Postgraduate in Natural Sciences and Engineering, Autonomous Metropolitan University, Cuajimalpa, Mexico City 05348, Mexico.
Departament of Natural Sciences, Autonomous Metropolitan University, Cuajimalpa, Mexico City 05348, Mexico.
Int J Mol Sci. 2024 Aug 5;25(15):8536. doi: 10.3390/ijms25158536.
The formation and analysis of amyloid fibers by two β-glucosidases, BglA and BglB, belonging to the GH1 enzyme family, are reported. Both proteins have the (β/α) TIM-barrel fold, which is characteristic of this family and is also the most common protein structure. BglA is an octamer, whereas BglB is a monomer. Amyloid fibrillation using pH and temperature as perturbing agents was investigated using fluorescence spectroscopy as a preliminary approach and corroborated using wide-field optical microscopy, confocal microscopy, and field-emission scanning electron microscopy. These analyses showed that both enzymes fibrillate at a wide range of acidic and alkaline conditions and at several temperature conditions, particularly at acidic pH (3-4) and at temperatures between 45 and 65 °C. Circular dichroism spectroscopy corroborated the transition from an α-helix to a β-sheet secondary structure of both proteins in conditions where fibrillation was observed. Overall, our results suggest that fibrillation is a rather common phenomenon caused by protein misfolding, driven by a transition from an α-helix to a β-sheet secondary structure, that many proteins can undergo if subjected to conditions that disturb their native conformation.
报告了属于 GH1 酶家族的两种β-葡萄糖苷酶，BglA 和 BglB，其纤维的形成和分析。这两种蛋白质都具有（β/α）TIM 桶折叠结构，这是该家族的特征，也是最常见的蛋白质结构。BglA 是八聚体，而 BglB 是单体。使用荧光光谱法作为初步方法，并使用宽场光学显微镜、共聚焦显微镜和场发射扫描电子显微镜进行验证，研究了使用 pH 和温度作为扰动剂的淀粉样纤维形成。这些分析表明，两种酶在广泛的酸性和碱性条件以及多种温度条件下都发生了纤维形成，特别是在酸性 pH（3-4）和 45 至 65°C 的温度下。圆二色性光谱法证实了在观察到纤维形成的条件下，两种蛋白质的从α-螺旋到β-折叠二级结构的转变。总的来说，我们的结果表明，纤维形成是由蛋白质错误折叠引起的一种相当普遍的现象，由从α-螺旋到β-折叠二级结构的转变驱动，如果蛋白质受到破坏其天然构象的条件的影响，许多蛋白质都可能发生这种转变。
