RXLR-mediated entry of Phytophthora sojae effector Avr1b into soybean cells does not require pathogen-encoded machinery
RXLR-mediated entry of Phytophthora sojae effector Avr1b into soybean cells does not require pathogen-encoded machinery
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DOI：
10.1105/tpc.107.056093
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发表时间：
2008-07-01
期刊：
影响因子：
11.6
通讯作者：
Tyler, Brett M.
中科院分区：
文献类型：
--
作者：
Dou, Daolong;Kale, Shiv D.;Tyler, Brett M.
据推测，卵菌和真菌病原体分泌的效应蛋白会进入宿主细胞，与宿主抗性基因产物相互作用。使用大豆疫霉（一种大豆（Glycine max）的卵菌病原体）的效应蛋白 Avr1b，我们证明一对序列基序 RXLR 和 dEER 以及周围序列对于将该蛋白递送至植物细胞来说是必要且充分的。粒子轰击实验证明这些基序在没有病原体的情况下发挥作用，表明效应蛋白进入宿主细胞不需要额外的病原体编码机制。此外，Avr1b RXLR-dEER 结构域与绿色荧光蛋白 (GFP) 的融合使 GFP 能够自主进入大豆根细胞。 RXLR 和 dEER 用于将卵菌效应子转导至宿主细胞的结论表明，酱油基因组序列中编码的 > 370 个含有 RXLR-dEER 的蛋白质是候选效应子。我们进一步表明，RXLR 和 dEER 基序可以被疟原虫（引起人类疟疾的原生动物）效应蛋白中发现的密切相关的红细胞靶向信号所取代。 RXLR基序的突变分析表明，疟原虫和疫霉菌的基序中所需的残基非常相似。因此，效应器所针对的宿主（大豆和人类）的机制可能非常古老。
Effector proteins secreted by oomycete and fungal pathogens have been inferred to enter host cells, where they interact with host resistance gene products. Using the effector protein Avr1b of Phytophthora sojae, an oomycete pathogen of soybean (Glycine max), we show that a pair of sequence motifs, RXLR and dEER, plus surrounding sequences, are both necessary and sufficient to deliver the protein into plant cells. Particle bombardment experiments demonstrate that these motifs function in the absence of the pathogen, indicating that no additional pathogen-encoded machinery is required for effector protein entry into host cells. Furthermore, fusion of the Avr1b RXLR-dEER domain to green fluorescent protein (GFP) allows GFP to enter soybean root cells autonomously. The conclusion that RXLR and dEER serve to transduce oomycete effectors into host cells indicates that the >370 RXLR-dEER-containing proteins encoded in the genome sequence of P. sojae are candidate effectors. We further show that the RXLR and dEER motifs can be replaced by the closely related erythrocyte targeting signals found in effector proteins of Plasmodium, the protozoan that causes malaria in humans. Mutational analysis of the RXLR motif shows that the required residues are very similar in the motifs of Plasmodium and Phytophthora. Thus, the machinery of the hosts (soybean and human) targeted by the effectors may be very ancient.