Castaneda Nicholas, Feuillie Cecile, Molinari Michael, Kang Ellen Hyeran
NanoScience Technology Center, University of Central Florida, Orlando, FL, United States.
Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, United States.
Front Mol Biosci. 2021 Nov 26;8:760950. doi: 10.3389/fmolb.2021.760950. eCollection 2021.
The structural and mechanical properties of actin bundles are essential to eukaryotic cells, aiding in cell motility and mechanical support of the plasma membrane. Bundle formation occurs in crowded intracellular environments composed of various ions and macromolecules. Although the roles of cations and macromolecular crowding in the mechanics and organization of actin bundles have been independently established, how changing both intracellular environmental conditions influence bundle mechanics at the nanoscale has yet to be established. Here we investigate how electrostatics and depletion interactions modulate the relative Young's modulus and height of actin bundles using atomic force microscopy. Our results demonstrate that cation- and depletion-induced bundles display an overall reduction of relative Young's modulus depending on either cation or crowding concentrations. Furthermore, we directly measure changes to cation- and depletion-induced bundle height, indicating that bundles experience alterations to filament packing supporting the reduction to relative Young's modulus. Taken together, our work suggests that electrostatic and depletion interactions may act counteractively, impacting actin bundle nanomechanics and organization.
肌动蛋白束的结构和力学特性对真核细胞至关重要，有助于细胞运动和对质膜的机械支撑。束的形成发生在由各种离子和大分子组成的拥挤细胞内环境中。尽管阳离子和大分子拥挤在肌动蛋白束的力学和组织中的作用已分别得到证实，但改变这两种细胞内环境条件如何在纳米尺度上影响束的力学仍有待确定。在这里，我们使用原子力显微镜研究静电和耗尽相互作用如何调节肌动蛋白束的相对杨氏模量和高度。我们的结果表明，阳离子诱导和耗尽诱导的束显示出相对杨氏模量的总体降低，这取决于阳离子或拥挤浓度。此外，我们直接测量了阳离子诱导和耗尽诱导的束高度的变化，表明束经历了细丝堆积的改变，支持相对杨氏模量的降低。综上所述，我们的工作表明静电和耗尽相互作用可能起反作用，影响肌动蛋白束的纳米力学和组织。
