Yang Jun, Prorok Mary, Castellino Francis J, Weliky David P
Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
Biophys J. 2004 Sep;87(3):1951-63. doi: 10.1529/biophysj.103.028530.
The human immunodeficiency virus type 1 (HIV-1) fusion peptide serves as a useful model system for understanding viral/target cell fusion, at least to the lipid mixing stage. Previous solid-state NMR studies have shown that the peptide adopts an oligomeric beta-strand structure when associated with a lipid and cholesterol mixture close to that of membranes of host cells of the virus. In this study, this structure was further investigated using four different peptide constructs. In aqueous buffer solution, two of the constructs were primarily monomeric whereas the other two constructs had significant populations of oligomers/aggregates. NMR measurements for all membrane-associated peptide constructs were consistent with oligomeric beta-strand structure. Thus, constructs that are monomeric in solution can be converted to oligomers as a result of membrane association. In addition, samples prepared by very different methods had very similar NMR spectra, which indicates that the beta-strand structure is an equilibrium rather than a kinetically trapped structure. Lipid mixing assays were performed to assess the fusogenicities of the different constructs, and there was not a linear correlation between the solution oligomeric state and fusogenicity. However, the functional assays do suggest that small oligomers may be more fusogenic than either monomers or large aggregates.
人类免疫缺陷病毒1型（HIV-1）融合肽是理解病毒/靶细胞融合的一个有用模型系统，至少对于脂质混合阶段来说是如此。先前的固态核磁共振研究表明，当该肽与接近病毒宿主细胞膜的脂质和胆固醇混合物结合时，会形成寡聚β链结构。在本研究中，使用四种不同的肽构建体对该结构进行了进一步研究。在水性缓冲溶液中，其中两种构建体主要为单体，而另外两种构建体则有大量的寡聚体/聚集体。所有与膜相关的肽构建体的核磁共振测量结果都与寡聚β链结构一致。因此，溶液中为单体的构建体可因与膜结合而转化为寡聚体。此外，通过非常不同的方法制备的样品具有非常相似的核磁共振光谱，这表明β链结构是一种平衡结构，而非动力学捕获结构。进行脂质混合测定以评估不同构建体的融合活性，溶液中的寡聚状态与融合活性之间不存在线性相关性。然而，功能测定确实表明，小寡聚体可能比单体或大聚集体更具融合活性。
