爪のようなループのライシン変異は,セルロビオヒドローラゼによる触媒を加速する
Zhiyou Zong1, Qiyu Li1, Zhangyong Hong1
1State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry , Nankai University , Tianjin 300071 , P. R. China.
Journal of the American Chemical Society
|August 22, 2019
まとめ
研究 者 たち は,セルロース を 分解 する 酵素 (GH7 CBHI) の 中 で,セルロビオース の 排出 を 加速 する"爪 の 腕"メカニズム を 発見 し まし た. 特定のライシン変異は酵素活性とセルロースの分解を著しく促進し,酵素の効率を向上させる戦略を提供した.
科学分野:
- 生物化学
- 酵素学
- 分子生物学
背景:
- セルロースは,セルロビオヒドローラゼI (CBHI) によって分解される.
- CBHIの触媒サイクルを加速することは,酵素効率の向上とコスト削減の鍵です.
- 酵素工学では,製品の排出メカニズムを理解することが不可欠です.
研究 の 目的:
- GH7 CBHIの触媒サイクルを加速させるための新しい戦略を調査する.
- セルロビオース排出のメカニズムとその酵素活動への影響を解明する.
- セルロースの分解を 強化するためにGH7 CBHIを設計する
主な方法:
- GH7 CBHIで広範な分子動力学 (MD) シミュレーション (12-μs) を実施した.
- 計算分析により,柔軟なループとキー残留物 (Thr389) を含む"爪腕"メカニズムが特定されました.
- 量子力学/分子力学 (QM/MM) の計算とサイト指向型変異 (ライシン変異体) が採用された.
主要な成果:
- セルロビオスの排出のための新しい"爪-腕"メカニズムが特定され,柔軟なループが"腕"として機能し,残留物Thr389が"爪"として機能する.
- Thr389のライシン変異は,セルロビオースの排出と多糖鎖の転位を著しく加速した.
- QM/MM計算では,ライシン置換により,グリコシル化バリアは2. 3kcal/mol減少した.
- 実験的に検証した結果, * Talaromyces emersonii* CBHI (TeCel7A) のライシン変異体において,より高い酵素反応率とセルロビオースの収穫量の増加が確認された.
結論:
- GH7 CBHIの活性を増強するための有効な戦略は"爪腕"作用と特定のライシン変異です.
- 加速されたセルロビオース解離によるGH7 CBHIは,セルロースの分解効率を向上させた.
- この研究は セルロースを分解する酵素を より効果的かつコスト効率的に設計するための洞察を提供します
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