Binding of human immunodeficiency virus type 1 Gag to membrane: Role of the matrix amino terminus
Binding of human immunodeficiency virus type 1 Gag to membrane: Role of the matrix amino terminus
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DOI：
10.1128/jvi.73.5.4136-4144.1999
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发表时间：
1999-05-01
影响因子：
5.4
通讯作者：
Freed, EO
中科院分区：
文献类型：
--
作者：
Ono, A;Freed, EO
人类免疫缺陷病毒1型（HIV-1） Gag蛋白前体Pr55（Gag）与膜结合是病毒组装过程中不可缺少的步骤。先前，我们报道了基质（MA）残基6取代（6VR）导致病毒组装缺陷，这与肉芽化缺陷突变体中观察到的相似，表明6VR的改变损害了膜结合。有趣的是，6VR突变对Gag肉豆荚化没有影响，6VR造成的缺陷表型被MA其他位置的变化逆转，包括残基97。在本研究中，我们使用了几种生化方法来证明残基6突变，以及MA氨基酸7和8的额外取代，减少了膜结合，但不影响n端肉豆荚化。这种效应是在Pr55（Gag）的背景下观察到的，截断的Gag只含有MA和CA，以及MA本身。由6VR突变引起的膜结合缺陷被MA残基20和97的第二位点改变所逆转，这两个位点单独存在时，使膜结合增加到比野生型更高的水平。由MA取代引起的膜结合的减弱和增强都依赖于n端肉豆蔻酸盐的存在。这些结果支持最近提出的调节Gag膜结合的肉豆蔻酸开关模型，根据该模型，膜结合是由n端肉豆蔻酸部分的暴露或隔离程度决定的。或者，肉豆蔻酸酯插入脂质双分子层可能是其他不同的ma编码膜结合域功能的先决条件。
Binding of the human immunodeficiency virus type 1 (HIV-1) Gag protein precursor, Pr55(Gag), to membrane is an indispensable step in virus assembly. Previously, we reported that a matrix (MA) residue 6 substitution (6VR) imposed a virus assembly defect similar to that observed with myristylation-defective mutants, suggesting that the 6VR change impaired membrane binding. Intriguingly, the 6VR mutation had no effect on Gag myristylation, The defective phenotype imposed by 6VR was reversed by changes at other positions in MA, including residue 97, In this study, we use several biochemical methods to demonstrate that the residue 6 mutation, as well as additional substitutions in MA amino acids 7 and 8, reduce membrane binding without affecting N-terminal myristylation. This effect is observed in the context of Pr55(Gag), a truncated Gag containing only MA and CA, and in MA itself. The membrane binding defect imposed by the 6VR mutation is reversed by second-site changes in MA residues 20 and 97, both of which, when present alone, increase membrane binding to levels greater than those for the wild type. Both reduced and enhanced membrane binding imposed by the MA substitutions depend upon the presence of the N-terminal myristate. The results support the myristyl switch model recently proposed for the regulation of Gag membrane binding, according to which membrane binding is determined by the degree of exposure or sequestration of the N-terminal myristate moiety. Alternatively, insertion of the myristate into the lipid bilayer might be a prerequisite event for the function of other distinct MA-encoded membrane binding domains.