Inhibition of Quinolone Biosynthesis in Pseudomonas aerugionsa and Burkholderia species

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Inhibiting quinolone biosynthesis of Burkholderia

2-Alkylquinolones are important signalling molecules of Burkholderia species. We developed a substrate-based chemical probe against the central quinolone biosynthesis enzyme HmqD and applied it in competitive profiling experiments to discover the first known HmqD inhibitors. The most potent inhibitors quantitatively blocked quinolone production in Burkholderia cultures with single-digit micromolar efficacy.publishe

Chemical probes for competitive profiling of the quorum sensing signal synthase PqsD of Pseudomonas aeruginosa

The human pathogen Pseudomonas aeruginosa uses the pqs quorum sensing system to coordinate the production of its broad spectrum of virulence factors to facilitate colonization and infection of its host. Hereby, the enzyme PqsD is a virulence related quorum sensing signal synthase that catalyzes the central step in the biosynthesis of the Pseudomonas quinolone signals HHQ and PQS. We developed a library of cysteine reactive chemical probes with an alkyne handle for fluorescence tagging and report the selective and highly sensitive in vitro labelling of the active site cysteine of this important enzyme. Interestingly, only one type of probe, with a reactive α-chloroacetamide was capable of covalently reacting with the active site. We demonstrated the potential of our probes in a competitive labelling platform where we screened a library of synthetic HHQ and PQS analogues with heteroatom replacements and found several inhibitors of probe binding that may represent promising scaffolds for the development of customized PqsD inhibitors as well as a chemical toolbox to investigate the activity and active site specificity of the enzyme.publishe

Inhibiting quinolone biosynthesis of <i>Burkholderia</i>

Competitive profiling with a chemical probe against the central quinolone biosynthesis enzyme HmqD results in inhibitors that quantitatively block quinolone production in Burkholderia.</p

Profiling structural diversity and activity of 2-alkyl-4(1<i>H</i>)-quinolone <i>N</i>-oxides of <i>Pseudomonas</i> and <i>Burkholderia</i>

Here, we report the synthesis of all major 2-alkyl-4(1H)-quinolone N-oxide classes of Pseudomonas and Burkholderia, quantification of their native production levels and their antibiotic activities against competing Staphylococcus aureus.</p

Competitive Live-Cell Profiling Strategy for Discovering Inhibitors of the Quinolone Biosynthesis of <i>Pseudomonas aeruginosa</i>

Quinolones of the human pathogen Pseudomonas aeruginosa serve as antibacterial weapons and quorum sensing signals and coordinate the production of important virulence factors. A central enzyme for the biosynthesis of these quinolones is the synthetase PqsD. We developed an activity-based probe strategy that allows to screen for PqsD inhibitors in a cellular model system of live cells of Escherichia coli overexpressing PqsD. This strategy allowed us to determine IC50 values for PqsD inhibition directly in live cells. Our most potent inhibitors were derived from the anthranilic acid core of the native substrate and resulted in single-digit micromolar IC50 values. The effectiveness of our approach was ultimately demonstrated in P. aeruginosa by the complete shutdown of the production of quinolone quorum sensing signals and quinolone N-oxides and a considerable inhibition of the production of phenazine virulence factors

Chemical probes for competitive profiling of the quorum sensing signal synthase PqsD of Pseudomonas aeruginosa

The human pathogen Pseudomonas aeruginosa uses the pqs quorum sensing system to coordinate the production of its broad spectrum of virulence factors to facilitate colonization and infection of its host. Hereby, the enzyme PqsD is a virulence related quorum sensing signal synthase that catalyzes the central step in the biosynthesis of the Pseudomonas quinolone signals HHQ and PQS. We developed a library of cysteine reactive chemical probes with an alkyne handle for fluorescence tagging and report the selective and highly sensitive in vitro labelling of the active site cysteine of this important enzyme. Interestingly, only one type of probe, with a reactive α-chloroacetamide was capable of covalently reacting with the active site. We demonstrated the potential of our probes in a competitive labelling platform where we screened a library of synthetic HHQ and PQS analogues with heteroatom replacements and found several inhibitors of probe binding that may represent promising scaffolds for the development of customized PqsD inhibitors as well as a chemical toolbox to investigate the activity and active site specificity of the enzyme