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植物におけるTIR1/AFBオクシン受容体のアデニラートサイクラゼ活性
Linlin Qi1, Mateusz Kwiatkowski2, Huihuang Chen1
1Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria.
Nature
|October 26, 2022
まとめ
植物オキシン受容体は,TRANSPORT INHIBITOR RESPONSE 1 (TIR1) /AUXIN-SIGNALING F-BOX (AFB) で,アデニラートサイクラゼ (AC) 活性を有している. このcAMP生成はオキシンシグナル伝達,植物発育,転写制御に不可欠である.
科学分野:
- 植物生物学
- 分子生物学
- 生物化学
背景:
- アクシンは,定規のシグナル伝達経路を介して植物発育を調節する重要な植物ホルモンです.
- TRANSPORT INHIBITOR RESPONSE 1 (TIR1) / AUXIN- SIGNALING F- BOX (AFB) タンパク質はオクシン受容体であり,ユビキチンリガゼ複合体のF- ボックスサブユニットである.
- これらの受容体は,Aux/IAA抑制剤を分解に標的として,オクシン反応を媒介する.
研究 の 目的:
- TIR1/AFBオキシン受容体の新しい機能を調査する.
- アクシン信号伝達経路における新しい分子メカニズムを特定する.
- 植物における第2のメッセンジャーとしてのサイクルAMP (cAMP) の役割を調査する.
主な方法:
- TIR1/AFB受容体におけるアデニラートサイクラゼ (AC) 活性を検出するための生化学的測定
- TIR1 C末端領域内のACモチーフのサイト指向型変異.
- 変異した植物の現象分析で,重量化と根の成長を評価する.
- オーキシン誘発による転写調節の分析
主要な成果:
- TIR1/AFB受容体は,陸上の植物全体でアデニラートサイクラゼ (AC) 活性を示す.
- アクシンとAux/IAAタンパク質は,TIR1/AFB受容体を通してcAMPの産生を刺激する.
- AC活性を廃止する変異により,TIR1は重力増殖,根の成長阻害,および転写調節を媒介することが無効になった.
- これは,FボックスとACモチーフを組み合わせた二重機能の受容カセットを識別します.
結論:
- TIR1/AFB受容体は,これまで認識されていないアデニラートサイクラゼ (AC) 活性を持ち,正規のオクシンシグナル伝達に不可欠である.
- このAC活動は,重量化と根の成長のような重要な植物発達の過程を媒介する上で極めて重要です.
- この発見は,植物シグナル伝達における新しい第2のメッセンジャーであるcAMPを明らかにし,FボックスとACの機能を持つユニークなフィトホルモン受容体を強調しています.
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