National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
SC1AI114843
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
5G12MD007603-30
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM103310
米国
Simons Foundation
349247
米国
引用
ジャーナル: mBio / 年: 2021 タイトル: Mechanism of DNA Interaction and Translocation by the Replicase of a Circular Rep-Encoding Single-Stranded DNA Virus. 著者: Elvira Tarasova / Sonali Dhindwal / Matthew Popp / Sakeenah Hussain / Reza Khayat / 要旨: Circular Rep-encoding single-stranded DNA (CRESS-DNA) viruses infect members from all three domains of life (, , and ). The replicase (Rep) from these viruses is responsible for initiating rolling ...Circular Rep-encoding single-stranded DNA (CRESS-DNA) viruses infect members from all three domains of life (, , and ). The replicase (Rep) from these viruses is responsible for initiating rolling circle replication (RCR) of their genomes. Rep is a multifunctional enzyme responsible for nicking and ligating ssDNA and unwinding double-stranded DNA (dsDNA). We report the structure of porcine circovirus 2 (PCV2) Rep bound to ADP and single-stranded DNA (ssDNA), and Rep bound to ADP and double-stranded DNA (dsDNA). The structures demonstrate Rep to be a member of the superfamily 3 (SF3) of ATPases Associated with diverse cellular Activities (AAA) superfamily clade 4. At the Rep N terminus is an endonuclease domain () that is responsible for ssDNA nicking and ligation, in the center of Rep is an oligomerization domain () responsible for hexamerization, and at the C terminus is an ATPase domain () responsible for ssDNA/dsDNA interaction and translocation. The Rep binds to DNA such that the faces the replication fork. The six spiral around the DNA to interact with the backbone phosphates from four consecutive nucleotides. Three of the six are able to sense the backbone phosphates from the second strand of dsDNA. Heterogeneous classification of the data demonstrates the and to be mobile. Furthermore, we demonstrate that Rep exhibits basal nucleoside triphosphatase (NTPase) activity. CRESS-DNA viruses encompass a significant portion of the biosphere's virome. However, little is known about the structure of Rep responsible for initiating the RCR of CRESS-DNA viruses. We use cryo-electron microscopy (cryo-EM) to determine the structure of PCV2 Rep in complex with ADP and ss/dsDNA. Our structures demonstrate CRESS-DNA Reps to be SF3 members (clade 4) of the AAA+ superfamily. The structures further provide the mechanism by which CRESS-DNA virus Reps recognize DNA and translocate DNA for genome replication. Our structures also demonstrate the and of PCV2 Rep to be highly mobile. We propose the mobile nature of these domains to be necessary for proper functioning of Reps. We further demonstrate that Reps exhibit basal NTPase activity. Our studies also provide initial insight into the mechanism of RCR.
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 277 K / 装置: FEI VITROBOT MARK IV 詳細: 4 uL samples were applied to the grids for 3 seconds and blotted using a blot force of 2, a blot time of 4 seconds, and a drain time of 0 seconds..
詳細
Sample was monodisperse according to size exclusion chromatography
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
撮影
フィルム・検出器のモデル: GATAN K2 SUMMIT (4k x 4k) 検出モード: COUNTING / 撮影したグリッド数: 1 / 平均露光時間: 6.0 sec. / 平均電子線量: 71.8 e/Å2
電子線
加速電圧: 300 kV / 電子線源: FIELD EMISSION GUN
電子光学系
照射モード: SPOT SCAN / 撮影モード: BRIGHT FIELD
実験機器
モデル: Titan Krios / 画像提供: FEI Company
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画像解析
初期モデル
モデルのタイプ: NONE / 詳細: Ab initio determined by cryoSPARC
最終 再構成
想定した対称性 - 点群: C1 (非対称) / 解像度のタイプ: BY AUTHOR / 解像度: 3.8 Å / 解像度の算出法: FSC 0.143 CUT-OFF / ソフトウェア - 名称: cryoSPARC (ver. 2.14) / 詳細: Resolution is based on 3DFSC global value / 使用した粒子像数: 169830
初期 角度割当
タイプ: COMMON LINE / ソフトウェア - 名称: cryoSPARC (ver. 2.14)
最終 角度割当
タイプ: OTHER / ソフトウェア - 名称: cryoSPARC (ver. 2.14) / 詳細: Non uniform refinement
最終 3次元分類
クラス数: 4
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原子モデル構築 1
精密化
空間: REAL / プロトコル: FLEXIBLE FIT / 温度因子: 65.3 / 当てはまり具合の基準: Correlation coefficient
得られたモデル
PDB-7lar: Cryo-EM structure of PCV2 Replicase bound to ssDNA