The complete influenza hemagglutinin fusion domain adopts a tight helical hairpin arrangement at the lipid:water interface
The complete influenza hemagglutinin fusion domain adopts a tight helical hairpin arrangement at the lipid:water interface
复制标题
DOI：
10.1073/pnas.1006142107
复制
发表时间：
2010-06-22
影响因子：
11.1
通讯作者：
Bax, Ad
中科院分区：
文献类型：
--
作者：
Lorieau, Justin L.;Louis, John M.;Bax, Ad
流感病毒糖蛋白血凝素（HA）的HA2结构域的N末端23个残基中，除了5个之外，在所有16种HA基因血清型中都严格保守。这种HA2融合肽（HAfp）的结构和功能一直是广泛的生物物理、计算和功能分析的焦点，但这些分析大多是针对不包括严格保守的残基色氨酸（21） - 酪氨酸（22） - 甘氨酸（23）的肽段。本文报道的对溶解在十二烷基磷脂酰胆碱中的H1血清亚型全长HAfp的异核三共振核磁共振研究揭示了一种非常紧密的螺旋发夹结构，其N末端α - 螺旋（甘氨酸（1） - 甘氨酸（12））与第二个α - 螺旋（色氨酸（14） - 甘氨酸（23））紧密堆积，7个保守的甘氨酸残基中有6个位于螺旋间界面。位于13位的第7个保守甘氨酸残基采用正的φ角，使得连接两个螺旋的发夹转角成为可能。该结构通过多个螺旋间的C（α）H到C = O氢键得以稳定，其特征是强烈的螺旋间H（N） - H（α）和H（α） - H（α）核 Overhauser效应（NOE）接触。许多先前已确定的使HA2失去融合能力的突变也与HAfp螺旋的紧密反平行发夹排列不相容。（15）N弛豫分析表明该结构在纳秒时间尺度上高度有序，NOE分析表明HAfp位于水 - 脂质界面，其疏水表面朝向脂质环境，螺旋 - 螺旋界面的富含甘氨酸的一侧暴露于溶剂。
All but five of the N-terminal 23 residues of the HA2 domain of the influenza virus glycoprotein hemagglutinin (HA) are strictly conserved across all 16 serotypes of HA genes. The structure and function of this HA2 fusion peptide (HAfp) continues to be the focus of extensive biophysical, computational, and functional analysis, but most of these analyses are of peptides that do not include the strictly conserved residues Trp(21)-Tyr(22)-Gly(23). The heteronuclear triple resonance NMR study reported here of full length HAfp of sero subtype H1, solubilized in dodecylphosphatidyl choline, reveals a remarkably tight helical hairpin structure, with its N-terminal alpha-helix (Gly(1)-Gly(12)) packed tightly against its second alpha-helix (Trp(14)-Gly(23)), with six of the seven conserved Gly residues at the interhelical interface. The seventh conserved Gly residue in position 13 adopts a positive phi angle, enabling the hairpin turn that links the two helices. The structure is stabilized by multiple interhelical C(alpha)H to C=O hydrogen bonds, characterized by strong interhelical H(N)-H(alpha) and H(alpha)-H(alpha) NOE contacts. Many of the previously identified mutations that make HA2 nonfusogenic are also incompatible with the tight antiparallel hairpin arrangement of the HAfp helices. (15)N relaxation analysis indicates the structure to be highly ordered on the nanosecond time scale, and NOE analysis indicates HAfp is located at the water-lipid interface, with its hydrophobic surface facing the lipid environment, and the Gly-rich side of the helix-helix interface exposed to solvent.