Interaction of HIV-1 Nef with the cellular dileucine-based sorting pathway is required for CD4 down-regulation and optimal viral infectivity
Interaction of HIV-1 Nef with the cellular dileucine-based sorting pathway is required for CD4 down-regulation and optimal viral infectivity
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DOI：
10.1073/pnas.95.19.11229
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发表时间：
1998-09-15
影响因子：
11.1
通讯作者：
Guatelli, JC
中科院分区：
文献类型：
--
作者：
Craig, HM;Pandori, MW;Guatelli, JC
HIV-1 Nef 蛋白对于发病机制很重要，增强病毒感染性，并调节至少两种细胞跨膜蛋白 CD4 和 I 类主要组织相容性复合物 (MHC) 的分选。尽管有几条证据支持 Nef 蛋白直接与细胞蛋白分选机制相互作用的假设，但 HIV-1 Nef 中的分选信号尚未确定。通过使用功能上区分基于双亮氨酸和基于酪氨酸的分选信号的竞争测定，我们将 Nef 与分选机制相互作用的基序归类为基于双亮氨酸的基序，对来自 HIV-1、HIV-2 和猿猴免疫缺陷病毒的多种 Nef 蛋白进行检查，发现在 Nef (E/DXXXL phi) 的 C 末端溶剂暴露环的中心区域有一个高度保守的序列，该序列符合共识在细胞跨膜蛋白中发现的基于双亮氨酸的分选基序的序列。 Nef(NL4-3)、ENTSLL 中的该序列在附加到异源蛋白的细胞质尾部时充当内吞信号。该基序中的亮氨酸残基是全长 Nef 与基于双亮氨酸的分选途径相互作用所必需的，并且是 Nef 介导的 CD4 下调所必需的。这些亮氨酸残基也是最佳病毒感染性所必需的。这些数据表明 Nef 中基于双亮氨酸的分选信号用于处理细胞分选机制。数据还表明，对细胞跨膜蛋白分布的影响可能在机制上将 Nef 的两个先前不同的特性结合起来：CD4 的下调和病毒感染性的增强。
The HIV-1 Nef protein is important for pathogenesis, enhances viral infectivity, and regulates the sorting of at least two cellular transmembrane proteins, CD4 and major histocompatibility complex (MHC) class I, Although several lines of evidence support the hypothesis that the Nef protein interacts directly with the cellular protein sorting machinery, the sorting signal in HIV-1 Nef has not been identified. By using a competition assay that functionally discriminates between dileucine-based and tyrosine-based sorting signals, we have categorized the motif through which Nef interacts with the sorting machinery as dileucine-based, Inspection of diverse Nef proteins from HIV-1, HIV-2, and simian immunodeficiency virus revealed a well-conserved sequence in the central region of the C-terminal, solvent-exposed loop of Nef (E/DXXXL phi) that conforms to the consensus sequence of the dileucine-based sorting motifs found in cellular transmembrane proteins. This sequence in Nef(NL4-3), ENTSLL, functioned as an endocytosis signal when appended to the cytoplasmic tail of a heterologous protein. The leucine residues in this motif were required for the interaction of full-length Nef with the dileucine-based sorting pathway and were required for Nef-mediated down-regulation of CD4, These leucine residues were also required for optimal viral infectivity, These data indicate that a dileucine-based sorting signal in Nef is utilized to address the cellular sorting machinery. The data also suggest that an influence on the distribution of cellular transmembrane proteins may mechanistically unite two previously distinct properties of Nef: down-regulation of CD4 and enhancement of viral infectivity.