トリコモナスヒドロゲノソームには,ミトコンドリア複合体IのNADH脱水素酶モジュールが含まれています
Ivan Hrdy1, Robert P Hirt, Pavel Dolezal
1Department of Parasitology, Charles University, Vinicna 7, 128 44 Prague 2, Czech Republic.
Nature
|December 4, 2004
まとめ
ハイドロゲノソームは,無酸素エウカリオットの臓器細胞であり,複合体Iの活性NADH脱水素酶サブユニットを含んでいます. この発見は,ヒドロゲノソームとミトコンドリアが,エンドシンビオシスから派生した同類の有機体であるという仮説を支持する.
科学分野:
- 細胞生物学 細胞生物学
- 進化生物学の進化生物学について
- バイオケミストリー バイオケミストリー
背景:
- ハイドロゲノソームは,無酸素性ユカリオットの二重膜の有機体で,ATPと水素の生成を担当する.
- ハイドロゲノソームの進化的起源は議論の余地があり,ミトコンドリアとの同質性,または異なる細菌の起源を示唆する理論がある.
- 重要な質問は,ヒドロゲノソームが継続的な機能のためにマラート酸化後にNAD+を再生する方法です.
研究 の 目的:
- Trichomonas vaginalisのヒドロゲノソームにおけるNADH脱水素酶サブユニットの存在と機能を調査する.
- 水素体とミトコンドリア複合体Iの構成要素の間の進化的関係を決定する.
- ハイドロゲノソームにおけるNAD+再生のメカニズムと,それがエンドシンビオティック理論に及ぼす意味を解明する.
主な方法:
- T. vaginalisのヒドロゲノソームにおけるNADHデヒドロゲナーゼの活性を検出および特徴づけるための生化学的分析.
- 酵素浄化と基板特異性の試験,ユビキノンとフェルドキシンを含む.
- 進化的関係を推論するために,コンプレックスIのサブユニットの系統遺伝分析.
主要な成果:
- 51kDaと24kDaのNADH脱水素酶 (複合体I) のサブユニットは,T. vaginalisの水素体内に活性化しています.
- 浄化されたヒドロゲノソーム酵素は,ウビキノンとフェルドキシンを減少させ,フェルドキシンが水素生成に不可欠である.
- 系統遺伝学的分析によると,51kDaのサブユニットはミトコンドリアの同位体と共通の祖先を共有している.
結論:
- ハイドロゲノソームにおける活性NADH脱水素酵素の存在は,マラート酸化後のNAD+再生を説明する.
- この発見は,水素体とミトコンドリアが同類の臓器細胞であるという強力な証拠を提供します.
- これは,エアロビック (ミトコンドリア) とアナエロビック (ヒドロゲノソーム) の形態を表す,両方の臓器細胞のエンドシンビオティックな起源を支持します.
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