Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2022

The cyclophilin, PpiA, is involved in motility, biofilm formation and polyhydroxybutyrate production in Burkholderia pseudomallei (82429)

Nicole M Bzdyl 1 , Nichollas E Scott 2 , Jua Iwasaki 1 3 , Charlene Kahler 1 , Mitali Sarkar-Tyson 1
  1. Marshall Centre of Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, WA, Australia
  2. Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria, Australia
  3. Wesfarmers Centre for Vaccines and Infectious Diseases, Telethon Kids Institute, Crawley, WA, Australia

Burkholderia pseudomallei is a Gram-negative pathogen which is endemic in the soil and water of the tropical regions. It is the causative agent of melioidosis, a disease with high mortality rates even with antibiotic therapy. B. pseudomallei is highly adapted to environmental survival and is able to overcome nutrient limiting conditions and various extracellular stresses. Cyclophilins are a family of highly conserved folding enzymes which play a pivotal role in maintaining cellular processes. They catalyse the cis-trans isomerisation of proline bonds, a rate limiting step in enabling correct protein structure. B. pseudomallei encodes for a putative cyclophilin, ppiA, the role of which was investigated in this study. Recombinant PpiA was shown to be an active protein which was inhibited by cyclosporin A. To understand the function of ppiA in B. pseudomallei a deletion strain, Bps∆ppiA, was constructed and global proteomic analysis was conducted. This identified 812 proteins that were differentially present in Bps∆ppiA when compared to the wild-type strain, including those important for motility and biofilm formation. This was confirmed in Bps∆ppiA which displayed a 25% reduction in swarming motility and a 65% reduction in biofilm production compared to the wild type strain, and are important factors in B. pseudomallei environmental survival. Additionally, pathways involved in energy acquisition under nutrient limiting conditions were affected, with electron microscopy demonstrating a decrease in polyhydroxybutyrate (PHB) granules, verified by quantification of PHB which showed a significant decrease in PHB production in Bps∆ppiA. Using a bacterial two-hybrid system it was confirmed that PpiA directly interacts with PhbB, the enzyme responsible for PHB production in B. pseudomallei. This study has shown that the cyclophilin, PpiA, plays a role in multiple cellular pathways in B. pseudomallei including motility, biofilm formation and polyhydroxybutyrate production, factors which promote environmental survival of this pathogen.