不对称的ClpX六合体的结构揭示了AAA+蛋白展开机器中的核酸依赖运动
Steven E Glynn1, Andreas Martin, Andrew R Nager
1Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Cell
|November 17, 2009
概括
蛋白质展开机器ClpX在结合ATP时在其环结构中表现出不对称性. 这种不对称性对于其在蛋白质加工和ATPase循环期间机械工作中的功能至关重要.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 结构生物学 结构生物学
背景情况:
- ClpX是一个AAA+机器,通过展开蛋白质并将其转移到ClpP酶中,对蛋白质降解至关重要.
- 了解ClpX的结构动态是阐明其作用机制的关键.
研究的目的:
- 为了确定无核酸和核酸结合的ClpX的高分辨率晶体结构.
- 阐明ClpX机械功能的结构基础和由ATP驱动的结构变化.
主要方法:
- 进行X射线晶体学,以在不同核酸结合状态下获得ClpX的结构.
- 分析结构差异,以了解形状变化及其功能影响.
主要成果:
- 揭示了依赖于核酸结合的ClpX六次环中的惊人的不对称性.
- 在个别子单位的AAA+域之间发现了很大的旋转变化,导致了分阶排列.
- 证明了一种合ATP结合/水解以改变环形状的机制.
结论:
- 观察到的不对称性为ClpX的蛋白质展开和转位功能提供了结构基础.
- 这些发现解释了之前的溶液研究,并预测了多转位期间孔隙弹性的机制.
- 建议在AAA+机器中将形状变化与机械工作相合的一般机制.
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