Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore, 119260.
Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore, 119260.
Biochem Biophys Res Commun. 2020 Jun 11;526(4):1112-1117. doi: 10.1016/j.bbrc.2020.04.014. Epub 2020 Apr 17.
In lens, αβγ-crystallins accounting for ∼90% of ocular proteins with concentrations >400 mg/ml need to remain soluble for the whole life-span and their aggregation can lead to cataract. Mysteriously, despite being a metabolically-quiescent organ, lens maintains ATP concentrations of 3-7 mM. Very recently, ATP was proposed to hydrotropically prevent aggregation of crystallins but the mechanism remains unexplored. Here by NMR, DLS and DSF, we characterized the association, thermal stability and conformation of the 178-residue human γS-crystallin at concentrations from 2 to 100 mg/ml in the absence and in the presence of ATP. Results together reveal for the first time that ATP does antagonize the crowding-induced destabilization, although it has no significant binding to γS-crystallin as well as no alteration of its conformation. Therefore, ATP prevents aggregation in lens by a novel mechanism, thus rationalizing the fact that declining concentrations of ATP upon being aged is related to age-related cataractogenesis. To restore the normal concentrations of ATP in lens may represent a promising therapeutic strategy to treat aggregation-causing eye diseases.
在晶状体中，占眼蛋白约 90%的αβγ-晶体蛋白浓度>400mg/ml，需要在整个生命周期中保持可溶性，其聚集可导致白内障。奇怪的是，尽管晶状体是一个代谢静止的器官，但它保持着 3-7mM 的 ATP 浓度。最近，有人提出 ATP 具有亲水性，可防止晶体蛋白聚集，但该机制仍未得到探索。在这里，通过 NMR、DLS 和 DSF，我们在没有和存在 ATP 的情况下，在 2 至 100mg/ml 的浓度下，对 178 个残基的人γS-晶体蛋白的结合、热稳定性和构象进行了表征。结果首次表明，ATP 确实拮抗了拥挤诱导的不稳定，尽管它与γS-晶体蛋白没有明显的结合，也没有改变其构象。因此，ATP 通过一种新的机制防止晶状体聚集，从而解释了随着年龄的增长，ATP 浓度下降与年龄相关性白内障发生有关的事实。在晶状体中恢复正常浓度的 ATP 可能是治疗引起聚集的眼部疾病的一种有前途的治疗策略。
