Elucidating the molecular basis of effector-triggered host susceptibility mediated by the TAL-like effector Brg11 from the bacterial pathogen Ralstonia solanacearum

阐明细菌病原体青枯菌中 TAL 样效应子 Brg11 介导的效应子触发宿主易感性的分子基础

• 批准号: 413908990
• 负责人: Professor Dr. Thomas Lahaye
• 金额: --
• 依托单位: Abteilung für Allgemeine Genetik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/413908990?language=en
• 关键词: Elucidating; molecular; basis; effector; triggered

Plant pathogens pose a permanent thread to global food security. To invade plants, phytopathogenic microbes rely on effector proteins that they inject into host cells to promote host susceptibility. Knowledge of effector targets inside host cells provides a possibility for knowledge-based breeding of pest-resistant crops. Thus, elucidation of the molecular basis of effector-triggered host susceptibility remains a major aim of fundamental and applied plant pathology.We study Ralstonia solanacearum a devastating bacterial pathogen that triggers bacterial wilt disease on numerous crop species. We have characterized Brg11, a R. solanacearum effector with high similarity to transcription activator-like effectors (TALEs) from the bacterial genus Xanthomonas. TALEs bind to effector binding elements (EBEs) present in host promoters and transcriptionally activate downstream host susceptibility (S) genes to promote disease. Given its relatedness to TALEs it’s conceivable that Brg11 promotes disease by transcriptional activation of host S genes. Thus, we aimed to identify host genes that are transcriptionally activated by Brg11 to clarify how it promotes disease.To identify Brg11 host target genes we determined a preferred target sequence of Brg11 (Brg11-EBE). A 18bp-motif resembling Brg11-EBE was identified upstream of all arginine decarboxylase (ADC) genes in R. solanacearum host genomes and accordingly this motif was designated as ADC-box. Combined analysis of RNA-Seq data and target site prediction suggests that ADC1 and ADC2 are the only direct target genes of Brg11 in tomato. Inspection of Brg11-induced versus intrinsic ADC transcripts revealed short (100 bps) and long (450 bps) 5’UTRs, respectively. Preliminary data suggest that differences in their 5’UTRs cause that translation of intrinsic but not Brg11-induced transcripts is feedback regulated by metabolites that accumulate due to activity of ADC enzymes. Thus, Brg11-induced ADC transcripts likely evade translational control mechanisms that limit translation from intrinsic transcripts. In summary, our findings suggest that R. solanacearum Brg11 promotes bacterial wilt disease by transcriptional activation of host ADC genes.In the framework of this proposal we aim to:- study translational regulation of intrinsic versus Brg11-induced ADC transcripts- establish a catalogue of metabolites that change as consequence of elevated ADC protein levels- Analyze growth-inhibiting/promoting activity of Brg11-induced metabolites on plant associated microbes- Establish cellular reporters to visualize Brg11 target cells and Brg11-induced changes- Investigate Brg11-induced changes at the transcriptional and translational levelIn summary, these studies shall provide insights into how Brg11-induced activation of ADC genes promotes bacterial wilt disease.

植物病原体为全球粮食安全构成了永久性的线索。为了入侵植物，植物致病性微生物依赖于将其注入宿主细胞的效应蛋白来促进宿主易感性。宿主细胞内部效应靶标知识的知识为抗虫害作物的基于知识的繁殖提供了可能。阐明效应诱导的宿主易感性的分子基础仍然是基本和应用的植物病理学的主要目的。我们研究了静电素的ralstonia solanacearum毁灭性的细菌病原体，该病原体触发细菌在许多作物上触发疾病。我们表征了BRG11，这是一种与细菌Xanthomonas的转录激活效应（Tales）高相似的溶剂疾病效应子。传说与宿主启动子中存在的效应结合元件（EB）结合，并转录激活下游宿主易感性（S）基因以促进疾病。鉴于它与故事的相关性，可以想象BRG11通过宿主基因的转录激活促进疾病。因此，我们旨在识别BRG11转录激活的宿主基因，以澄清其促进疾病的方式。为了鉴定BRG11宿主靶基因，我们确定了BRG11（BRG11-EBE）的首选靶靶序列。在R. solanacearum宿主基因组中，所有精氨酸脱羧酶（ADC）基因的上游确定了一个类似于BRG11-EBE的18BP-MOTIF，因此，该基序被指定为ADC-Box。 RNA-seq数据和目标位点预测的组合分析表明，ADC1和ADC2是番茄中BRG11的唯一直接靶基因。对BRG11诱导的固有ADC转录本的检查分别显示短（100 bps）和长（450 bps）5'Utrs。初步数据表明，其5'UTRS的差异会导致内在的但不是BRG11诱导的转录本的翻译是由由于ADC酶的活性而累积的代谢物调节的反馈。这就是BRG11诱导的ADC转录本可能逃避了限制了固有转录物转换的翻译控制机制。总而言之，我们的发现表明，溶植菌BRG11通过宿主ADC基因的转录激活来促进细菌枯萎病疾病。在该提案的框架中，我们的目的是： - 研究内在的固有性和BRG11诱导的ADC转录的翻译调节，以促进ADC蛋白质水平的促进质量分析的质量分析，以促进ADC的转录。植物相关微生物上的代谢产物 - 建立细胞记者来可视化BRG11靶细胞和BRG11诱导的变化 - 研究了转录和翻译的Levelin摘要中BRG11诱导的变化，这些研究应提供有关BRG11诱导的ADC基因激活的洞察力，从而促进细菌枯萎病。