains the channel protein Sam50, which cooperates with Sam35 in precursor recognition, and the peripheral membrane protein Sam37. The molecular function of Sam37 has been unknown. We report that Sam37 is crucial for formation of the TOM-SAM supercomplex. Sam37 interacts with the receptor domain of Tom22 on the cytosolic side of the mitochondrial outer membrane and links TOM and SAM complexes. Sam37 thus promotes efficient transfer of β-barrel precursors to the SAM complex. We conclude that Sam37 functions as a coupling factor of the translocase supercomplex of the mitochondrial outer membrane.
线粒体β-桶状蛋白的生物合成需要两种前体蛋白转运酶，即外膜通用转运酶（TOM）和分选与组装机器（SAM）。TOM和SAM形成一个促进β-桶状前体转移的超级复合物。SAM核心复合物包含通道蛋白Sam50，其在识别前体时与Sam35协同作用，以及外周膜蛋白Sam37。Sam37的分子功能一直未知。我们报告称，Sam37对于TOM-SAM超级复合物的形成至关重要。Sam37在线粒体外膜的胞质侧与Tom22的受体结构域相互作用，并连接TOM和SAM复合物。因此，Sam37促进β-桶状前体向SAM复合物的有效转移。我们得出结论，Sam37作为线粒体外膜转运酶超级复合物的偶联因子发挥作用。
