一个SET域蛋白甲基转移酶的结构和催化机制
Raymond C Trievel1, Bridgette M Beach, Lynnette M A Dirk
1Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Cell
|October 10, 2002
概括
研究人员阐明了Rubisco大亚单元甲基转移酶的结构,揭示了它如何甲基化蛋白质. 这种甲基化过程对于基因调节和植物新陈代谢至关重要.
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:
- 蛋白质氨酸甲基化,由SET域酶催化,在各种生物过程中发挥关键作用,包括染色质结构,基因沉默,转录激活和植物代谢.
- 了解这些酶的结构基础对于破译它们的调节机制至关重要.
研究的目的:
- 为了确定Rubisco大亚单元甲基转移酶的高分辨率结构.
- 阐明这种酶的甲基转移和基质识别机制.
主要方法:
- 采用X射线晶体学,获得了2.6A分辨率的结构.
- 对于涉及S-adenosylhomocysteine和HEPES离子的伪双基质复合物,确定了结构.
主要成果:
- 该结构显示了SET域的全β架构,集成在一个更大的alpha-helical酶折叠中.
- 在SET域内保留的区域形成了S-adenosylmethionine和基质lysine的两个不同的结合点,由一个孔连接在一起.
- 建议在狭孔处保存的氨酸残留物催化甲基转移.
- 辅助因子 (S-adenosylmethionine) 通过一个"后门"机制进入活性部位,与基质结合部位不同.
结论:
- 结构洞察力为Rubisco大亚单元甲基转移酶活性提供了机械的理解.
- 该酶的结构促进了高度特定的蛋白质识别和多个甲基组添加的潜力.
- 这项研究有助于更广泛地了解蛋白质甲基化及其在生物系统中的调节作用.
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