杆状病毒HaF融合肽在中性pH溶液中的NMR结构研究

膜融合蛋白在介导膜融合过程中会发生构象的转变. 以同核2D NMR为手段，测定了pH 7.0条件下棉铃虫核多角体病毒(Helicoverpa armigerasingle- nucleocapsid Nucleopolyhedrovirus，HearNPV)的HaF融合肽在类膜环境中的3级结构. 通过与酸性条件下该融合肽的结构作比较，证实了该融合肽在从融合蛋白内部暴露出来到插入宿主细胞膜的过程中发生了构象的转变. 并且这个构象的转变是一个结构趋向稳定、两亲性趋向完整的变化过程. 这些结论对研究其他融合肽的插膜过程有普遍的意义，为探索膜融合机制提供了信息.

NMR Structure of Fusion Peptide of the Helicoverpa Armigera Single Nucleocapsid Nucleopolyhedrovirus F Protein at pH 7.0

Fusion between viral and cellular membranes is an essential process for enveloped viruses to enter into cells. This process is usually mediated by fusion proteins on the surfaces of viral membranes. When pH changes from 7.0 to 5.0, the fusion proteins transform and expose their fusion peptide to anchor the cellular membrane and induce the subsequent fusion process. Ha133 (HaF) is the fusion protein of baculoviruse Helicoverpa armigera Single Nucleocapsid Nucleopolyhedrovirus (HearNPV). Its fusion peptide is composed of 20 residues, and located at the N-terminus of the F₁ subunit. In this study, NMR methods were used to determine the solution structure of the fusion peptide in a membrane-mimicking environment at pH 7.0. It was found that the structure of the fusion peptide is composed of a 3₁₀ -helix from V⁷ to S⁹, a turn at V¹⁰, a regular α-helix from D¹¹ to G¹⁶ and two flexible coils at the N- and C-terminus. Comparing this structure to the available structure of this fusion peptide at pH 5.0, it is noted that, with decreasing pH, the conformation of the fusion peptide alters to be more stable and to have a more complete amphiphilic surface. These results should allow us to further investigate the mechanism of membrane fusion.