OPEN STATE STRUCTURE OF THE GATED MECHANOSENSOR MSCL

拟议研究的目标是表征一种开放（导电）形式的机械敏感通道MscL。我们将采用几种方法，包括定向自旋标记，二硫扫描和x射线晶体学来阐明该离子通道的开放态结构和激活机制。机械敏感通道在系统发育树的所有基本分支中都被发现，并且在人类的多种组织类型中都被观察到。目前有很大比例的药物是针对离子通道的，然而这些通道如何打开和关闭（门控）的机制仍然未知。最近对封闭构象的机械敏感通道MscL的结构测定提供了这种普遍存在的蛋白质类的第一个高分辨率图像。MscL蛋白是目前唯一可用的系统，可以在高水平的结构分辨率下研究离子通道是如何门控的。为了帮助结晶，定向自旋标记和二硫扫描研究也将进行，以提供适合结晶的材料，即在开放状态下，以及确定更多关于通道门控的一般信息。

The goal of the proposed research is to characterize an open (conducting) form of the mechanosensitve channel MscL. We will employ a several approaches including site-directed spin labeling, disulfide scanning and X-ray crystallography to elucidate the open state structure and mechanism of activation of this ion channel. Mechanosensitive channels have been found in all basic branches of the phylogenetic tree, and have been observerved in multiple tissue types in humans. A large percentage of current pharmaceuticals are targeted to ion channels, yet the mechanism of how these channels are opened and closed (gated) remains unknown. The recent structural determination of the mechanosensitive channel MscL in a closed conformation provided the first high resolution picture of this ubiquitous class of protein. The MscL protein is currently the only available system with which to study, at a high level of structural resolution, how ion channels are gated. To aid in crystallization, site-directed spin labeling and disulfide scanning studies will also be performed to both provide materail suitable for crystallization, i.e. in an open state, as well as determine more general information on channel gating.