クロロフレクソタの無酸素光受容体は,タイプI反応センターを使用する
J M Tsuji1,2,3, N A Shaw4, S Nagashima5,6
1University of Waterloo, Waterloo, Ontario, Canada. jackson.tsuji@jamstec.go.jp.
Nature
|March 14, 2024
まとめ
研究者達は湖水の中で 新種の無酸素光栄養細菌を発見しました このバクテリアはI型反応センター (RCI) を使っているが,II型反応センター (RCII) の光栄養菌と祖先を共有し,光合成の進化に関する新しい洞察を明らかにしている.
科学分野:
- 微生物学
- 進化生物学
- 生物化学
背景:
- 遺伝学的なギャップは,光栄養の進化の理解を妨げている.
- 以前の研究では,異なる反応センターを持つ光栄養細菌の異なるグループが特定されました.
研究 の 目的:
- 光合成の進化を,光栄養細菌の遺伝的隙間を探索することによって調査する.
- クロロフレクソタ属の新種の光栄養菌を特徴づけること
主な方法:
- ボレアルシールドの湖水サンプルを育成する.
- 無酸素光栄養細菌の培養
- 生理学,遺伝学,およびメタトランスクリプトミックの分析.
主要な成果:
- クロロフレクソタ内の未知の順序からの新しい無酸素光栄養細菌が栽培されました.
- このバクテリアはI型反応センター (RCI) を利用するが,通常II型反応センター (RCII) フォトトロフと関連付けられた特徴 (クロロソーム,バクテリオクロロフィール) を有する.
- 系統遺伝学的なデータは,RCIとRCIIを利用したクロロフレキアの共有された光栄養的祖先を示しています.
結論:
- クロロフレクソタ属は 光合成の進化における 移行形態である.
- この発見は,細菌における光栄養の多様化を理解するための新しい文脈を提供します.
- クロロフレクソタ属に保存されている遺伝的に関連したバクテリアの中には,相反する光食性モードが存在する.
関連する概念動画
The Photochemical Reaction Center
4.1K
Reaction centers are pigment-protein complexes that initiate energy conversion from photons to chemical entities. Therefore, photochemical reaction center is a more appropriate term that describes these complexes. The Nobel laureates Robert Emerson and William Arnold provided the first experimental evidence of photochemical reaction centers by demonstrating the participation of nearly 2,500 chlorophyll molecules for the release of just one molecule of oxygen. Despite thousands of photosynthetic...
4.1K
The Antenna Complex
6.0K
Plants and other photosynthetic organisms comprise pigments capable of absorption of direct sunlight. These pigments are present in the reaction center - the main site of photochemical reactions as well as in the antenna complex. Under average light conditions, the rate at which reaction center pigments absorb light is far below the electron transport chain's capacity. As a result, the reaction center alone cannot provide enough energy to drive photosynthesis. The photosynthetic efficiency...
6.0K
Channel Rhodopsins
2.6K
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,...
2.6K
The Z-Scheme of Electron Transport in Photosynthesis
10.1K
The light reactions of photosynthesis assume a linear flow of electrons from water to NADP+. During this process, light energy drives the splitting of water molecules to produce oxygen. However, oxidation of water molecules is a thermodynamically unfavorable reaction and requires a strong oxidizing agent. This is accomplished by the first product of light reactions: oxidized P680 (or P680+), the most powerful oxidizing agent known in biology. The oxidized P680 that acquires an electron from the...
10.1K
Photosystem II
70.3K
The multi-protein complex photosystem II (PS II) harvests photons and transfers their energy through its bound pigments to its reaction center, and ultimately to photosystem I (PSI) through the electron transport chain. The pigments responsible for caputirng the light energy in photosystems include chlorophyll a, chlorophyll b, and carotenoids.
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment...
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment...
70.3K
Photosystems
4.8K
Photosystems are multiprotein complexes that form the functional units of photosynthesis in plants, algae, and cyanobacteria. They are found embedded in the membrane of tiny sac-like structures called thylakoids placed inside the chloroplast.
Functioning of Photosystems
Photosystems contain many pigment molecules, such as chlorophylls and carotenoids, arranged in a particular organization across two domains — the antenna complex and the reaction center. The main aim of the pigment...
Functioning of Photosystems
Photosystems contain many pigment molecules, such as chlorophylls and carotenoids, arranged in a particular organization across two domains — the antenna complex and the reaction center. The main aim of the pigment...
4.8K


