革兰氏阴性菌的Cpx双组分调控系统

细菌主要通过单组分、双组分、三组分调控系统来适应外界环境变化以保证自身的正常生长和繁殖。Cpx系统是革兰氏阴性菌中普遍存在的双组分调控系统之一,作为双组分调控系统的重要一元,它由细胞膜组氨酸蛋白激酶CpxA、细胞质响应调节蛋白CpxR以及细胞周质空间辅助调节蛋白CpxP构成。本文着重介绍了Cpx系统各组分的结构特征,并结合前人的文献和我们近期的研究成果,综述了Cpx系统信号整合的最新研究进展,提出了尚待解决的问题及进一步的研究方向,为科研人员对Cpx双组分调控系统的研究提供一定的帮助。     

革兰氏阴性菌的Cpx双组分调控系统

摘要:细菌主要通过单组分、双组分、三组分调控系统来适应外界环境变化以保证自身的正常生长和繁殖。Cpx系统是革兰氏阴性菌中普遍存在的双组分调控系统之一,作为双组分调控系统的重要一元,它由细胞膜组氨酸蛋白激酶CpxA、细胞质响应调节蛋白CpxR以及细胞周质空间辅助调节蛋白CpxP构成。本文着重介绍了Cpx系统各组分的结构特征,并结合前人的文献和我们近期的研究成果,综述了Cpx系统信号整合的最新研究进展,提出了尚待解决的问题及进一步的研究方向,为科研人员对Cpx双组分调控系统的研究提供一定的帮助。     

乳酸菌双组分信号转导系统研究进展

乳酸菌中存在着一种重要的调控机制--双组分信号转导系统,它可以通过调控乳酸菌的多种生理生化过程来适应外界环境的变化.就双组分信号转导系统的组成、作用机制以及乳酸菌中调控耐酸机制、细菌素的合成和黏性吸附等生理过程的双组分信号转导系统作一综述.     

细菌Cpx信号转导系统的功能及调控机制研究进展

Cpx (conjugative pilus expression)双组分信号转导系统是革兰阴性细菌中一种复杂的包膜应激系统,能感应从不同信号传输点传入的多种包膜信号。位于胞质中的反应调节子CpxR磷酸化后能够调节众多编码内外膜上相关蛋白基因的表达。Cpx系统的激活还能调节细菌对抗生素和酸等压力的抵抗性。本文介绍了Cpx系统的组成,重点对Cpx系统的信号感应及调控机制进行综述,以期为Cpx系统的调控网络及其调节细菌重要生理过程的研究提供参考依据。     

细菌双组分信号转导系统

细菌能感应外界环境各种不同信号,调控菌体内相关基因表达,以适应不断变化的环境。其中双组分信号转导系统广泛存在于各种原核生物中,其基本结构为一个组氨酸蛋白激酶和一个反应调节蛋白。由于双组分系统在结构和作用机制上与人类细胞的信号转导系统有本质的不同,因而在抗微生物感染方面有着诱人的应用前景。     

沙门菌PhoP-PhoQ双组分信号转导系统

PhoP-PhoQ是调控沙门菌毒力的重要双组分信号转导系统,由组氨酸蛋白激酶PhoQ和反应调节蛋白PhoP组成。PhoP-PhoQ可调节沙门菌对Mg2+及其他周质环境的适应性,并调控沙门菌感染中毒力基因的转录和表达。PhoP-PhoQ调控的毒力基因参与沙门菌对上皮细胞的侵袭、胞内生存、对抗菌肽的抵抗反应、脂质A的修饰、Ⅲ型分泌系统效应蛋白的分泌等环节。PhoP-PhoQ还可与其他双组分信号转导系统或调节子合作,调控沙门菌的毒力。因此,PhoP-PhoQ双组分信号转导系统在沙门菌的毒力调控中发挥重要作用。     

