8T5X

Probing the dissociation pathway of a kinetically labile transthyretin mutant (A25T)

8T5X の概要

• エントリーDOI: 10.2210/pdb8t5x/pdb
• 分子名称: Transthyretin (2 entities in total)
• 機能のキーワード: aggregation, amyloid, transport protein
• 由来する生物種: Homo sapiens (human)
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 27614.77

構造登録者

Ferguson, J.A.,Sun, X.,Leach, B.I.,Stanfield, R.L.,Dyson, H.J.,Wright, P.E. (登録日: 2023-06-14, 公開日: 2023-08-02, 最終更新日: 2024-01-17)

主引用文献

Sun, X.,Ferguson, J.A.,Leach, B.I.,Stanfield, R.L.,Dyson, H.J.,Wright, P.E.
Probing the Dissociation Pathway of a Kinetically Labile Transthyretin Mutant.
J.Am.Chem.Soc., 146:532-542, 2024

PubMed Abstract: Aggregation of transthyretin (TTR) is associated with devastating amyloid diseases. Amyloidosis begins with the dissociation of the native homotetramer (a dimer of dimers) to form a monomeric intermediate that assembles into pathogenic aggregates. This process is accelerated at low pH, but the process by which TTR dissociates and reassembles at neutral pH remains poorly characterized due to the low population of intermediates. Here, we use F-nuclear magnetic resonance (NMR) and a highly sensitive trifluoromethyl probe to determine the relative populations of the species formed by the dissociation of a destabilized variant, A25T. The A25T mutation perturbs both the strong dimer and weak dimer-dimer interfaces. A tetramer ⇌ dimer ⇌ monomer (TDM) equilibrium model is proposed to account for concentration- and temperature-dependent population changes. Thermodynamic and kinetic parameters and activation energetics for dissociation of the native A25T tetramer, as well as a destabilized alternative tetramer (T*) with a mispacked F87 side chain, were extracted by van't Hoff and F-NMR line shape analysis, saturation transfer, and transition state theory. Chemical shifts for the dimer and T* species are degenerate for F and methyl probes close to the strong dimer interface, implicating interfacial perturbation as a common structural feature of these destabilized species. All-atom molecular dynamics simulations further suggest more frequent F87 ring flipping on the nanosecond time scale in the A25T dimer than in the native A25T tetramer. Our integrated approach offers quantitative insights into the energy landscape of the dissociation pathway of TTR at neutral pH.

PubMed: 38134439
DOI: 10.1021/jacs.3c10083

実験手法

X-RAY DIFFRACTION (1.63 Å)