National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM082545
米国
引用
ジャーナル: J Mol Biol / 年: 2020 タイトル: Distinct Conformational States Underlie Pausing during Initiation of HIV-1 Reverse Transcription. 著者: Kevin P Larsen / Junhong Choi / Lynnette N Jackson / Kalli Kappel / Jingji Zhang / Betty Ha / Dong-Hua Chen / Elisabetta Viani Puglisi / 要旨: A hallmark of the initiation step of HIV-1 reverse transcription, in which viral RNA genome is converted into double-stranded DNA, is that it is slow and non-processive. Biochemical studies have ...A hallmark of the initiation step of HIV-1 reverse transcription, in which viral RNA genome is converted into double-stranded DNA, is that it is slow and non-processive. Biochemical studies have identified specific sites along the viral RNA genomic template in which reverse transcriptase (RT) stalls. These stalling points, which occur after the addition of three and five template dNTPs, may serve as checkpoints to regulate the precise timing of HIV-1 reverse transcription following viral entry. Structural studies of reverse transcriptase initiation complexes (RTICs) have revealed unique conformations that may explain the slow rate of incorporation; however, questions remain about the temporal evolution of the complex and features that contribute to strong pausing during initiation. Here we present cryo-electron microscopy and single-molecule characterization of an RTIC after three rounds of dNTP incorporation (+3), the first major pausing point during reverse transcription initiation. Cryo-electron microscopy structures of a +3 extended RTIC reveal conformational heterogeneity within the RTIC core. Three distinct conformations were identified, two of which adopt unique, likely off-pathway, intermediates in the canonical polymerization cycle. Single-molecule Förster resonance energy transfer experiments confirm that the +3 RTIC is more structurally dynamic than earlier-stage RTICs. These alternative conformations were selectively disrupted through structure-guided point mutations to shift single-molecule Förster resonance energy transfer populations back toward the on-pathway conformation. Our results support the hypothesis that conformational heterogeneity within the HIV-1 RTIC during pausing serves as an additional means of regulating HIV-1 replication.
名称: HIV-1 reverse transcriptase / タイプ: complex / ID: 2 / 親要素: 1 / 含まれる分子: #1-#2 詳細: The C-terminus of p66 contains an unstructured linker and a six-histidine tag that was cleaved prior to full complex formation.
由来(天然)
生物種: Human immunodeficiency virus 1 (ヒト免疫不全ウイルス)
組換発現
生物種: Escherichia coli (大腸菌)
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超分子 #3: HIV-1 RNA genome fragment
超分子
名称: HIV-1 RNA genome fragment / タイプ: complex / ID: 3 / 親要素: 1 / 含まれる分子: #3 詳細: A fragment of the HIV-1 RNA genome that is 101 nucleotides in length.
由来(天然)
生物種: Human immunodeficiency virus 1 (ヒト免疫不全ウイルス)
組換発現
生物種: Escherichia coli (大腸菌)
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超分子 #4: tRNA lysine 3
超分子
名称: tRNA lysine 3 / タイプ: complex / ID: 4 / 親要素: 1 / 含まれる分子: #4 詳細: Chemically synthesized and extended tRNA lysine 3. A modified dG containing an N2-cystamine was placed at position 71 and the sequence was extended on the 3' end by a dC, dT, and ddG to bring ...詳細: Chemically synthesized and extended tRNA lysine 3. A modified dG containing an N2-cystamine was placed at position 71 and the sequence was extended on the 3' end by a dC, dT, and ddG to bring its total length to 79 nucleotides.
由来(天然)
生物種: Homo sapiens (ヒト)
組換発現
生物種: Escherichia coli (大腸菌)
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実験情報
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構造解析
手法
クライオ電子顕微鏡法
解析
単粒子再構成法
試料の集合状態
particle
-
試料調製
濃度
5.0 mg/mL
緩衝液
pH: 8 構成要素:
濃度
式
名称
75.0 mM
NaCl
sodium chloride
10.0 mM
C4H11NO3
tris
6.0 mM
MgCl2
magnesium chloride
0.2 % w/v
beta-octyl glucoside
詳細: Full complex was prepared 5-8 hours before freezing. Beta-OG was added just prior to freezing.
凍結
凍結剤: ETHANE / チャンバー内湿度: 95 % / チャンバー内温度: 292 K / 装置: LEICA EM GP / 詳細: 3 microliters applied, 2s pre-blot, 2.5s blot..