粘质沙雷氏菌AS-1中SpnR功能及卤化呋喃对其群体感应的抑制

The function of SpnR and the inhibitory effects by halogenated furanone on quorum sensing in Serratia marcescens AS-1

摘要:

通过分泌和感知一系列信号分子, 细菌能够根据自身菌体密度的变化调控基因的表达, 从而控制一系列重要的表现型, 包括毒力因子的产生, 生物膜的形成以及菌体发光等。这种广泛存在的信号机制被称为群体感应。在沙雷氏菌种中已经发现了多套群体感应机制。粘质沙雷氏菌AS-1从土壤中分离, 其中含有LuxI/LuxR 的同类蛋白, 被称为 SpnI/SpnR。粘质沙雷氏菌AS-1合成AHLs分子N-hexanoyl-L-homoserine lactone (C6-HSL) 和N-(3-oxohexanoyl)-L- homoserine lactone (3-oxo-C6-HSL)作为其信号分子, 通过群体感应感知菌体密度来控制基因的表达。通过基因替代的方法制得了spnR基因破坏的变异株, 命名为粘质沙雷氏菌AS-1R。对粘质沙雷氏菌AS-1R的研究表明SpnR蛋白消极的调控沙雷氏菌红色色素的产生, 运动性以及生物膜的形成等一系列由群体感应控制的性状; 另一方面, 作为一种天然的群体感应抑制剂, 卤化呋喃能够有效的抑制粘质沙雷氏菌AS-1的群体感应, 但并不干扰AHL-SpnR的相互作用。为运用粘质沙雷氏菌群体感应调节抑制其致病性提供了方法和依据, 同时也为卤化呋喃对群体感应抑制机理的研究提供了新的思路。

Abstract:

By secretion and detection of a series of signaling molecules, bacteria are able to coordinate gene expression as a community, to regulate a variety of important phenotypes, from virulence factor production to biofilm formation to symbiosis related behaviours such as bioluminescence. This widespread signaling mechanism is called quorum sensing. There are several quorum sensing systems described in Serratia. Serratia marcescens AS-1, isolated from soil, had the LuxI/LuxR homologues called SpnI/SpnR. S. marcescens AS-1 produced two kinds of N-acyl-L-homoserine lactones, N-hexanoyl-L-homoserine lac-tone and N-(3-oxohexanoyl)-L-homoserine lactone as signal molecules, which involved in quorum sensing to control the gene expression in response to increased cell density. By gene replacement method, the spnR mutant was constructed, named S. marcescens AS-1R. SpnR acted as a negative regulator for the production of prodigiosin, swarming motility and biofilm for-mation, which were regulated by quorum sensing. Halogenated furanone, known as a natural inhibitor of quorum sensing, could effectively inhibit the quorum sensing of S. marcescens AS-1 but without interrupting AHL-SpnR interaction. All results will be helpful to understand the mechanisms of halogenated furanone inhibition on quorum sensing and the potential applica-tion of halogenated furanone in effectively preventing infection disease caused by Serratia strains.