来自无氧光热细菌Chloroflexus aurantiacus的与HQNO结合的替代复合物III的冷-EM结构
Jiyu Xin1,2, Zhenzhen Min1,2, Lu Yu3
1Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou 311121, China.
The Plant cell
|February 1, 2024
概括
替代性复合物III (ACIII) 替代了细菌电子运输链中的必需酶. 化EM结构显示了CaACIIIp的存在.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 微生物学 微生物学
背景情况:
- 替代复合物III (ACIII) 在功能上与细菌电子运输链 (ETC) 中的细胞染色体bc1/b6f复合物相似.
- ACIII的精确组成,结构和功能仍然不完全理解.
- 在细菌能量保存和新陈代谢中,ACIII起着至关重要的作用.
研究的目的:
- 为了确定来自Chloroflexus aurantiacus (CaACIIIp) 的光合作用ACIII的高分辨率结构.
- 阐明CaACIIIp.中menaquinol氧化和电子转移的结构基础.
- 了解新型子单位和结构特征在ACIII功能和稳定性中的作用.
主要方法:
- 低温电子显微镜 (cryo-EM) 用于结构的确定.
- 频谱电化学和电子磁共振 (EPR) 为机械的洞察力.
- 酶分析和分子动力学 (MD) 模拟用于功能分析.
主要成果:
- 确定了CaACIIIp在Apo和Menadiol类似结合形式中的冷-EM结构.
- 识别并解决了两种以前未被描述的亚单元,ActG和ActI的构造,有助于复杂的稳定性.
- 阐明了从menaquinol氧化通过 [3Fe-4S] 集群和环向周等离子接受器的电子转移途径.
- 在ActE中发现了一个独特的插入循环,负责下游电子受体结合特异性.
结论:
- 这项研究为光合作用ACIII提供了前所未有的结构细节,揭示了其子单元组成和结构.
- 这些发现澄清了menaquinol氧化和电子转移的机制,突出了特定子单元和辅助因子的作用.
- 这项工作扩大了对ACIII结构多样性和进化的理解,为细菌能量保存机制提供了洞察力.
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