title: Targeting to rhoptry organelles of Toxoplasma gondii involves evolutionarily conserved mechanisms.
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 micro-chain subunits of T. gondii and mammalian adaptors, and conforms to the YXXstraight phi 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 YXXstraight phi- 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.
authors.affiliation: Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8022, USA.
authors.forename: H C
authors.initials: HC
authors.lastname: Hoppe
authors.forename: H M
authors.initials: HM
authors.lastname: Ngô
authors.forename: M
authors.initials: M
authors.lastname: Yang
authors.forename: K A
authors.initials: KA
authors.lastname: Joiner
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D015703:Antigens, CD / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D002966:Clathrin / Q000378:metabolism; D017124:Conserved Sequence / Q000235:genetics / Q000502:physiology*; D019143:Evolution, Molecular; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000378:metabolism; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D015388:Organelles / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding; D021382:Protein Sorting Signals / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011973:Receptors, LDL / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014122:Toxoplasma / Q000166:cytology* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D020798:Two-Hybrid System Techniques; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D002966:Clathrin; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D021382:Protein Sorting Signals; D015800:Protozoan Proteins; C090555:ROP 2 protein, Toxoplasma gondii; D011973:Receptors, LDL; D011993:Recombinant Fusion Proteins; D014443:Tyrosine