细菌群体感应LuxR solos蛋白研究进展

N-酰基高丝氨酸内酯(N-acyl-L-homoserine lactones,AHLs)信号分子介导的群体感应(quorum sensing,QS)是一种普遍的革兰氏阴性细菌信息交流方式。AHL-QS系统包括Lux I型AHLs合成酶和LuxR型受体蛋白。然而,部分革兰氏阴性菌缺失1个或多个LuxI型AHLs合成酶,仅有未配对的LuxR型受体蛋白,该LuxR型受体蛋白称为LuxR solo或Orphan蛋白。LuxR solos蛋白在细菌窃听、种间和种内的信号交流中起重要作用,为群体感应研究领域的热点。本文主要综述细菌LuxR solos蛋白的发现、基本概念、蛋白结构及类型,阐述感应AHLs和非AHLs信号分子的重要LuxR solos蛋白及功能,并对群体感应LuxR solos蛋白的研究前景和意义进行了展望。     

革兰氏阳性菌群体感应系统研究进展

细菌利用群体感应系统进行细菌间以及细菌与宿主间的交流,革兰氏阳性与阴性菌的群体感应系统差异显著,阳性菌的群体感应系统主要由寡肽类信号分子和受体蛋白组成,对细菌致病性等相关生理特性具有重要作用。就常见的革兰氏阳性菌：蜡样芽孢杆菌、枯草芽孢杆菌、金黄色葡萄球菌和肺炎链球菌的群体感应系统的基因组成、信号分子及其调控机制特点的研究进行了总结,对群体感应系统在细菌营养吸收、生物膜形成、毒力因子和孢子产生等重要生理活动的调节机制进行了重点阐述,为革兰氏阳性菌群体感应的相关研究提供了有益参考。     

蛋白组学解析拟南芥响应细菌信号分子N-3-oxo-hexanoyl-homoserine-lactone（OHHL）的机制

细菌来源的群体感应信号分子能诱导与调控植物的抗病性与生长发育,本文用细菌群体感应信号分子N一3-oxo—hexanoyl-homoserine—lactone（OHHL）对拟南芥进行不同时间的处理,提取蛋白进行双向电泳分析,用蛋白组学的方法解析拟南芥响应细菌信号分子的机制。双向电泳与质谱分析共鉴定出47个点,这些蛋白中随处理时间的增加表达量上调的蛋白点数目增加,并且与植物抗氧化、物质代谢和细胞信号转导密切相关。因此通过蛋白组学分析结果可以更好的解释植物与细菌的相互作用机制,进一步利用其之间的联系来促进植物更好的生长发育。     

细菌群体感应及其干扰策略的研究进展

群体感应（QS）广泛存在于细菌中,是细菌根据细胞密度变化调控基因表达的一种机制。许多植物病原菌依赖QS调控致病基因和毒性因子的表达,导致植物发病,因此通过抑制QS效应就为控制细菌病害提供了一种有效的方法。目前发现许多途径可以干扰细菌的QS,如：产生可使信号分子降解的酶,产生病原菌信号分子的类似物与信号分子受体蛋白竞争结合来阻断病原菌的群体感应,利用QS中信号分子来诱发寄主抗性。系统阐述了细菌QS及其干扰策略。     

基于天然产物的群体感应抑制剂的研究进展

细菌的群体感应现象是近年来微生物学、食品保藏学以及天然产物化学等领域研究的热点。随着对群体感应系统研究的不断深入,越来越多的群体感应类型不断地被报道,不同类型的群体感应现象由不同种类的信号分子来介导,各种群体感应抑制剂也不断地涌现。群体感应抑制剂可以阻断细菌的群体感应系统,抑制细菌毒力基因的表达而不影响细菌的生长与增殖,因此,应用群体感应抑制剂可以避免细菌因生长压力而产生耐药性。本文中,笔者主要按照信号分子的种类综述目前已报道的细菌群体感应系统的类型、群体感应的干扰策略以及天然产物来源的群体感应抑制剂的研究现状。另外,笔者还介绍了不同种类信号分子介导的细菌群体感应机制以及已报道的天然产物来源的细菌群体感应抑制剂的种类,并展望其应用前景。     

铜绿假单胞菌群体感应系统的研究进展

细菌的群体感应也称自身诱导,是指细菌通过产生和感应信号分子浓度的变化来监测其群体密度,协调群体行为的过程.自身诱导物随着细菌密度增高而增高,当自身诱导物达到某一阈值后,会与一些转录调节子结合,从而诱导或抑制多种基因的表达.群体感应系统内由多种信号分子和效应蛋白组成复杂的调节网络,调控包括细菌毒力因子产生与释放、生物膜形成、接合反应等,从而影响细菌的致病过程.本文主要对铜绿假单胞菌的群体感应系统及其与宿主关系、群体感应抑制剂等方面的研究进展进行综述.     

