Gawrisch K, Han K H, Yang J S, Bergelson L D, Ferretti J A
Laboratory of Biophysical Chemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
Biochemistry. 1993 Mar 30;32(12):3112-8. doi: 10.1021/bi00063a024.
The interaction of the peptide fragment 828-848, called P828, from the carboxy-terminal region of the envelope glycoprotein gp41 of HIV-I with model membranes composed of phosphatidylcholine (PC) and phosphatidylglycerol (PG) was investigated using microelectrophoretic mobility of liposomes, fluorescence polarization of labeled lipids, NMR, and differential scanning calorimetry. The peptide binds to negatively charged lipid surfaces. No interaction between P828 and neutral PC surfaces is observed. The interaction between the peptide and the lipid is exclusively electrostatic with the six positively charged arginines of P828 acting as binding sites for PG. Circular dichroism measurements of P828 indicate that the peptide undergoes a transition from a random coil to an ordered conformation upon binding to negatively charged PG bilayers or SDS micelles, but not in the presence of neutral PC bilayers. The ordered structure has an apparent helical content of 60%. IN DOPG/DOPC mixtures containing 20 mol % DOPG, the peptide causes the formation of lipid domains enriched in DOPG, as assessed by measurement of fluorescence energy transfer between labeled PG and PC. The formation of these domains requires energy and therefore reduces the strength of peptide binding to the lipid matrix. Our data support and quantitate the results from antibody binding studies [Haffar, O.K., Dowbenko, D. J., & Berman, P. W. (1988) J. Cell Biol. 107, 1677-1687] that the carboxy-terminal segment of the envelope glycoprotein gp41 interacts with microsomal membranes.
利用脂质体的微电泳迁移率、标记脂质的荧光偏振、核磁共振和差示扫描量热法，研究了来自HIV-1包膜糖蛋白gp41羧基末端区域的名为P828的肽片段828-848与由磷脂酰胆碱（PC）和磷脂酰甘油（PG）组成的模型膜之间的相互作用。该肽与带负电荷的脂质表面结合。未观察到P828与中性PC表面之间的相互作用。肽与脂质之间的相互作用完全是静电作用，P828的六个带正电荷的精氨酸作为与PG的结合位点。P828的圆二色性测量表明，该肽在与带负电荷的PG双层或SDS胶束结合时会从无规卷曲转变为有序构象，但在中性PC双层存在时则不会。这种有序结构的表观螺旋含量为60%。在含有20 mol% DOPG的DOPG/DOPC混合物中，通过测量标记的PG和PC之间的荧光能量转移评估，该肽会导致富含DOPG的脂质结构域形成。这些结构域的形成需要能量，因此会降低肽与脂质基质结合的强度。我们的数据支持并量化了抗体结合研究的结果[哈法尔，O.K.，多本科，D.J.，& 伯曼，P.W.（1988年）《细胞生物学杂志》107卷，1677 - 1687页]，即包膜糖蛋白gp41的羧基末端片段与微粒体膜相互作用。
