The quorum-quenching N -acyl homoserine lactone acylase PvdQ is an Ntn-hydrolase with an unusual substrate-binding pocket
- 22 December 2009
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 107 (2), 686-691
- https://doi.org/10.1073/pnas.0911839107
Abstract
In many Gram-negative pathogens, their virulent behavior is regulated by quorum sensing, in which diffusible signals such as N-acyl homoserine lactones (AHLs) act as chemical messaging compounds. Enzymatic degradation of these diffusible signals by, e. g., lactonases or amidohydrolases abolishes AHL regulated virulence, a process known as quorum quenching. Here we report the first crystal structure of an AHL amidohydrolase, the AHL acylase PvdQ from Pseudomonas aeruginosa. PvdQ has a typical alpha/beta heterodimeric Ntn-hydrolase fold, similar to penicillin G acylase and cephalosporin acylase. However, it has a distinct, unusually large, hydrophobic binding pocket, ideally suited to recognize C12 fatty acid-like chains of AHLs. Binding of a C12 fatty acid or a 3-oxo-C12 fatty acid induces subtle conformational changes to accommodate the aliphatic chain. Furthermore, the structure of a covalent ester intermediate identifies Ser beta 1 as the nucleophile and Asn beta 269 and Val beta 70 as the oxyanion hole residues in the AHL degradation process. Our structures show the versatility of the Ntn-hydrolase scaffold and can serve as a structural paradigm for Ntn-hydrolases with similar substrate preference. Finally, the quorum-quenching capabilities of PvdQ may be utilized to suppress the quorum-sensing machinery of pathogens.Keywords
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