Ambidextrous helical nanotubes from self-assembly of designed helical hairpin motifs
Ambidextrous helical nanotubes from self-assembly of designed helical hairpin motifs
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DOI：
10.1073/pnas.1903910116
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发表时间：
2019-07-16
影响因子：
11.1
通讯作者：
Conticello, Vincent P.
中科院分区：
文献类型：
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作者：
Hughes, Spencer A.;Wang, Fengbin;Conticello, Vincent P.
串联重复序列蛋白质具有天然的可设计性，并代表了潜在的有用的支架，用于构建合成的仿生组件。我们设计了2个合成肽，HEAT_R1和LRV_M3 Delta 1，分别基于嗜热HEAT（PBS_HEAT）和富含亮氨酸变体（LRV）结构基序的单重复序列。肽的自组装提供了高纵横比的螺旋纳米管。冷冻电子显微镜与直接电子检测被用来分析的结构的溶剂化的细丝。来自冷冻-EM图的3D重建导致分别在6.0和4.4埃的分辨率下的HEAT_R1和LRV_M3 Delta 1细丝的原子模型。令人惊讶的是，尽管横向包装界面处的序列相似，HEAT_R1和LRV_M3 Delta 1细丝采用相反的螺旋手，并且螺旋几何形状显着不同，同时保留了与之前表征的同类重复蛋白相似的局部构象。2种细丝的差异可以根据横向和轴向界面处内聚相互作用的差异来合理化。这些结构数据加强了以前的观察螺旋蛋白组装体的结构可塑性和需要高分辨率的结构分析。尽管有这些观察结果，串联重复蛋白质的天然可设计性提供了机会，工程师新的螺旋纳米管。此外，所得纳米管具有独立可寻址和化学可区分的内表面和外表面，这将有助于选择性识别，运输和释放的应用。
Tandem repeat proteins exhibit native designability and represent potentially useful scaffolds for the construction of synthetic biomimetic assemblies. We have designed 2 synthetic peptides, HEAT_R1 and LRV_M3 Delta 1, based on the consensus sequences of single repeats of thermophilic HEAT (PBS_HEAT) and Leucine-Rich Variant (LRV) structural motifs, respectively. Self-assembly of the peptides afforded high-aspect ratio helical nanotubes. Cryo-electron microscopy with direct electron detection was employed to analyze the structures of the solvated filaments. The 3D reconstructions from the cryo-EM maps led to atomic models for the HEAT_R1 and LRV_M3 Delta 1 filaments at resolutions of 6.0 and 4.4 angstrom, respectively. Surprisingly, despite sequence similarity at the lateral packing interface, HEAT_R1 and LRV_M3 Delta 1 filaments adopt the opposite helical hand and differ significantly in helical geometry, while retaining a local conformation similar to previously characterized repeat proteins of the same class. The differences in the 2 filaments could be rationalized on the basis of differences in cohesive interactions at the lateral and axial interfaces. These structural data reinforce previous observations regarding the structural plasticity of helical protein assemblies and the need for high-resolution structural analysis. Despite these observations, the native designability of tandem repeat proteins offers the opportunity to engineer novel helical nanotubes. Moreover, the resultant nanotubes have independently addressable and chemically distinguishable interior and exterior surfaces that would facilitate applications in selective recognition, transport, and release.