外膜は,グラム陰性細菌の欠かせない負荷要素である
Enrique R Rojas1,2,3, Gabriel Billings4, Pascal D Odermatt1,5
1Department of Bioengineering, Stanford University, Stanford, CA, USA.
Nature
|July 20, 2018
まとめ
細胞壁ではなく グラム陰性細菌の外膜が 硬さと強さを大部分提供します 細胞膜の変形と溶解が増加し,以前の機械的モデルに挑戦します
科学分野:
- 微生物学
- バイオ物理学
- 細胞生物学
背景:
- グラム陰性細菌は,プラズマ膜,ペプチドグリカン細胞壁,外膜を含む複雑な細胞膜を持っています.
- 細胞膜は細胞の形状を維持し,機械的ストレス (ターゴル圧力など) に抵抗し,選択的障壁として作用する.
- 封筒の主要な機械的性質はペプチドグリカンの細胞壁に起因すると考えられていた.
研究 の 目的:
- グラム陰性細菌の細胞壁に対する外膜の機械的貢献を調査する.
- 細胞壁が 主要な構造要素であるという 既成概念に挑戦する
主な方法:
- エシェリキア・コーライの細胞を様々な条件 (伸縮,曲げ,インデント) で機械的に検査する.
- 外膜の遺伝的・化学的な破壊
- 機械的ストレス下での細胞解離率とL型増殖の分析
主要な成果:
- 外膜は細胞の硬さと強さの主要な決定因子であることが判明しました.
- 細胞外膜を損なうことにより,細胞膜の変形が増加し,細胞解離率が上昇しました.
- 外膜タンパク質とリポポリサッカリドは,その機械的性質に大きく寄与する.
- 機械的負荷は,以前の仮定に反して,外膜と細胞壁の間に分配されます.
結論:
- 外膜は,これまで理解していたよりも,グラム陰性細菌の機械的整合性において重要な役割を果たします.
- この発見は,細菌の細胞封筒のメカニズムに関する現在のモデルの見直しを必要としています.
- 外側の膜の構造的な貢献は 細胞壁のそれと同等,あるいはそれ以上です
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