一个更接近封闭的环:ES3基甲基双合成酶中间体的晶体结构
Helene J Bustad1, Marthe S Christie1, Mikko Laitaoja2
1Norwegian Porphyria Centre (NAPOS), Department for Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway.
The FEBS journal
|October 20, 2023
概括
基甲基双合成酶 (HMBS) 突变通过改变酶中间体而影响血生物合成. Arg167影响延长,而Arg195影响产品释放,提供了对急性间歇性皮症的见解.
科学领域:
- 生物化学 生化学
- 酶学 是一种酶学.
- 分子生物学分子生物学
背景情况:
- 基甲基比兰合成酶 (HMBS) 对于血红素生物合成至关重要,催化了基比伦素 (PBG) 单元的顺序添加.
- 该酶在合成四氧化产物1-基甲基比兰的过程中形成稳定中间体 (ESn).
研究的目的:
- 调查HMBS的催化机制和与急性间歇性病 (AIP) 相关的突变的影响.
- 阐明中间积累和产品释放的结构基础.
主要方法:
- 原生PAGE和质谱法用于分析酶中间体.
- 动力参数的确定.
- 介质ES3的X射线晶体学 (PDB: 8PND).
- 位点定向的突变发生.
主要成果:
- 与AIP相关的HMBS变异p.Arg167Gln显示ES3积累增加,表明延伸受损.
- 结构分析显示,聚烯延伸通过中间烯位点3 (IPS3) 发生.
- 这种p.Arg195Cys变体累积了ES4,表明产品水解受阻.
- 在IPS3附近的残留物涉及到六甲的水解.
结论:
- 167对于HMBS延长步骤和催化速率至关重要,而195对于产品释放至关重要.
- 对于完全保留的六甲可能存在于IPS3附近的新型水解部位.
- 了解这些机制,可以了解AIP的病原性.
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