局部控制细胞死亡对植物对病原体的抗性至关重要。木瓜蛋白酶样半胱氨酸蛋白酶（PLCPs）调节植物防御以驱动细胞死亡并防止营养缺陷型病原体。在玉米（Zea mays）中，PLCP在配制水杨酸（SA）依赖性防御信号传导中至关重要。尽管在免疫中起着核心作用，但PLCPs如何激活以及诱导哪些下游信号引发植物免疫尚不清楚。在这里，我们发现一种免疫信号肽Z. mays免疫信号肽1（Zip1），它是在水杨酸（SA）处理后产生的。体外研究表明PLCPs需要从其前肽前体释放生物活性Zip1。相反，Zip1处理强烈地引起叶片中SA积累。此外，转录组分析揭示Zip1和SA诱导高度重叠的转录变化。因此，Zip1促进坏死性真菌Botrytis cinerea的感染，同时降低生物营养真菌Ustilago maydis的毒力。因此，Zip1表示由PLCP释放的用于激活SA防御信令的先前丢失的信号。
Localized control of cell death is crucial for the resistance of plants to pathogens. Papain-like cysteine proteases (PLCPs) regulate plant defence to drive cell death and protection against biotrophic pathogens. In maize (Zea mays), PLCPs are crucial in the orchestration of salicylic acid (SA)-dependent defence signalling. Despite this central role in immunity, it remains unknown how PLCPs are activated, and which downstream signals they induce to trigger plant immunity. Here, we discover an immune signalling peptide, Z. mays immune signalling peptide 1 (Zip1), which is produced after salicylic acid (SA) treatment. In vitro studies demonstrate that PLCPs are required to release bioactive Zip1 from its propeptide precursor. Conversely, Zip1 treatment strongly elicits SA accumulation in leaves. Moreover, transcriptome analyses revealed that Zip1 and SA induce highly overlapping transcriptional changes. Consequently, Zip1 promotes the infection of the necrotrophic fungus Botrytis cinerea, while it reduces virulence of the biotrophic fungus Ustilago maydis. Thus, Zip1 represents the previously missing signal that is released by PLCPs to activate SA defence signalling.
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Adenine base editors (ABEs), composed of an engineered deaminase and a catalytically impaired CRISPR–Cas9 variant, are powerful new tools for targeted base editing in cells and organisms. Together with cytosine base editors (CBEs), ABEs enable single-nucleotide conversions cleanly, efficiently and reversibly without double-stranded DNA cleavage, advancing genome editing in a new dimension.
由工程脱氨酶和催化性受损的CRISPR-Cas9变体组成的腺嘌呤碱基编辑器（ABE）是用于细胞和生物体中靶向碱基编辑的强大新工具。 与胞嘧啶碱基编辑器（CBEs）一起，ABEs能够在不发生双链DNA切割的情况下，实现单核苷酸转换的干净，高效和可逆性，从而推动基因组编辑工作在新的层面。
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The brassinosteroid (BR) receptor BRI1 provides a paradigm for understanding receptor-mediated signaling in plants. Different posttranslational modifications have been implicated in the regulation of BRI1 activity. Here, we show that BR perception promotes BRI1 association with plant U-box E3 ubiquitin ligases PUB12 and PUB13, which in turn directly ubiquitinate BRI1. Importantly, the BRI1 protein abundance and plasma membrane-residence time are increased while the endosomal pool of BRI1 is reduced in the pub12pub13 mutant, indicating that PUB12/PUB13-mediated ubiquitination regulates BRI1 endocytosis and degradation. BRI1 phosphorylates PUB13 on a specific residue to enhance its association with BRI1, suggesting a unique regulatory circuit of phosphorylation-regulated E3 ligase–substrate association. Our study elucidates a mechanism of BRI1 internalization through E3 ubiquitin ligase-mediated ubiquitination.
Plants largely rely on plasma membrane (PM)-resident receptor-like kinases (RLKs) to sense extracellular and intracellular stimuli and coordinate cell differentiation, growth, and immunity. Several RLKs have been shown to undergo internalization through the endocytic pathway with a poorly understood mechanism. Here, we show that endocytosis and protein abundance of the Arabidopsis brassinosteroid (BR) receptor, BR INSENSITIVE1 (BRI1), are regulated by plant U-box (PUB) E3 ubiquitin ligase PUB12- and PUB13-mediated ubiquitination. BR perception promotes BRI1 ubiquitination and association with PUB12 and PUB13 through phosphorylation at serine 344 residue. Loss of PUB12 and PUB13 results in reduced BRI1 ubiquitination and internalization accompanied with a prolonged BRI1 PM-residence time, indicating that ubiquitination of BRI1 by PUB12 and PUB13 is a key step in BRI1 endocytosis. Our studies provide a molecular link between BRI1 ubiquitination and internalization and reveal a unique mechanism of E3 ligase–substrate association regulated by phosphorylation.
Arabidopsis
BRI1
ubiquitination
E3 ligase
endocytosis
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