Antanasijevic Aleksandar, Kingsley Carolyn, Basu Arnab, Bowlin Terry L, Rong Lijun, Caffrey Michael
Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 S Ashland, Chicago, IL, 60607, USA.
Microbiotix Inc., Worcester, MA, 01605, USA.
J Biomol NMR. 2016 Mar;64(3):255-65. doi: 10.1007/s10858-016-0025-1. Epub 2016 Feb 26.
The membrane proteins of viruses play critical roles in the virus life cycle and are attractive targets for therapeutic intervention. Virus-like particles (VLP) present the possibility to study the biochemical and biophysical properties of viral membrane proteins in their native environment. Specifically, the VLP constructs contain the entire protein sequence and are comprised of native membrane components including lipids, cholesterol, carbohydrates and cellular proteins. In this study we prepare VLP containing full-length hemagglutinin (HA) or neuraminidase (NA) from influenza and characterize their interactions with small molecule inhibitors. Using HA-VLP, we first show that VLP samples prepared using the standard sucrose gradient purification scheme contain significant amounts of serum proteins, which exhibit high potential for non-specific interactions, thereby complicating NMR studies of ligand-target interactions. We then show that the serum contaminants may be largely removed with the addition of a gel filtration chromatography step. Next, using HA-VLP we demonstrate that WaterLOGSY NMR is significantly more sensitive than Saturation Transfer Difference (STD) NMR for the study of ligand interactions with membrane bound targets. In addition, we compare the ligand orientation to HA embedded in VLP with that of recombinant HA by STD NMR. In a subsequent step, using NA-VLP we characterize the kinetic and binding properties of substrate analogs and inhibitors of NA, including study of the H274Y-NA mutant, which leads to wide spread resistance to current influenza antivirals. In summary, our work suggests that VLP have high potential to become standard tools in biochemical and biophysical studies of viral membrane proteins, particularly when VLP are highly purified and combined with control VLP containing native membrane proteins.
病毒的膜蛋白在病毒生命周期中发挥着关键作用,是治疗干预的有吸引力的靶点。病毒样颗粒(VLP)为在其天然环境中研究病毒膜蛋白的生化和生物物理特性提供了可能性。具体而言,VLP构建体包含完整的蛋白质序列,由包括脂质、胆固醇、碳水化合物和细胞蛋白在内的天然膜成分组成。在本研究中,我们制备了含有流感病毒全长血凝素(HA)或神经氨酸酶(NA)的VLP,并表征了它们与小分子抑制剂的相互作用。使用HA-VLP,我们首先表明,使用标准蔗糖梯度纯化方案制备的VLP样品含有大量血清蛋白,这些血清蛋白具有很高的非特异性相互作用潜力,从而使配体-靶点相互作用的核磁共振研究变得复杂。然后我们表明,通过添加凝胶过滤色谱步骤可以很大程度上去除血清污染物。接下来,使用HA-VLP我们证明,对于研究配体与膜结合靶点的相互作用,WaterLOGSY核磁共振比饱和转移差异(STD)核磁共振明显更灵敏。此外,我们通过STD核磁共振比较了嵌入VLP中的HA与重组HA的配体取向。在随后的步骤中,使用NA-VLP我们表征了NA的底物类似物和抑制剂的动力学和结合特性,包括对H274Y-NA突变体的研究,该突变体导致对当前流感抗病毒药物产生广泛抗性。总之,我们的工作表明,VLP在病毒膜蛋白的生化和生物物理研究中具有很高的潜力成为标准工具,特别是当VLP高度纯化并与含有天然膜蛋白的对照VLP结合时。