Lee Clarence C, Revington Matthew, Dunn Stanley D, Petersen Nils O
Department of Chemistry, The University of Western Ontario, London, Canada.
Biophys J. 2003 Mar;84(3):1756-64. doi: 10.1016/s0006-3495(03)74983-2.
We have systematically investigated the effect of aggregation of a transmembrane peptide on its diffusion in dimyristoylphosphatidylcholine and in palmitoyloleoylphosphatidylcholine model membranes. The hydrophobic segment of the b subunit from E. coli F(1)F(0)-ATP synthase was modified with a histidine tag at the carbonyl terminus and was aggregated selectively by using a series of multivalent, dendritic chelating agents with nitrilotriacetic acid functional groups. Peptide complexes ranging from monomers to hexamers were formed and studied in giant unilamellar vesicles. The rate of diffusion for the transmembrane peptide complexes were found to depend on the size of the complex. The results agree with predictions from the free area model for monomers and dimers, and the hydrodynamic continuum model for tetramers, pentamers, and hexamers. Comparisons with diffusion of lipids confirm that the diffusion of a transmembrane peptide is enhanced by coupling of density fluctuations between the two monolayers.
我们系统地研究了一种跨膜肽聚集对其在二肉豆蔻酰磷脂酰胆碱和棕榈酰油酰磷脂酰胆碱模型膜中扩散的影响。来自大肠杆菌F(1)F(0)-ATP合酶的b亚基的疏水片段在羰基末端用组氨酸标签进行了修饰,并通过使用一系列带有次氮基三乙酸官能团的多价树枝状螯合剂进行选择性聚集。在巨型单层囊泡中形成并研究了从单体到六聚体的肽复合物。发现跨膜肽复合物的扩散速率取决于复合物的大小。结果与单体和二聚体的自由面积模型以及四聚体、五聚体和六聚体的流体动力学连续介质模型的预测一致。与脂质扩散的比较证实,跨膜肽的扩散通过两个单层之间密度波动的耦合而增强。