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イーストのアミノ酸感知スーパーコンプレックスSEAC-EGOCの構造と機能

Lucas Tafur^1,2, Lenny Bonadei³, Yiqiang Zheng³

¹Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland. ltafur@cnio.es.

Nature structural & molecular biology

|February 12, 2026

まとめ

Seh1関連複合体 (SEAC) は,アミノ酸信号を細胞成長調節体TORC1.1とリンクする. そのSEACITサブコンプレックスはEGOCを結合し,TORC1調節のための重要なアミノ酸感知ハブとして機能します.

科学分野:

セルラー・シグナリング
細胞成長調節の分子メカニズム
アミノ酸感知経路について

背景:

哺乳類のGATORとして知られるSeh1関連複合体 (SEAC) は,アミノ酸の可用性信号をラパミシン複合体1 (TORC1) のターゲットに変換するために重要である.
SEACは,Gtr1に対するGTPase-activating protein (GAP) 活性を持つTORC1阻害剤であるSEACIT (GATOR1) と,SEACITの活性を調節するSEACAT (GATOR2) を含む.
SEACATがSEACITを調節する正確な分子機構は,まだ完全に理解されていません.

研究の目的:

クリオ電子顕微鏡を用いてSEAC-EGOC相互作用の構造的基礎を解明する.
TORC1.1.へのアミノ酸シグナル伝達におけるSEAC-EGOC複合体の機能的役割を調査する.
TORC1経路の活性化の規制に関与するSEACAT,特にSea2の重要なコンポーネントを特定する.

主な方法:

クリオ電子顕微鏡 (cryo-EM) で,SEAC-EGOC複合体の構造を決定する.
SEACITのGTPase活性化タンパク質 (GAP) 活性を評価するための生化学的分析.
TORC1.1へのアミノ酸シグナル伝達への影響を評価するために,サブユニット削除 (例えば,Sea2) を含む遺伝子研究.

主要な成果:

Cryo-EM構造は,SEACITがSEACATとは独立して,2つのEGOC分子に直接結合することを示しています.
SEACITのGAP活動は,アミノ酸依存のTORC1調節に不可欠であり,その障害はGtr1-Gtr2欠乏症のフェノタイプを模倣する.
Sea2またはそのN端βプロペラドメインの喪失は,TORC1へのアミノ酸シグナル伝達を著しく低下させ,GAP阻害剤を募集する役割を示唆する.

結論:

SEAC-EGOC複合体は,アミノ酸を感知し,TORC1.1に信号を送信するための中央ハブとして機能しています.
Sea2 β-プロペラドメインは,GAP阻害剤を勧誘することによって,TORC1への迅速なアミノ酸シグナル伝達を媒介し,追加の遅い調節経路も関与しています.

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