Departamento de Química , Centro de Investigación y de Estudios Avanzados (Cinvestav) , Mexico City 07360 , Mexico.
J Phys Chem B. 2019 Jul 11;123(27):5671-5677. doi: 10.1021/acs.jpcb.9b01818. Epub 2019 Jun 27.
γD-Crystallin (HγDC) is a key structural protein in the human lens, whose aggregation has been associated with the development of cataracts. Single-point mutations and post-translational modifications destabilize HγDC interactions, forming partially folded intermediates, where hydrophobic residues are exposed and thus triggering its aggregation. In this work, we used alchemical free-energy calculations to predict changes in thermodynamic stability (ΔΔ) of 10 alanine-scanning variants and 12 HγDC mutations associated with the development of congenital cataract. Our results show that W42R is the most destabilizing mutation in HγDC. This has been corroborated through experimental determination of ΔΔ employing differential scanning calorimetry. Calculations of hydration free energies from the HγDC WT and the W42R mutant suggested that the mutant has a higher aggregation propensity. Our combined theoretical and experimental results contribute to understand HγDC destabilization and aggregation mechanisms in age-onset cataracts.
γD-晶体蛋白（HγDC）是人类晶状体中的关键结构蛋白，其聚集与白内障的发展有关。单点突变和翻译后修饰会破坏 HγDC 相互作用，形成部分折叠的中间体，暴露出疏水性残基，从而引发其聚集。在这项工作中，我们使用变分自由能计算预测了与先天性白内障发展相关的 10 个丙氨酸扫描变体和 12 个 HγDC 突变的热力学稳定性变化（ΔΔ）。我们的结果表明，W42R 是 HγDC 中最具破坏性的突变。这一点通过使用差示扫描量热法实验测定 ΔΔ 得到了证实。从 HγDC WT 和 W42R 突变体计算水合自由能表明，突变体具有更高的聚集倾向。我们的理论和实验结果有助于理解年龄相关性白内障中 HγDC 失稳和聚集机制。
