Catalytic Reactions and Energy Conservation in the Cytochrome bc1 and b6f Complexes of Energy-Transducing Membranes,Chemical Reviews

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Catalytic Reactions and Energy Conservation in the Cytochrome bc1 and b6f Complexes of Energy-Transducing Membranes
Chemical Reviews ( IF 51.4 ) Pub Date : 2021-01-19 , DOI: 10.1021/acs.chemrev.0c00712
Marcin Sarewicz ₁ , Sebastian Pintscher ₁ , Rafał Pietras ₁ , Arkadiusz Borek ₁ , Łukasz Bujnowicz ₁ , Guy Hanke ₂ , William A Cramer ₃ , Giovanni Finazzi ₄ , Artur Osyczka ₁

Affiliation

This review focuses on key components of respiratory and photosynthetic energy-transduction systems: the cytochrome bc₁ and b₆f (Cytbc₁/b₆f) membranous multisubunit homodimeric complexes. These remarkable molecular machines catalyze electron transfer from membranous quinones to water-soluble electron carriers (such as cytochromes c or plastocyanin), coupling electron flow to proton translocation across the energy-transducing membrane and contributing to the generation of a transmembrane electrochemical potential gradient, which powers cellular metabolism in the majority of living organisms. Cytsbc₁/b₆f share many similarities but also have significant differences. While decades of research have provided extensive knowledge on these enzymes, several important aspects of their molecular mechanisms remain to be elucidated. We summarize a broad range of structural, mechanistic, and physiological aspects required for function of Cytbc₁/b₆f, combining textbook fundamentals with new intriguing concepts that have emerged from more recent studies. The discussion covers but is not limited to (i) mechanisms of energy-conserving bifurcation of electron pathway and energy-wasting superoxide generation at the quinol oxidation site, (ii) the mechanism by which semiquinone is stabilized at the quinone reduction site, (iii) interactions with substrates and specific inhibitors, (iv) intermonomer electron transfer and the role of a dimeric complex, and (v) higher levels of organization and regulation that involve Cytsbc₁/b₆f. In addressing these topics, we point out existing uncertainties and controversies, which, as suggested, will drive further research in this field.

中文翻译：

能量转导膜细胞色素 bc1 和 b6f 复合物的催化反应和能量守恒

本综述重点关注呼吸和光合能量传导系统的关键组成部分：细胞色素bc ₁和b ₆ f (Cyt bc ₁ / b ₆ f ) 膜多亚基同二聚体复合物。这些非凡的分子机器催化电子从膜醌转移到水溶性电子载体（例如细胞色素c或质体蓝素），将电子流与穿过能量转换膜的质子易位耦合，并有助于产生跨膜电化学势梯度，为大多数生物体的细胞新陈代谢提供动力。 Cyts bc ₁ / b ₆ f有许多相似之处，但也有显着差异。尽管数十年的研究提供了关于这些酶的广泛知识，但其分子机制的几个重要方面仍有待阐明。我们总结了 Cyt bc ₁ / b ₆ f功能所需的广泛结构、机制和生理方面，将教科书基础知识与最近研究中出现的新的有趣概念相结合。讨论涵盖但不限于（i）电子途径的节能分叉机制和对苯二酚氧化位点产生浪费能量的超氧化物的机制，（ii）半醌在醌还原位点稳定的机制，（iii） ) 与底物和特定抑制剂的相互作用，(iv) 单体间电子转移和二聚体复合物的作用，以及 (v) 涉及 Cyts bc ₁ / b ₆ f的更高水平的组织和调节。在讨论这些主题时，我们指出了现有的不确定性和争议，正如所建议的那样，这将推动该领域的进一步研究。

更新日期：2021-02-24

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