タンパク質キナーゼERK2による近接誘導触媒

Mark A Rainey¹, Kari Callaway, Richard Barnes

¹College of Pharmacy, University of Texas at Austin, Austin, Texas 78712-1074, USA.

Journal of the American Chemical Society

|July 28, 2005

まとめ

ERK2が特定の部位をリン酸化する理由を理解することは鍵となる. 活性部位だけでなく,ドッキング相互作用は,プロリン誘導タンパク質キナーゼの基質認識と触媒効率を高めます.

科学分野:

バイオケミストリーバイオケミストリー
分子生物学は分子生物学である.
酵素学酵素学とは

背景:

タンパク質のリン酸化は,多数のタンパク質キナーゼとリン酸化部位を含む細胞シグナル伝達に不可欠です.
複数のキナーゼが類似した部位を標的とするフォスフォプロテオームの重複特性は,メカニズム上不明のままである.
細胞外信号調節キナーゼ2 (ERK2) は,プロリン誘導タンパク質キナーゼで,特定の基板認識パターンを有する.

研究の目的:

ERK2の基板特異性のメカニズム的根拠を調査する.
ERK2が,潜在的 (Ser/Thr-Pro) サイトの一部分のみを,かなりの割合でリン酸化する理由を理解する.
ERK2媒介のリン酸化におけるドッキング相互作用の役割を明らかにする.

主な方法:

ERK2認識領域 (pnt領域) とリン酸化部位 (T38) を含む確立された基板,EtsDelta138を使用しました.
活性部位によって認識されるTPモチーフを変更するために,部位指向型変異を生成した.
F120A変異によるERK2-pntドメインの相互作用を妨害する影響を調査した.

主要な成果:

T-38/P-39モチーフの変異は,触媒速度 (kcat) に影響したが,三重複合体の安定性には影響しなかった.
pntドメイン (F120A) の変異は結合親和性を著しく低下させましたが,kcat.を変化させませんでした.
データは,非活性サイトドッキング相互作用によって駆動される近接媒介の触媒機構を支持しています.

結論:

ERK2活性部位の外のドッキング相互作用は,初期基質認識に不可欠である.
このドッキングは,酸化モチーフの局所的濃度を増やすことにより,触媒効率を高めます.
基板特異性は,ドッキング相互作用と,残留物が正しい幾何学で活性部位にアクセスする能力の組み合わせによって決定されます.

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