6et3
Crystal structure of PqsBC (C129S) mutant from Pseudomonas aeruginosa (crystal form 4)Crystal structure of PqsBC (C129S) mutant from Pseudomonas aeruginosa (crystal form 4)
Structural highlights
Function[PQSC_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. The PqsC/PqsB complex catalyzes the condensation of 2-aminobenzoylacetate (2-ABA) and octanoyl-CoA to form HHQ. First, PqsC acquires an octanoyl group from octanoyl-CoA and forms an octanoyl-PqsC intermediate. Then, together with PqsB, it catalyzes the coupling of 2-ABA with the octanoate group, leading to decarboxylation and dehydration, and resulting in closure of the quinoline ring.[1] [2] [PQSB_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. The PqsC/PqsB complex catalyzes the condensation of 2-aminobenzoylacetate (2-ABA) and octanoyl-CoA to form HHQ. PqsB, together with PqsC, catalyzes the coupling of 2-ABA with the octanoate group, leading to decarboxylation and dehydration, and resulting in closure of the quinoline ring. PqsB is probably required for the proper folding of PqsC rather than for a direct enzymatic role in the process.[3] [4] Publication Abstract from PubMedPseudomonas aeruginosa is a bacterial pathogen that causes life-threatening infections in immunocompromised patients. It produces a large armory of saturated and mono-unsaturated 2-alkyl-4(1H)-quinolones (AQs) and AQ N-oxides (AQNOs) that serve as signaling molecules to control the production of virulence factors and that are involved in membrane vesicle formation and iron chelation; furthermore, they also have, for example, antibiotic properties. It has been shown that the beta-ketoacyl-acyl-carrier protein synthase III (FabH)-like heterodimeric enzyme PqsBC catalyzes the last step in the biosynthesis of the most abundant AQ congener, 2-heptyl-4(1H)-quinolone (HHQ), by condensing octanoyl-coenzyme A (CoA) with 2-aminobenzoylacetate (2-ABA), but the basis for the large number of other AQs/AQNOs produced by P. aeruginosa is not known. Here, we demonstrate that PqsBC uses different medium-chain acyl-CoAs to produce various saturated AQs/AQNOs and that it also biosynthesizes mono-unsaturated congeners. Further, we determined the structures of PqsBC in four different crystal forms at 1.5 to 2.7 A resolution. Together with a previous report, the data reveal that PqsBC adopts open, intermediate, and closed conformations that alter the shape of the acyl-binding cavity and explain the promiscuity of PqsBC. The different conformations also allow us to propose a model for structural transitions that accompany the catalytic cycle of PqsBC that might have broader implications for other FabH-enzymes, for which such structural transitions have been postulated but have never been observed. The Alkylquinolone Repertoire of Pseudomonas aeruginosa is Linked to Structural Flexibility of the FabH-like 2-Heptyl-3-hydroxy-4(1H)-quinolone (PQS) Biosynthesis Enzyme PqsBC.,Witzgall F, Depke T, Hoffmann M, Empting M, Bronstrup M, Muller R, Blankenfeldt W Chembiochem. 2018 May 3. doi: 10.1002/cbic.201800153. PMID:29722462[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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