德国马克斯·普朗克生物物理研究所H. Michel和W. Kühlbrandt等研究人员合作报道了细菌呼吸链氧化酶的冷冻电镜结构。相关论文2019年10月4日发表在国际学术期刊《科学》上。

研究人员通过单颗粒冷冻电镜确定了2.7埃分辨率的大肠杆菌细胞色素bd-I氧化酶的结构。这个结构包含以前未知的辅助亚基CydH、L亚家族特异的Q环结构域、结构性泛醌8辅因子，一个被认为是双氧的活性位点密度、独特的充水质子通道以及导氧途径。与另一种细胞色素bd氧化酶的比较揭示了该家族的结构差异，包括高自旋血红素的重排和跨膜螺旋的构象适应以产生独特的氧结合位点。

据悉，在许多人类致病细菌中，细胞色素bd型喹诺醇氧化酶催化呼吸链中的分子氧还原为水。它们在结构上与线粒体细胞色素C氧化酶无关，因此是开发抗菌药物的主要目标。

附：英文原文

Title: Active site rearrangement and structural divergence in prokaryotic respiratory oxidases

Author: S. Safarian, A. Hahn, D. J. Mills, M. Radloff, M. L. Eisinger, A. Nikolaev, J. Meier-Credo, F. Melin, H. Miyoshi, R. B. Gennis, J. Sakamoto, J. D. Langer, P. Hellwig, W. Kühlbrandt, H. Michel

Issue&Volume: Volume 366 Issue 6461

Abstract: Cytochrome bd–type quinol oxidases catalyze the reduction of molecular oxygen to water in the respiratory chain of many human-pathogenic bacteria. They are structurally unrelated to mitochondrial cytochrome c oxidases and are therefore a prime target for the development of antimicrobial drugs. We determined the structure of the Escherichia coli cytochrome bd-I oxidase by single-particle cryo–electron microscopy to a resolution of 2.7 angstroms. Our structure contains a previously unknown accessory subunit CydH, the L-subfamily–specific Q-loop domain, a structural ubiquinone-8 cofactor, an active-site density interpreted as dioxygen, distinct water-filled proton channels, and an oxygen-conducting pathway. Comparison with another cytochrome bd oxidase reveals structural divergence in the family, including rearrangement of high-spin hemes and conformational adaption of a transmembrane helix to generate a distinct oxygen-binding site.

DOI: 10.1126/science.aay0967

Source: https://science.sciencemag.org/content/366/6461/100