Zhu Guoliang, Zeng Hui, Zhang Shuangbo, Juli Jana, Pang Xiaoyun, Hoffmann Jan, Zhang Yan, Morgner Nina, Zhu Yun, Peng Guohong, Michel Hartmut, Sun Fei
National Laboratory of Biomacromolecules, Institute of Biophysics (IBP), Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China.
University of Chinese Academy of Sciences, Beijing, 100101, China.
Angew Chem Int Ed Engl. 2020 Jan 2;59(1):343-351. doi: 10.1002/anie.201911554. Epub 2019 Nov 28.
Respiratory chain complexes convert energy by coupling electron flow to transmembrane proton translocation. Owing to a lack of atomic structures of cytochrome bc complex (Complex III) from thermophilic bacteria, little is known about the adaptations of this macromolecular machine to hyperthermophilic environments. In this study, we purified the cytochrome bc complex of Aquifex aeolicus, one of the most extreme thermophilic bacteria known, and determined its structure with and without an inhibitor at 3.3 Å resolution. Several residues unique for thermophilic bacteria were detected that provide additional stabilization for the structure. An extra transmembrane helix at the N-terminus of cyt. c was found to greatly enhance the interaction between cyt. b and cyt. c , and to bind a phospholipid molecule to stabilize the complex in the membrane. These results provide the structural basis for the hyperstability of the cytochrome bc complex in an extreme thermal environment.
呼吸链复合物通过将电子流与跨膜质子转运偶联来转换能量。由于缺乏嗜热细菌细胞色素bc复合物（复合物III）的原子结构，人们对这种大分子机器如何适应超嗜热环境知之甚少。在本研究中，我们纯化了已知的最极端嗜热细菌之一——嗜泉古菌的细胞色素bc复合物，并在有无抑制剂的情况下以3.3 Å分辨率测定了其结构。检测到了一些嗜热细菌特有的残基，这些残基为结构提供了额外的稳定性。发现细胞色素c N端的一个额外跨膜螺旋极大地增强了细胞色素b与细胞色素c之间的相互作用，并结合一个磷脂分子以稳定膜中的复合物。这些结果为细胞色素bc复合物在极端热环境中的超稳定性提供了结构基础。
