A Salmonella type III secretion effector interacts with the mammalian serine/threonine protein kinase PKN1
A Salmonella type III secretion effector interacts with the mammalian serine/threonine protein kinase PKN1
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DOI：
10.1111/j.1462-5822.2005.00670.x
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发表时间：
2006-05-01
影响因子：
3.4
通讯作者：
Miller, SI
中科院分区：
文献类型：
--
作者：
Haraga, A;Miller, SI
沙门氏菌致病的关键是一种称为III型分泌系统(TTSS)的输出装置，它介导细菌效应蛋白从细菌细胞转移到宿主细胞细胞质。一旦进入宿主细胞，这些效应器就能够改变宿主细胞的各种功能，以促进细菌的生存和定植。SspH1是一种伤寒沙门氏菌TTSS效应器，定位于哺乳动物的细胞核，通过抑制依赖于核因子(NF)-kappa B的基因表达来下调促炎细胞因子的产生。为了鉴定SspH1的哺乳动物结合伙伴，我们用酵母双杂交技术对人脾cDNA文库进行了筛选。它产生了一种丝氨酸/苏氨酸蛋白激酶，称为蛋白激酶N1(PKN1)。SspH1富含亮氨酸的重复结构域介导了这种相互作用，也抑制了依赖于NF-kappa B的基因表达。这提示PKN1可能在调节核因子-kappaB信号通路中发挥作用。事实上，我们发现在哺乳动物细胞中，具有结构性活性的PKN1的表达会导致表达减少，而通过RNA干扰耗尽PKN1会导致依赖于NF-kappa B的报告基因表达增加。这些数据表明，SspH1可能通过与PKN1相互作用来抑制宿主的炎症反应。
Essential to salmonellae pathogenesis is an export device called the type III secretion system (TTSS), which mediates the transfer of bacterial effector proteins from the bacterial cell into the host cell cytoplasm. Once inside the host cell, these effectors are then capable of altering a variety of host cellular functions in order to promote bacterial survival and colonization. SspH1 is a Salmonella enterica serovar Typhimurium TTSS effector that localizes to the mammalian nucleus and down-modulates production of proinflammatory cytokines by inhibiting nuclear factor (NF)-kappa B-dependent gene expression. To identify mammalian binding partners of SspH1 a yeast two-hybrid screen against a human spleen cDNA library was performed. It yielded a serine/threonine protein kinase called protein kinase N 1 (PKN1). The leucine-rich repeat domain of SspH1 was demonstrated to mediate this interaction and also inhibition of NF-kappa B-dependent gene expression. This suggested that PKN1 may play a role in modulation of the NF-kappa B signalling pathway. Indeed, we found that expression of constitutively active PKN1 in mammalian cells results in a decrease, while depletion of PKN1 by RNA interference causes an increase in NF-kappa B-dependent reporter gene expression. These data indicate that SspH1 may inhibit the host's inflammatory response by interacting with PKN1.