The polymorphic pseudokinase ROP5 controls virulence in Toxoplasma gondii by regulating the active kinase ROP18.
The polymorphic pseudokinase ROP5 controls virulence in Toxoplasma gondii by regulating the active kinase ROP18.
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DOI：
10.1371/journal.ppat.1002992
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发表时间：
2012
期刊：
影响因子：
6.7
通讯作者：
Sibley LD
中科院分区：
文献类型：
--
作者：
Behnke MS;Fentress SJ;Mashayekhi M;Li LX;Taylor GA;Sibley LD
分泌型多态性丝氨酸/苏氨酸激酶控制小鼠弓形虫的发病机制遗传学研究表明，假激酶ROP 5是急性毒力所必需的，但没有揭示其作用机制。在这里，我们证明ROP 5通过阻断活化的巨噬细胞中IFN-γ介导的清除来控制毒力。ROP 5是活性S/T激酶ROP 18的催化活性所必需的，其磷酸化宿主免疫相关的GTP酶（IRGs）并保护寄生虫免于清除。ROP 5在体外直接调节ROP 18的活性，并且这两种蛋白质对于避免巨噬细胞中IRG募集和清除是必需的。Δ rop 5和Δ rop 18突变体的清除在缺乏IRG功能所需的Irgm 3的巨噬细胞中被逆转，并且在Irgm 3 −/−小鼠中完全恢复了毒力缺陷。我们的研究结果证实，假激酶ROP 5控制ROP 18的活性，从而阻断IRG介导的巨噬细胞清除。此外，R 0 P5还具有Irgm 3和IFN-γ依赖的其他功能，表明其在控制阻断免疫的毒力因子中起一般作用。微生物在其宿主中引起疾病的能力通常由病原体分泌到宿主细胞中的蛋白质介导，作为解除宿主信号传导的手段。先前对原生动物寄生虫弓形虫的研究表明，寄生虫蛋白激酶分泌到宿主细胞中介导了小鼠的毒力，小鼠是一种天然的传播宿主。奇怪的是，这些毒力因子中的一些是活性蛋白激酶，而其他相关的假激酶缺乏酶活性;因此，尚不清楚它们如何在促进毒力方面发挥作用。在目前的工作中，我们证明，ROP 5，这个蛋白激酶家族的非活性成员，调节活性蛋白激酶ROP 18，这通常会阻止干扰素激活的巨噬细胞中的寄生虫的清除。酶的变构调节是生物学中的一个常见主题，但这是这种机制调节病原体毒力因子的第一个例子。这种分层过程的潜在优势是，它可能允许更大的时间或空间控制，并可能保护寄生虫免受宿主的禁用策略。
Secretory polymorphic serine/threonine kinases control pathogenesis of Toxoplasma gondii in the mouse. Genetic studies show that the pseudokinase ROP5 is essential for acute virulence, but do not reveal its mechanism of action. Here we demonstrate that ROP5 controls virulence by blocking IFN-γ mediated clearance in activated macrophages. ROP5 was required for the catalytic activity of the active S/T kinase ROP18, which phosphorylates host immunity related GTPases (IRGs) and protects the parasite from clearance. ROP5 directly regulated activity of ROP18 in vitro, and both proteins were necessary to avoid IRG recruitment and clearance in macrophages. Clearance of both the Δrop5 and Δrop18 mutants was reversed in macrophages lacking Irgm3, which is required for IRG function, and the virulence defect was fully restored in Irgm3−/− mice. Our findings establish that the pseudokinase ROP5 controls the activity of ROP18, thereby blocking IRG mediated clearance in macrophages. Additionally, ROP5 has other functions that are also Irgm3 and IFN-γ dependent, indicting it plays a general role in governing virulence factors that block immunity. The ability of microorganisms to cause disease in their hosts is often mediated by proteins that are secreted by the pathogen into the host cell as a means of disarming host signaling. Previous studies with the protozoan parasite Toxoplasma gondii have revealed that secretion of parasite protein kinases into the host cell mediates virulence in mouse, a natural host for transmission. Curiously, some of these virulence factors are active protein kinases, while other related pseudokinases lack enzymatic activity; hence, it was unclear how they functioned in promoting virulence. In the present work we demonstrate that ROP5, an inactive member of this protein kinase family, regulates the active protein kinase ROP18, which normally prevents clearance of the parasite in interferon-activated macrophages. Allosteric regulation of enzymes is a common theme in biology, but this is the first example of such a mechanism regulating a pathogen virulence factor. The potential advantage of such a layered process is that it might allow greater temporal or spatial control and perhaps protect the parasite from disabling strategies by the host.
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影响因子：
3.4
作者：
Khaminets A;Hunn JP;Könen-Waisman S;Zhao YO;Preukschat D;Coers J;Boyle JP;Ong YC;Boothroyd JC;Reichmann G;Howard JC
通讯作者：
Howard JC
影响因子：
4
作者：
Fentress, Sarah J.;Sibley, L. David
通讯作者：
Sibley, L. David
影响因子：
56.9
作者：
Kim, Bae-Hoon;Shenoy, Avinash R.;MacMicking, John D.
通讯作者：
MacMicking, John D.
影响因子：
14.9
作者：
Khan A;Taylor S;Su C;Mackey AJ;Boyle J;Cole R;Glover D;Tang K;Paulsen IT;Berriman M;Boothroyd JC;Pfefferkorn ER;Dubey JP;Ajioka JW;Roos DS;Wootton JC;Sibley LD
通讯作者：
Sibley LD
影响因子：
2.1
作者：
CHARIF, H;DARCY, F;CAPRON, A
通讯作者：
CAPRON, A