A native chemical chaperone in the human eye lens.
A native chemical chaperone in the human eye lens.
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DOI：
10.7554/elife.76923
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发表时间：
2022-06-20
期刊：
影响因子：
7.7
通讯作者：
Shakhnovich, Eugene, I
中科院分区：
文献类型：
--
作者：
Serebryany, Eugene;Chowdhury, Sourav;Woods, Christopher N.;Thorn, David C.;Watson, Nicki E.;McClelland, Arthur A.;Klevit, Rachel E.;Shakhnovich, Eugene, I
白内障是最普遍的蛋白质聚集疾病之一，并且仍然是全世界视力丧失的最常见原因。人类晶状体的代谢静止核心区域缺乏细胞或蛋白质更新；因此，它进化出了非凡的机制来终生抵抗光散射蛋白质聚集。我们现在报道，其中一种机制涉及异常丰富的晶状体代谢物，肌醇，抑制晶状体晶状体蛋白的聚集。我们使用先前充分表征的模拟氧化人 γD-晶状体蛋白变体的体外聚集测定来量化聚集抑制，并使用溶液 NMR、负染色 TEM、差示扫描荧光测定法、热扫描拉曼光谱、氧化还原缓冲液中的浊度测定和游离硫醇定量研究肌醇的分子作用机制。与许多已知的化学伴侣不同，肌醇的主要目标不是蛋白质的天然状态、未折叠状态或最终聚集状态。相反，我们认为这是聚集途径中的限速双分子步骤。鉴于最近的代谢组学证据表明，与年龄匹配的对照相比，人类白内障晶状体中的肌醇严重耗尽，我们建议维持或恢复晶状体中肌醇的健康水平可能是预防或延缓年龄发病性白内障引起的晶状体混浊的一种简单、安全且全球可及的策略。
Cataract is one of the most prevalent protein aggregation disorders and still the most common cause of vision loss worldwide. The metabolically quiescent core region of the human lens lacks cellular or protein turnover; it has therefore evolved remarkable mechanisms to resist light-scattering protein aggregation for a lifetime. We now report that one such mechanism involves an unusually abundant lens metabolite, myo-inositol, suppressing aggregation of lens crystallins. We quantified aggregation suppression using our previously well-characterized in vitro aggregation assays of oxidation-mimicking human γD-crystallin variants and investigated myo-inositol’s molecular mechanism of action using solution NMR, negative-stain TEM, differential scanning fluorometry, thermal scanning Raman spectroscopy, turbidimetry in redox buffers, and free thiol quantitation. Unlike many known chemical chaperones, myo-inositol’s primary target was not the native, unfolded, or final aggregated states of the protein; rather, we propose that it was the rate-limiting bimolecular step on the aggregation pathway. Given recent metabolomic evidence that it is severely depleted in human cataractous lenses compared to age-matched controls, we suggest that maintaining or restoring healthy levels of myo-inositol in the lens may be a simple, safe, and globally accessible strategy to prevent or delay lens opacification due to age-onset cataract.