Ju Lining, Lou Jizhong, Chen Yunfeng, Li Zhenhai, Zhu Cheng
Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia; Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia; Heart Research Institute, Camperdown, New South Wales, Australia; Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales, Australia.
Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
Biophys J. 2015 Nov 3;109(9):1781-4. doi: 10.1016/j.bpj.2015.08.050.
Leucine-rich repeat (LRR) is a versatile motif widely present in adhesive proteins and signal-transducing receptors. The concave structure formed by a group of LRRs is thought to facilitate binding to globular protein domains with increased affinities. However, little is known about the conformational dynamics of LRRs in such a structure, e.g., whether and how force induces conformational changes in LRRs to regulate protein binding and signal transduction. Here we investigated the platelet glycoprotein Ibα (GPIbα), a demonstrated mechanoreceptor with known crystal structures for the N-terminal domain (GPIbαN), as a model for LRR-containing proteins using a combined method of steered molecular dynamics simulations and single-molecule force spectroscopy with a biomembrane force probe. We found that force-induced unfolding of GPIbαN starts with LRR2-4 and propagates to other LRRs. Importantly, force-dependent lifetimes of individual VWF-A1 bonds with GPIbα are prolonged after LRR unfolding. Enhancement of protein-protein interactions by force-induced LRR unfolding may be a phenomenon of interest in biology.
富含亮氨酸重复序列（LRR）是一种广泛存在于黏附蛋白和信号转导受体中的多功能基序。一组LRR形成的凹面结构被认为有助于以更高的亲和力结合球状蛋白结构域。然而，对于这种结构中LRR的构象动力学知之甚少，例如，力是否以及如何诱导LRR的构象变化以调节蛋白质结合和信号转导。在这里，我们使用导向分子动力学模拟和生物膜力探针单分子力谱相结合的方法，研究了血小板糖蛋白Ibα（GPIbα），它是一种已证实的机械感受器，其N端结构域（GPIbαN）具有已知的晶体结构，作为含LRR蛋白质的模型。我们发现，力诱导的GPIbαN展开始于LRR2 - 4，并传播到其他LRR。重要的是，在LRR展开后，与GPIbα的单个VWF - A1键的力依赖寿命延长。力诱导的LRR展开增强蛋白质 - 蛋白质相互作用可能是生物学中一个有趣的现象。
