使用一种共同的催化机制,对 (βα) 8-桶折叠甲-四二氨基缩酶的突变和结构研究
Manuel Gehl1, Ulrike Demmer2, Ulrich Ermler2
1Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
概括
这项研究揭示了一种常见的甲-四二氨酸减少酶的催化机制,尽管其序列相同性较低,但这表明了趋同的进化. 结构和突变分析阐明了这些C1代谢酶的关键中间体和进化途径.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 分子进化分子进化
背景情况:
- 甲四二还原酶对于单碳 (C1) 代谢至关重要,利用各种辅助因子和机制.
- 虽然MTHFR的结构和机制是已知的,但F420依赖的甲四甲二二二二 (甲-H4MPT) 减少酶 (Mer) 和flavin独立的甲四二酸盐 (甲-H4F) 减少酶 (Mfr) 的结构和机制仍然没有被描述.
- 了解这些还原酶对于理解C1代谢途径至关重要.
研究的目的:
- 为了阐明来自Methanocaldococcus jannaschii (jMer) 的Mer的结构和催化机制.
- 为了研究Mer,Mfr和MTHFR之间的进化关系.
- 为了识别不同的甲四二降解酶中保存的催化特征和中间体.
主要方法:
- 异质的生产和结晶的jMer.
- 确定jMer的晶体结构,有或没有F420.
- 使用现有的MTHFR结构数据建模一个jMer三元复合体.
- 在jMer中关键氨基酸残留物的位点定向突变发生.
- 减少酶家族的遗传学分析.
主要成果:
- 确定了与F420复合的jMer的晶体结构,使三元复合模型成为可能.
- 突变分析揭示了保存的功能性氨基酸和一个常见的催化机制,其中包括一个5 - 微离子中间体.
- 结构,突变和遗传学数据强烈支持这些还原酶的融合进化路径.
结论:
- 一个保存的催化机制,包括一个质子化5-中间体,存在于Mer,Mfr和MTHFR.
- 融合进化是这些减少酶发展的最可能的场景.
- 这项研究为C1代谢中的结构和机制多样性提供了关键的见解.
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