Toxoplasma Rhoptry Protein 16 (ROP16) Subverts Host Function by Direct Tyrosine Phosphorylation of STAT6
Toxoplasma Rhoptry Protein 16 (ROP16) Subverts Host Function by Direct Tyrosine Phosphorylation of STAT6
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DOI：
10.1074/jbc.m110.112359
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发表时间：
2010-09-10
影响因子：
4.8
通讯作者：
Boothroyd, John C.
中科院分区：
文献类型：
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作者：
Ong, Yi-Ching;Reese, Michael L.;Boothroyd, John C.
专性细胞内寄生虫弓形虫以各种高度特异的方式调节宿主免疫。先前的工作揭示了一种多态的注射寄生因子ROP16，它是宿主细胞转录的关键毒力决定因素和调节因子。这些特性被证明部分是通过寄主转录因子STAT3和STAT6的失调来调节的，但这种表型背后的分子机制尚不清楚。在这里，我们使用了一种缺乏ROP16的I型弓形虫菌株来证明ROP16不仅可以诱导STAT6的持续激活，而且还可以极快地(在1分钟内)初始激活STAT6。利用重组野生型和激酶缺陷型ROP16，我们在体外证明了ROP16具有内在的酪氨酸激酶活性，并能够直接磷酸化STAT6激活的关键酪氨酸残基Tyr(641)。此外，ROP16与感染细胞中的STAT6共沉淀。综上所述，这些数据有力地表明，STAT6是体内ROP16的直接底物。
The obligate intracellular parasite, Toxoplasma gondii, modulates host immunity in a variety of highly specific ways. Previous work revealed a polymorphic, injected parasite factor, ROP16, to be a key virulence determinant and regulator of host cell transcription. These properties were shown to be partially mediated by dysregulation of the host transcription factors STAT3 and STAT6, but the molecular mechanisms underlying this phenotype were unclear. Here, we use a Type I Toxoplasma strain deficient in ROP16 to show that ROP16 induces not only sustained activation but also an extremely rapid (within 1 min) initial activation of STAT6. Using recombinant wild-type and kinase-deficient ROP16, we demonstrate in vitro that ROP16 has intrinsic tyrosine kinase activity and is capable of directly phosphorylating the key tyrosine residue for STAT6 activation, Tyr(641). Furthermore, ROP16 co-immunoprecipitates with STAT6 from infected cells. Taken together, these data strongly suggest that STAT6 is a direct substrate for ROP16 in vivo.