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Acyl‐homoserine lactone acylase from Ralstonia strain XJ12B represents a novel and potent class of quorum‐quenching enzymes
Author(s) -
Lin YiHan,
Xu JinLing,
Hu Jiangyong,
Wang LianHui,
Ong Say Leong,
Leadbetter Jared Renton,
Zhang LianHui
Publication year - 2003
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2003.03351.x
Subject(s) - quorum quenching , quorum sensing , biology , homoserine , microbiology and biotechnology , biochemistry , ralstonia , virulence , bacteria , biofilm , pyocyanin , pseudomonas aeruginosa , chromobacterium violaceum , escherichia coli , enzyme , gene , genetics
Summary N‐acylhomoserine lactones (AHLs) are used as signal molecules by many quorum‐sensing Proteobacteria. Diverse plant and animal pathogens use AHLs to regulate infection and virulence functions. These signals are subject to biological inactivation by AHL‐lactonases and AHL‐acylases. Previously, little was known about the molecular details underlying the latter mechanism. An AHL signal‐inactivating bacterium, identified as aRalstoniasp., was isolated from a mixed‐species biofilm. The signal inactivation encoding gene from this organism, which we callaiiD, was cloned and successfully expressed inEscherichia coliand inactivated three AHLs tested. The predicted 794‐amino‐acid polypeptide was most similar to the aculeacin A acylase (AAC) fromActinoplanes utahensisand also shared significant similarities with cephalosporin acylases and other N‐terminal (Ntn) hydrolases. However, the most similar homologues of AiiD are deduced proteins of undemonstrated function from availableRalstonia,DeinococcusandPseudomonasgenomes. LC‐MS analyses demonstrated that AiiD hydrolyses the AHL amide, releasing homoserine lactone and the corresponding fatty acid. Expression of AiiD inPseudomonas aeruginosa PAO1 quenched quorum sensing by this bacterium, decreasing its ability to swarm, produce elastase and pyocyanin and to paralyse nematodes. Thus, AHL‐acylases have fundamental implications and hold biotechnological promise in quenching quorum sensing.