Dong Y H, Wang L H, Xu J L, Zhang H B, Zhang X F, Zhang L H
Institute of Molecular Agrobiology, National University of Singapore, Singapore.
Nature. 2001 Jun 14;411(6839):813-7. doi: 10.1038/35081101.
Bacterial cells sense their population density through a sophisticated cell-cell communication system and trigger expression of particular genes when the density reaches a threshold. This type of gene regulation, which controls diverse biological functions including virulence, is known as quorum sensing. Quorum-sensing signals, such as acyl-homoserine lactones (AHLs), are the essential components of the communication system. AHLs regulate virulence gene expression in a range of plant and animal (including human) bacterial pathogens. AHL-producing tobacco restored the pathogenicity of an AHL-negative mutant of Erwinia carotovora. Different bacterial species may produce different AHLs, which vary in the length and substitution of the acyl chain but contain the same homoserine lactone moiety. Here we show that the acyl-homoserine lactonase (AHL-lactonase), a new enzyme from Bacillus sp., inactivates AHL activity by hydrolysing the lactone bond of AHLs. Plants expressing AHL-lactonase quenched pathogen quorum-sensing signalling and showed significantly enhanced resistance to E. carotovora infection. Our results highlight a promising potential to use quorum-sensing signals as molecular targets for disease control, thereby broadening current approaches for prevention of bacterial infections.
细菌细胞通过一种复杂的细胞间通讯系统感知其群体密度，并在密度达到阈值时触发特定基因的表达。这种控制包括毒力在内的多种生物学功能的基因调控类型，被称为群体感应。群体感应信号，如酰基高丝氨酸内酯（AHLs），是通讯系统的重要组成部分。AHLs在一系列植物和动物（包括人类）细菌病原体中调节毒力基因的表达。产生AHL的烟草恢复了胡萝卜软腐欧文氏菌AHL阴性突变体的致病性。不同的细菌物种可能产生不同的AHLs，它们的酰基链长度和取代基不同，但都含有相同的高丝氨酸内酯部分。在这里，我们表明，来自芽孢杆菌属的一种新酶——酰基高丝氨酸内酯酶（AHL-内酯酶），通过水解AHLs的内酯键使AHL活性失活。表达AHL-内酯酶的植物消除了病原体的群体感应信号，并对胡萝卜软腐欧文氏菌感染表现出显著增强的抗性。我们的结果突出了将群体感应信号用作疾病控制分子靶点的巨大潜力，从而拓宽了当前预防细菌感染的方法。
