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PDBsum entry 3zle
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Membrane protein
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PDB id
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3zle
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References listed in PDB file
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Key reference
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Title
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Toxoplasma gondii sporozoites invade host cells using two novel paralogues of ron2 and ama1.
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Authors
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A.Poukchanski,
H.M.Fritz,
M.L.Tonkin,
M.Treeck,
M.J.Boulanger,
J.C.Boothroyd.
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Ref.
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Plos One, 2013,
8,
e70637.
[DOI no: ]
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PubMed id
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Abstract
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Toxoplasma gondii is an obligate intracellular parasite of the phylum
Apicomplexa. The interaction of two well-studied proteins, Apical Membrane
Antigen 1 (AMA1) and Rhoptry Neck protein 2 (RON2), has been shown to be
critical for invasion by the asexual tachyzoite stage. Recently, two paralogues
of these proteins, dubbed sporoAMA1 and sporoRON2 (or RON2L2), respectively,
have been identified but not further characterized in proteomic and
transcriptomic analyses of Toxoplasma sporozoites. Here, we show that sporoAMA1
and sporoRON2 localize to the apical region of sporozoites and that, in vitro,
they interact specifically and exclusively, with no detectable interaction of
sporoAMA1 with generic RON2 or sporoRON2 with generic AMA1. Structural studies
of the interacting domains of sporoRON2 and sporoAMA1 indicate a novel pairing
that is similar in overall form but distinct in detail from the previously
described interaction of the generic pairing. Most notably, binding of sporoRON2
domain 3 to domains I/II of sporoAMA1 results in major alterations in the latter
protein at the site of binding and allosterically in the membrane-proximal
domain III of sporoAMA1 suggesting a possible role in signaling. Lastly,
pretreatment of sporozoites with domain 3 of sporoRON2 substantially impedes
their invasion into host cells while having no effect on tachyzoites, and vice
versa for domain 3 of generic RON2 (which inhibits tachyzoite but not sporozoite
invasion). These data indicate that sporozoites and tachyzoites each use a
distinct pair of paralogous AMA1 and RON2 proteins for invasion into host cells,
possibly due to the very different environment in which they each must function.
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