KaiCリン酸化の昼間リズムで転写-翻訳フィードバックがない
Jun Tomita1, Masato Nakajima, Takao Kondo
1Division of Biological Science, Graduate School of Science, Nagoya University, and Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
Science (New York, N.Y.)
|November 20, 2004
まとめ
サイアノバクテリアの昼間時計は,KaiCのリン酸化によって動かされ,新しい転写と翻訳から独立して機能します. この強固なリズムは,メッセンジャーRNAの蓄積なしにでも,温度補償を示しています.
科学分野:
- * 循環器の生物学について
- * 生物学的時計の分子機構
- * サイアノバクテリアの生理学
背景:
- *自己調節性転写-翻訳フィードバックループは,ほとんどの生物で昼夜リズム生成に不可欠と考えられています.
- * Synechococcus elongatusのKaiCタンパク質は,そのようなネガティブなフィードバックループの一部であると仮定されました.
- *日中時計のコアコンポーネントを理解することは,人生における時間調節を解読する上で極めて重要です.
研究 の 目的:
- * Synechococcus elongatus.における昼夜リズム性のトランスクリプションとトランスレーションの必要性を調査する.
- * KaiCのリン酸化サイクルが,遺伝子発現を阻害する条件下で温度補償され,強固であるかどうかを判断する.
- * シアノバクテリアの時間計測の根本的なメカニズムを解明する.
主な方法:
- *継続的な暗闇条件下でKaiCのリン酸化サイクルをモニタリングする.
- * 転写および翻訳阻害剤の存在下でのリズム持続性を評価する.
- * KaiCのオートフォスフォリレーション-デフォスフォリレーション比率のインビトロ運動分析.
主要な成果:
- * 耐久性があり,温度補償されたカイCリン酸化の昼夜循環は,カイBCメッセンジャーRNAの蓄積なしに観察されました.
- * 転写または翻訳が抑制された場合でも,観察されたリズムが持続しました.
- * in vitro運動研究では,KaiCの自己リン酸化-脱リン酸化における温度補償が確認されました.
結論:
- * サイアノバクテリアの昼夜時計は,de novoの転写と翻訳から独立して,強固な,温度補償の計時を維持することができます.
- * Synechococcus elongatusの循環リズムは,自己調節性転写-翻訳フィードバックループにのみ依存しているわけではありません.
- *これらの発見は,日中リズム生成のための転写・翻訳フィードバックの普遍的な要件に異議を唱える.
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