Role of the specific amino acid sequence of the membrane-spanning domain of human immunodeficiency virus type 1 in membrane fusion
Role of the specific amino acid sequence of the membrane-spanning domain of human immunodeficiency virus type 1 in membrane fusion
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DOI：
10.1128/jvi.79.8.4720-4729.2005
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发表时间：
2005-04-01
影响因子：
5.4
通讯作者：
Matsuda, Z
中科院分区：
文献类型：
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作者：
Miyauchi, K;Komano, J;Matsuda, Z
gp 41介导的细胞膜与病毒膜的融合启动了人类免疫缺陷病毒1型的生命周期。相对于胞外域结构与功能关系的研究，跨膜结构域（MSD）的研究相对较少。特别是，MSD的特定氨基酸序列在膜融合中可能具有的作用以及其他gp 4l功能还没有很好地理解。gp 41的MSD含有形成GXXXG基序（G，甘氨酸; X，其他氨基酸残基）的高度保守的甘氨酸残基，GXXXG基序是通常在跨膜α-螺旋的螺旋-螺旋界面处发现的基序。在这里，我们通过制备两种类型的MSD突变体来检查gp 41 MSD的特定氨基酸序列在gp 41功能中，特别是在膜融合中的作用：（i）甘氨酸取代突变体，其中MSD的甘氨酸残基突变为丙氨酸或亮氨酸残基，和（ii）置换突变体，其中整个MSD被来自血型糖蛋白A或来自水泡性口炎病毒G的MSD置换。甘氨酸的取代不影响gp 41的功能。然而，MSD置换突变体表现出严重受损的融合活性。使用Env表达载体的测定揭示了MSD置换突变体中CD 4结合步骤后的膜融合缺陷。此外，注意到MSD置换突变体的Env加工变化。这些结果表明，gp 4l的MSD对突变具有相对宽但不是无限的耐受性，并且在膜融合以及Env生物发生的其他步骤中起关键作用。
Fusion between cell and virus membranes mediated by gp41 initiates the life cycle of human immunodeficiency virus type 1. In contrast to the many studies that have elucidated the structure-function relationship of the ectodomain, the study of the membrane-spanning domain (MSD) has been rather limited. In particular, the role that the MSD's specific amino acid sequences may have in membrane fusion as well as other gp4l functions is not well understood. The MSD of gp41 contains well-conserved glycine residues that form the GXXXG motif (G, glycine; X, other amino acid residues), a motif often found at the helix-helix interface of membrane spanning alpha-helices. Here we examined the role that the specific amino acid sequence of the gp41 MSD has in gp41 function, particularly in membrane fusion, by making two types of MSD mutants: (i) glycine substitution mutants in which glycine residues of the MSD were mutated to alanine or leucine residues, and (ii) replacement mutants in which the entire MSD was replaced with one derived from glycophorin A or from vesicular stomatitis virus G. The substitution of glycines did not affect gp41 function. MSD-replacement mutants, however, showed severely impaired fusion activity. The assay using the Env expression vector revealed defects in membrane fusion after CD4 binding steps in the MSD-replacement mutants. In addition, the change in Env processing was noted for MSD-replacement mutants. These results suggest that the MSD of gp4l has a relatively wide but not unlimited tolerance for mutations and plays a critical role in membrane fusion as well as in other steps of Env biogenesis.