Article abstract
Nature Cell Biology 2, 449 - 456 (2000)
Published online: 20 June 2000 | doi:10.1038/35017090
Targeting to rhoptry organelles of Toxoplasma gondii involves evolutionarily conserved mechanisms.
Heinrich C. Hoppe1, Huân M. Ngô1, Mei Yang1 & Keith A. Joiner1
Abstract
Intracellular parasites of the phylum Apicomplexa contain specialized rhoptry
secretory organelles that have a crucial function in host-cell invasion and
establishment of the parasitophorous vacuole. Here we show that localization
of the Toxoplasma gondii rhoptry protein ROP2 is dependent on a YEQL
sequence in the cytoplasmic tail that binds to 
-chain subunits of
T. gondii and mammalian adaptors, and conforms to the YXX
mammalian
sorting motif. Chimaeric reporters, containing the transmembrane domains and
cytoplasmic tails of the low-density lipoprotein receptor and of Lamp-1, are
sorted to the Golgi or the trans-Golgi network (TGN), and partially
to apical microneme organelles of the parasite, respectively. Targeting of
these reporters is mediated by YXX- and NPXY-type signals. This is the
first demonstration of tyrosine-dependent sorting in protozoan parasites,
indicating that T. gondii proteins may be targeted to, and involved
in biogenesis of, morphologically unique organelles through the use of evolutionarily
conserved signals and machinery.
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8022, USA
Correspondence to: Keith A. Joiner1 e-mail: keith.joiner@yale.edu
