The C. Eugene Bennett Department of Chemistry, West Virginia University , Morgantown, West Virginia 26505, United States.
Biochemistry. 2014 Apr 15;53(14):2355-65. doi: 10.1021/bi401619q. Epub 2014 Apr 4.
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 α-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 (Nt17Q35P10KK), and this peptide preferentially accumulated on curved membranes, consistent with the ability of AHs to sense membrane curvature.
亨廷顿病（HD）是一种遗传性神经退行性疾病，由亨廷顿（Htt）蛋白第一外显子中扩展的多聚谷氨酰胺（polyQ）结构域引起，促进其聚集。Htt 与细胞内的多种膜结构相互作用，Htt 直接位于 polyQ 结构域侧翼的前 17 个氨基酸（Nt17）包含一个两亲性α-螺旋（AH）脂质结合结构域。AH 也已知可检测膜曲率。为了确定 Htt 外显子 1 是否优先结合弯曲的膜，进行了原位原子力显微镜（AFM）研究。支持的脂质双层通常用作 AFM 研究蛋白质聚集的模型膜。然而，这些支持的双层通常缺乏曲率。通过在硅基底上沉积的硅纳米珠（50±10nm）上形成双层，可以开发具有平坦和弯曲区域的模型支持脂质双层用于 AFM 研究。通过连续成像双层的形成、高度测量和使用扫描探针加速显微镜对所得双层进行空间分辨机械测量，验证了双层在珠上的存在。通过对整个成像过程的数值模拟，方便了对该数据的解释。与平坦的支持双层相比，与珠相关的弯曲支持双层具有更高的顺应性，这与诱导曲率引起的脂质排列密度改变一致。该模型双层系统暴露于合成的截断 Htt 外显子 1 肽（Nt17Q35P10KK），该肽优先积累在弯曲的膜上，这与 AH 感知膜曲率的能力一致。
