一个由信号输入控制的化学受体构造平衡.
Mikaila C Hoffman1, Mingshan Li2, Gerald L Hazelbauer2
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.
概括
细菌使用化学受体进行定向运动. 这项研究揭示了连接体结合和修饰改变受体几何,而不仅仅是切换状态,影响细菌化学反应信号.
科学领域:
- 微生物学 微生物学
- 生物化学 生化学
- 结构生物学 结构生物学
背景情况:
- 细菌通过化学反应 (chemotaxis) 导航化学梯度,这是一个由跨膜化学受体介导的过程.
- 化疗受体通过细胞膜发出信号,控制下游通路,并进行适应的修改.
- 目前的模型提出,化疗受体在基于连接体结合和修饰的基础上,在两个不同的信号状态 (激酶关闭和激酶启动) 之间切换.
研究的目的:
- 为了研究大肠杆菌 (Escherichia coli) 的阿斯巴酸化学受体Tar. Tar的结构平衡.
- 确定连接体占用和适应性修饰如何影响这种平衡.
- 澄清细菌化学反应中的跨膜信号的结构基础.
主要方法:
- 单分子福斯特共振能量转移 (smFRET) 用于监测螺旋分离.
- 测量重点是Tar受体的细胞质四螺旋绕的卷轴捆.
- 在各种条件下分析了对联体占用和适应性修饰的合规变化.
主要成果:
- 在所有条件下,在每个螺旋对中观察到两个明显的螺旋分离,相对占用率不同.
- 连接物占用使捆从对称转移到形包装.
- 适应性修改影响了哪个螺旋对在形包装中占据了中心位置.
结论:
- 化学受体信号涉及结构平衡的动态变化,而不是简单的两种状态开关.
- 连接物结合改变了四螺旋束的集体几何,影响了信号传输.
- 这些发现为跨膜受体功能提供了新的见解,并可能适用于其他受体系统.
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