Analysis of HIV-1 Matrix-Envelope Cytoplasmic Tail Interactions
Analysis of HIV-1 Matrix-Envelope Cytoplasmic Tail Interactions
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DOI：
10.1128/jvi.01079-19
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发表时间：
2019-11-01
影响因子：
5.4
通讯作者：
Barklis, Eric
中科院分区：
文献类型：
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作者：
Alfadhli, Ayna;Staubus, Auguat O.;Barklis, Eric
HIV-1前体Gag （PrGag）蛋白的基质（MA）结构域将PrGag蛋白引导到质膜（PM）组装位点，在那里包膜（Env）蛋白三聚体被整合到病毒颗粒中。MA通过与磷脂酰肌醇-(4,5)-二磷酸[PI(4,5)P2]结合而靶向PM位点，并且MA与细胞rna结合似乎具有伴侣功能，阻止MA在到达富含PI(4,5)P2的PM之前与细胞膜结合。研究表明，遗传证据表明，MA与Env三聚体的细胞质尾部（CTs）之间存在相互作用，这有助于Env并入病毒粒子，但证明MA- ct直接相互作用更为困难。在直接结合实验中，我们发现MA与Env ct结合。利用MA突变体、基质衣壳（MACA）蛋白和在肌醇聚磷酸酯存在下培养的MA蛋白，我们发现了MA三聚化和CT结合之间的相关性。对MA具有高亲和力的RNA配体降低了MA- ct的结合水平，表明MA-RNA的结合干扰了三聚化和/或直接或间接阻断了MA- ct的结合。粗略的定位研究表明，c端CT螺旋参与了MA结合，并且与复制能力强的病毒的细胞培养研究一致。我们的研究结果支持一个模型，即全长HIV-1 Env三聚体通过与MA三聚体的结合在组装PrGag晶格中被捕获。HIV-1包膜（Env）蛋白三聚体组装成病毒颗粒的机制尚不清楚，但涉及到Env细胞质尾部（CTs）和结构前体Gag （PrGag）蛋白的基质（MA）结构域之间的相互作用。我们在这里表明，MA与Env CT的直接结合与MA三聚化相关，表明MA晶格调节CT相互作用和/或MA-CT三聚体-三聚体结合的模型增加了MA-CT结合的快快度。我们还表明，MA与RNA配体的结合可能通过干扰MA三聚化和/或直接或变构阻断MA- ct结合位点而损害MA- ct的结合。粗略的图谱显示，CT c端螺旋参与了MA的结合，这与MA-CT相互作用的细胞培养研究结果一致。我们的研究结果表明，靶向HIV-1 MA-CT相互作用可能是抗病毒治疗的一个有希望的途径。
The matrix (MA) domains of HIV-1 precursor Gag (PrGag) proteins direct PrGag proteins to plasma membrane (PM) assembly sites where envelope (Env) protein trimers are incorporated into virus particles. MA targeting to PM sites is facilitated by its binding to phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2], and MA binding to cellular RNAs appears to serve a chaperone function that prevents MA from associating with intracellular membranes prior to arrival at the PI(4,5)P2-rich PM. Investigations have shown genetic evidence of an interaction between MA and the cytoplasmic tails (CTs) of Env trimers that contributes to Env incorporation into virions, but demonstrations of direct MA-CT interactions have proven more difficult. In direct binding assays, we show here that MA binds to Env CTs. Using MA mutants, matrix-capsid (MACA) proteins, and MA proteins incubated in the presence of inositol polyphosphate, we show a correlation between MA trimerization and CT binding. RNA ligands with high affinities for MA reduced MA-CT binding levels, suggesting that MA-RNA binding interferes with trimerization and/or directly or indirectly blocks MA-CT binding. Rough-mapping studies indicate that C-terminal CT helices are involved in MA binding and are in agreement with cell culture studies with replication-competent viruses. Our results support a model in which full-length HIV-1 Env trimers are captured in assembling PrGag lattices by virtue of their binding to MA trimers.IMPORTANCE The mechanism by which HIV-1 envelope (Env) protein trimers assemble into virus particles is poorly understood but involves an interaction between Env cytoplasmic tails (CTs) and the matrix (MA) domain of the structural precursor Gag (PrGag) proteins. We show here that direct binding of MA to Env CTs correlates with MA trimerization, suggesting models where MA lattices regulate CT interactions and/or MA-CT trimer-trimer associations increase the avidity of MA-CT binding. We also show that MA binding to RNA ligands impairs MA-CT binding, potentially by interfering with MA trimerization and/or directly or allosterically blocking MA-CT binding sites. Rough mapping implicated CT C-terminal helices in MA binding, in agreement with cell culture studies on MA-CT interactions. Our results indicate that targeting HIV-1 MA-CT interactions may be a promising avenue for antiviral therapy.