Zhao Jing, Liu Xinyue, Kao Chelsea, Zhang Emily, Li Quanhong, Zhang Fuming, Linhardt Robert J
College of Food Science & Nutritional Engineering, China Agricultural University (CAU) , Beijing 100083, China.
Departments of Biology and Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
Biochemistry. 2016 Aug 16;55(32):4552-9. doi: 10.1021/acs.biochem.6b00555. Epub 2016 Aug 3.
Langerin, a C-type lectin, is expressed in Langerhans cells. It was reported that langerin binds sulfated glycans, which is an important initial step for its role in blocking human immunodeficiency virus (HIV) transmission by capturing HIV pathogens and mediating their internalization into Birbeck granules for their elimination. It is fundamentally important to understand these interactions at the molecular level for the design of new highly specific therapeutic agents for HIV. Surface plasmon resonance (SPR), which allows for the real-time, direct, quantitative analysis of the label-free molecular interactions, has been used successfully for biophysical characterization of glycosaminoglycan (GAG)-protein interactions. In this study, we report kinetics, structural analysis, and the effects of physiological conditions (e.g., pH, salt concentration, and Ca(2+) and Zn(2+)concentrations) on the interactions between GAGs and langerin using SPR. SPR results revealed that langerin binds to heparin with high affinity (KD ∼ 2.4 nM) and the oligosaccharide length required for the interactions is larger than a tetrasaccharide. This heparin/heparan sulfate-binding protein also interacts with other GAGs, including dermatan sulfate, chondroitin sulfates C-E and KS. In addition, liquid chromatography-mass spectrometry analysis was used to characterize the structure of sulfated glycans that bound to langerin.
朗格素是一种C型凝集素，在朗格汉斯细胞中表达。据报道，朗格素能结合硫酸化聚糖，这是其通过捕获HIV病原体并介导其内化至伯贝克颗粒中以实现清除从而在阻断人类免疫缺陷病毒（HIV）传播中发挥作用的重要起始步骤。从分子水平理解这些相互作用对于设计新型高效特异性HIV治疗药物至关重要。表面等离子体共振（SPR）可对无标记分子相互作用进行实时、直接、定量分析，已成功用于糖胺聚糖（GAG）-蛋白质相互作用的生物物理表征。在本研究中，我们使用SPR报告了GAG与朗格素之间相互作用的动力学、结构分析以及生理条件（如pH、盐浓度、Ca(2+)和Zn(2+)浓度）的影响。SPR结果显示，朗格素以高亲和力（KD ∼ 2.4 nM）结合肝素，相互作用所需的寡糖长度大于四糖。这种肝素/硫酸乙酰肝素结合蛋白还与其他GAG相互作用，包括硫酸皮肤素、硫酸软骨素C - E和硫酸角质素。此外，液相色谱 - 质谱分析用于表征与朗格素结合的硫酸化聚糖的结构。
