Fig. 6

The DCX domain alone does not support stable microtubule binding in Xenopus cells, or conoid targeting in Toxoplasma. a-b Deconvolved wide-field images of Xenopus S3 cells expressing EGFP-tubulin (green) and either mCherryFP-TgDCX148–243 (a, red) or mCherryFP-TgDCX71–243 (b, red). The boxed insets in b are 1.5x enlarged and contrast-enhanced views of small regions over the nucleus that include the slices from the 3D stacks in which these individual arcs are clearly seen (also see Additional file 5: Movie S3). The DCX domain alone (TgDCX148–243) is not sufficient for microtubule binding, but P25α + DCX domain together (TgDCX71–243) cause binding to microtubules and generation of short arcs. c-d Deconvolved wide-field images of the parental RHΔku80Δhx (“WT”) and TgDCX knockout (“ΔTgDCX”) parasites expressing either mCherryFP-TgDCX148–243 (c), or mCherryFP-TgDCX71–243 (d), two examples are shown for ΔTgDCX). Arrowheads in c indicate the nucleus. Arrows in d point to the conoid; arrowhead in d points to a daughter conoid. e-h EM images of the conoid region of negatively stained T. gondii. Parental RHΔku80Δhx (e, “WT”); TgDCX knockout (f, “ΔTgDCX”); knockout parasites transfected with a plasmid expressing either EGFP tagged full-length TgDCX (g, “ΔTgDCX/TgDCX”), or mCherryFP-TgDCX71–243 (h, “ΔTgDCX/TgDCX71–243”), both expressed under control of the T. gondii α-tubulin promoter (constitutive, See Fig. 9d). i Plaque assays (see Methods) of the parasite strains used for e-h; the parental T. gondii, TgDCX-knockout parasites, and knockout parasites complemented with full-length TgDCX or the fragment containing only the partial P25α domain and the DCX domain, TgDCX71–243. Annotations are the same as e-h. j Domain structure of TgDCX in which the amino acid boundaries of the partial P25α domain and the DCX domain are numbered