Activation and desensitization of heat-sensor TRPV1

项目摘要 热激活和辣椒素激活的离子通道TRPV1是一种重要的细胞传感器 正常的体温和检测有毒的环境，因此是重要的药物靶标。 TRPV1也是理解不同TRP多模式激活的原型模型 频道。用低温电子显微镜(CERO-EM)测定了TRPV1的结构，最高温度为2.9℃。 然而，对通道激活的机械性理解，特别是热激活，仍然存在 初步的。一个主要的限制是缺乏有效的工具来探测结构动力学 功能通道。我们最近从蛇毒中鉴定出两种结构上相关的多肽毒素 中国红头蜈蚣，命名为RhTx1和RhTx2，表现出高度特异性和亚μM 与TRPV1的外孔区的亲和结合。有趣的是，虽然RhTx1强烈激活了 通道，RhTx2，在其N端只有四个额外的氨基酸，是一个强有力的抑制剂。我们的 初步研究进一步表明RhTx1特异性地促进热激活。因为这些 小而紧凑的多肽毒素可以很容易地合成和修饰，它们提供了独特的机会 探讨TRPV1激活的分子机制及其快速开关动力学 特别有利于生物物理研究。拟议的研究将利用 这些新的毒素通过揭示TRPV1的激活机制来更好地了解它的激活机制 使用多学科方法的结构动力学结合了结构、电生理、 光学和计算建模方法。

Project Summary Heat- and capsaicin-activated ion channel TRPV1 is an important cellular sensor for maintaining normal body temperature and detecting noxious ambient environment, hence an important drug target. TRPV1 also serves as a prototypical model for understanding polymodal activation of diverse TRP channels. Structures of TRPV1 have been solved by cryo-electron microscopy (cyro-EM) at up-to-2.9- Å resolutions, yet mechanistic understanding of channel activation, in particular by heat, remains preliminary. A major limitation has been the lack of effective tools for probing structural dynamics in functional channels. We have recently identified two structurally related peptide toxins from the venom of Chinese red-headed centipede, termed RhTx1 and RhTx2, that exhibit highly specific and sub-μM affinity binding to the outer pore region of TRPV1. Interestingly, while RhTx1 strongly activates the channel, RhTx2, having just four additional amino acids at its N-terminus, is a potent inhibitor. Our preliminary study further suggested that RhTx1 specifically promotes heat activation. Because these small, compact peptide toxins can be readily synthesized and modified, they offer unique opportunities to probe the molecular mechanism underlying TRPV1 activation, with their rapid ON and OFF kinetics being particularly favorable for biophysical investigation. The proposed study will take advantage of these novel toxins to gain a better understanding of TRPV1 activation mechanism by revealing its structural dynamics using a multidisciplinary approach combines structural, electrophysiological, optical, and computational modeling methods.