Kukol A, Arkin I T
Cambridge Center for Molecular Recognition, Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, England.
Biophys J. 1999 Sep;77(3):1594-601. doi: 10.1016/S0006-3495(99)77007-4.
The recently developed method of site-directed Fourier transform infrared dichroism for obtaining orientational constraints of oriented polymers is applied here to the transmembrane domain of the vpu protein from the human immunodeficiency virus type 1 (HIV-1). The infrared spectra of the 31-residue-long vpu peptide reconstituted in lipid vesicles reveal a predominantly alpha-helical structure. The infrared dichroism data of the (13)C-labeled peptide yielded a helix tilt beta = (6.5 +/- 1.7) degrees from the membrane normal. The rotational pitch angle omega, defined as zero for a residue located in the direction of the helix tilt, is omega = (283 +/- 11) degrees for the (13)C labels Val(13)/Val(20) and omega = (23 +/- 11) degrees for the (13)C labels Ala(14)/Val(21). A global molecular dynamics search protocol restraining the helix tilt to the experimental value was performed for oligomers of four, five, and six subunits. From 288 structures for each oligomer, a left-handed pentameric coiled coil was obtained, which best fits the experimental data. The structure reveals a pore occluded by Trp residues at the intracellular end of the transmembrane domain.
最近开发的用于获取取向聚合物取向约束的定点傅里叶变换红外二色性方法，在此应用于人类免疫缺陷病毒1型（HIV-1）vpu蛋白的跨膜结构域。在脂质囊泡中重构的31个残基长的vpu肽的红外光谱显示出主要为α螺旋结构。（13）C标记肽的红外二色性数据得出螺旋倾斜角β = （6.5 ± 1.7）度，相对于膜法线方向。旋转螺距角ω，对于位于螺旋倾斜方向上的残基定义为零，对于（13）C标记的Val（13）/Val（20）为ω = （283 ± 11）度，对于（13）C标记的Ala（14）/Val（21）为ω = （23 ± 11）度。对四聚体、五聚体和六聚体的寡聚物进行了将螺旋倾斜限制在实验值的全局分子动力学搜索协议。从每个寡聚物的288个结构中，获得了一个左手五聚体卷曲螺旋，其最符合实验数据。该结构揭示了跨膜结构域细胞内末端被色氨酸残基封闭的孔。
