AP-1 in Toxoplasma gondii mediates biogenesis of the rhoptry secretory organelle from a post-Golgi compartment

Huân M. Ngô, Mei Yang, Kerstin Paprotka, Marc Pypaert, Heinrich Hoppe, Keith A Joiner

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We have previously demonstrated that Toxoplasma gondii has a tyrosine-based sorting system, which mediates protein targeting to the lysosome-like rhoptry secretory organelle. We now show that rhoptry protein targeting is also dependent on a dileucine motif and occurs from a post-Golgi endocytic organelle to mature rhoptries in an adaptin-dependent fashion. The T. gondii AP-1 adaptin complex is implicated in this transport because the μ1 chain of T. gondii AP-1 (a) was localized to multivesicular endosomes and the limiting and luminal membranes of the rhoptries; (b) bound to endocytic tyrosine motifs in rhoptry proteins, but not in proteins from dense granule secretory organelles; (c) when mutated in predicted tyrosine-binding motifs, led to accumulation of the rhoptry protein ROP2 in a post-Golgi multivesicular compartment; and (d) when depleted via antisense mRNA, resulted in accumulation of multivesicular endosomes and immature rhoptries. These are the first results to implicate AP-1 in transport from a post-Golgi compartment to a mature secretory organelle and substantially expand the role for AP-1 in anterograde protein transport.

Original languageEnglish (US)
Pages (from-to)5343-5352
Number of pages10
JournalJournal of Biological Chemistry
Issue number7
Publication statusPublished - Feb 14 2003
Externally publishedYes


ASJC Scopus subject areas

  • Biochemistry

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