替代复合物III与细胞氧化酶的超复合物的结构
Chang Sun1,2, Samir Benlekbir3, Padmaja Venkatakrishnan1,4
1Department of Biochemistry, University of Illinois, Urbana, IL, USA.
Nature
|April 27, 2018
概括
替代性复合物III (ACIII) 是一种关键的细菌电子载体,首次在结构上进行了表征. 这项冷EM研究揭示了其独特的结构和功能超级复合物与细胞染色体c氧化酶.
科学领域:
- 生物化学
- 结构生物学
- 微生物学
背景情况:
- 替代复合物III (ACIII) 对于细菌电子传输至关重要,但缺乏结构数据.
- ACIII与复合物III (bc1复合物) 共享功能,但具有不同的结构.
- ACIII子单元与复杂的铁硫酶 (CISM) 超级家族具有同质性.
研究的目的:
- 来确定来自Flavobacterium johnsoniae的ACIII的高分辨率结构.
- 研究ACIII功能的结构基础及其与细胞染色体c氧化酶的超复杂形成.
- 阐明在ACIII中脂质固子单元和翻译后修改的结构作用.
主要方法:
- 使用 styrene maleic 酸共聚物分离 ACIII 和其超级复合物.
- 低温电子显微镜 (cryo-EM) 用于以3.4 Å分辨率进行结构测定.
- 原子模型构建ACIII的六个子单元和超级复杂的建模.
主要成果:
- ACIII的3.4 Å冷-EM结构显示了6个含有 [3Fe-4S], [4Fe-4S] 集群的子单元和6个heme c单元.
- 在ACIII中使用已知的电子传输元素.
- 相关的a3细胞在结构上被修改为超复合体,突出显示功能整合.
- 将两个子单元固定在脂质双层上的N端三化半氨酸残留物在结构上被分解.
结论:
- 这种结构为ACIII独特的架构和机制提供了前所未有的洞察力.
- 具有cytaaa3的功能超复合体形成得到了结构性的支持,强调其在电子传输中的重要性.
- 该结构揭示了 prokaryotes 中膜蛋白固的关键翻译后修饰.
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