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ゲオバクテリア・ピリの構造は,ナノワイヤではなく,分泌的行動を示している

Yangqi Gu^1,2, Vishok Srikanth^1,3, Aldo I Salazar-Morales^1,3

¹Microbial Sciences Institute Yale University, West Haven, CT, USA.

|September 2, 2021

まとめ

ゲオバクテリアの種はナノワイヤではなくピリを使います PilA-NとPilA-Cタンパク質から成るこのピルは,ナノワイヤの分泌に不可欠であり,バイオエネルギーとバイオリメディエーションの応用に影響を与えます.

科学分野:

微生物学と微生物生態学
バイオエネルギーとバイオリメディエーション
構造生物学とナノテクノロジー

背景:

ゲオバクテリアの種は微生物のナノワイヤを通して細胞外電子の転送を容易にし,環境プロセスやバイオテクノロジーの応用に不可欠です.
以前は,これらのナノワイヤは, PilA-Nタンパク質のみで構成されるタイプ4の piliであると推定されていました.
以前の構造研究は,電子移転中に細胞はピリではなく,サイトクロームOmcSとOmcZのナノワイヤを生成することを示した.

研究の目的:

Geobacter sulfurreducensにおける PilA-N および PilA-C タンパク質の構造的および機能的役割を調査する.
ゲオバクテリア種におけるナノワイヤの集合と分泌のメカニズムを解明する.
PilA-N-C piliの細胞外電子伝送および関連する応用への貢献を決定する.

主な方法:

クリオ電子顕微鏡を用いて,PilA-N-Cフィラメントの構造を決定した.
生物化学分析では,PilA-NとPilA-Cタンパク質の共ポリマー化が評価されました.
これらのタンパク質のナノワイヤの分泌における役割を研究するために,遺伝子操作 (pilA- N 削除と再構成) が使用されました.

主要な成果:

Geobacter sulfurreducensは,細胞外電子移転中に周辺プラズマに残るヘテロディメア型ピリ (PilA-N-C) を組み立てている.
PilA-N-Cフィラメントは,OmcZナノワイヤと比較して有意に低い伝導性を示し,タイプ2の分泌シドオピリに類似して機能します.
OmcSとOmcZナノワイヤの分泌は,PilA-N-Cフィラメントの存在と適切な組み立てに依存しています.

結論:

この研究は,ゲオバクテルの細胞外電子移転を媒介する4型ピリという長きにわたるモデルを否定している.
PilA-N-C piliは,機能的なOmcSとOmcZナノワイヤの分泌に不可欠な転位機構として作用する.
このメカニズムの理解は,電子伝達微生物の進化と合成タンパク質ナノワイヤの設計に広範囲に及ぶ.

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