Jacqueline M Leung1, Eiji Nagayasu2, Yu-Chen Hwang3, Jun Liu1, Phillip G Pierce4, Isabelle Q Phan5, Robin A Prentice5,6, John M Murray1, Ke Hu7. 1. Department of Biology, Indiana University, Bloomington, IN, 47405, USA. 2. Department of Infectious Diseases, Division of Parasitology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan. 3. Nikon Instruments Inc, Melville, New York, 11747, USA. 4. UCB, and Seattle Structural Genomics Center for Infectious Disease, Bainbridge Island, WA, 98110, USA. 5. Center for Global Infectious Disease Research, Seattle Children's Research Institute, and Seattle Structural Genomics Center for Infectious Disease, Seattle, WA, 98109, USA. 6. University of Washington, Brotman Bady Institute, Seattle, WA, 98195, USA. 7. Department of Biology, Indiana University, Bloomington, IN, 47405, USA. kehu@indiana.edu.
Abstract
BACKGROUND: TgDCX is a doublecortin-domain protein associated with the conoid fibers, a set of strongly curved non-tubular tubulin-polymers in Toxoplasma. TgDCX deletion impairs conoid structure and parasite invasion. TgDCX contains two tubulin-binding domains: a partial P25α and the DCX/doublecortin domain. Orthologues are found in apicomplexans and their free-living relatives Chromera and Vitrella. RESULTS: We report that isolated TgDCX-containing conoid fibers retain their pronounced curvature, but loss of TgDCX destabilizes the fibers. We crystallized and determined the 3D-structure of the DCX-domain, which is similar to those of human doublecortin and well-conserved among TgDCX orthologues. However, the orthologues vary widely in targeting to the conoid in Toxoplasma and in modulating microtubule organization in Xenopus cells. Several orthologues bind to microtubules in Xenopus cells, but only TgDCX generates short, strongly curved microtubule arcs. EM analysis shows microtubules decorated with TgDCX bundled into rafts, often bordered on one edge by a "C"-shaped incomplete tube. A Chromera orthologue closely mimics TgDCX targeting in Toxoplasma and binds to microtubules in Xenopus cells, but does not generate arcs or "C"-shaped tubes, and fails to rescue the defects of the TgDCX-knockout parasite. CONCLUSIONS: These observations suggest that species-specific features of TgDCX enable it to generate strongly curved tubulin-polymers to support efficient host-cell invasion.
BACKGROUND:TgDCX is a doublecortin-domain protein associated with the conoid fibers, a set of strongly curved non-tubular tubulin-polymers in Toxoplasma. TgDCX deletion impairs conoid structure and parasite invasion. TgDCX contains two tubulin-binding domains: a partial P25α and the DCX/doublecortin domain. Orthologues are found in apicomplexans and their free-living relatives Chromera and Vitrella. RESULTS: We report that isolated TgDCX-containing conoid fibers retain their pronounced curvature, but loss of TgDCX destabilizes the fibers. We crystallized and determined the 3D-structure of the DCX-domain, which is similar to those of humandoublecortin and well-conserved among TgDCX orthologues. However, the orthologues vary widely in targeting to the conoid in Toxoplasma and in modulating microtubule organization in Xenopus cells. Several orthologues bind to microtubules in Xenopus cells, but only TgDCX generates short, strongly curved microtubule arcs. EM analysis shows microtubules decorated with TgDCX bundled into rafts, often bordered on one edge by a "C"-shaped incomplete tube. A Chromera orthologue closely mimics TgDCX targeting in Toxoplasma and binds to microtubules in Xenopus cells, but does not generate arcs or "C"-shaped tubes, and fails to rescue the defects of the TgDCX-knockout parasite. CONCLUSIONS: These observations suggest that species-specific features of TgDCX enable it to generate strongly curved tubulin-polymers to support efficient host-cell invasion.
Authors: Ludek Koreny; Mohammad Zeeshan; Konstantin Barylyuk; Eelco C Tromer; Jolien J E van Hooff; Declan Brady; Huiling Ke; Sara Chelaghma; David J P Ferguson; Laura Eme; Rita Tewari; Ross F Waller Journal: PLoS Biol Date: 2021-03-11 Impact factor: 8.029
Authors: Stella Y Sun; Li-Av Segev-Zarko; Muyuan Chen; Grigore D Pintilie; Michael F Schmid; Steven J Ludtke; John C Boothroyd; Wah Chiu Journal: Proc Natl Acad Sci U S A Date: 2022-02-08 Impact factor: 11.205
Authors: Jonathan Munera Lopez; Isadonna F Tengganu; Jun Liu; John M Murray; Luisa F Arias Padilla; Ying Zhang; Peter T Brown; Laurence Florens; Ke Hu Journal: PLoS Pathog Date: 2022-08-22 Impact factor: 7.464