STRUCTURAL STUDIES OF MULTIDRUG BINDING AND TRANSCRIPTION ACTIVATION BY BMRR

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心机构，不一定为研究者机构。随着越来越多的人类病原体对现有治疗方法产生耐药性，细菌多药耐药性（mdr）对人类健康构成了严重威胁。多药耐药的机制之一是通过多药外排转运蛋白将有毒化合物从细胞中排出。这些膜蛋白已被证明可以结合并流出各种各样的结构和化学上不同的化合物。这些转运蛋白如何识别和清除药物的分子细节尚未完全了解，部分原因是与纯化和结晶内在膜蛋白相关的困难。然而，越来越多的蛋白质已被确定为调节多药转运蛋白的表达，以响应转运蛋白挤出的相同毒性化合物。这些转录调节因子更适合于结构和生物化学研究，因为它们是可溶性的胞质蛋白，可以更容易地纯化，并且其量是结构和生物化学研究所必需的。来自枯草芽孢杆菌的一种这样的转录调节因子BmrR（细菌多药耐药性调节因子）通过结合大量结构上不同的亲脂性阳离子化合物（其中许多是Bmr的底物）来激活bmr多药转运蛋白基因的转录。在没有药物的情况下，BmrR保持与bmr启动子结合，并作为抗激活剂发挥作用。结合不同诱导分子的BmrR-DNA的结构研究沿着与多药物结合口袋突变体的结构将有助于阐明BmrR可以识别多种结构不同的药物的原理。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Bacterial multidrug resistance (mdr) presents a serious health risk as an increasing number of human pathogens are showing resistance to currently available treatments. One mechanism of mdr involves export of toxic compounds from the cell by multidrug efflux transporters. These membrane proteins have been shown to bind to and efflux a diverse array of structurally and chemically dissimilar compounds. The molecular details of how these transporters recognize and expunge drugs is not fully understood, in part due to the difficulty associated with purifying and crystallizing intrinsic membrane proteins. However, a growing number of proteins have been identified that regulate the expression of multidrug transporters in response to the same toxic compounds that the transporters extrude. These transcriptional regulators are much more amenable to structural and biochemical studies as they are soluble, cytosolic proteins which can be purified more easily and in the quantities that are necessary for structural and biochemical studies. One such transcriptional regulator from Bacillus subtilis, BmrR (bacterial multidrug resistance regulator), activates transcription of the bmr multidrug transporter gene by binding to a plethora of structurally dissimilar lipophilic cationic compounds, many of which are substrates of Bmr. In the absence of drug, BmrR remains bound to the bmr promoter and functions as an anti-activator. Structural studies of BmrR-DNA bound to different inducer molecules along with structures of multidrug binding pocket mutants will help to elucidate the principles by which BmrR can recognize multiple structurally dissimilar drugs.