Oxygen-17は, (17) O2 2とラベルを貼った,水ストレスを受けた大豆の葉のタンパク質にのみ現れます

Terry Gullion¹, Tsyr-Yan Yu, Manmilan Singh

¹Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, USA.

Journal of the American Chemical Society

|August 5, 2010

まとめ

大豆の葉の水圧は,酸素酶反応で生成されるグリシンを直接タンパク質合成に誘導します. この発見は,水ストレスがこれらの植物における光呼吸を効果的に抑制することを示している.

科学分野:

植物生理学植物生理学
バイオケミストリーバイオケミストリー
分子生物学は分子生物学である.

背景:

リブルロース・ビスホスファート・カルボキシラーゼ-酸素酵素 (Rubisco) は光合成の重要な酵素ですが,その酸素酵素の活動により光呼吸が起こり,無駄なプロセスになります.
グリシンは光呼吸の産物であり,その代謝の運命は植物における炭素の流れを理解するために重要である.
水圧は,ガス交換と光合成を含む植物生理学的プロセスに影響することが知られている.

研究の目的:

水圧下にある大豆の葉でRubiscoの酸素酵素活性によって生成されるグリシンの代謝運命を調査する.
ウォーターストレスが,タンパク質や他の細胞成分にグリシンを組み込むことに影響するかどうかを判断する.
大豆の植物における光呼吸に対する水ストレスの影響を解明するため.

主な方法:

ローテーション・エコー・アディアバティック・パサージ・ダブル・レゾナンス (13) C{(17) O} 固体核磁気共鳴 (NMR) 実験を利用した.
無傷で,水ストレスを受けた大豆の葉は,同位体として標識された二酸化炭素 ((13) CO(2)) と酸素 ((17) O(2)) に暴露されます.
グリシン中の (13) C と (17) O の同位体濃縮と,タンパク質への組み込みが監視されています.

主要な成果:

オキシゲンゼ反応で生成されたグリシンは,水ストレスを受けた大豆の葉のタンパク質またはタンパク質前駆体にのみ組み込まれました.
水圧は,ガス交換の減少と口腔抵抗の増大により,カルビンサイクル (13) C濃縮を35%まで低下させた.
十分な (17) O(2) ラベル付けにより,酸素酶産物形成の増加が確認され, (17) Oの同位体濃度が20倍に上昇した.

結論:

水中ストレス下でのグリシンのタンパク質への直接的組み込みは,光呼吸の有意な抑制を示しています.
水圧は,大豆の葉の炭素分割を変化させ,光呼吸経路よりもタンパク質合成を好む.
固体NMRは,ストレス条件下で,無傷の植物組織における代謝経路を追跡するための強力なツールです.

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