E-Poster with pre-recorded video presentation Lorne Infection and Immunity 2021

Taming the beast: disarming pathogenic bacteria with novel anti-virulence agents (#310)

Geqing Wang 1 , Anthony D. Verderosa 2 , Jason J. Paxman 1 , Rabeb Dhouib 2 , Wesam Alwan 3 , Bradley Doak 3 , Jennifer L. Martin 4 , Martin J. Scanlon 3 , Makrina Totsika 2 , Begoña Heras 1
  1. La Trobe Institute for Molecular Science, Bundoora, VIC, Australia
  2. Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia
  3. Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Parkville, VIC, Australia
  4. Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD

The emergence and spread of antibiotic resistance has jeopardized the effectiveness of current treatments that fight bacterial infections and motivated an active search for novel antibacterial targets and strategies. Bacteria rely on the biosynthesis of virulence factors to establish an infection in a host and cause disease. Disarming bacteria by anti-virulence agents has emerged as a promising approach to contain bacterial infections. This approach may have advantages over traditional antibiotics as it specifically targets virulence factors required for pathogenesis and do not inhibit bacterial viability or growth, potentially reducing selection pressure for resistance development. Many of these virulence factors, such as secreted toxins, adhesins, components of secretion systems and motility organelles, require folding into their native state by the thiol-disulfide oxidoreductase enzyme DsbA.1 Bacteria lacking a functional DsbA displays reduced virulence, increased sensitivity to antibiotics and diminished capacity to cause infection in many Gram-negative pathogens.1 DsbA thus has been identified as a viable target to sabotage bacterial virulence.

 

In our drug discovery program, we carried out multiple compound screening campaigns against DsbA and identified several classes of small molecule inhibitors binding to two proximal sites adjacent to the catalytic site of DsbA.2-4 We examined simultaneous targeting of both DsbA binding sites by separate inhibitors and evaluated their impact on DsbA function in vitro and in vivo. Using X-ray crystallography, molecular modelling along with other biochemical assays, we demonstrated that combining these two inhibition modes enhanced DsbA inhibitory activity in vitro. More importantly, a synergistic effect of these compounds was also observed in vivo, where co-treatment of the pathogen Salmonella enterica serovar Typhimurium with two types of inhibitors resulted in increased attenuation of virulence. Overall, this work provides a new avenue for designing more potent DsbA inhibitors with enhanced anti-virulence activity and could lead to a new generation of antibacterial agents to treat drug-resistant bacterial infections.

  1. 1. B. Heras, et al. (2009), DSB proteins and bacterial pathogenicity, Nat. Rev. Microbiol., 7,215-225 2. 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 3. M.Totsika, et al. (2018), Inhibition of diverse DsbA enzymes in multi-DsbA encoding pathogens. Antioxid. Redox. Signal., 29(7): 653–666. 4. L.F. Duncan, et al. (2019), The Fragment-Based Development of a Benzofuran Hit as a New Class of Escherichia coli DsbA Inhibitors, Molecules, 24(20), 3756