Poster Presentation Lorne Infection and Immunity 2020

The search for evolutionarily robust antibacterials: fragment-based development of inhibitors of a key mediator of bacterial virulence (#106)

Tony Wang 1 , Wesam Alwan 2 , Matthew Bentley 2 , Rabeb Dhouib 3 , Makrina Totsika 3 , Roisin McMahon 4 , Benvenuto Capuano 2 , Peter Scammells 2 , Bradley Doak 2 , Jennifer L. Martin 4 , Martin J. Scanlon 2 , Begoña Heras 1
  1. La Trobe Institute for Molecular Science, Bundoora, VIC, Australia
  2. Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Parkville, VIC, Australia
  3. Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia
  4. Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD

Disulfide bond formation protein A (DsbA) is a thiol-disulfide oxidoreductase enzyme which catalyses disulfide bond formation in the periplasm of Gram-negative bacteria. DsbA facilitates folding of multiple virulent factors that bacteria use for adhesion, secretion, toxicity and motility. Consequently, loss of DsbA has a pleiotropic effect and influences multiple downstream virulence pathways. Previous studies showed that bacteria lacking a functional DsbA display reduced virulence, increased sensitivity to antibiotics and diminished capacity to cause infection.1 This protein has been shown to be required for the pathogenesis of critical human pathogens such as Escherichia coli, Vibrio cholerae, Salmonella enterica Typhimurium and Pseudomonas aeruginosa, which show high levels of resistance to many antibiotics.2 The critical role of DsbA in bacterial virulence makes it an attractive anti-virulence target to combat multi-drug-resistant (MDR) bacteria. As DsbA is not essential for bacterial viability, targeting DsbA potentially minimises resistance development due to reduced selection pressure and preserve non-virulent gut microbiota.

Escherichia coli DsbA (EcDsbA) comprises a classical “CPHC” redox active site that catalyses disulfide bond exchange. Using fragment-based screening approach, we identified two binding sites in the vicinity of the catalytic site. Small molecule inhibitors targeting these sites were found to inhibit EcDsbA activity in vitro and in cell-based phenotypic assays. 3 In addition, inhibitors developed against EcDsbA were also demonstrated to inhibit the diverse DsbA homologues found in two important human pathogens uropathogenic E.coli CFT073 and S. Typhimurium SL1344 and attenuate their virulence. 4 This work presents an exciting new opportunity for anti-virulence drug development and could potentially lead to more evolutionarily robust antimicrobials that can be used to treat MDR bacterial infections.

 

  1. 1. B. Heras, et al. (2009), DSB proteins and bacterial pathogenicity, Nat. Rev. Microbiol., 7,215-225 2. W.H.O, (2017), Global priority list of antibiotic-resistant bacteria to guide research, discovery, and development of new antibiotics 3. L.A. Adams, et al. (2015), Application of fragment-based screening to the design of inhibitors of Escherichia coli DsbA, Angew. Chem. Int. Ed., 54, 2179-2184 4. M.Totsika, et al. (2018), Inhibition of diverse DsbA enzymes in multi-DsbA encoding pathogens. Antioxid. Redox. Signal., 29(7):653-666