Department of Molecular Medicine, Institute of Biochemistry, University of Pavia, Pavia, Italy.
Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, London, United Kingdom.
J Biol Chem. 2020 Aug 14;295(33):11379-11387. doi: 10.1074/jbc.RA120.014026. Epub 2020 Jun 22.
Systemic amyloidosis caused by extracellular deposition of insoluble fibrils derived from the pathological aggregation of circulating proteins, such as transthyretin, is a severe and usually fatal condition. Elucidation of the molecular pathogenic mechanism of the disease and discovery of effective therapies still represents a challenging medical issue. The preparation of amyloid fibrils that exhibit structural and biochemical properties closely similar to those of natural fibrils is central to improving our understanding of the biophysical basis of amyloid formation and may offer an important tool for drug discovery. Here, we compared the morphology and thermodynamic stability of natural transthyretin fibrils with those of fibrils generated either using the common acidification procedure or primed by limited selective cleavage by plasmin. The free energies for fibril formation were -12.36, -8.10, and -10.61 kcal mol, respectively. The fibrils generated via plasmin cleavage were more stable than those prepared at low pH and were thermodynamically and morphologically similar to natural fibrils extracted from human amyloidotic tissue. Determination of thermodynamic stability is an important tool that is complementary to other methods of structural comparison between fibrils and fibrils generated Our finding that fibrils created via an amyloidogenic pathway are structurally similar to human amyloid fibrils does not necessarily establish that the fibrillogenic pathway is the same for both, but it narrows the current knowledge gap between models and pathophysiology.
系统性淀粉样变是由可溶性纤维丝在细胞外沉积引起的，这些纤维丝来源于循环蛋白的病理性聚集，如转甲状腺素蛋白。这种疾病通常是严重且致命的。阐明疾病的分子发病机制并发现有效的治疗方法仍然是一个具有挑战性的医学问题。制备结构和生化特性与天然纤维丝非常相似的淀粉样纤维丝，对于提高我们对淀粉样形成的生物物理基础的理解至关重要，并且可能为药物发现提供重要工具。在这里，我们比较了天然转甲状腺素蛋白纤维丝的形态和热力学稳定性，以及通过常见酸化程序或通过纤溶酶有限选择性切割引发生成的纤维丝的形态和热力学稳定性。纤维丝形成的自由能分别为-12.36、-8.10 和-10.61 kcal/mol。通过纤溶酶切割生成的纤维丝比在低 pH 下制备的纤维丝更稳定，并且在热力学和形态上与从人类淀粉样组织中提取的天然纤维丝相似。确定热力学稳定性是一种重要的工具，它与纤维丝之间的结构比较的其他方法互补。我们发现通过淀粉样形成途径生成的纤维丝在结构上与人类淀粉样纤维丝相似，这不一定表明两者的纤维丝形成途径相同，但它缩小了模型和病理生理学之间当前的知识差距。
