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Crystal structure of Pseudomonas aeruginosa PvdQ in complex with a transition state analogueCrystal structure of Pseudomonas aeruginosa PvdQ in complex with a transition state analogue
Structural highlights
FunctionPVDQ_PSEAE Catalyzes the deacylation of acyl-homoserine lactone (AHL or acyl-HSL), releasing homoserine lactone (HSL) and the corresponding fatty acid. Possesses a specificity for the degradation of long-chain acyl-HSLs (side chains of 11 to 14 carbons in length). Degrades 3-oxo-C12-HSL, one of the two main AHL signal molecules of P.aeruginosa, and thereby functions as a quorum quencher, inhibiting the las quorum-sensing system. Therefore, may enable P.aeruginosa to modulate its own quorum-sensing-dependent pathogenic potential. Also appears to be required for pyoverdin biosynthesis.[1] [2] [3] Publication Abstract from PubMedThe Pseudomonas aeruginosa enzyme PvdQ can process different substrates involved in quorum-sensing or in siderophore biosynthesis. Substrate selectivity was evaluated using steady-state kinetic constants for hydrolysis of N-acyl-homoserine lactones (HSLs) and p-nitrophenyl fatty acid esters. PvdQ prefers substrates with alkyl chains between 12 and 14 carbons long that do not bear a 3-oxo substitution and is revealed here to have a relatively high specificity constant for selected N-acyl-HSLs (kcat/KM = 105 to 106 M-1 s-1). However, endogenous P. aeruginosa N-acyl-HSLs are >/=100-fold disfavored, supporting the conclusion that PvdQ was not primarily evolved to regulate endogenous quorum-sensing. PvdQ plays an essential biosynthetic role for the siderophore pyoverdine, on which P. aeruginosa depends for growth in iron-limited environments. A series of alkylboronate inhibitors was found to be reversible, competitive, and extremely potent (Ki >/= 190 pM). A 1.8 A X-ray structure shows that 1-tridecylboronic acid forms a monocovalent bond with the N-terminal beta-chain Ser residue in the PvdQ heterodimer, mimicking a reaction transition state. This boronic acid inhibits growth of P. aeruginosa in iron-limited media, reproducing the phenotype of a genetic pvdQ disruption, although co-administration of an efflux pump inhibitor is required to maintain growth inhibition. These findings support the strategy of designing boron-based inhibitors of siderophore biosynthetic enzymes to control P. aeruginosa infections. Rational Design of a Transition State Analogue with Picomolar Affinity for Pseudomonas aeruginosa PvdQ, a Siderophore Biosynthetic Enzyme.,Clevenger KD, Wu R, Er JA, Liu D, Fast W ACS Chem Biol. 2013 Aug 6. PMID:23883096[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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