Structural dynamics of peptide-translocating ABC transporters

蛋白质跨膜输出是生命的关键过程。在原核生物中，多种蛋白质 运输系统的进化促进了两亲性和亲水性蛋白质的转移。 跨越脂质疏水屏障的令人印象深刻的尺寸。这些系统中最简单的包括 一种三磷酸腺苷结合盒(ABC)运输器，它利用三磷酸腺苷水解的能量来 为货运肽或蛋白质在细胞膜上的移动提供动力。革兰氏阳性 细菌，ABC转运蛋白输出抗菌肽或群体感应多肽 使生物体在有限的资源条件下具有生存优势。《长河》 本申请的术语目标是阐明含肽酶的构象动力学 ABC转运体(PCAT)，它利用内置的半胱氨酸蛋白酶结构域来切割信号 出口前货物多肽的序列。我们战略的前提是1) 最近的PCAT的高分辨结构，定义了它们的分子结构并设置了 详细研究这些转运蛋白启用蛋白质的机制的阶段 2)PI在最新电子应用中的跟踪记录 顺磁共振(EPR)波谱结合诱变分析活性 传送者。这些具体目标旨在解决该领域尚未解答的问题。 包括以ATP周转为动力的交替接入的结构基础、决定因素 货物蛋白的专一性，以及货物蛋白的结构和环境 通过传送器进行转换。在过去的十年中，我们的方法与 分子模拟在揭示多种药物的结构动力学方面发挥了重要作用。 ABC出口商，并提供了对这个家族内部机械多样性的洞察。这个 拟议的研究的意义来自于位于 抗菌肽转运、细菌免疫和代表生物化学的基础 蛋白质跨脂双分子层输出的过程。

Protein export across membranes is a critical process for life. In prokaryotes, multiple protein transport systems were evolved to facilitate the transfer of amphipathic and hydrophilic proteins of impressive sizes across lipid hydrophobic barriers. The simplest of these systems consist of an ATP binding Cassette (ABC) transporter which harnesses the energy of ATP hydrolysis to power the movement of cargo peptides or proteins across the cell membranes. In gram positive bacteria, ABC transporters export antimicrobial or quorum sensing peptides which serve to endow the organism with survival advantages under conditions of limited resources. The long term goal of this application is to illuminate the conformational dynamics of peptidase-containing ABC transporters (PCATs) which utilizes a built in cysteine protease domain to cleave the signal sequence of the cargo peptide prior to export. The premise of our strategy is grounded in 1) recent high resolution structures of PCATs that define their molecular architecture and set the stage for detailed investigation of the mechanism by which these transporters enable protein translocation and 2) the track record of the PI in the application of state of the art electron paramagnetic resonance (EPR) spectroscopy in conjunction with mutagenic analysis to active transporters. The specific aims are designed to address unanswered questions in the field including the structural basis of alternating access powered by ATP turnover, the determinants of cargo protein specificity, and the structure and environment of the cargo protein as it transitions through the transporter. Over the last decade, our approach integrated with molecular modeling has been instrumental in revealing the structural dynamics of multidrug ABC exporters and providing insight into the mechanistic diversity within this family. The significance of the proposed research stems from a molecular target at the junction of antibacterial peptide transport, bacterial immunity and represents a fundamental biochemical process by which proteins are exported across lipid bilayers.