細胞外電子移転における排泄キノンの役割
1Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA. dkn@gps.caltech.edu
Nature
|May 16, 2000
まとめ
バクテリアは,呼吸のためにミネラルを利用できますが,どのように電子を鉄酸化物などの不溶性化合物に移すかは不明です. この研究は,排泄されたメナキノン分子が,シェワネッラ putrefaciens.でこのプロセスを促進することを明らかにしています.
科学分野:
- 微生物学 微生物学とは
- 環境科学 環境科学
- バイオケミストリー バイオケミストリー
背景:
- 細菌の呼吸は,不溶性ミネラルを含む,端末の電子受容体として多様な化合物を利用します.
- 鉄酸化物などの不溶性化合物への電子輸送は,溶性受容体と比較してほとんど理解されていません.
- ヒューミック物質は,無酸素環境で電子受容体と鉄酸化物へのシャトルとして作用します.
研究 の 目的:
- ヒューミックな物質に対する細菌の呼吸のメカニズムを調査する.
- シェワネッラ・プトレファシエンス (Shewanella putrefaciens) の不溶性電子受容体の呼吸に不可欠な遺伝子を特定する.
- 微生物の電子移転における小分子の役割を明示する.
主な方法:
- ヒューミックな物質で呼吸できないシェワネッラ・プートレファキエンス (Shewanella putrefaciens) の変異体を特定するための遺伝子スクリーニング.
- ヒト物質の呼吸に影響を与える突然変異を特定するための遺伝子破壊分析.
- ミュータントの呼吸機能を回復するために排泄された分子を用いた補充アッセイ.
主要な成果:
- ヒューミック物質の呼吸能力を欠いた突然変異者は,メナキノン生物合成に関与する遺伝子に障害がありました.
- 野生型のシェワネッラ・プトレファキエンス (Shewanella putrefaciens) は,メナキノンに関連する分子を媒質に放出する.
- 排泄されたこの分子は,ミュータントのヒューミックな物質で呼吸する能力を回復させた.
結論:
- メナキノン生物合成は,シェワネッラ・プトレファキエンス (Shewanella putrefaciens) が水性物質を呼吸するために不可欠です.
- 微生物によって排泄されるキノンは,鉱物を含む不溶性酸化物質への電子移転を媒介する可能性があります.
- この発見は,微生物の電子伝送と生地化学の循環に関する私たちの理解を広げています.
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