Effects of an HIV-1 maturation inhibitor on the structure and dynamics of CA-SP1 junction helices in virus-like particles
Effects of an HIV-1 maturation inhibitor on the structure and dynamics of CA-SP1 junction helices in virus-like particles
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DOI：
10.1073/pnas.1917755117
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发表时间：
2020-05-12
影响因子：
11.1
通讯作者：
Tycko, Robert
中科院分区：
文献类型：
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作者：
Gupta, Sebanti;Louis, John M.;Tycko, Robert
HIV-1成熟涉及未成熟的Gag多聚蛋白晶格（其排列在病毒膜的内表面上）转化为成熟的衣壳蛋白（CA）晶格（其包围病毒RNA）。成熟抑制剂如贝韦瑞（BVM）结合在六螺旋束内，所述六螺旋束由跨越Gag的CA和间隔肽1（SP1）亚基之间的连接的区段形成，并干扰由HIV-1蛋白酶（PR）催化的CA和SP1之间的裂解。我们报告的固态NMR（ssNMR）测量球形病毒样颗粒（VLP），促进了节段性同位素标记，提供信息的影响BVM的结构和动态的CA-SP1结螺旋在未成熟的晶格。尽管BVM强烈阻断VLP中PR催化的CA-SP1裂解并阻断VLP向管状CA组装体的转化，但具有和不具有BVM的片段标记的VLP的N-15和C-13 ssNMR化学位移非常相似，表明与BVM的相互作用不会明显改变六螺旋束结构。只有A280（SP1的第一个残基）的N-15化学位移发生显著变化，与BVM结合到L279残基疏水侧链的内环一致。横向N-15自旋弛豫速率的测量揭示了骨干N-H键运动的振幅和/或时间尺度的减少，对应于六螺旋束的刚性化。总的来说，我们的数据表明，BVM对HIV-1成熟的抑制涉及结构和动力学的变化，这些变化令人惊讶地微妙，但仍然足以对CA-SP1裂解产生很大的影响。
HIV-1 maturation involves conversion of the immature Gag polyprotein lattice, which lines the inner surface of the viral membrane, to the mature capsid protein (CA) lattice, which encloses the viral RNA. Maturation inhibitors such as bevirimat (BVM) bind within six-helix bundles, formed by a segment that spans the junction between the CA and spacer peptide 1 (SP1) subunits of Gag, and interfere with cleavage between CA and SP1 catalyzed by the HIV-1 protease (PR). We report solid-state NMR (ssNMR) measurements on spherical virus-like particles (VLPs), facilitated by segmental isotopic labeling, that provide information about effects of BVM on the structure and dynamics of CA-SP1 junction helices in the immature lattice. Although BVM strongly blocks PR-catalyzed CA-SP1 cleavage in VLPs and blocks conversion of VLPs to tubular CA assemblies, N-15 and C-13 ssNMR chemical shifts of segmentally labeled VLPs with and without BVM are very similar, indicating that interaction with BVM does not alter the six-helix bundle structure appreciably. Only the N-15 chemical shift of A280 (the first residue of SP1) changes significantly, consistent with BVM binding to an internal ring of hydrophobic side chains of L279 residues. Measurements of transverse N-15 spin relaxation rates reveal a reduction in the amplitudes and/or timescales of backbone N-H bond motions, corresponding to a rigidification of the six-helix bundles. Overall, our data show that inhibition of HIV-1 maturation by BVM involves changes in structure and dynamics that are surprisingly subtle, but still sufficient to produce a large effect on CA-SP1 cleavage.