Curvature Enhances Binding and Aggregation of Huntingtin at Lipid Membranes
Curvature Enhances Binding and Aggregation of Huntingtin at Lipid Membranes
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DOI：
10.1021/bi401619q
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发表时间：
2014-04-15
期刊：
影响因子：
2.9
通讯作者：
Legleiter, Justin
中科院分区：
文献类型：
--
作者：
Chaibva, Maxmore;Burke, Kathleen A.;Legleiter, Justin
亨廷顿病（Huntington disease，HD）是一种遗传性神经退行性疾病，由亨廷顿蛋白（Huntingtin，Htt）第一外显子的多聚谷氨酰胺（polyQ）结构域扩展，促进其聚集引起。Htt与细胞内的多种膜结构相互作用，并且Htt的直接侧接polyQ结构域的前17个氨基酸（Nt 17）包含两亲性α-螺旋（AH）脂质结合结构域。AH还已知检测膜曲率。为了确定Htt外显子1是否优先结合弯曲膜，进行原位原子力显微镜（AFM）研究。支持的脂质双层通常被用作AFM研究蛋白质聚集的模型膜。然而，这些支撑的双层通常缺乏曲率。通过在沉积在硅基底上的二氧化硅纳米珠（50 +/-10 nm）的顶部上形成双层，开发了具有平坦和弯曲区域的模型支撑的脂质双层用于AFM研究。通过使用扫描探针加速度显微镜对双层的形成、高度测量和所得双层的空间分辨机械测量的连续成像来验证珠上双层的存在。通过对整个成像过程的数值模拟，促进了对这些数据的解释。与珠相关的弯曲支撑双层被发现比平坦支撑双层更柔顺，这与由诱导曲率引起的脂质的改变的堆积密度一致。将该模型双层系统暴露于合成的截短的Htt外显子1肽（Nt 17 Q（35）P（10）KK），并且该肽优先在弯曲的膜上积累，这与AH感知膜弯曲的能力一致。
Huntington disease (HD) is a genetic neurodegenerative disease caused by an expanded polyglutamine (polyQ) domain in the first exon of the huntingtin (Htt) protein, facilitating its aggregation. Htt interacts with a variety of membraneous structures within the cell, and the first 17 amino acids (Nt17) of Htt directly flanking the polyQ domain comprise an amphiphathic alpha-helix (AH) lipid-binding domain. AHs are also known to detect membrane curvature. To determine if Htt exon 1 preferentially binds curved membranes, in situ atomic force microscopy (AFM) studies were performed. Supported lipid bilayers are commonly used as model membranes for AFM studies of protein aggregation. However, these supported bilayers usually lack curvature. By forming a bilayer on top of silica nanobeads (50 +/- 10 nm) deposited on a silicon substrate, model supported lipid bilayers with flat and curved regions were developed for AFM studies. The presence of the bilayer over the beads was validated by continual imaging of the formation of the bilayer, height measurements, and spatially resolved mechanical measurements of the resulting bilayer using scanning probe acceleration microscopy. Interpretation of this data was facilitated by numerical simulations of the entire imaging process. The curved supported bilayers associated with the beads were found to be more compliant than flat supported bilayers, consistent with the altered packing density of lipids caused by the induced curvature. This model bilayer system was exposed to a synthetic truncated Htt exon 1 peptide (Nt17Q(35)P(10)KK), and this peptide preferentially accumulated on curved membranes, consistent with the ability of AHs to sense membrane curvature.