ジャーナル: Nature / 年: 2016 タイトル: Cryo-EM reveals a novel octameric integrase structure for betaretroviral intasome function. 著者: Allison Ballandras-Colas / Monica Brown / Nicola J Cook / Tamaria G Dewdney / Borries Demeler / Peter Cherepanov / Dmitry Lyumkis / Alan N Engelman / 要旨: Retroviral integrase catalyses the integration of viral DNA into host target DNA, which is an essential step in the life cycle of all retroviruses. Previous structural characterization of integrase- ...Retroviral integrase catalyses the integration of viral DNA into host target DNA, which is an essential step in the life cycle of all retroviruses. Previous structural characterization of integrase-viral DNA complexes, or intasomes, from the spumavirus prototype foamy virus revealed a functional integrase tetramer, and it is generally believed that intasomes derived from other retroviral genera use tetrameric integrase. However, the intasomes of orthoretroviruses, which include all known pathogenic species, have not been characterized structurally. Here, using single-particle cryo-electron microscopy and X-ray crystallography, we determine an unexpected octameric integrase architecture for the intasome of the betaretrovirus mouse mammary tumour virus. The structure is composed of two core integrase dimers, which interact with the viral DNA ends and structurally mimic the integrase tetramer of prototype foamy virus, and two flanking integrase dimers that engage the core structure via their integrase carboxy-terminal domains. Contrary to the belief that tetrameric integrase components are sufficient to catalyse integration, the flanking integrase dimers were necessary for mouse mammary tumour virus integrase activity. The integrase octamer solves a conundrum for betaretroviruses as well as alpharetroviruses by providing critical carboxy-terminal domains to the intasome core that cannot be provided in cis because of evolutionarily restrictive catalytic core domain-carboxy-terminal domain linker regions. The octameric architecture of the intasome of mouse mammary tumour virus provides new insight into the structural basis of retroviral DNA integration.
pH: 7.4 詳細: 25 mM Tris-HCl, 200 mM NaCl, 2 mM DTT, 25 uM ZnCl2, 10 mM CaCl2
グリッド
詳細: 400 mesh C-flat, plasma-treated for 6 seconds
凍結
凍結剤: ETHANE / チャンバー内湿度: 90 % / チャンバー内温度: 77 K / 装置: HOMEMADE PLUNGER 手法: 3 uL of sample was applied to the grid, adsorbed for 30 seconds, blotted, and plunge-frozen in liquid ethane.
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
アライメント法
Legacy - 非点収差: Objective lens astigmatism was corrected using Leginon, and coma-free alignment was established.
アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 6.0 Å / 解像度の算出法: OTHER / ソフトウェア - 名称: Frealign / 詳細: Local FSC values range from 5 to 6 Angstrom. / 使用した粒子像数: 41475