College of Chemistry and Molecular Engineering and Beijing NMR Center, Peking University, Beijing, China.
Food, Nutrition, and Health Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada.
J Biol Chem. 2020 Oct 23;295(43):14548-14562. doi: 10.1074/jbc.RA120.014311. Epub 2020 Jul 10.
In plants, many natural defense mechanisms include cellular membrane fusion as a way to resist infection by external pathogens. Several plant proteins mediate membrane fusion, but the detailed mechanism by which they promote fusion is less clear. Understanding this process could provide valuable insights into these proteins' physiological functions and guide bioengineering applications ( the design of antimicrobial proteins). The plant-specific insert (PSI) from can help reduce certain pathogen attack via membrane fusion. To gain new insights into the process of PSI-induced membrane fusion, a combined approach of NMR, FRET, and studies was used. Our results indicate that (i) under acidic conditions, the PSI experiences a monomer-dimer equilibrium, and the dimeric PSI induces membrane fusion below a certain critical pH; (ii) after fusion, the PSI resides in a highly dehydrated environment with limited solvent accessibility, suggesting its capability in reducing repulsive dehydration forces between liposomes to facilitate fusion; and (iii) as shown by molecular dynamics simulations, the PSI dimer can bind stably to membrane surfaces and can bridge liposomes in close proximity, a critical step for the membrane fusion. In summary, this study provides new and unique insights into the mechanisms by which the PSI and similar proteins induce membrane fusion.
在植物中，许多天然防御机制包括细胞膜融合，以此来抵抗外部病原体的感染。几种植物蛋白介导膜融合，但它们促进融合的详细机制尚不清楚。了解这个过程可以为这些蛋白质的生理功能提供有价值的见解，并指导生物工程应用（抗菌蛋白的设计）。 来自 的植物特异性插入片段（PSI）可以通过膜融合帮助减少某些病原体的攻击。为了更深入地了解 PSI 诱导的膜融合过程，采用了 NMR、FRET 和 研究相结合的方法。我们的结果表明：（i）在酸性条件下，PSI 经历单体-二聚体平衡，并且二聚体 PSI 在低于一定临界 pH 值下诱导膜融合；（ii）融合后，PSI 处于高度去水化的环境中，溶剂可及性有限，表明其能够降低脂质体之间的排斥去水化力，从而促进融合；（iii）如分子动力学模拟所示，PSI 二聚体可以稳定地结合到膜表面上，并可以桥接近距离的脂质体，这是膜融合的关键步骤。总之，这项研究为 PSI 和类似蛋白诱导膜融合的机制提供了新的独特见解。
