バクテリアホドプシン経由の温度依存固体電子輸送:タンパク質経由の複数の輸送経路の実験的証拠
Lior Sepunaru1, Noga Friedman, Israel Pecht
1Department of Materials and Interfaces, Weizmann Institute of Science, POB 26, Rehovot 76100, Israel.
Journal of the American Chemical Society
|February 3, 2012
まとめ
バクテリアホドプシン (bR) 経由の電子輸送 (ETp) は,温度に依存する行動を示し,熱的に活性化される状態から温度に依存しない状態に変化します. このタンパク質は高電流密度を促進し,タンパク質における一般化された電子輸送機構を示唆する.
科学分野:
- バイオフィジックス 生物物理学
- タンパク質は電子を移転する.
- 分子電子 (モレキュラー・エレクトロニクス)
背景:
- バクテリアホドプシン (bR) は,天然の陽子ポンプとして機能します.
- 固体タンパク質単層における電子輸送 (ETp) は,バイオエレクトロニクスの応用において極めて重要です.
- タンパク質の温度に依存するETpを理解することは,それらの機能的特徴づけの鍵です.
研究 の 目的:
- 乾燥した単層のバクテリアホドプシンにおける電子輸送の温度依存性を調査する.
- bRにおける異なる熱条件下での電子輸送を制御するメカニズムを解明する.
- タンパク質媒介による電子伝送の一般化モデルを提案する.
主な方法:
- 温度に応じてバクテリアホドプシン単層の電子輸送を研究する.
- 200K以上の温度と130K以下の温度で輸送行動を分析する.
- 網膜染色体の変化が電子伝送に与える影響を調査する.
主要な成果:
- bRにおける電子輸送は,熱活性化 (T > 200 K) から温度独立性 (T < 130 K) に移行する.
- bRは高い電流密度と室温以上の温度安定性を示しています.
- 網膜群の改変により,熱的に活性化された代替輸送経路が導入されました.
結論:
- タンパク質間のETpの一般化メカニズムは,トンネリングおよびホッピング輸送レジムの共存を含む.
- この発見は,高性能バイオエレクトロニックデバイスのためのbRの潜在能力を強調しています.
- タンパク質の構造と染色体の改変は,電子輸送経路に大きな影響を与えます.
関連する概念動画
01:29Electron Transport Chain Components
The electron transport chain (ETC) is a crucial metabolic pathway that facilitates energy conversion in prokaryotic and eukaryotic cells. In eukaryotes, the ETC comprises four membrane-associated protein complexes in the inner mitochondrial membrane. In prokaryotes, the ETC in the plasma membrane can vary in composition, with fewer or different complexes depending on the organism and environmental conditions. These complexes transfer electrons from electron donors, such as NADH and FADH2, to...
01:11Channel Rhodopsins
Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
01:22Protein Transport to the Thylakoids
Thylakoids are membrane-bound sac-like structures within the chloroplast that serve as sites for photosynthesis. Thylakoid lumen contains many electron transport proteins and is enclosed by a thylakoid membrane rich in the light-harvesting complex. Proteins targeted to the thylakoids are transported as precursors and are sorted by the general TOC/TIC import pathway. Once the precursor reaches the stroma, stromal processing peptidases remove their transit signal and expose thylakoid signal...
01:09Multi-pass Transmembrane Proteins and β-barrels
In multi-pass transmembrane proteins, the polypeptide chain crosses the membrane more than once. The transmembrane polypeptide chain either forms an α-helix or β-strand structure. α-Helix containing multi-pass transmembrane proteins are ubiquitous, whereas β-strand containing ones are mainly found in gram-negative bacteria, mitochondria, and chloroplasts.
α-Helix containing multi-pass transmembrane proteins
Multi-pass transmembrane proteins such as G-protein-linked receptors (GPCRs) and...
α-Helix containing multi-pass transmembrane proteins
Multi-pass transmembrane proteins such as G-protein-linked receptors (GPCRs) and...
01:30Anoxygenic Photosynthesis
Anoxygenic photosynthesis is a phototrophic process that captures light energy to drive carbon fixation without producing molecular oxygen. Unlike oxygenic photosynthesis, which utilizes water as an electron donor and releases oxygen, anoxygenic phototrophs use alternative electron donors such as hydrogen sulfide (H₂S), elemental sulfur (S⁰), or thiosulfate (S₂O₃²⁻). This process is carried out by diverse groups of bacteria, including purple bacteria, green sulfur bacteria, heliobacteria, and...
01:43Electron Transport Chain: Complex III and IV
During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then transfer the electrons to ubiquinol, which carries them further to complex III. Complex III passes the electrons across the intermembrane space to Cyt c, which carries them further to complex IV. Complex IV donates electrons to oxygen and reduces it to water. As electrons pass through complexes I, III, and IV, the energy released aids the pumping...