Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305-5126, USA.
J Mol Biol. 2011 Jul 29;410(5):863-74. doi: 10.1016/j.jmb.2011.04.024.
Initiation of reverse transcription of genomic RNA is a key early step in replication of the human immunodeficiency virus (HIV) upon infection of a host cell. Viral reverse transcriptase initiates from a specific RNA-RNA complex formed between a host transfer RNA (tRNA(Lys)(3)) and a region at the 5' end of genomic RNA; the 3' end of the tRNA acts as a primer for reverse transcription of genomic RNA. We report here the secondary structure of the HIV genomic RNA-human tRNA(Lys)(3) initiation complex using heteronuclear nuclear magnetic resonance methods. We show that both RNAs undergo large-scale conformational changes upon complex formation. Formation of the 18-bp primer helix with the 3' end of tRNA(Lys)(3) drives large conformational rearrangements of the tRNA at the 5' end while maintaining the anticodon loop for potential loop-loop interactions. HIV RNA forms an intramolecular helix adjacent to the intermolecular primer helix. This helix, which must be broken by reverse transcription, likely acts as a kinetic block to reverse transcription.
基因组 RNA 的逆转录起始是感染宿主细胞后人类免疫缺陷病毒 (HIV) 复制的关键早期步骤。病毒逆转录酶从宿主转移 RNA (tRNA(Lys)(3)) 和基因组 RNA 5' 端的一个区域之间形成的特定 RNA-RNA 复合物开始；tRNA 的 3' 端充当基因组 RNA 逆转录的引物。我们在此使用异核核磁共振方法报告 HIV 基因组 RNA-人 tRNA(Lys)(3)起始复合物的二级结构。我们表明，两种 RNA 在复合物形成时都会发生大规模构象变化。与 tRNA(Lys)(3)的 3' 端形成 18 个碱基的引物螺旋驱动 tRNA 在 5' 端发生大的构象重排，同时保持反密码环以进行潜在的环-环相互作用。HIV RNA 形成与分子间引物螺旋相邻的分子内螺旋。该螺旋必须通过逆转录被打断，可能会作为逆转录的动力学障碍。
