Identification of Toxoplasma TgpH1, a pleckstrin homology domain-containing protein that binds to the phosphoinositide PI(3,5)P2

Mol Biochem Parasitol. 2016 Apr 7. pii: S0166-6851(16)30028-7. doi: 10.1016/j.molbiopara.2016.03.011. [Epub ahead of print]

Daher W¹, Morlon-Guyot J¹, Alayi TD², Tomavo S³, Wengelnik K¹, Lebrun M⁴.

The phosphoinositide phosphatidylinositol-3,5-bisphosphate (PI(3,5)P₂) plays crucial roles in the maintenance of lysosome/vacuole morphology, membrane trafficking and regulation of endolysosome-localized membrane channel activity. In Toxoplasma gondii, we previously reported that PI(3,5)P₂ is essential for parasite survival by controlling homeostasis of the apicoplast, a particular organelle of algal origin. Here, by using a phosphoinositide pull-down assay, we identified TgpH1 in Toxoplasma a protein conserved in many apicomplexan parasites. TgpH1 binds specifically to PI(3,5)P₂, shows punctate intracellular localization, but plays no vital role for tachyzoite growth in vitro. TgpH1 is a protein predominantly formed by a pleckstrin homology (pH) domain. So far, pH domains have been described to bind preferentially to bis- or trisphosphate phosphoinositides containing two adjacent phosphates (i.e. PI(3,4)P₂, PI(4,5)P₂, PI(3,4,5)P₃). Therefore, our study reveals an unusual feature of TgpH1 which binds preferentially to PI(3,5)P₂.
Copyright © 2016 Elsevier B.V. All rights reserved.

KEYWORDS:

Apicoplast; PI(3,5)P(2); Phosphoinositides; Pleckstrin homology domain; Toxoplasma gondii

PMID:

27063980

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