Assembly of E.Coli Outer Membrane Proteins

描述(申请人提供)：蛋白质折叠和组装是中心生物过程，必须正确地发生，才能使所有活细胞正常运作。许多毁灭性的人类疾病，包括神经退行性阿尔茨海默病和普里恩病，都是蛋白质折叠和组装错乱的结果。相对大量的细胞活动致力于确保蛋白质的正确折叠和组装。在错误折叠的情况下，蛋白质被驱动到聚集和降解途径。错误折叠的蛋白质的降解至关重要，因为它们可能会形成有毒的聚集体，这可能会干扰正常的细胞功能。因此，最大限度地减少聚集(伴侣和折叠酶)或移除聚集体(蛋白酶)的组装因子是互补的细胞活动，受细胞蛋白质折叠状态的调节。 由于膜蛋白复杂的折叠行为，研究膜蛋白的组装一直是一项具有挑战性的任务。然而，最近许多膜蛋白的结构分辨率的爆炸性增长，包括本研究中的那些，重新推动了膜蛋白生物发生领域的发展。这项拟议的研究旨在了解大肠杆菌独特的OMP TolC的组装，该OMP折叠成新的三维结构。TolC蛋白具有多种重要的医学和生理功能，包括抗生素外排和毒素分泌。这项研究将确定和表征有助于TolC组装成由α-螺旋和β-链组成的三聚体桶的基因内和基因外因素。这些方面将通过利用遗传、分子和生化方法进行研究。现有数据表明，TolC遵循与迄今研究的所有其他OMP不同的组装路径，从而为揭示OMP靶向和组装的新原理提供了机会。

DESCRIPTION (provided by applicant): Protein folding and assembly are central biological processes that must occur correctly for the proper functioning of all living cells. Many devastating human diseases, including neurodegenerative Alzheimer and prion diseases, are the consequence of disarrayed protein folding and assembly. A relatively large amount of cellular activity is dedicated to ensure the correct folding and assembly of proteins. In the event of misfolding, proteins are driven to aggregation and degradation pathways. Degradation of misfolded proteins is crucial because they may form toxic aggregates, which can interfere with normal cellular functions. Assembly factors that minimize aggregation (chaperones and foldases) or remove aggregates (proteases) are therefore complementary cellular activities that are regulated in response to the protein-folding status of the cell. Studying the assembly of membrane proteins has been a challenging task owing to their complex folding behavior. However, a recent explosion in the structural resolution of many membrane proteins, including those included in this study, has given a renewed impetus to the field of membrane protein biogenesis. The proposed research is directed at understanding the assembly of a unique OMP of E. coli, TolC, which folds into a novel three-dimensional structure. The TolC protein carries out several medically and physiologically important functions, including antibiotic efflux and toxin secretion. This research will identify and characterize intragenic and extragenic factors that contribute to TolC's assembly into trimeric barrels composed of alpha-helices and beta-strands. These aspects will be studied through exploiting genetic, molecular, and biochemical methods. The available data show that TolC follows an assembly pathway distinct from all other OMPs studied so far, thus providing an opportunity to uncover novel principles governing OMP targeting and assembly.