受體類(lèi)蛋白是由胞外亮氨酸富集重復(fù)序列,、單跨膜區(qū)以及短的胞內(nèi)區(qū)構(gòu)成的植物免疫反應(yīng)受體,。
9月14日，北京生命科學(xué)研究所張躍林研究小組發(fā)現(xiàn)一個(gè)免疫反應(yīng)組成型激活的獲得功能型突變體snc2-1D (suppressor of npr1-1, constitutive 2),。該研究成果發(fā)表于最新一期Plant Cell雜志上,。
圖位克隆發(fā)現(xiàn)突變基因編碼了一個(gè)受體類(lèi)蛋白。在snc2-1D 中,，跨膜區(qū)GXXXG motif的第二個(gè)Gly變成Arg,，提示我們這個(gè)氨基酸對(duì)蛋白功能的負(fù)調(diào)控起到重要作用。上下位遺傳分析表明snc2-1D激活了一條不同于NB-LRR類(lèi)R蛋白介導(dǎo)的免疫反應(yīng)通路,。對(duì)snc2-1D 進(jìn)行抑制子篩選,，發(fā)現(xiàn)轉(zhuǎn)錄因子WRKY70 的突變能抑制snc2-1D激活的免疫反應(yīng)，說(shuō)明WRKY70在snc2-1D 的下游發(fā)揮功能,。先前在擬南芥中沒(méi)有研究受體類(lèi)蛋白介導(dǎo)的免疫反應(yīng)的平臺(tái),，snc2-1D的發(fā)現(xiàn)成為我們研究受體類(lèi)蛋白免疫通路的出發(fā)點(diǎn)。
博士生張亞晰為本文的第一作者,，參與此工作的還有中國(guó)農(nóng)業(yè)大學(xué)的楊元愛(ài), 北京師范大學(xué)的方斌和丁平濤, University of British Columbia的Patrick Gannon和李昕教授,。我所研究員張躍林博士是本文的通訊作者。此項(xiàng)研究為科技部863和北京市科委資助課題,，在北京生命科學(xué)研究所完成,。(生物谷Bioon.com)
生物谷推薦英文摘要：
Plant Cell DOI:10.1105/tpc.110.074120
Arabidopsis snc2-1D Activates Receptor-Like Protein-Mediated Immunity Transduced through WRKY70
Yaxi Zhanga,b, Yuanai Yanga, Bin Fanga, Patrick Gannonc, Pingtao Dinga, Xin Lic and Yuelin Zhanga,1
a National Institute of Biological Sciences, Beijing 102206, People’s Republic of China
b Beijing Normal University, Beijing 100875, People's Republic of China
c Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, Canada
Plant immune receptors belonging to the receptor-like protein (RLP) family contain extracellular leucine-rich repeats (LRRs) and a short cytoplasmic tail linked by a single transmembrane motif. Here, we report the identification of snc2-1D (for suppressor of npr1-1, constitutive 2), a semidominant Arabidopsis thaliana mutant with constitutively activated defense responses. Map-based cloning of snc2-1D showed that it encodes an RLP. The point mutation in snc2-1D leads to substitution of the second Gly for Arg in the conserved GXXXG motif of the transmembrane helix, suggesting that this residue is important for negative regulation of the protein. Epistasis analysis revealed that the snc2-1D mutant phenotype is not affected by mutations in genes known to be required for the nucleotide binding (NB)-LRR Resistance (R) protein signaling. A suppressor screen of snc2-1D was performed, and map-based cloning of one suppressor revealed that mutations in WRKY70 suppress the constitutive defense responses in snc2-1D, suggesting that WRKY70 functions downstream of snc2-1D. The identification of snc2-1D provides us with a unique system for genetic analysis of resistance pathways downstream of RLPs, which may be distinct from those downstream of NB-LRR type R proteins.
