科尔贝型脱碳酶的结构基础,由糖基基酶催化
Berta M Martins1, Martin Blaser, Mikolaj Feliks
1Institute für Biologie, Strukturbiologie/Biochemie, Humboldt-Universität zu Berlin, D-10115 Berlin, Germany. berta.martins@biologie.hu-berlin.de
Journal of the American Chemical Society
|August 10, 2011
概括
对4-基酸乙酸脱碳酶的结构洞察力揭示了p-cresol形成的新机制,这是Clostridium difficile中的毒性因子. 这种糖基酶利用一种独特的基质结合模式来发酵氨酸.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 酶学 是一种酶学.
背景情况:
- 4-Hydroxyphenylacetate脱碳酶是一种糖基酶酶,对克洛斯特里迪亚的铁酸发酵至关重要.
- 它的产物p-cresol是一种已知的毒性因子,与致病原体Clostridium difficile有关.
研究的目的:
- 为了阐明4-基乙酸脱碳酶活性的结构基础.
- 了解由这种酶催化的p-cresol形成的机制.
主要方法:
- 采用X射线晶体学,以高分辨率 (1.75和1.81 Å) 来确定来自Clostridium scatologenes的无基质和基质结合的4-基酸乙酸脱碳酶的结构.
- 结构分析的重点是酶的四级结构, [4Fe-4S] 集群的作用和基质-活性位点相互作用.
主要成果:
- 该酶形成一个 (βγ) ((4) 四基聚合物,其中催化β子单元和含有两个 [4Fe-4S] 集群的γ子单元.
- γ子单元的域结构类似于高潜力铁硫蛋白,通过histidine和cysteine残留物协调集群.
- 与之前的假设相反,基质通过其碳素基团与活性部位的氨酸 (Cys503) 结合,而氧基团则被其他残留物定,这表明Kolbe型脱碳化.
结论:
- 确定的结构提供了对4-基酸乙酸脱碳酶活性位点及其基质结合模式的详细视图.
- 这些发现表明了p-cresol形成的修订机制,涉及Kolbe型脱碳氧化.
- 这项研究提供了关于Clostridium difficile毒性机制的见解,以及治疗干预的潜在目标.
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