ヒストン脱アセチル化酵素2による植物の遠赤色光感知におけるPhyA安定性の調節機構を解明(Researchers Reveal Histone Deacetylase 2-Mediated Regulation of PhyA Stability in Plant Far-Red Light Sensing)

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2025-08-20 中国科学院(CAS)

中国科学院華南植物園の劉訓成教授らは、植物が遠赤色光を感知する分子機構を解明した。シロイヌナズナの遠赤色光受容体phytochrome A(phyA)は暗所で蓄積するが、光照射で急速に分解される。本研究は、この安定性がリジン残基のアセチル化により制御されることを明らかにした。特にK65のアセチル化状態が分解に重要で、脱アセチル化によってユビキチン化が促進され、26Sプロテアソーム経路で分解が進むことを突き止めた。実験では、K65を改変した変異体でphyAの分解や光応答遺伝子の発現が大きく変化した。また、ヒストン脱アセチル化酵素2(HDT2)が光依存的にphyAのK65を脱アセチル化する酵素であることを同定し、過剰発現で分解が加速し、欠損で抑制されることを実証。これにより「脱アセチル化—ユビキチン化カスケード」が光依存的phyA分解の必須経路であることを世界で初めて示した。成果は植物の光応答や作物の生育制御研究に新たな道を拓く。

<関連情報>

HDT2を介したリシン脱アセチル化は、アラブidopsisにおける光形態形成中にフィトクロムAの分解を促進する HDT2-mediated lysine deacetylation promotes phytochrome A degradation during photomorphogenesis in Arabidopsis

Feng Zheng ∙ Wenli Ou ∙ Ling Deng ∙ … ∙ Yongyi Yang ∙ Jaime A. Teixeira da Silva ∙ Xuncheng Liu
Molecular Plant  Published:August 6, 2025
DOI:https://doi.org/10.1016/j.molp.2025.08.002

Abstract

The switch from skotomorphogenesis to photomorphogenesis, a key developmental transition in the life cycle of seed plants, involves dramatic proteomic changes. Lysine acetylation (Lys-Ac) is an evolutionarily conserved and widely recognized post-translational modification that plays an important role in plant development, whereas its role in seedling deetiolation remains unclear. Here, we conducted a comparative lysine acetylomic analysis of etiolated Arabidopsis seedlings before and after red (R) light irradiation, revealing that exposure to R light mainly led to widespread protein lysine deacetylation during seedling deetiolation. Phytochrome A (phyA), the unique far-red (FR) light photoreceptor, was deacetylated at lysine 65 (K65) when etiolated seedlings were transferred to light. This residue served as a critical ubiquitination site that regulates phyA stability. Furthermore, K65 deacetylation facilitates phyA ubiquitination and 26S proteasome-mediated degradation, and is essential for the function of phyA in FR light signaling and seedling photomorphogenesis. We identified a plant-specific lysine deacetylase HDT2 that interacts with and deacetylates phyA in the nucleus, thereby promoting the ubiquitination and degradation of phyA during seedling deetiolation. Genetic analysis revealed that HDT2 plays a crucial role in phyA-mediated photomorphogenic growth. These findings suggest that lysine deacetylation of phyA by HDT2 plays an essential role in modulating phyA turnover in response to light, revealing that Lys-Ac is central to the rewiring of plants for photomorphogenic growth.

生物化学工学
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