5DWZ

Structural and functional characterization of PqsBC, a condensing enzyme in the biosynthesis of the Pseudomonas aeruginosa quinolone signal

Summary for 5DWZ

• Entry DOI: 10.2210/pdb5dwz/pdb
• Descriptor: 3-oxoacyl-[acyl-carrier-protein] synthase 3, SODIUM ION, 3-oxoacyl-(Acyl carrier protein) synthase III, ... (11 entities in total)
• Functional Keywords: protein complex, pqsb, pqsc, transferase
• Biological source: Pseudomonas aeruginosa; More
• Total number of polymer chains: 8
• Total formula weight: 279502.87

Authors

Drees, S.L.,Li, C.,Prasetya, F.,Saleem, M.,Dreveny, I.,Hennecke, U.,Williams, P.,Emsley, J.,Fetzner, S. (deposition date: 2015-09-23, release date: 2016-02-03, Last modification date: 2024-05-08)

Primary citation

Drees, S.L.,Li, C.,Prasetya, F.,Saleem, M.,Dreveny, I.,Williams, P.,Hennecke, U.,Emsley, J.,Fetzner, S.
PqsBC, a Condensing Enzyme in the Biosynthesis of the Pseudomonas aeruginosa Quinolone Signal: CRYSTAL STRUCTURE, INHIBITION, AND REACTION MECHANISM.
J.Biol.Chem., 291:6610-6624, 2016

PubMed Abstract: Pseudomonas aeruginosaproduces a number of alkylquinolone-type secondary metabolites best known for their antimicrobial effects and involvement in cell-cell communication. In the alkylquinolone biosynthetic pathway, the β-ketoacyl-(acyl carrier protein) synthase III (FabH)-like enzyme PqsBC catalyzes the condensation of octanoyl-coenzyme A and 2-aminobenzoylacetate (2-ABA) to form the signal molecule 2-heptyl-4(1H)-quinolone. PqsBC, a potential drug target, is unique for its heterodimeric arrangement and an active site different from that of canonical FabH-like enzymes. Considering the sequence dissimilarity between the subunits, a key question was how the two subunits are organized with respect to the active site. In this study, the PqsBC structure was determined to a 2 Å resolution, revealing that PqsB and PqsC have a pseudo-2-fold symmetry that unexpectedly mimics the FabH homodimer. PqsC has an active site composed of Cys-129 and His-269, and the surrounding active site cleft is hydrophobic in character and approximately twice the volume of related FabH enzymes that may be a requirement to accommodate the aromatic substrate 2-ABA. From physiological and kinetic studies, we identified 2-aminoacetophenone as a pathway-inherent competitive inhibitor of PqsBC, whose fluorescence properties could be used forin vitrobinding studies. In a time-resolved setup, we demonstrated that the catalytic histidine is not involved in acyl-enzyme formation, but contributes to an acylation-dependent increase in affinity for the second substrate 2-ABA. Introduction of Asn into the PqsC active site led to significant activity toward the desamino substrate analog benzoylacetate, suggesting that the substrate 2-ABA itself supplies the asparagine-equivalent amino function that assists in catalysis.

PubMed: 26811339
DOI: 10.1074/jbc.M115.708453

Experimental method

X-RAY DIFFRACTION (2.04 Å)