Expanding the family of extracellular chaperones: Identification of human plasma proteins with chaperone activity
Expanding the family of extracellular chaperones: Identification of human plasma proteins with chaperone activity
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DOI：
10.1002/pro.4189
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发表时间：
2021-10-04
期刊：
影响因子：
8
通讯作者：
Wilson, Mark R.
中科院分区：
文献类型：
--
作者：
Geraghty, Nicholas J.;Satapathy, Sandeep;Wilson, Mark R.
蛋白质稳态，即蛋白质合成、折叠和降解的平衡，对于维持细胞功能和活力至关重要，许多已知的细胞内伴侣被认为在维持生命中发挥着关键作用。相比之下，组成型分泌的细胞外伴侣（EC）的身份及其在细胞外蛋白质稳态中的生理作用尚不完全清楚。我们设计并实施了一种新策略，基于分子伴侣与错误折叠蛋白上暴露的疏水性区域结合的众所周知的倾向，以发现人类血液中存在的新 EC。我们使用一种在 37 摄氏度下错误折叠的不稳定蛋白质作为“诱饵”，与人血清中潜在的 EC 结合，并捕获在磁珠上形成的复合物。通过质谱法鉴定从珠子中洗脱的蛋白质，并选择一组七种丰富的血清蛋白用于伴侣活性的体外分析。其中五种蛋白质被证明可以特异性抑制蛋白质聚集。玻连蛋白和纤溶酶原激活剂 3 既能抑制阿尔茨海默病 β 肽 (A beta(1-42)) 体外聚集形成纤维状淀粉样蛋白，又能抑制柠檬酸合酶 (CS) 聚集形成非结构化（无定形）聚集体。相反，凝血酶原、C1r 和 C1s 抑制 A beta(1-42) 聚集，但不抑制 CS 聚集。因此，这项研究确定了五种新颖且丰富的推定 EC，它们可能在维持细胞外蛋白质稳态中发挥重要作用，并且显然具有不同的抑制无定形和淀粉样蛋白形成蛋白聚集途径的能力。
Proteostasis, the balance of protein synthesis, folding and degradation, is essential to maintain cellular function and viability, and the many known intracellular chaperones are recognized as playing key roles in sustaining life. In contrast, the identity of constitutively secreted extracellular chaperones (ECs) and their physiological roles in extracellular proteostasis is less completely understood. We designed and implemented a novel strategy, based on the well-known propensity of chaperones to bind to regions of hydrophobicity exposed on misfolding proteins, to discover new ECs present in human blood. We used a destabilized protein that misfolds at 37 degrees C as "bait" to bind to potential ECs in human serum and captured the complexes formed on magnetic beads. Proteins eluted from the beads were identified by mass spectrometry and a group of seven abundant serum proteins was selected for in vitro analysis of chaperone activity. Five of these proteins were shown to specifically inhibit protein aggregation. Vitronectin and plasminogen activator-3 inhibited both the in vitro aggregation of the Alzheimer's beta peptide (A beta(1-42)) to form fibrillar amyloid, and the aggregation of citrate synthase (CS) to form unstructured (amorphous) aggregates. In contrast, prothrombin, C1r, and C1s inhibited the aggregation of A beta(1-42) but did not inhibit CS aggregation. This study thus identified five novel and abundant putative ECs which may play important roles in the maintenance of extracellular proteostasis, and which apparently have differing abilities to inhibit the amorphous and amyloid-forming protein aggregation pathways.