氧化葡萄糖酸杆菌中一种潜在的双组分系统蛋白的功能研究

氧化葡萄糖酸杆菌(Gluconobacteroxydans)基因组编码的蛋白质中,有相当数量的传感器激酶和反应调控蛋白组成了细菌的多个双组分信号转导系统(two-componentsignaltransduction systems, TCSs),这些系统能够介导细菌对外界环境变化做出反应。但目前对G. oxydans中潜在的双组分系统成员蛋白质结构和功能缺少必要的研究【。目的】研究菌株G. oxydans 621H中GOX0645基因序列所编码蛋白质的自磷酸化活性,探究其与细菌趋化性运动的关联,揭示其是否作为一种双组分系统成员蛋白在细胞内发挥作用。【方法】以菌株G. oxydans 621H基因组中一段可能编码双组分系统蛋白质的基因GOX0645为基础,通过生物信息学分析其保守结构域;采用体外化学发光实验证明其编码蛋白的自磷酸化活性;利用基因定点突变筛选出与自磷酸化活性相关的氨基酸位点;通过差速离心法寻找双组分蛋白的亚细胞定位;最后运用体内双分子荧光互补和体外生物大分子相互作用实验印证其与下游鞭毛马达蛋白之间的相互作用。【结果】生物信息学分析发现GOX0645编码蛋白同时具有组氨酸激...     

肠杆菌科细菌的Rcs信号转导系统——毒力、应激

Rcs是肠杆菌科细菌中的一种复杂的双组分信号转导系统,能调节细菌荚膜异多糖酸合成,以及细菌鞭毛基因、抗酸性基因等的表达。Rcs不同于典型的双组分系统,其由3个蛋白构成,磷酸转移过程分3步进行。不同细菌中的Rcs功能有所区别,主要为调控细菌的毒力和应激。本文在简单介绍细菌双组分信号转导系统的基础上,重点对肠杆菌科细菌Rcs的组成、功能及磷酸转移机制进行综述。     

VicRK(YycFG)双组分调节系统

细菌双组分调节系统,或称之为双组分信号转导系统,是细菌感应外界多变环境,维持自身存活和生长繁衍的重要感应系统.在这些调节系统中,最早发现于枯草芽孢杆菌的VicRK(YycFG)系统因与细胞存活密切相关而倍受关注.该系统存在于少数低G+C含量的革兰氏阳性菌中,包括金黄色葡萄球菌和肺炎链球菌等致病菌,高度保守.许多证据显示,VicRK(YycFG)具有调控细胞壁合成与代谢、胞膜完整、细胞分裂、脂类代谢、多糖合成与被膜形成以及细菌毒力等多种功能,参与细胞的生长、分裂与感染.该系统异常可导致细菌生活力严重下降,甚至死亡,因而成为防治该类病原菌的重要靶标.     

肺炎链球菌二元信号转导系统研究进展

肺炎链球菌是引起细菌性肺炎的主要病原菌。透彻地了解肺炎链球菌的信号转导对于系统地认识该菌的致病机制和靶标药物的设计具有重要意义。二元信号转导系统作为在病原菌中普遍存在的一种跨膜信号转导机制,在细菌响应外界环境变化并作出适应性反应的过程中起着主要作用。随着大规模基因组测序、信号标签诱变、差异荧光诱导以及DNA微阵列等技术的蓬勃发展,关于肺炎链球菌的二元信号转导系统已经取得了许多重要的研究成果。本文就肺炎链球菌二元信号转导系统的研究进展作一综述。     

Dynamic Interaction between the CpxA Sensor Kinase and the Periplasmic Accessory Protein CpxP Mediates Signal Recognition in E. coli

