Department of Applied Molecular Chemistry, Graduate School of Industrial Technology, Nihon University, Narashino, Chiba 275-8575, Japan.
Langmuir. 2012 Jan 31;28(4):2299-305. doi: 10.1021/la2038075. Epub 2012 Jan 17.
Membrane fusion proteins such as the hemagglutinin glycoprotein have target recognition and fusion accelerative domains, where some synergistically working elements are essential for target-selective and highly effective native membrane fusion systems. In this work, novel membrane fusion devices bearing such domains were designed and constructed. We selected a phenylboronic acid derivative as a recognition domain for a sugar-like target and a transmembrane-peptide (Leu-Ala sequence) domain interacting with the target membrane, forming a stable hydrophobic α-helix and accelerating the fusion process. Artificial membrane fusion behavior between the synthetic devices in which pilot and target liposomes were incorporated was characterized by lipid-mixing and inner-leaflet lipid-mixing assays. Consequently, the devices bearing both the recognition and transmembrane domains brought about a remarkable increase in the initial rate for the membrane fusion compared with the devices containing the recognition domain alone. In addition, a weakly acidic pH-responsive device was also constructed by replacing three Leu residues in the transmembrane-peptide domain by Glu residues. The presence of Glu residues made the acidic pH-dependent hydrophobic α-helix formation possible as expected. The target-selective liposome-liposome fusion was accelerated in a weakly acidic pH range when the Glu-substituted device was incorporated in pilot liposomes. The use of this pH-responsive device seems to be a potential strategy for novel applications in a liposome-based delivery system.
膜融合蛋白，如血凝素糖蛋白，具有靶向识别和融合加速结构域，其中一些协同作用的元素对于靶向选择性和高效的天然膜融合系统是必不可少的。在这项工作中，设计并构建了具有这些结构域的新型膜融合装置。我们选择了苯硼酸衍生物作为糖样靶标的识别域，以及与靶细胞膜相互作用的跨膜肽（Leu-Ala 序列）域，形成稳定的疏水性α-螺旋并加速融合过程。通过脂质混合和内层脂质混合测定，对含有先导和靶脂质体的合成装置之间的人工膜融合行为进行了表征。结果，与仅含有识别结构域的装置相比，同时具有识别和跨膜结构域的装置使膜融合的初始速率显著增加。此外，还通过将跨膜肽结构域中的三个亮氨酸残基替换为谷氨酸残基，构建了一种弱酸性 pH 响应装置。如预期的那样，谷氨酸残基的存在使得酸性 pH 依赖性疏水性α-螺旋形成成为可能。当将 Glu 取代的装置掺入先导脂质体中时，在弱酸性 pH 范围内，靶向选择性脂质体-脂质体融合得到加速。这种 pH 响应装置的使用似乎为基于脂质体的递药系统中的新应用提供了一种潜在策略。
