Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142.
Institute of Materials, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne, Switzerland.
Proc Natl Acad Sci U S A. 2020 Aug 4;117(31):18470-18476. doi: 10.1073/pnas.1902597117. Epub 2020 Jul 20.
Lipid membrane fusion is an essential process for a number of critical biological functions. The overall process is thermodynamically favorable but faces multiple kinetic barriers along the way. Inspired by nature's engineered proteins such as SNAP receptor [soluble N-ethylmale-imide-sensitive factor-attachment protein receptor (SNARE)] complexes or viral fusogenic proteins that actively promote the development of membrane proximity, nucleation of a stalk, and triggered expansion of the fusion pore, here we introduce a synthetic fusogen that can modulate membrane fusion and equivalently prime lipid membranes for calcium-triggered fusion. Our fusogen consists of a gold nanoparticle functionalized with an amphiphilic monolayer of alkanethiol ligands that had previously been shown to fuse with lipid bilayers. While previous efforts to develop synthetic fusogens have only replicated the initial steps of the fusion cascade, we use molecular simulations and complementary experimental techniques to demonstrate that these nanoparticles can induce the formation of a lipid stalk and also drive its expansion into a fusion pore upon the addition of excess calcium. These results have important implications in general understanding of stimuli-triggered fusion and the development of synthetic fusogens for biomedical applications.
脂质体融合是许多关键生物功能所必需的过程。总的过程在热力学上是有利的，但在整个过程中会遇到多个动力学障碍。受自然界工程蛋白（如 SNAP 受体[可溶性 N-乙基马来酰亚胺敏感因子附着蛋白受体（SNARE）]复合物或病毒融合蛋白）的启发，这些蛋白可以主动促进膜接近、柄的成核以及触发融合孔的扩展，我们在这里引入了一种合成融合蛋白，它可以调节膜融合，并等效地为钙触发融合的脂质膜做好准备。我们的融合蛋白由金纳米粒子功能化的两亲单层烷硫醇配体组成，先前已证明该配体可以与脂质双层融合。虽然以前开发合成融合蛋白的努力仅复制了融合级联的初始步骤，但我们使用分子模拟和互补的实验技术证明，这些纳米粒子可以诱导形成脂质柄，并在添加过量钙时驱动其扩展成融合孔。这些结果对刺激触发融合的一般理解以及用于生物医学应用的合成融合蛋白的发展具有重要意义。