Two-component systems, consisting of an inner membrane sensor kinase and a cytosolic response regulator, allow bacteria to respond to changes in the environment. Some two-component systems are additionally orchestrated by an accessory protein that integrates additional signals. It is assumed that spatial and temporal interaction between an accessory protein and a sensor kinase modifies the activity of a two-component system. However, for most accessory proteins located in the bacterial envelope the mechanistic details remain unclear. Here, we analyzed the interaction between the periplasmic accessory protein CpxP and the sensor kinase CpxA in Escherichia coli in dependency of three specific stimuli. The Cpx two-component system responds to envelope stress and plays a pivotal role for the quality control of multisubunit envelope structures, including type three secretion systems and pili of different pathogens. In unstressed cells, CpxP shuts off the Cpx response by a yet unknown mechanism. We show for the first time the physical interaction between CpxP and CpxA in unstressed cells using bacterial two-hybrid system and membrane-Strep-tagged protein interaction experiments. In addition, we demonstrate that a high salt concentration and the misfolded pilus subunit PapE displace CpxP from the sensor kinase CpxA in vivo. Overall, this study provides clear evidence that CpxP modulates the activity of the Cpx system by dynamic interaction with CpxA in response to specific stresses.     

铜绿假单胞菌的双组分系统

双组分系统是存在于原核和少部分真核生物细胞中的信号转导系统,主要由组氨酸蛋白激酶和反应调节蛋白组成,通过感应外界环境信号、信号输入、磷酸基团传递、信号输出等环节调节基因表达,使细胞能更加适应环境变化。铜绿假单胞菌为条件致病菌,其双组分系统构成多样、功能复杂且参与介导耐药性产生,因此铜绿假单胞菌的双组分系统日益引起人们关注。本文对铜绿假单胞菌双组分系统的组成、信号转导机制、种类、研究方法及其临床意义进行了综述。     

The mechanism of action of inhibitors of bacterial two-component signal transduction systems

Two-component signal transduction systems allow bacteria to sense and respond rapidly to changes in their environment leading to specific gene activation or repression. These two-component systems are integral in the ability of pathogenic bacteria to mount and establish a successful infection within the host and, consequently, have been recognized as targets for new anti-microbial agents. In this paper, we define the site and mechanism of action of several previously identified inhibitors of bacterial two-component systems. We show that the most potent inhibitors target the carboxyl-terminal catalytic domain of the sensor kinase and exert their affect by causing structural alterations of the kinase leading to aggregation. Recognition of this phenomenon has important implications for the development of novel inhibitors of two-component systems and should facilitate the rapid identification and elimination of compounds with nonspecific affects from medicinal chemistry drug discovery programs.     

One-component systems dominate signal transduction in prokaryotes

Two-component systems that link environmental signals to cellular responses are viewed as the primary mode of signal transduction in prokaryotes. By analyzing information encoded by 145 prokaryotic genomes, we found that the majority of signal transduction systems consist of a single protein that contains input and output domains but lacks phosphotransfer domains typical of two-component systems. One-component systems are evolutionarily older, more widely distributed among bacteria and archaea, and display a greater diversity of domains than two-component systems.     

蓝藻的二元信号传导系统

二元系统是细菌中主要的信号传导途径 ,磷酸根转移介导的信号途径使细胞得以感受各种环境刺激并产生应答。组氨酸蛋白质激酶的自动磷酸化将磷酸基团传给反应调节蛋白 ,反过来作为分子开关控制不同的效应物活性。蓝藻是地球上最早出现的光合自养原核生物 ,在长期的生物进化过程中 ,它们发展了一系列独特的形态和生理代谢机制 ,使其能在各种不同生境中生长、繁殖和扩增。研究蓝藻信号传导途径为阐明其高度的环境适应性提供了理论基础。     

Role of two-component regulatory systems in intracellular survival of Mycobacterium tuberculosis

The typical two-component regulatory systems (TCSs), consisting of response regulator and histidine kinase, play a central role in survival of pathogenic bacteria under stress conditions such as nutrient starvation, hypoxia, and nitrosative stress. A total of 11 complete paired two-component regulatory systems have been found in Mycobacterium tuberculosis, including a few isolated kinase and regulatory genes. Increasing evidence has shown that TCSs are closely associated with multiple physiological process like intracellular persistence, pathogenicity, and metabolism. This review gives the two-component signal transduction systems in M. tuberculosis and their signal transduction roles in adaption to the environment.     

