The nuclear pore complex regulates nucleocytoplasmic transport by means of a tightly synchronized suite of biochemical reactions. The physicochemical properties of the translocating cargos are emerging as master regulators of their shuttling dynamics. As well as being affected by molecular weight and surface-exposed amino acids, the kinetics of the nuclear translocation of protein cargos also depend on their nanomechanical properties, yet the mechanisms underpinning the mechanoselectivity of the nuclear pore complex are unclear. Here we show that proteins with locally soft regions in the vicinity of the nuclear-localization sequence exhibit higher nuclear-import rates, and that such mechanoselectivity is specifically impaired upon knocking down nucleoporin 153, a key protein in the nuclear pore complex. This allows us to design a short, easy-to-express and chemically inert unstructured peptide tag that accelerates the nuclear-import rate of stiff protein cargos. We also show that U2OS osteosarcoma cells expressing the peptide-tagged myocardin-related transcription factor import this mechanosensitive protein to the nucleus at higher rates and display faster motility. Locally unstructured regions lower the free-energy barrier of protein translocation and might offer a control mechanism for nuclear mechanotransduction.

核孔复合体通过一系列紧密同步的生化反应来调节核细胞质运输。易位货物的物理化学特性正在成为其穿梭动力学的主要调节因素。除了受到分子量和表面暴露的氨基酸的影响外，蛋白质货物的核转位动力学还取决于它们的纳米力学特性，但支撑核孔复合物的机械选择性的机制尚不清楚。在这里，我们表明，在核定位序列附近具有局部软区域的蛋白质表现出更高的核输入率，并且这种机械选择性在敲除核孔蛋白 153（核孔复合物中的关键蛋白质）时特别受损。这使我们能够设计一种短的、易于表达的、化学惰性的非结构化肽标签，加速硬蛋白货物的核输入速率。我们还表明，表达肽标记心肌素相关转录因子的 U2OS 骨肉瘤细胞将这种机械敏感蛋白以更高的速率导入细胞核，并表现出更快的运动性。局部非结构化区域降低了蛋白质易位的自由能垒，并可能为核力转导提供控制机制。