Poster Presentation 16th Lorne Infection and Immunity 2026

Structural and Functional Specialisation of Bordetella pertussis DsbA for Pertussis Toxin Folding (133252)

Stephanie Penning 1 , Lachlan Mitchell 1 , Yaoqin Hong 2 3 , Taylor Cunliffe 1 , Pramod Subedi 1 , Geqing Hong 1 , Lilian Hor 4 , Makrina Totsika 2 , Jason J Paxman 1 , Begona Heras 1
  1. La Trobe University, Macleod, VICTORIA, Australia
  2. Centre for Immunology and Infection Control, Queensland University of Technology, Brisbane, Queensland, Australia
  3. Biomedical Sciences and Molecular Biology, College of Medicine and Dentistry, James Cook University, Townsville, Q
  4. Burnet Diagnostics Initiative , Melbourne, Victoria, Australia

Whooping cough, caused by the gram-negative bacteria Bordetella pertussis, is a global health burden and a leading cause of infant mortality worldwide. The continued relevance of this disease is driven by the emergence of B. pertussis strains that evade immunity conferred by current acellular vaccines  [1] in addition to increasing resistance against macrolide antibiotics- currently the treatment of choice for B. pertussis infections [2]. These limitations highlight the need for novel therapeutic strategies, including those that target bacterial virulence pathways.

In B. pertussis, BperDsbA (an enzyme responsible for catalysing disulphide bond formation)  is essential for the folding of the pertussis toxin (PTX)- a key virulence determinant [3, 4], making it a compelling target for anti-virulence drug development [5]. Here, we provide the first comprehensive structural and functional characterisation of BperDsbA.

Our data show that this protein is a structurally canonical but functionally specialised member of the DsbA family. BperDsbA adopts a canonical TRX fold with a CPHC active site and a threonine-containing cis-proline loop but displays striking deviations from prototypical DsbAs. Notably, it contains a highly destabilising catalytic disulphide bond, resulting in one of the most oxidising redox potentials recorded for a DsbA enzyme. Surface electrostatic analysis reveals an unusual distribution of positive and negative charge around the active site, in contrast to the broadly hydrophobic catalytic surfaces of other DsbAs. Functionally, BperDsbA shows limited substrate promiscuity and selectively catalyses the oxidative folding of a PTX–derived peptide, supporting a model of substrate specialisation. Together, these findings suggest that BperDsbA has evolved unique redox and structural features to support virulence factor maturation in B. pertussis. This work expands our understanding of the mechanistic diversity of DsbA enzymes and highlights their potential as pathogen-specific targets for anti-virulence therapeutics.

  1. 1. Ma, L., et al., Pertactin-Deficient Bordetella pertussis, Vaccine-Driven Evolution, and Reemergence of Pertussis. Emerg Infect Dis, 2021. 27(6): p. 1561-1566.
  2. 2. Ivaska, L., et al., Macrolide Resistance in Bordetella pertussis: Current Situation and Future Challenges. Antibiotics (Basel), 2022. 11(11).
  3. 3. Smith, A.M., C.A. Guzmán, and M.J. Walker, The virulence factors of Bordetella pertussis: a matter of control. FEMS Microbiol Rev, 2001. 25(3): p. 309-33.
  4. 4. Stenson, T.H. and A.A. Weiss, DsbA and DsbC Are Required for Secretion of Pertussis Toxin by Bordetella pertussis. Infection and Immunity, 2002. 70(5): p. 2297-2303.
  5. 5. Heras, B., M.J. Scanlon, and J.L. Martin, Targeting virulence not viability in the search for future antibacterials. British Journal of Clinical Pharmacology, 2015. 79(2): p. 208-215.