AidH, an Alpha/Beta-Hydrolase Fold Family Member from an Ochrobactrum sp Strain, Is a Novel N-Acylhomoserine Lactonase
AidH, an Alpha/Beta-Hydrolase Fold Family Member from an Ochrobactrum sp Strain, Is a Novel N-Acylhomoserine Lactonase
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DOI：
10.1128/aem.00477-10
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发表时间：
2010-08-01
影响因子：
4.4
通讯作者：
Zhang, Li-Qun
中科院分区：
文献类型：
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作者：
Mei, Gui-Ying;Yan, Xiao-Xue;Zhang, Li-Qun
n -酰基高丝氨酸内酯（AHLs）是许多群体感应（QS）系统中的信号分子，调节各种致病菌与其宿主之间的相互作用。ahl酶灭活的群体猝灭在预防和治疗感染方面具有很大的前景，并且已经报道了几种这样的酶。在这项研究中，我们报道了从土壤细菌Ochrobactrum sp.菌株T63中提取的一种新的ahl降解蛋白的特性。这种蛋白被称为AidH，与任何已知的AHL降解酶没有相似之处，但与人类Ochrobactrum anthropi ATCC 49188的水解酶高度同源，该酶含有α / β水解酶折叠。通过液相色谱-质谱（MS）分析，我们证明了AidH作为ahl内酯酶水解ahl的同丝氨酸内酯环的酯键。突变分析表明，G-X-Nuc-X-G基序或α / β水解酶中保守的组氨酸残基对AidH的活性至关重要。此外，AidH的ahl灭活活性需要Mn2+，而不需要其他几种已测试的二价阳离子。我们还发现AidH显著降低了荧光假单胞菌2P24的生物膜形成和胡萝卜乳杆菌的致病性，表明该酶能够通过降解ahl有效地抑制这些细菌中qs依赖性的功能。
N-Acylhomoserine lactones (AHLs) are signaling molecules in many quorum-sensing (QS) systems that regulate interactions between various pathogenic bacteria and their hosts. Quorum quenching by the enzymatic inactivation of AHLs holds great promise in preventing and treating infections, and several such enzymes have been reported. In this study, we report the characterization of a novel AHL-degrading protein from the soil bacterium Ochrobactrum sp. strain T63. This protein, termed AidH, shares no similarity with any of the known AHL degradases but is highly homologous with a hydrolytic enzyme from Ochrobactrum anthropi ATCC 49188 that contains the alpha/beta-hydrolase fold. By liquid chromatography-mass spectrometry (MS) analysis, we demonstrate that AidH functions as an AHL-lactonase that hydrolyzes the ester bond of the homoserine lactone ring of AHLs. Mutational analyses indicate that the G-X-Nuc-X-G motif or the histidine residue conserved among alpha/beta-hydrolases is critical for the activity of AidH. Furthermore, the AHL-inactivating activity of AidH requires Mn2+ but not several other tested divalent cations. We also showed that AidH significantly reduces biofilm formation by Pseudomonas fluorescens 2P24 and the pathogenicity of Pectobacterium carotovorum, indicating that this enzyme is able to effectively quench QS-dependent functions in these bacteria by degrading AHLs.