title: Small molecule inhibitors of disulfide bond formation by the bacterial DsbA-DsbB dual enzyme system.
abstract: The DsbA:DsbB redox machinery catalyzes disulfide bond formation in secreted proteins and is required for bacterial virulence factor assembly. Both enzymes have been identified as targets for antivirulence drugs. Here, we report synthetic analogues of ubiquinone (dimedone derivatives) that inhibit disulfide bond formation (IC50∼1 μM) catalyzed by E. coli DsbA:DsbB. The mechanism involves covalent modification of a single free cysteine leaving other cysteines unmodified. A vinylogous anhydride in each inhibitor is cleaved by the thiol, which becomes covalently modified to a thioester by a propionyl substituent. Cysteines and lysines on DsbA and DsbB and a nonredox enzyme were modified in a manner that implies some specificity. Moreover, human thioredoxin was not inhibited under the same conditions that inhibited EcDsbA. This proof of concept work uses small molecules that target specific cysteines to validate the DsbA and DsbB dual enzyme system as a viable and potentially druggable antivirulence target.
authors.affiliation: †Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Halili
authors.affiliation: †Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Prabhakar
authors.initials: P
authors.lastname: Bachu
authors.affiliation: †Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Lindahl
authors.affiliation: ‡Department of Chemistry, South Parks Road, Oxford OX1 3QZ, United Kingdom.
authors.forename: Chérine
authors.initials: C
authors.lastname: Bechara
authors.affiliation: §Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052, Australia.
authors.forename: Biswaranjan
authors.initials: B
authors.lastname: Mohanty
authors.affiliation: †Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Reid
authors.affiliation: §Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052, Australia.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Scanlon
authors.affiliation: ‡Department of Chemistry, South Parks Road, Oxford OX1 3QZ, United Kingdom.
authors.forename: Carol V
authors.initials: CV
authors.lastname: Robinson
authors.affiliation: †Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: David P
authors.initials: DP
authors.lastname: Fairlie
authors.affiliation: †Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Martin
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry*; D015195:Drug Design; D004353:Drug Evaluation, Preclinical / Q000379:methods; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D008239:Lysine / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D019704:Protein Disulfide-Isomerases / Q000737:chemistry* / Q000378:metabolism; D054852:Small Molecule Libraries / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013879:Thioredoxins / Q000037:antagonists & inhibitors; D014451:Ubiquinone / Q000031:analogs & derivatives
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004220:Disulfides; C079503:DsbB protein, Bacteria; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D054852:Small Molecule Libraries; D014451:Ubiquinone; D013879:Thioredoxins; D019704:Protein Disulfide-Isomerases; C526648:dsbA protein, E coli; D008239:Lysine; D003545:Cysteine