Abe Y, Shodai T, Muto T, Mihara K, Torii H, Nishikawa S, Endo T, Kohda D
Department of Structural Biology, Biomolecular Engineering Research Institute, Suita, Osaka, Japan.
Cell. 2000 Mar 3;100(5):551-60. doi: 10.1016/s0092-8674(00)80691-1.
Most mitochondrial proteins are synthesized in the cytosol as precursor proteins with a cleavable N-terminal presequence and are imported into mitochondria. We report here the NMR structure of a general import receptor, rat Tom20, in a complex with a presequence peptide derived from rat aldehyde dehydrogenase. The cytosolic domain of Tom20 forms an all alpha-helical structure with a groove to accommodate the presequence peptide. The bound presequence forms an amphiphilic helical structure with hydrophobic leucines aligned on one side to interact with a hydrophobic patch in the Tom20 groove. Although the positive charges of the presequence are essential for import ability, presequence binding to Tom20 is mediated mainly by hydrophobic rather than ionic interactions.
大多数线粒体蛋白在细胞质中以前体蛋白的形式合成，这些前体蛋白带有可裂解的N端前导序列，并被导入线粒体。我们在此报告一种通用导入受体——大鼠Tom20与源自大鼠醛脱氢酶的前导序列肽形成复合物的核磁共振结构。Tom20的胞质结构域形成一个全α螺旋结构，带有一个用于容纳前导序列肽的凹槽。结合的前导序列形成一个两亲性螺旋结构，疏水亮氨酸排列在一侧，与Tom20凹槽中的疏水区域相互作用。尽管前导序列的正电荷对于导入能力至关重要，但前导序列与Tom20的结合主要由疏水相互作用而非离子相互作用介导。
