Our lab aims to reveal fundamental molecular mechanisms underlying pathogenesis in the Apicomplexa – a collection of notorious human and animal parasites. Apicomplexan parasites are related based on similarities in their infection mechanism and include Plasmodium spp (malaria), Cryptosporidium spp (severe diarrhoea) and Toxoplasma gondii (toxoplasmosis).

We use a range of molecular and biochemical techniques to unveil essential processes that govern their behaviour and ability to thwart our body’s defences. Our aim is to find chinks in their armour to use for therapeutic advantage.

The lab has broad interests and currently focusses on the following questions:

  • how do parasites sense their environment to regulate motility and invasion?
  • how does latent Toxoplasma persist and cause brain dysfunction?


Selected publications from A/Prof Chris Tonkin

Uboldi AD, Wilde ML, McRae EA, Stewart RJ, Dagley LF, Yang L, Katris NJ, Hapuarachchi SV, Coffey MJ, Lehane AM, Botte CY, Waller RF, Webb AI, McConville MJ, Tonkin CJ. Protein kinase A negatively regulates Ca2+ signalling in Toxoplasma gondii. PLoS Biol. 2018 Sep 12;16(9):e2005642 PMID: 30208022

Khurana S#, Coffey MJ#, John A, Uboldi AD, Huynh MH, Stewart RJ, Carruthers V, Tonkin CJ*, Goddard-Borger ED*, Scott NE*. Protein O-fucosyltransferase 2-mediated O-glycosylation of the adhesin MIC2 is dispensable for Toxoplasma gondii tachyzoite infection. J Biol Chem. 2018 Dec 4. pii: jbc.RA118.005357. PMID: 30514763. *Co-corresponding authors # Equal contribution

McCoy JM, Stewart RJ, Uboldi AD, Li D, Schröder J, Scott NE, Papenfuss AT, Lehane AM, Foster LJ, Tonkin CJ. A forward genetic screen identifies a negative regulator of rapid Ca(2+)-dependent cell egress (MS1) in the intracellular parasite Toxoplasma gondii. J Biol Chem. 2017 May 5;292(18):7662-7674. PMID: 28258212

Stewart RJ, Whitehead L, Nijagal B, Sleebs BE, Lessene G, McConville MJ, Rogers KL, Tonkin CJ. Analysis of Ca2+ mediated signaling regulating Toxoplasma infectivity reveals complex relationships between key molecules. Cell Microbiol. 2017 Apr;19(4). PMID: 27781359

Uboldi AD#, McCoy JM#, Blume M, Gerlic M, Ferguson DJ, Dagley LF, Beahan CT, Stapleton DI, Gooley PR, Bacic A, Masters SL, Webb AI, McConville MJ, Tonkin CJ. Regulation of Starch Stores by a Ca2+-Dependent Protein Kinase Is Essential for Viable Cyst Development in Toxoplasma gondii. Cell Host Microbe. 2015 Dec 9;18(6):670-81. PMID: 26651943. # Equal contribution

Coffey MJ, Sleebs BE, Uboldi AD, Garnham A, Franco M, Marino ND, Panas MW, Ferguson DJ, Enciso M, O’Neill MT, Lopaticki S, Stewart RJ, Dewson G, Smyth GK, Smith BJ, Masters SL, Boothroyd JC, Boddey JA*, Tonkin CJ*. An aspartyl protease defines a novel pathway for export of Toxoplasma proteins into the host cell. Elife. 2015 Nov 18;4. pii: e10809. PMID: 26576949 * Co-corresponding authors

Williams MJ, Alonso H, Enciso M, Egarter S, Sheiner L, Meissner M, Striepen B, Smith BJ, Tonkin CJ. Two Essential Light Chains Regulate the MyoA Lever Arm To Promote Toxoplasma Gliding Motility. MBio. 2015 Sep 15;6(5):e00845-15. PMID: 26374117

Howard BL, Harvey KL, Stewart RJ, Azevedo MF, Crabb BS, Jennings IG, Sanders PR, Manallack DT, Thompson PE*, Tonkin CJ*, Gilson PR*. Identification of potent phosphodiesterase inhibitors that demonstrate cyclic nucleotide-dependent functions in apicomplexan parasites. ACS Chem Biol. 2015 Apr 17;10(4):1145-54. PMID: 25555060. *co-corresponding authors

McCoy JM, Whitehead L, van Dooren GG, Tonkin CJ. TgCDPK3 regulates calcium-dependent egress of Toxoplasma gondii from host cells. PLoS Pathog. 2012;8(12):e1003066 PMID: 23226109

Nebl T, Prieto JH, Kapp E, Smith BJ, Williams MJ, Yates JR 3rd, Cowman AF, Tonkin CJ. Quantitative in vivo analyses reveal calcium-dependent phosphorylation sites and identifies a novel component of the Toxoplasma invasion motor complex. PLoS Pathog. 2011 Sep;7(9):e1002222 PMID: 21980283

Lab research projects

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