5his
Crystal Structure of PQS Response Protein PqsE in Complex with 3-methylthiophene-2-carboxylic acid
Structural highlights
FunctionPQSE_PSEAE Required for the biosynthesis of the quorum-sensing signaling molecules 2-heptyl-4(1H)-quinolone (HHQ) and 2-heptyl-3-hydroxy-4(1H)-quinolone (Pseudomonas quinolone signal or PQS), which are important for biofilm formation and virulence. Catalyzes the hydrolysis of the intermediate 2-aminobenzoylacetyl-CoA (2-ABA-CoA) to form 2-aminobenzoylacetate (2-ABA), the precursor of HHQ. In vitro, can also hydrolyze other substrates such as S-ethyl-acetothioacetate and acetoacetyl-CoA, but is inactive against anthraniloyl-CoA, malonyl-CoA and octanoyl-CoA (PubMed:25960261, PubMed:27082157). Beyond its thioesterase function, is involved in the regulation of diverse genes coding for key virulence determinants and biofilm development (PubMed:27851827).[1] [2] [3] Publication Abstract from PubMedPseudomonas aeruginosa uses quorum sensing (QS) as a cell-to-cell communication system to orchestrate the expression of virulence determinants. The biosynthesis of the important Pseudomonas quinolone signal (PQS) requires the pqsABCDE operon. Here, PqsE acts as a pathway-specific thioesterase, but it also contributes to the regulation of bacterial virulence via an unknown mechanism. In this manuscript, we report the discovery of PqsE inhibitors as tool compounds to gain further insights into its different functions. Differential scanning fluorimetry (DSF) was used to screen a fragment library, and isothermal titration calorimetry (ITC) was employed as a secondary filter. As proven by X-ray crystallography, hit molecules bound to the active center inhibiting PqsE's thioesterase activity in cell-based and in vitro assays. Notably, the ligands did not affect the levels of the PqsE-regulated virulence factor pyocyanin. These findings indicate that the regulatory function of PqsE is not linked to its thioesterase activity and must be encoded outside of the active center. This study highlights the potential of fragment-based screening for the discovery of tool compounds. This approach provided novel insight into complex biological systems, which could not be obtained by knockout studies. Dissecting the Multiple Roles of PqsE in Pseudomonas aeruginosa Virulence by Discovery of Small Tool Compounds.,Zender M, Witzgall F, Drees SL, Weidel E, Maurer CK, Fetzner S, Blankenfeldt W, Empting M, Hartmann RW ACS Chem Biol. 2016 Apr 28. PMID:27082157[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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