Characterizing the Cpx stress response in E. coli

描述（由申请人提供）：所有生物体都进化出了一种机制，以确保蛋白质在面对各种压力时正确折叠和定位，否则这些压力会杀死它们。在细菌中，如大肠杆菌，以及高等真核生物，专门的调节系统的作用，以监测细胞蛋白质的完整性。具体地说，无论是在E。大肠杆菌中未折叠蛋白质的应答和真核细胞中未折叠蛋白质的应答分别利用跨膜激酶在内质网（ER）或周质内感知和转导信号。然后，该信号被传递到转录调节因子，其导致适当定位的蛋白质折叠和运输因子的上调，所述蛋白质折叠和运输因子可以用于对抗刺激应激。大肠杆菌的Cpx诱导的应激反应通过由激酶（CpxA）和转录反应调节因子（CpxR）组成的双组分信号传导系统对抗胞质外毒性，例如错误折叠蛋白聚集体的形成。周质蛋白CpxP是唯一确定的Cpx应激反应的负调节因子，并且推测在确保该反应被适当调节中起重要作用。虽然很明显，CpxP功能需要一个功能性的周质CpxA传感结构域，相对较少的是知道如何CpxP通常在细胞中的功能。这项研究的目的是使用生化和遗传分析来剖析CpxP功能，并了解其活性是如何与Cpx双组分系统协调，以减轻与应激相关的压力，并确保适当激活Cpx反应。这项拟议的研究将阐明细胞适应避免有毒蛋白质聚集体存在的影响的方式。这种聚集体似乎是几种人类疾病包括α-1抗胰蛋白酶缺乏症和亨廷顿病的发病机制的核心。

DESCRIPTION (provided by applicant): All organisms have evolved mechanisms to ensure the proper folding and localization of proteins in the face of a variety of stresses that would otherwise kill them. In bacteria, such as Escherichia coli, as well as higher eukaryotes, specialized regulatory systems act to monitor the integrity of cellular proteins. Specifically, both the periplasmic stress response in E. coli and the unfolded protein response in eukaryotic cells employ a transmembrane kinase that senses and transduces a signal within the endoplasmic reticulum (ER) or periplasm, respectively. This signal is then relayed to transcriptional regulators which results in an upregulation of appropriately localized protein folding and trafficking factors that can act to combat the inciting stress. The Cpx-induced stress response of Escherichia coli combats extracytoplasmic toxicities such as the formation of misfolded protein aggregates through a two-component signal transduction system comprised of a kinase (CpxA) and a transcriptional response regulator (CpxR). The periplasmic protein, CpxP, is the only identified negative regulator of the Cpx stress response and presumptively plays an important role in ensuring that this response is properly modulated. While it is clear that CpxP function requires a functional periplasmic CpxA sensing domain, relatively little is known about how CpxP normally functions in the cell. The purpose of this proposed study is to use both biochemical and genetic analysis to dissect CpxP function and understand how its activity is coordinated with the Cpx two-component system to alleviate envelope-associated stress and ensure appropriate activation of the Cpx response. The proposed study will illuminate the way in which the cell adapts to stave off the effects of the presence of toxic protein aggregates. Such aggregates appear to be central to the pathogenesis of several human diseases including alpha-1 antitrypsin deficiency and Huntington's disease.