外源基因表达造成的群体感应细菌生存压力的建模分析

外源基因的表达及其对细菌种群的影响对于群体感应系统和合成生物学产业的研究具有重要意义。然而,人们对于表达外源蛋白的细菌本身的行为模式仍然知之甚少。为了研究菌落生长和外源基因表达的过程究竟受到哪些因素的影响,文中测量了受Lux类受体调控的外源基因在N-酰基高丝氨酸内酯 (N-acyl homoserine lactone,N-AHL) 信号分子诱导下的表达,并模拟了其对细菌种群动态的影响。文中建立了一个假设性的数学模型,对信号分子诱导表达下细菌种群生长受影响的现象进行了分析。先前的研究通常将细菌种群生长受群体感应系统影响的现象归咎于合成群体感应信号分子的消耗与N-AHL信号分子的毒性,文中提供了对于这种生存压力的另一种可能的解释。     

外源基因表达造成的群体感应细菌生存压力的建模分析（英文）

外源基因的表达及其对细菌种群的影响对于群体感应系统和合成生物学产业的研究具有重要意义。然而,人们对于表达外源蛋白的细菌本身的行为模式仍然知之甚少。为了研究菌落生长和外源基因表达的过程究竟受到哪些因素的影响,文中测量了受Lux类受体调控的外源基因在N-酰基高丝氨酸内酯(N-acyl homoserine lactone,N-AHL)信号分子诱导下的表达,并模拟了其对细菌种群动态的影响。文中建立了一个假设性的数学模型,对信号分子诱导表达下细菌种群生长受影响的现象进行了分析。先前的研究通常将细菌种群生长受群体感应系统影响的现象归咎于合成群体感应信号分子的消耗与N-AHL信号分子的毒性,文中提供了对于这种生存压力的另一种可能的解释。     

细菌群体感应信号分子淬灭酶的研究进展

群体感应(Quorum sensing,QS)是细菌细胞间通过信号分子互相交流的一种现象,细菌细胞通过分泌并感应特定的信号分子浓度,当信号分子浓度达到一定阈值时,细菌细胞会启动特定基因尤其是很多致病基因的表达,这就给防治某些植物、动物性疾病提供了一种新思维。群体淬灭(Quorum quenching,QQ)就是基于群体感应而提出的,它主要是通过分解细菌细胞所产生的信号分子,使信号分子浓度在阈值之内,从而使细菌无法表达特定致病因子,进而防治病害的一种方法,群体淬灭酶是研究的最多也是最有效的淬灭途径。到目前为止,很多群体淬灭酶已经被分离出来。系统总结了群体淬灭酶的种类、特性、催化机制和生理功能方面的进展。     

细菌生物膜群体感应系统研究进展

细菌生物膜群体感应系统是指细菌通过分泌信号分子并通过感知其在周围环境中的浓度,调控某些基因的特异性表达及生理功能和生活习性的系统,是细菌生命活动的主要调控机制之一。通过对细菌生物膜群体感应的研究,可以了解其内部机理和特性,从而找到抑制生物膜有害作用的最好方法。对细菌生物膜群体感应系统的种类、特征和相关应用的研究进行综述。     

Quorum Sensing Circuits in the Communicating Mechanisms of Bacteria and Its Implication in the Biosynthesis of Bacteriocins by Lactic Acid Bacteria: a Review

It is well established that bacteria communicate between each other by using different mechanisms; among which, quorum sensing (QS) is the best known one. Indeed, intra- and intercellular communications of microorganisms, as well as the regulation of metabolism and reaction to the surrounding environmental conditions, are carried out by using different signaling molecules. N-Acyl homoserine lactones control the QS in Gram-negative bacteria, while Gram-positive bacteria use communicating peptides. These compounds, by diffusing through the bacterial membrane cell from the extracellular medium, directly or indirectly control the expression of specific genes that induce bacteria to react to their surrounding environment and stressing agents. In the case of lactic acid bacteria and bifidobacteria which are widely used in the dairy industry, QS is of extreme importance for their survival and the extent of their activity in the dairy matrix. Moreover, it is also via QS that these bacteria synthesize various antimicrobial agents such as bacteriocins. The aim of this review is to highlight the quorum sensing circuits involved in the communicating mechanisms of bacteria with emphasis on current applications of QS in lactic acid bacteria. More particularly, the implication of QS in the biosynthesis of bacteriocins by lactic acid bacteria will be detailed.

