National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM077234
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM062750
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM120923
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM128577
米国
引用
ジャーナル: Proc Natl Acad Sci U S A / 年: 2025 タイトル: Structural basis of nearest-neighbor cooperativity in the ring-shaped gene regulatory protein TRAP from protein engineering and cryo-EM. 著者: Weicheng Li / Haoyun Yang / Kye Stachowski / Andrew S Norris / Katie Lichtenthal / Skyler Kelly / Paul Gollnick / Vicki H Wysocki / Mark P Foster / 要旨: The homo-dodecameric ring-shaped RNA binding attenuation protein (TRAP) from binds up to twelve tryptophan ligands (Trp) and becomes activated to bind a specific sequence in the 5' leader region of ...The homo-dodecameric ring-shaped RNA binding attenuation protein (TRAP) from binds up to twelve tryptophan ligands (Trp) and becomes activated to bind a specific sequence in the 5' leader region of the operon mRNA, thereby downregulating biosynthesis of Trp. Thermodynamic measurements of Trp binding have revealed a range of cooperative behavior for different TRAP variants, even if the averaged apparent affinities for Trp have been found to be similar. Proximity between the ligand binding sites, and the ligand-coupled disorder-to-order transition has implicated nearest-neighbor interactions in cooperativity. To establish a solid basis for describing nearest-neighbor cooperativity in TRAP, we engineered variants constructed with two subunits connected by a flexible linker (dTRAP). We mutated the binding sites of alternating protomers such that only every other site was competent for Trp binding (WT-Mut dTRAP). Ligand binding monitored by NMR, calorimetry, and native mass spectrometry revealed strong cooperativity in dTRAP containing adjacent binding-competent sites, but a severe binding defect when the wild-type sites were separated by mutated sites. Cryo-EM experiments of dTRAP in its ligand-free apo state, and both dTRAP and WT-Mut dTRAP in the presence of Trp, revealed progressive stabilization of loops that gate the Trp binding site and participate in RNA binding. These studies provide important insights into the thermodynamic and structural basis for the observed ligand binding cooperativity in TRAP. Such insights can be useful for understanding allosteric control networks and for the development of those with defined ligand sensitivity and regulatory control.
モデル: Quantifoil R1.2/1.3 / 材質: GOLD / メッシュ: 300 / 前処理 - タイプ: GLOW DISCHARGE / 前処理 - 時間: 60 sec. 詳細: 20 mA, 30 sec hold, 1 min glow discharge using a PELCO easiGlow Discharge System
凍結
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 277.15 K / 装置: FEI VITROBOT MARK IV 詳細: lotted with a blot force of 1 for 4 seconds at 277.15K and 100% relative humidity before being plunged frozen into liquid ethane.
詳細
An aliquot of 10 mg/mL of apo dTRAP was diluted with cryo-EM buffer (20 mM HEPES, 200 mM NaCl, pH 8) supplemented with a 0.6% stock of Triton X-100 to obtain a final sample of 6 mg/mL protein and 0.05% Triton X-100.
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電子顕微鏡法
顕微鏡
TFS KRIOS
撮影
フィルム・検出器のモデル: GATAN K3 BIOCONTINUUM (6k x 4k) 平均電子線量: 60.0 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): 2.0 µm / 最小 デフォーカス(公称値): 0.5 µm
実験機器
モデル: Titan Krios / 画像提供: FEI Company
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画像解析
初期モデル
モデルのタイプ: NONE
最終 再構成
解像度のタイプ: BY AUTHOR / 解像度: 4.24 Å / 解像度の算出法: FSC 0.143 CUT-OFF / 使用した粒子像数: 91038