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.
構造決定の手法: 分子置換 / 解像度: 2.028→21.8 Å / Cor.coef. Fo:Fc: 0.963 / Cor.coef. Fo:Fc free: 0.949 / SU B: 3.285 / SU ML: 0.087 / 交差検証法: THROUGHOUT / ESU R: 0.119 / ESU R Free: 0.115 / 立体化学のターゲット値: MAXIMUM LIKELIHOOD / 詳細: HYDROGENS HAVE BEEN ADDED IN THE RIDING POSITIONS
Rfactor
反射数
%反射
Selection details
Rfree
0.19944
14013
5 %
RANDOM
Rwork
0.17224
-
-
-
obs
0.17357
269065
99.58 %
-
溶媒の処理
イオンプローブ半径: 0.8 Å / 減衰半径: 0.8 Å / VDWプローブ半径: 1.2 Å / 溶媒モデル: MASK