転写静音化および長寿タンパク質Sir2はNAD依存ヒストン脱酸化酵素である
S Imai1, C M Armstrong, M Kaeberlein
1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
Nature
|February 29, 2000
まとめ
酵母Sir2はヒストン脱酸化酵素で,ヒストンからアセチル群を除去することで遺伝子を静止させ,寿命を延長します. このNAD依存型脱酸化は,代謝,遺伝子静止,そして老化を結びつける.
科学分野:
- 分子生物学は分子生物学である.
- 遺伝学 遺伝学とは
- バイオケミストリー バイオケミストリー
背景:
- 酵母Sir2はヘテロクロマチンの重要な成分であり,遺伝子サイレンス,再結合,寿命を調節する.
- ヒストンH3およびH4の特定のライジンは静音化に不可欠であり,アセチル化パターンは活性または静音化クロマチンと相関しています.
- Sir2の過剰発現は,全体的なヒストン脱エチル化につながり,ヒストン脱エチラゼとしての役割を示唆する.
研究 の 目的:
- イーストとマウスのSir2タンパク質の酵素活性を調べる.
- 特定のヒストンの標的と,Sir2の脱セチラゼ活性におけるニコチナミドアデニン・ディヌクレオチド (NAD) の役割を決定する.
- Sir2の脱エチラゼ機能と,静音化,再結合抑制,寿命延長におけるin vivoの役割とを結びつけるため.
主な方法:
- ヒストン脱酸化酵素の活性を測定するための生化学的測定法.
- イーストとマウスのSir2タンパク質の分析.
- SIR2遺伝子の変異分析.
- 遺伝子サイレンシング,再結合,複製寿命を評価するインビボ研究.
主要な成果:
- 酵母とマウスのSir2タンパク質は,NAD依存ヒストン脱酸化酵素として機能する.
- Sir2はヒストンH3のライシン9とライシン14,ヒストンH4のライシン16を特異的に脱酸化する.
- SIR2の変異は,その脱エチラゼの活性を低下させ,静止,再結合抑制,寿命延長における欠陥と相関する.
結論:
- Sir2のNAD依存ヒストン脱酸化酵素の活動は,酵母における生物学的機能に不可欠である.
- このメカニズムは,代謝,ゲノムサイレンシング,そして老化との間の分子リンクを提供します.
- この発見は,より高いエウカリオットにも及ぶ可能性があり,NAD依存型脱エチル化の役割が保存されていることを示唆しています.
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