A UV-B-specific signaling component orchestrates plant UV protection
A UV-B-specific signaling component orchestrates plant UV protection
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DOI：
10.1073/pnas.0507187102
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发表时间：
2005-12-13
影响因子：
11.1
通讯作者：
Jenkins, GI
中科院分区：
文献类型：
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作者：
Brown, BA;Cloix, C;Jenkins, GI
阳光中的 UV-B 辐射对人类、动物、植物和微生物有多种影响。 UV-B 会对分子和细胞造成损伤，因此生物体需要防御和修复紫外线损伤才能在阳光下生存。在植物中，低水平的非破坏性 UV-B 会刺激参与紫外线防护反应的基因转录。然而，人们对 UV-B 感知和信号转导的潜在机制知之甚少。在此，我们报道拟南芥抗紫外线基因座 8 (UVR8) 是一种 UV-B 特异性信号传导成分，可协调一系列具有重要紫外线防护功能的基因的表达。此外，我们还发现，当植物暴露于 UV-B 时，UVR8 会特别调节转录因子 HY5 的表达。我们证明 HY5 是 UVR8 途径的关键效应子，并且它是 UV-B 辐射下生存所必需的。 UVR8与真核鸟嘌呤核苷酸交换因子RCC1具有序列相似性，但我们发现它几乎没有交换活性。然而，UVR8 与 RCC1 一样，主要位于细胞核中，并通过历史与染色质相关联。染色质免疫沉淀显示 UVR8 与 HY5 启动子区域的染色质结合，为其参与转录调节提供了机制基础。我们得出的结论是，UVR8 定义了植物中 UV-B 特异性信号通路，该通路协调植物在阳光下生存所需的对 UV-B 的保护性基因表达反应。
UV-B radiation in sunlight has diverse effects on humans, animals, plants, and microorganisms. UV-B can cause damage to molecules and cells, and consequently organisms need to protect against and repair UV damage to survive in sunlight. In plants, low nondamaging levels of UV-B stimulate transcription of genes involved in UV-protective responses. However, remarkably little is known about the underlying mechanisms of UV-B perception and signal transduction. Here we report that Arabidopsis UV RESISTANCE LOCUS 8 (UVR8) is a UV-B-specific signaling component that orchestrates expression of a range of genes with vital UV-protective functions. Moreover, we show that UVR8 regulates expression of the transcription factor HY5 specifically when the plant is exposed to UV-B. We demonstrate that HY5 is a key effector of the UVR8 pathway, and that it is required for survival under UV-B radiation. UVR8 has sequence similarity to the eukaryotic guanine nucleotide exchange factor RCC1, but we found that it has little exchange activity. However, UVR8, like RCC1, is located principally in the nucleus and associates with chromatin via histories. Chromatin immunoprecipitation showed that UVR8 associates with chromatin in the HY5 promoter region, providing a mechanistic basis for its involvement in regulating transcription. We conclude that UVR8 defines a UV-B-specific signaling pathway in plants that orchestrates the protective gene expression responses to UV-B required for plant survival in sunlight.