Cao Thong M, King Michael R
Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235 USA.
Cell Mol Bioeng. 2021 Feb 4;14(1):65-74. doi: 10.1007/s12195-021-00666-z. eCollection 2021 Feb.
E-selectin is a member of the selectin family of cell adhesion molecules expressed on the plasma membrane of inflamed endothelium and facilitates initial leukocyte tethering and subsequent cell rolling during the early stages of the inflammatory response binding to glycoproteins expressing sialyl Lewis and sialyl Lewis (sLe). Existing crystal structures of the extracellular lectin/EGF-like domain of E-selectin complexed with sLe have revealed that E-selectin can exist in two conformation states, a low affinity (bent) conformation, and a high affinity (extended) conformation. The differentiating characteristic of the two conformations is the interdomain angle between the lectin and the EGF-like domain.
Using molecular dynamics (MD) simulations we observed that in the absence of tensile force E-selectin undergoes spontaneous switching between the two conformational states at equilibrium. A single amino acid substitution at residue 2 (serine to tyrosine) on the lectin domain favors the extended conformation.
Steered molecular dynamics (SMD) simulations of E-selectin and PSGL-1 in conjunction with experimental cell adhesion assays show a longer binding lifetime of E-selectin (S2Y) to PSGL-1 compared to wildtype protein.
The findings in this study advance our understanding into how the structural makeup of E-selectin allosterically influences its adhesive dynamics.
E-选择素是细胞黏附分子选择素家族的成员,表达于炎症内皮细胞的质膜上,在炎症反应早期促进初始白细胞的 tethering 以及随后的细胞滚动,它与表达唾液酸化路易斯和唾液酸化路易斯(sLe)的糖蛋白结合。E-选择素细胞外凝集素/表皮生长因子样结构域与 sLe 复合的现有晶体结构表明,E-选择素可以存在两种构象状态,即低亲和力(弯曲)构象和高亲和力(伸展)构象。两种构象的区别特征是凝集素和表皮生长因子样结构域之间的结构域间角度。
使用分子动力学(MD)模拟,我们观察到在没有拉力的情况下,E-选择素在平衡状态下会在两种构象状态之间自发切换。凝集素结构域上第 2 位残基(丝氨酸突变为酪氨酸)的单个氨基酸取代有利于伸展构象。
E-选择素和 PSGL-1 的定向分子动力学(SMD)模拟与实验性细胞黏附测定相结合,显示与野生型蛋白相比,E-选择素(S2Y)与 PSGL-1 的结合寿命更长。
本研究中的发现推进了我们对 E-选择素的结构组成如何变构影响其黏附动力学的理解。