     

Quorum sensing regulation in bacteria of the family enterobacteriaceae

Bacteria are able to sense an increase in population density and can respond to it by coordinated regulation of the expression of certain sets of genes in the total population of bacteria. This specific mode of regulation is known as Quorum Sensing (QS). The QS systems include low-molecular-weight signaling molecules of different chemical nature and the regulatory proteins that interact with the signaling molecules. The QS systems are global regulators of bacterial gene expression. They play an important role in controlling metabolic processes in bacteria. This review describes QS systems in members of the bacterial family Enterobacteriaceae functioning with the involvement of various signaling molecules, including N-acyl-homoserine lactones, AI-2, AI-3, peptides, and indole. The differences of the QS system in these bacteria from those in other taxonomic groups of bacteria are discussed. Data on the role of different types of QS systems in the regulation of different cellular processes in bacteria, i.e., their virulence, the synthesis of enzymes and antibiotics, biofilm formation, apoptosis, etc. are presented.     

Development and comparison of whole-cell assay systems for quorum-sensing inhibitors based on TraR, LasR, and QscR

Quorum sensing (QS) is a cell density-dependent signaling system that is used by bacteria to coordinate gene expression within their population. In this study, the authors describe the development and characterization of various cell-based bioassay systems for detecting QS inhibitors based on three LuxR family proteins, TraR, LasR, and the recently identified QscR. Three different gram-negative bacteria, Escherichia coli, Agrobacterium tumefaciens, and Pseudomonas aeruginosa, were employed as reporter strains to overproduce one of the aforementioned QS activator proteins and respond to inhibitors. The nine different whole-cell assay systems (three reporter strains × three QS proteins) were evaluated for their applicability and reliability by studying quantitative responses to various furanones, which are potent inhibitors of the LuxR family proteins. These results demonstrate that the cell-based bioassay systems are sensitive and reliable tools for screening of QS activators and inhibitors. This study also suggests that furanones are potentially important QS inhibitors for many LuxR-type activator proteins.     

Bacterial quorum sensing in symbiotic and pathogenic relationships with hosts*

Gram-negative bacteria communicate with each other by producing and sensing diffusible signaling molecules. This mechanism is called quorum sensing (QS) and regulates many bacterial activities from gene expression to symbiotic/pathogenic interactions with hosts. Therefore, the elucidation and control of bacterial QS systems have been attracted increasing attention over the past two decades. The most common QS signals in Gram-negative bacteria are N-acyl homoserine lactones (AHLs). There are also bacteria that employ different QS systems, for example, the plant pathogen Ralstonia solanacearum utilizes 3-hydroxy fatty acid methyl esters as its QS signals. The QS system found in the endosymbiotic bacterium associated with the fungus Mortierella alpina, the development of an affinity pull-down method for AHL synthases, and the elucidation of a unique QS circuit in R. solanacearum are discussed herein.     

细菌群体感应信号分子——酰基高丝氨酸内酯的检测

革兰氏阴性菌根据信号分子N-酰基高丝氨酸内酯(AHLs)的浓度可以监测周围环境中自身或其他细菌的数量变化,当信号分子达到一定浓度阈值时,能启动相关基因的表达来适应环境的变化,这一调控系统被称为细菌的群体感应(quorumsensing,QS)系统。快速简便而有效地检测细菌是否以及产生何种信号分子成为深入研究和了解细菌群体感应的重要手段。现对信号分子AHLs敏感的用于检测不同的信号分子AHLs的微生物传感菌进行综述,并对其检测能力进行了讨论。     

Detection of quorum-sensing N-acyl homoserine lactone signal molecules by bacterial biosensors

Many Gram-negative bacteria use N-acyl homoserine lactones (AHLs) as quorum-sensing (QS) signal molecules. AHL QS has been the subject of extensive investigation in the last decade and has become a paradigm for bacterial intercellular signaling. Research in AHL QS has been considerably aided by simple methods devised to detect AHLs using bacterial biosensors that phenotypically respond when exposed to exogenous AHLs. This article reviews and discusses the currently available bacterial biosensors which can be used in detecting and studying the different AHLs.     

Quorum sensing and communication in bacteria

Bacteria are able “to sense” an increase in the cell population density and to respond to it by the induction of special sets of genes. This type of regulation, called Quorum Sensing (QS), includes the production and excretion of low-molecular-weight signaling molecules (autoinducers, AI), which diffuse readily through the cell wall, from cells into the medium. As the bacterial population reaches the critical level of density, the concentration of these signaling molecules in the medium increases as a function of population density. On reaching the critical threshold concentration, AIs bind to specific receptor regulatory proteins, which induce the expression of target genes. By means of AIs, bacteria accomplish the communication that is the transmission of information between bacteria belonging to the same or different species, genera, and even families: the signaling molecules of some bacteria affect the receptors of others causing a coordinated reply of cells of the bacterial population. Bacteria of different taxonomic groups use the QS systems in regulation of a broad range of physiological activities. These processes include virulence, symbiosis, conjugation, biofilm formation, bioluminescence, synthesis of enzymes, antibiotic substances, etc. Here we review different QS systems of bacteria, the role of QS in bacterial communication, and some applied aspects of QS regulation application.