Ma Ling, Wang Qiang, Yuan Meng, Zou Tingting, Yin Ping, Wang Shiping
National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
Biochem Biophys Res Commun. 2018 Feb 5;496(2):608-613. doi: 10.1016/j.bbrc.2018.01.059. Epub 2018 Jan 10.
The Xanthomonas genus includes Gram-negative plant-pathogenic bacteria, which infect a broad range of crops and wild plant species, cause symptoms with leaf blights, streaks, spots, stripes, necrosis, wilt, cankers and gummosis on leaves, stems and fruits in a wide variety of plants via injecting their effector proteins into the host cell during infection. Among these virulent effectors, transcription activator-like effectors (TALEs) interact with the γ subunit of host transcription factor IIA (TFIIAγ) to activate the transcription of host disease susceptibility genes. Functional TFIIA is a ternary complex comprising α, β and γ subunits. However, whether TALEs recruit TFIIAα, TFIIAβ, or both remains unknown. The underlying molecular mechanisms by which TALEs mediate host susceptibility gene activation require full elucidation. Here, we show that TALEs interact with the α+γ binary subcomplex but not the α+β+γ ternary complex of rice TFIIA (holo-OsTFIIA). The transcription factor binding (TFB) regions of TALEs, which are highly conserved in Xanthomonas species, have a dominant role in these interactions. Furthermore, the interaction between TALEs and the α+γ complex exhibits robust DNA binding activity in vitro. These results collectively demonstrate that TALE-carrying pathogens hijack the host basal transcription factors TFIIAα and TFIIAγ, but not TFIIAβ, to enhance host susceptibility during pathogen infection. The uncovered mechanism widens new insights on host-microbe interaction and provide an applicable strategy to breed high-resistance crop varieties.
黄单胞菌属包括革兰氏阴性植物病原菌，可感染多种农作物和野生植物物种，在感染过程中通过将效应蛋白注入宿主细胞，在各种植物的叶片、茎和果实上引发叶枯病、条纹、斑点、条斑、坏死、枯萎、溃疡和流胶病等症状。在这些毒性效应蛋白中，转录激活样效应因子（TALEs）与宿主转录因子IIA（TFIIA）的γ亚基相互作用，以激活宿主感病基因的转录。功能性TFIIA是一种由α、β和γ亚基组成的三元复合物。然而，TALEs是招募TFIIAα、TFIIAβ还是两者都招募仍不清楚。TALEs介导宿主感病基因激活的潜在分子机制需要全面阐明。在这里，我们表明TALEs与水稻TFIIA（全OsTFIIA）的α+γ二元亚复合物相互作用，但不与α+β+γ三元复合物相互作用。TALEs的转录因子结合（TFB）区域在黄单胞菌属物种中高度保守，在这些相互作用中起主导作用。此外，TALEs与α+γ复合物之间的相互作用在体外表现出强大的DNA结合活性。这些结果共同表明，携带TALE的病原体劫持宿主基础转录因子TFIIAα和TFIIAγ，而不是TFIIAβ，以在病原体感染期间增强宿主易感性。所揭示的机制拓宽了对宿主-微生物相互作用的新见解，并为培育高抗性作物品种提供了一种适用策略。
