エッジホッグシグナリングにおける滑らかなアクティベーションの構造的基礎
Pengxiang Huang1, Sanduo Zheng2, Bradley M Wierbowski1
1Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
Cell
|May 29, 2018
まとめ
コレステロールとスムージド (SMO) の結合は,システインに富んだドメイン (CRD) の方向転換によってヘッジホッグのシグナリングを活性化します. この構造の変化は阻害的な鎖を壊し,ステロールの移動と受容体の活性化のための経路を開きます.
科学分野:
- 生物化学
- 分子生物学
- 構造生物学
背景:
- スムージド (SMO) はヘッジホッグのシグナル伝達における重要なタンパク質で,胚の発達と癌の進行に不可欠です.
- SMOの活性化は,コレステロールが細胞外システイン豊富な領域 (CRD) に結合することによって引き起こされます.
- コレステロール結合とSMO活性化の正確なメカニズムは不明である.
研究 の 目的:
- ステロール媒介SMOの活性化に伴う構造的メカニズムを解明する.
- コレステロールがCRDに結合することで,トランスメブラン領域 (TMD) の形状にどのように影響を与えるかを定義する.
- 抗体によるSMO抑制の構造的基礎を特徴づける.
主な方法:
- ステロール活性化SMOの構造を決定するX線結晶学.
- アクティブと非アクティブのSMO構造を比較するための構造分析.
- π-カチオン鎖と水害性トンネルの役割を調査する生化学的測定.
主要な成果:
- 結晶構造は,ステロール結合によるCRDの方向転換が,活性Gタンパク質結合受容体を模倣してTMDをアロステリックに活性化することを明らかにする.
- SMOにおける独特の抑制性π-カタン鎖は活性化時に破壊され,この鎖は腫瘍性変異体において変化する.
- SMOの活性化により,内膜小葉からCRDへのコレステロール転移の経路を示唆する水害性トンネルが形成されます.
- しかし,サイクロパミンはCRDにも結合し,アクティブなTMD構造を誘発する.
結論:
- この研究は,コレステロールによるSMO活性化と,抗生物質による抑制の構造的メカニズムを定義している.
- CRDの方向転換と,その後のTMDの構成の変化は,SMOの活性化の中心です.
- 特定された水害性トンネルとπ-カタンロックは,SMOのアロステリック調節と薬物ターゲティングの洞察を提供します.
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