- EMDB-60268: Cryo-EM structure of W89F mutated Glutamate dehydrogenase from Th... -
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基本情報
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データベース: EMDB / ID: EMD-60268
タイトル
Cryo-EM structure of W89F mutated Glutamate dehydrogenase from Thermococcus profundus incorporating NADPH and a substrate in the steady stage of reaction
マップデータ
試料
複合体: Hexamer of W89F mutated glutamate dehydrogenase
Ministry of Education, Culture, Sports, Science and Technology (Japan)
jp15076210
日本
Ministry of Education, Culture, Sports, Science and Technology (Japan)
jp20050030
日本
Ministry of Education, Culture, Sports, Science and Technology (Japan)
jp22018027
日本
Ministry of Education, Culture, Sports, Science and Technology (Japan)
jp23120525
日本
Ministry of Education, Culture, Sports, Science and Technology (Japan)
jp25120725
日本
Ministry of Education, Culture, Sports, Science and Technology (Japan)
jp15H01647
日本
Ministry of Education, Culture, Sports, Science and Technology (Japan)
jp17H05891
日本
引用
ジャーナル: FEBS J / 年: 2025 タイトル: CryoEM and crystal structure analyses reveal the indirect role played by Trp89 in glutamate dehydrogenase enzymatic reactions. 著者: Taiki Wakabayashi / Yuka Matsui / Masayoshi Nakasako / 要旨: Glutamate dehydrogenase from Thermococcus profundus is a homo-hexameric enzyme that catalyzes the reversible deamination of glutamate to 2-oxoglutarate in the presence of a cofactor. In each subunit, ...Glutamate dehydrogenase from Thermococcus profundus is a homo-hexameric enzyme that catalyzes the reversible deamination of glutamate to 2-oxoglutarate in the presence of a cofactor. In each subunit, a large active-site cleft is formed between the two functional domains, one of which displays motion to open and close the cleft. Trp89 in the cleft displays two sidechain conformers in the open cleft and a single conformer in the closed cleft. To reveal the role of the Trp89 sidechain in the domain motion, we mutated Trp89 to phenylalanine. Despite the Trp89 sidechain being located away from the reaction center, the catalytic constant decreased to 1/38-fold of that of the wild-type without a fatal reduction of the affinities to the cofactor and ligand molecules. To understand the molecular mechanism underlying this reduction, we determined the crystal structure in the unliganded state and the metastable conformations appearing in the steady stage of the reaction using cryo-electron microscopy (cryoEM). The four identified metastable conformations were similar to the three conformations observed in the wild-type, but their populations were different from those of the wild-type. In addition, a conformation with a completely closed active-site cleft necessary for the reaction to proceed was quite rare. The crystal structure and the four metastable conformations suggested that the reduction in the catalytic constant could be attributed to changes in the interactions between Gln13 and the 89th side chains, preventing the closing domain motion.
詳細: 0.5 mM NADP, 100 mM Glutamate in 5 mM Tris-HCl at pH7.5.
グリッド
モデル: Quantifoil R1.2/1.3 / 材質: COPPER / メッシュ: 200 / 支持フィルム - 材質: CARBON / 支持フィルム - トポロジー: HOLEY / 前処理 - タイプ: GLOW DISCHARGE / 前処理 - 時間: 45 sec. / 前処理 - 雰囲気: AIR / 前処理 - 気圧: 0.02 kPa 詳細: Both sides of the grid were glow-discharged for 45 s at 20 mA and 20 Pa.
凍結
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 281 K / 装置: FEI VITROBOT MARK IV 詳細: The sample solution was flash-frozen 2-h after mixing the protein solution and buffer solution..
詳細
8.96 mg/mL GDH W89F
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電子顕微鏡法
顕微鏡
JEOL CRYO ARM 300
撮影
フィルム・検出器のモデル: GATAN K3 (6k x 4k) / 撮影したグリッド数: 1 / 実像数: 7651 / 平均露光時間: 2.0 sec. / 平均電子線量: 50.0 e/Å2
電子線
加速電圧: 300 kV / 電子線源: FIELD EMISSION GUN
電子光学系
照射モード: OTHER / 撮影モード: BRIGHT FIELD / 最大 デフォーカス(公称値): 5.0 µm 最小 デフォーカス(公称値): 0.35000000000000003 µm
タイプ: MAXIMUM LIKELIHOOD / ソフトウェア - 名称: RELION (ver. 4.0)
最終 角度割当
タイプ: MAXIMUM LIKELIHOOD / ソフトウェア - 名称: RELION (ver. 4.0)
最終 3次元分類
クラス数: 32 / 平均メンバー数/クラス: 115000 / ソフトウェア - 名称: RELION (ver. 4.0) 詳細: The final 3D classification carried out by two-step process. In the first, all particles were separated into eight classes. Subsequently, each of these classes was further classified into ...詳細: The final 3D classification carried out by two-step process. In the first, all particles were separated into eight classes. Subsequently, each of these classes was further classified into four subclasses. This entire process was conducted following a symmetry expansion operation on all particles, in accordance with the D3 symmetry of GDH.