Iwata S, Lee J W, Okada K, Lee J K, Iwata M, Rasmussen B, Link T A, Ramaswamy S, Jap B K
Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA.
Science. 1998 Jul 3;281(5373):64-71. doi: 10.1126/science.281.5373.64.
Mitochondrial cytochrome bc1 complex performs two functions: It is a respiratory multienzyme complex and it recognizes a mitochondrial targeting presequence. Refined crystal structures of the 11-subunit bc1 complex from bovine heart reveal full views of this bifunctional enzyme. The "Rieske" iron-sulfur protein subunit shows significant conformational changes in different crystal forms, suggesting a new electron transport mechanism of the enzyme. The mitochondrial targeting presequence of the "Rieske" protein (subunit 9) is lodged between the two "core" subunits at the matrix side of the complex. These "core" subunits are related to the matrix processing peptidase, and the structure unveils how mitochondrial targeting presequences are recognized.
线粒体细胞色素bc1复合物具有两种功能：它是一种呼吸多酶复合物，并且能够识别线粒体靶向前序列。来自牛心的11亚基bc1复合物的精细晶体结构揭示了这种双功能酶的全貌。“里氏”铁硫蛋白亚基在不同晶体形式中显示出显著的构象变化，提示该酶存在一种新的电子传递机制。“里氏”蛋白（亚基9）的线粒体靶向前序列位于复合物基质侧的两个“核心”亚基之间。这些“核心”亚基与基质加工肽酶相关，该结构揭示了线粒体靶向前序列是如何被识别的。
