Student Posters 51st Lorne Proteins Conference 2026

Characterisation of the protein-protein complex formed by the zinc binding proteins PA4063 and PA4066 from Pseudomonas aeruginosa (#130)

Josephine Goodall 1 2 , Megan Maher 1 2 3 , Christopher McDevitt 4 5
  1. School of Chemistry, The University of Melbourne, Parkville, Victoria, Australia
  2. The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
  3. Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
  4. The Peter Doherty Institute for Infection and Immunity , The University of Melbourne and The Royal Melbourne Hospital, Parkville, Victoria, Australia
  5. The Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia

Pseudomonas aeruginosa is a gram-negative bacterium that can cause a wide range of serious infections that are challenging to treat via traditional methods [1]. Like many organisms P. aeruginosa has evolved complex systems to preserve internal zinc homeostasis allowing for the maintenance of optimal levels of this life-sustaining, but potentially toxic, micronutrient [1,2].  For pathogenic bacteria these systems are critical to their ability to effectively colonise eukaryotic hosts as they assist in overcoming host immune responses which sequester Zn2+ to slow pathogen growth [3].  Even amongst pathogenic bacteria P. aeruginosa is notably adept at thriving in zinc deficient environments which has been attributed to the presence of several high affinity zinc import systems in addition to the well characterised ZnuABC system found in most gram-negative bacteria [4].  These additional systems have been found to contribute significantly to P. aeruginosa’s extreme virulence making discovering how these systems function a focus of research efforts aiming to build a comprehensive model of how P. aeruginosa infects hosts [5].

One of these additional systems is the putative ABC transporter PA4063-66, which has been found to be the system with the highest expression in low zinc environments [6]. Unlike a typical ABC transporter the PA4063-66 system has two potential substrate binding proteins (SBPs), PA4063 and PA4066, which, despite both having a nanomolar affinity to zinc and being localised to the periplasm, lack typical SBP structures [4,5]. We have shown that these two proteins form a complex with a micromolar affinity, however, the addition of excess zinc causes complex dissociation suggesting that the binding of Zn2+ to one or both proteins destabilizes the complex structure. This poster will present our work on characterising the relationship between zinc binding and complex dissociation, in addition to the possible consequences of our results for mechanisms of Zn2+ homeostasis in P. aeruginosa.

  1. Gonzalez, M. A., Ducret, V., Leoni, S., & Perron, K. (2018). Pseudomonas aeruginosa zinc homeostasis: Key issues for an opportunistic pathogen. Biochimica et Biophysica Acta, 1862(7), 722–733. https://doi.org/10.1016/j.bbagrm.2018.01.018
  2. Wang, S., Cheng, J., Niu, Y., Li, P., Zhang, X., & Lin, J. (2021). Strategies for Zinc Uptake in Pseudomonas aeruginosa at the Host–Pathogen Interface. Frontiers in Microbiology, 12. https://doi.org/10.3389/fmicb.2021.741873
  3. Murdoch, C. C., & Skaar, E. P. (2022). Nutritional immunity: the battle for nutrient metals at the host–pathogen interface. Nature Reviews Microbiology, 20(11), 657–670. https://doi.org/10.1038/s41579-022-00745-6
  4. Pederick, V. G., Eijkelkamp, B. A., Begg, S. L., Ween, M. P., McAllister, L. J., Paton, J. C., & McDevitt, C. A. (2015). ZnuA and zinc homeostasis in Pseudomonas aeruginosa. Scientific Reports, 5(1). https://doi.org/10.1038/srep13139
  5. Mastropasqua, M. C., Lamont, I., Martin, L. W., Reid, D. W., D’Orazio, M., & Battistoni, A. (2018). Efficient zinc uptake is critical for the ability of Pseudomonas aeruginosa to express virulence traits and colonize the human lung. Journal of Trace Elements in Medicine and Biology, 48, 74–80. https://doi.org/10.1016/j.jtemb.2018.03.009
  6. Ducret, V., Abdou, M., Goncalves Milho, C., Leoni, S., Martin--Pelaud, O., Sandoz, A., Segovia Campos, I., Tercier-Waeber, M.-L., Valentini, M., & Perron, K. (2021). Global Analysis of the Zinc Homeostasis Network in Pseudomonas aeruginosa and Its Gene Expression Dynamics. Frontiers in Microbiology, 12. https://doi.org/10.3389/fmicb.2021.739988