Max Planck Institute of Biochemistry, Martinsried near Munich, Germany.
Technical University of Munich, Garching Near Munich, Germany.
Soft Matter. 2021 Jan 22;17(2):276-287. doi: 10.1039/d0sm00150c.
Membrane-active cytoskeletal elements, such as FtsZ, septin or actin, form filamentous polymers able to induce and stabilize curvature on cellular membranes. In order to emulate the characteristic dynamic self-assembly properties of cytoskeletal subunits in vitro, biomimetic synthetic scaffolds were here developed using DNA origami. In contrast to our earlier work with pre-curved scaffolds, we specifically assessed the potential of origami mimicking straight filaments, such as actin and microtubules, by origami presenting cholesteryl anchors for membrane binding and additional blunt end stacking interactions for controllable polymerization into linear filaments. By assessing the interaction of our DNA nanostructures with model membranes using fluorescence microscopy, we show that filaments can be formed, upon increasing MgCl2 in solution, for structures displaying blunt ends; and can subsequently depolymerize, by decreasing the concentration of MgCl2. Distinctive spike-like membrane protrusions were generated on giant unilamellar vesicles at high membrane-bound filament densities, and the presence of such deformations was reversible and shown to correlate with the MgCl2-triggered polymerization of DNA origami subunits into filamentous aggregates. In the end, our approach reveals the formation of membrane-bound filaments as a minimal requirement for membrane shaping by straight cytoskeletal-like objects.
膜活性细胞骨架元件，如 FtsZ、隔膜或肌动蛋白，形成丝状聚合物，能够在细胞膜上诱导和稳定曲率。为了在体外模拟细胞骨架亚基的特征动态自组装特性，使用 DNA 折纸术开发了仿生合成支架。与我们之前使用预弯曲支架的工作相比，我们特别评估了折纸术模拟直丝（如肌动蛋白和微管）的潜力，通过呈现胆固醇锚用于膜结合的折纸术以及用于可控聚合成长丝的附加钝端堆积相互作用。通过使用荧光显微镜评估我们的 DNA 纳米结构与模型膜的相互作用，我们表明，对于显示钝端的结构，可以在溶液中增加 MgCl2 时形成丝状；并且可以通过降低 MgCl2 的浓度进行解聚。在高膜结合丝密度下，在巨大的单层囊泡上产生了独特的刺状膜突起，并且这种变形是可逆的，并显示与 MgCl2 触发 DNA 折纸术亚基聚合成长丝聚集相关。最后，我们的方法揭示了作为直细胞骨架样物体对膜成型的最小要求的膜结合丝的形成。
