Tuesday, April 12, 2016

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

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

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.


Apicoplast; PI(3,5)P(2); Phosphoinositides; Pleckstrin homology domain; Toxoplasma gondii
[PubMed - as supplied by publisher]

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