HIV-1 Matrix Protein Interactions with tRNA: Implications for Membrane Targeting
HIV-1 Matrix Protein Interactions with tRNA: Implications for Membrane Targeting
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DOI：
10.1016/j.jmb.2018.04.042
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发表时间：
2018-07-06
影响因子：
5.6
通讯作者：
Summers, Michael F.
中科院分区：
文献类型：
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作者：
Gaines, Christy R.;Tkacik, Emre;Summers, Michael F.
HIV-1 Gag 多蛋白的 N 末端肉豆蔻酰化基质 (MA) 结构域通过将 Gag 靶向质膜的内层来促进病毒组装。最近的研究表明，在膜结合之前，MA 与细胞质 tRNA（包括 tRNA(Lys3)）相关，并且对 tRNA 依赖性 MA 与模型膜相互作用的体外研究提出了竞争性 tRNA 相互作用有助于膜辨别的建议。我们通过核磁共振波谱和等温滴定量热法表征了天然、突变和未肉豆蔻酰化 (myr-) MA 蛋白与重组 tRNA (Lys3) 之间的相互作用。 NMR 实验证实 tRNA(Lys3) 与一组碱性残基相互作用，这些残基对于结合质膜标记磷脂酰肌醇 1-4,5-二磷酸 [PI(4,5)P-2] 也很重要。出乎意料的是，MA 对 tRNA(Lys3) 的亲和力 (K-d = 0.63 +/- 0.03 mu M) 比其对富含 PI(4,5)P-2 的脂质体的亲和力 (K-d(表观) = 10.2 +/- 2.1 mu M) 大大约 1 个数量级，并且 NMR 研究表明 tRNA(Lys3) 结合会阻断 MA 与脂质体，包括那些 富含 PI(4,5)P-2、磷脂酰丝氨酸和胆固醇。然而，MA 对 tRNA(Lys3) 的亲和力会因促进肉豆蔻酸酯暴露的突变或样品条件而减弱。由于已知 Gag-Gag 相互作用会促进肉豆蔻酸酯暴露，因此我们的研究结果支持病毒组装模型，其中膜靶向和基因组结合机械耦合。 (C) 2018 Elsevier Ltd. 保留所有权利。
The N-terminally myristoylated matrix (MA) domain of the HIV-1 Gag polyprotein promotes virus assembly by targeting Gag to the inner leaflet of the plasma membrane. Recent studies indicate that, prior to membrane binding, MA associates with cytoplasmic tRNAs (including tRNA(Lys3)), and in vitro studies of tRNA-dependent MA interactions with model membranes have led to proposals that competitive tRNA interactions contribute to membrane discrimination. We have characterized interactions between native, mutant, and unmyristylated (myr-) MA proteins and recombinant tRNA(Lys3) by NMR spectroscopy and isothermal titration calorimetry. NMR experiments confirm that tRNA(Lys3) interacts with a patch of basic residues that are also important for binding to the plasma membrane marker, phosphatidylinosito1-4,5-bisphosphate [PI(4,5)P-2]. Unexpectedly, the affinity of MA for tRNA(Lys3) (K-d = 0.63 +/- 0.03 mu M) is approximately 1 order of magnitude greater than its affinity for PI(4,5)P-2-enriched liposomes (K-d(apparent) = 10.2 +/- 2.1 mu M), and NMR studies indicate that tRNA(Lys3) binding blocks MA association with liposomes, including those enriched with PI(4,5)P-2, phosphatidylserine, and cholesterol. However, the affinity of MA for tRNA(Lys3) is diminished by mutations or sample conditions that promote myristate exposure. Since Gag-Gag interactions are known to promote myristate exposure, our findings support virus assembly models in which membrane targeting and genome binding are mechanistically coupled. (C) 2018 Elsevier Ltd. All rights reserved.