Several small-molecule perturbagens of the plant endomembrane system are known, but few selectively disrupt endoplasmic reticulum (ER) structure and function. We conducted a microscopy-based screen for small-molecule disruptors of ER structure and discovered eroonazole, a 1,2-4-triazole that induces extensive ER vesiculation in Arabidopsis seedlings. To identify eroonazole targets, we synthesized a clickable photoaffinity derivative and used it for whole-seedling labeling experiments. These reveal that the probe labels multiple oleosins, plant membrane proteins that stabilize ER-derived lipid droplets. Oleosin labeling is absent in an oleosin1234 quadruple mutant and reduced using an inactive analog. Cellular analyses of the ER in the quadruple mutant demonstrate that oleosins are required for normal ER structure during seed germination and suggest that perturbation of oleosin function by eroonazole underlies its effects on seedling ER structure.

中文翻译：

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在植物标记中使用可点击的 ER 破坏探针表明油质蛋白在拟南芥幼苗 ER 完整性中的作用

植物内膜系统的几种小分子干扰素是已知的，但很少有选择性地破坏内质网 (ER) 的结构和功能。我们对 ER 结构的小分子破坏物进行了基于显微镜的筛选，并发现了 eroonazole，一种 1,2-4-三唑，可在拟南芥幼苗中诱导广泛的 ER 囊泡。为了识别埃隆唑靶点，我们合成了一种可点击的光亲和衍生物，并将其用于全苗标记实验。这些揭示了探针标记了多种油质蛋白，即稳定ER衍生的脂滴的植物膜蛋白。油质蛋白标记在缺席oleosin1234四倍突变体并使用非活性类似物减少。四重突变体中 ER 的细胞分析表明，油质蛋白是种子萌发过程中正常 ER 结构所必需的，并表明 eroonazole 对油质蛋白功能的干扰是其对幼苗 ER 结构影响的基础。