Laboratory of Applied Microbiology and Biotechnology, Nara Women's University, Nara, Japan.
Photochem Photobiol. 2021 Sep;97(5):903-910. doi: 10.1111/php.13459. Epub 2021 Jun 21.
Considering previously reported action spectra and molecular evidence, I propose a hypothetical model for UV RESISTANCE LOCUS8 (UVR8)-mediated photomorphogenesis. Upon UV-B irradiation, a UVR8 dimer dissociates and accumulates in the nucleus and photomorphogenesis begins following two pathways: one in which the UVR8 monomer binds to transcription factor(s) of gene(s) supporting hypocotyl growth to stop gene expression resulting in hypocotyl growth inhibition and the other in which the UVR8 monomer binds both with CONSTITUTIVELY PHOTOMORPHOGENIC1-SUPPRESSOR OF PHYA (COP1-SPA) to release HY5 (referred to as "stabilized") and WRKY DNA-BINDING PROTEIN 36 (WRKY36) on the ELONGATED HYPOCOTYL 5 (HY5) gene to release HY5 transcription, and both HY5 and another UV-B-activated UV-B sensor (denoted the Hyp sensor in this article) through a self-interacting factor (HIF) associates with the HY5 promoter to initiate HY5 transcription, leading to anthocyanin synthesis. These two pathways can be distinguished by action spectra in the UV-B region, with a single peak at 280 nm and two peaks (or a broad peak near 280-300 nm) for the former and the latter, respectively. Expanding the concept to cyanobacteria and other algae, I discuss the evolution of a UV-B sensor in green plants.
考虑到之前报道的作用光谱和分子证据，我提出了一个假设模型，用于解释 UVR8 介导的光形态建成。在 UV-B 照射下，UVR8 二聚体解离并积累在细胞核中，光形态建成开始通过两种途径进行：一种途径是 UVR8 单体结合到支持下胚轴生长的基因的转录因子（s），以停止基因表达，导致下胚轴生长抑制；另一种途径是 UVR8 单体与 CONSTITUTIVELY PHOTOMORPHOGENIC1-SUPPRESSOR OF PHYA（COP1-SPA）两者结合，释放 HY5（称为“稳定”）和 WRKY DNA-BINDING PROTEIN 36（WRKY36）在上胚轴伸长 5（HY5）基因上，释放 HY5 转录，HY5 和另一个 UV-B 激活的 UV-B 传感器（本文中称为 Hyp 传感器）通过自相互作用因子（HIF）与 HY5 启动子结合，启动 HY5 转录，导致花青素合成。这两种途径可以通过 UV-B 区域的作用光谱来区分，前者在 280nm 处有一个单一峰值，后者在 280-300nm 处有两个峰值（或一个接近 280-300nm 的宽峰）。将这一概念扩展到蓝细菌和其他藻类，我讨论了绿藻中 UV-B 传感器的进化。