Cpx signaling pathway monitors biogenesis and affects assembly and expression of P pili

P pili are important virulence factors in uropathogenic Escherichia coli. The Cpx two-component signal transduction system controls a stress response and is activated by misfolded proteins in the periplasm. We have discovered new functions for the Cpx pathway, indicating that it may play a critical role in pathogenesis. P pili are assembled via the chaperone/usher pathway. Subunits that go 'OFF-pathway' during pilus biogenesis generate a signal. This signal is derived from the misfolding and aggregation of subunits that failed to come into contact with the chaperone in the periplasm. In response, Cpx not only controls the stress response, but also controls genes necessary for pilus biogenesis, and is involved in regulating the phase variation of pap expression and, potentially, the expression of a panoply of other virulence factors. This study demonstrates how the prototypic chaperone/usher pathway is intricately linked and dependent upon a signal transduction system.     

Expression,purification and activities of the entire family of intact membrane sensor kinases from Enterococcus faecalis

Two-component signal transduction systems are the main mechanism by which bacteria sense and respond to their environment, and their membrane-located histidine protein kinases generally constitute the sensory components of these systems. Relatively little is known about their fundamental mechanisms and precise nature of the molecular signals sensed, because of the technical challenges of producing sufficient quantities of these hydrophobic membrane proteins. This study evaluated the heterologous production, purification and activities of the 16 intact membrane sensor kinases of Enterococcus faecalis. Following the cloning of the genes into expression plasmid pTTQ18His, all but one kinase was expressed successfully in Escherichia coli inner membranes. Purification of the hexa-histidine ‘tagged’ recombinant proteins was achieved for 13, and all but one were verified as intact. Thirteen intact kinases possessed autophosphorylation activity with no added signal when assayed in membrane vesicles or as purified proteins. Signal testing of two functionally-characterized kinases, FsrC and VicK, was successful examplifying the potential use of in vitro activity assays of intact proteins for systematic signal identification. Intact FsrC exhibited an approximately 10-fold increase in activity in response to a two-fold molar excess of synthetic GBAP pheromone, whilst glutathione, and possibly redox potential, were identified for the first time as direct modulators of VicK activity in vitro. The impact of DTT on VicK phosphorylation resulted in increased levels of phosphorylated VicR, the downstream response regulator, thereby confirming the potential of this in vitro approach for investigations of modulator effects on the entire signal transduction process of two-component systems.     

Plant two-component systems: principles,functions, complexity and cross talk

Two-component systems have emerged as important sensing/response mechanisms in higher plants. They are composed of hybrid histidine kinases, histidine-containing phosphotransfer domain proteins and response regulators that are biochemically linked by His-to-Asp phosphorelay. In plants two-component systems play a major role in cytokinin perception and signalling and contribute to ethylene signal transduction and osmosensing. Furthermore, developmental processes like megagametogenesis in Arabidopsis thaliana and flowering promotion in rice (Oryza sativa) involve elements of two-component systems. Two-component-like elements also function as components of the Arabidopsis circadian clock. Because of the molecular mode of signalling, plant two-component systems also appear to serve as intensive cross talk and signal integration machinery. In this review we summarize the present knowledge about the principles and functions of two-component systems in higher plants and address several critical points with respect to cross talk, signal integration and specificity.Abbreviations AHK Arabidopsis histidine kinase - AHP Arabidopsis histidine-containing phosphotransfer domain protein - APRR Arabidopsis pseudo response regulator - ARR Arabidopsis response regulator - CCT CONSTANS CONSTANS-like TOC1 - CKI Cytokinin insensitive - CRE Cytokinin response - CTR Constitutive triple response - Ehd Early heading date - EIN Ethylene insensitive - ERS Ethylene response sensor - ETR Ethylene resistant - GARP-motif Found in Golden2 of maize, Arabidopsis B-type response regulators and Chlamydomonas Psr1 - HPt Histidine-containing phosphotransfer domain - NLS Nuclear localization signal - phyB Phytochrome B - TCS Two-component signalling - TOC Timing of CAB (chlorophyll a/b-binding protein) expression - WOL Wooden leg