Schibli D J, Montelaro R C, Vogel H J
Department of Biological Sciences, University of Calgary, Alberta, Canada.
Biochemistry. 2001 Aug 14;40(32):9570-8. doi: 10.1021/bi010640u.
The membrane-proximal tryptophan-rich region of the HIV transmembrane glycoprotein, gp41, plays an important role in the membrane fusion reaction. Using NMR spectroscopy, we have studied the tertiary structure of a synthetic 19-residue amidated peptide (NH2-KWASLWNWFNITNWLWYIK-CONH2) corresponding to this region in membrane-mimetic environments. Initial experiments in sodium dodecyl sulfate/H2O micelles and trifluoroethanol gave poor results, because of low solubility. However, in dodecylphosphocholine micelles, we obtained excellent 500 and 800 MHz NMR spectra, suggesting that the peptide has a preference for a zwitterionic membrane-like environment. The final NMR structures demonstrated a well-defined helical peptide with a backbone rmsd of 0.47 +/- 0.18 A. Four of the five tryptophan residues, as well as the tyrosine residue, formed a "collar" of aromatic residues along the axial length of the helix. By analogy to related tryptophan-rich antimicrobial peptides, the structure indicates that the aromatic residues of the HIV peptide are positioned within the membrane-water interface of a phospholipid bilayer. This is confirmed by the observation of direct NOEs between the aromatic residues of the peptide to the headgroup and interfacial protons of prototonated dodecylphosphocholine. The bulk of the polar residues are positioned on one face of this structure, with the hydrophobic phenylalanine side chain on the opposing face, forming an amphipathic structure. This work shows that the Trp-rich membrane-proximal region of HIV and related viruses can bind to the surfaces of zwitterioninc membranes in a "Velcro-like" manner.
人类免疫缺陷病毒跨膜糖蛋白gp41的膜近端富含色氨酸区域在膜融合反应中发挥重要作用。我们利用核磁共振光谱研究了一种合成的19个残基的酰胺化肽（NH2-KWASLWNWFNITNWLWYIK-CONH2）在模拟膜环境中对应于该区域的三级结构。最初在十二烷基硫酸钠/水胶束和三氟乙醇中的实验结果不佳，因为溶解度较低。然而，在十二烷基磷胆碱胶束中，我们获得了出色的500和800兆赫核磁共振光谱，表明该肽偏好两性离子的膜样环境。最终的核磁共振结构显示出一个明确的螺旋肽，主链均方根偏差为0.47±0.18埃。五个色氨酸残基中的四个以及酪氨酸残基沿着螺旋的轴向长度形成了一个芳香族残基的“环”。与相关的富含色氨酸的抗菌肽类似，该结构表明HIV肽的芳香族残基位于磷脂双层的膜-水界面内。肽的芳香族残基与质子化十二烷基磷胆碱的头部基团和界面质子之间直接核Overhauser效应的观察证实了这一点。大部分极性残基位于该结构的一个面上，疏水的苯丙氨酸侧链位于相对面上，形成了一种两亲结构。这项工作表明，HIV及相关病毒富含色氨酸的膜近端区域能够以“类似维可牢”的方式结合到两性离子膜的表面。
