Del Giudice Rita, Arciello Angela, Itri Francesco, Merlino Antonello, Monti Maria, Buonanno Martina, Penco Amanda, Canetti Diana, Petruk Ganna, Monti Simona Maria, Relini Annalisa, Pucci Piero, Piccoli Renata, Monti Daria Maria
Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy.
Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy; Istituto Nazionale di Biostrutture e Biosistemi (INBB), Rome, Italy.
Biochim Biophys Acta. 2016 Feb;1860(2):434-44. doi: 10.1016/j.bbagen.2015.10.019. Epub 2015 Oct 26.
Amyloidoses are devastating diseases characterized by accumulation of misfolded proteins which aggregate in fibrils. Specific gene mutations in Apolipoprotein A I (ApoAI) are associated with systemic amyloidoses. Little is known on the effect of mutations on ApoAI structure and amyloid properties. Here we performed a physico-chemical characterization of L75P- and L174S-amyloidogenic ApoAI (AApoAI) variants to shed light on the effects of two single point mutations on protein stability, proteolytic susceptibility and aggregation propensity. Both variants are destabilized in their N-terminal region and generate fibrils with different morphological features. L75P-AApoAI is significantly altered in its conformation and compactness, whereas a more flexible and pronounced aggregation-competent state is associated to L174S-AApoAI. These observations point out how single point mutations in ApoAI gene evocate differences in the physico-chemical and conformational behavior of the corresponding protein variants, with the common feature of diverting ApoAI from its natural role towards a pathogenic pathway.
淀粉样变性是一类严重的疾病，其特征是错误折叠的蛋白质聚集形成纤维。载脂蛋白A I（ApoAI）中的特定基因突变与系统性淀粉样变性有关。关于这些突变对ApoAI结构和淀粉样特性的影响，人们了解甚少。在此，我们对L75P和L174S淀粉样变ApoAI（AApoAI）变体进行了物理化学表征，以阐明两个单点突变对蛋白质稳定性、蛋白水解敏感性和聚集倾向的影响。两种变体在其N端区域均不稳定，并产生具有不同形态特征的纤维。L75P - AApoAI的构象和紧密性显著改变，而L174S - AApoAI则与一种更灵活且明显具有聚集能力的状态相关。这些观察结果指出，ApoAI基因中的单点突变如何引发相应蛋白质变体在物理化学和构象行为上的差异，其共同特征是使ApoAI偏离其自然功能，走向致病途径。
