概括
硫利用因子 (SUF) 路径.
科学领域:
- 生物地质化学生物地质化学
- 分子进化分子进化
- 生物化学 生物化学
背景情况:
- 大氧化事件 (GOE) 显著影响了早期生命,导致许多无氧微生物的灭绝.
- 铁硫 (Fe-S) 集群是所有生命形式的重要辅助因子,但它们适应不断增加的氧气水平的理解仍然不充分.
- 硫利用因子 (SUF) 途径是Fe-S集群生物发生的主要途径.
研究的目的:
- 为了研究SUF通路的分子适应,特别是SufE蛋白,在地球历史上氧气水平上升.
- 阐明SufE及其伴侣SufS在应对大氧化事件的进化轨迹.
- 了解SufE在氧化应激下弹性的生化和结构基础.
主要方法:
- 分子时钟的约会确定了SufE和SufS的进化时间表.
- 祖先 SufS/SufE 复合物的重建和生物化学分析.
- 使用大肠杆菌*突变的细菌生长实验.
- 酶结构预测分析.
主要成果:
- SufE起源于大约2670亿年前 (Ga),并在GOE (~2.14 Ga) 附近多样化.
- 祖先的SufS/SufE复合体表现出增加的氧气耐受性,GOE版本在高O2度下活跃,高于它们的最后共同祖先 (LCA) 对应物.
- 过度生产GOE SufE或SufS/SufE比LCA版本更有效地增强了对氧敏感*大肠杆菌*突变体的生长.
- 结构分析表明,在关键催化位点的氨基酸替代使适应成为可能.
结论:
- SufE蛋白进化了分子机制,以在氧化应激下维持功能,在大氧化事件期间促进Fe-S集群组装.
- 这些适应性为生命适应地球历史上波动的氧化还原条件提供了至关重要的弹性.
- 这项研究揭示了生物圈和地球圈在对氧气水平上升的反应中共同演变的分子基础.
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