为了探究真核生物呼吸作用的功能和结构多样性，研究人员探索了四膜虫Tetrahymena thermophila（Tt）的呼吸链。在混合样品上使用冷冻电镜，研究人员解析了Tt-复合物I（CI）和Tt-CIII2（Tt-SC I+III2）之间的超级复合物的结构以及Tt-CIV2的结构。Tt-SC I+III2（约2.3 MDa）是一个弯曲的组合体，其结构和功能对称性被打破。Tt-CIV2是一个约2.7 MDa的二聚体，每个质体有超过52个亚单位，包括线粒体载体和一个TIM83-TIM133类似结构域。
研究人员对四膜虫呼吸链的结构和功能研究揭示了真核生物呼吸关键成分的分歧，扩大了人们对核心代谢的理解。
据悉，呼吸作用是一个核心的生物能量转换过程，其最后步骤是由线粒体内膜中的多亚单位复合体链完成的。
附：英文原文
Title: Structures of Tetrahymena’s respiratory chain reveal the diversity of eukaryotic core metabolism
Author: Long Zhou, María Maldonado, Abhilash Padavannil, Fei Guo, James A. Letts
Issue&Volume: 2022-04-01
Abstract: Respiration is a core biological energy-converting process whose last steps are carried out by a chain of multi-subunit complexes in the inner mitochondrial membrane. To probe the functional and structural diversity of eukaryotic respiration, we examined the respiratory chain of the ciliate Tetrahymena thermophila (Tt). Using cryo-electron microscopy on a mixed sample, we solved structures of a supercomplex between Tt-complex I (CI) and Tt-CIII2 (Tt-SC I+III2) and a structure of Tt-CIV2. Tt-SC I+III2 (~2.3 MDa) is a curved assembly with structural and functional symmetry breaking. Tt-CIV2 is a ~2.7 MDa dimer with over 52 subunits per protomer, including mitochondrial carriers and a TIM83-TIM133-like domain. Our structural and functional study of the T. thermophila respiratory chain reveals divergence in key components of eukaryotic respiration, expanding our understanding of core metabolism.
DOI: abn7747
Source: https://www.science.org/doi/10.1126/science.abn7747