ジャーナル: ACS Nano / 年: 2015 タイトル: Self-Assembly of an Alphavirus Core-like Particle Is Distinguished by Strong Intersubunit Association Energy and Structural Defects. 著者: Joseph Che-Yen Wang / Chao Chen / Vamseedhar Rayaprolu / Suchetana Mukhopadhyay / Adam Zlotnick / 要旨: Weak association energy can lead to uniform nanostructures: defects can anneal due to subunit lability. What happens when strong association energy leads to particles where defects are trapped? ...Weak association energy can lead to uniform nanostructures: defects can anneal due to subunit lability. What happens when strong association energy leads to particles where defects are trapped? Alphaviruses are enveloped viruses whose icosahedral nucleocapsid core can assemble independently. We used a simplest case system to study Ross River virus (RRV) core-like particle (CLP) self-assembly using purified capsid protein and a short DNA oligomer. We find that capsid protein binds the oligomer with high affinity to form an assembly competent unit (U). Subsequently, U assembles with concentration dependence into CLPs. We determined that U-U pairwise interactions are very strong (ca. -6 kcal/mol) compared to other virus assembly systems. Assembled RRV CLPs appeared morphologically uniform and cryo-EM image reconstruction with imposed icosahedral symmetry yielded a T = 4 structure. However, 2D class averages of the CLPs show that virtually every class had disordered regions. These results suggested that irregular cores may be present in RRV virions. To test this hypothesis, we determined 2D class averages of RRV virions using authentic virions or only the core from intact virions isolated by computational masking. Virion-based class averages were symmetrical, geometric, and corresponded well to projections of image reconstructions. In core-based class averages, cores and envelope proteins in many classes were disordered. These results suggest that partly disordered components are common even in ostensibly well-ordered viruses, a biological realization of a patchy particle. Biological advantages of partly disordered complexes may arise from their ease of dissociation and asymmetry.
名称: Cryo-EM structure of Ross River virus / タイプ: sample / ID: 1000 詳細: The virus was purified from Baby Hamster Kidney cells Number unique components: 1
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超分子 #1: Ross River virus
超分子
名称: Ross River virus / タイプ: virus / ID: 1 / NCBI-ID: 11029 / 生物種: Ross River virus / ウイルスタイプ: VIRION / ウイルス・単離状態: OTHER / ウイルス・エンベロープ: Yes / ウイルス・中空状態: No
宿主
生物種: Aedes (カ) / 別称: INVERTEBRATES
Host system
生物種: Mesocricetus auratus (ネズミ) / 組換細胞: BHK-21 / 組換プラスミド: cDNA clone of Ross River T48 virus
ウイルス殻
Shell ID: 1 / T番号(三角分割数): 4
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実験情報
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構造解析
手法
ネガティブ染色法, 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
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試料調製
緩衝液
pH: 7.4 / 詳細: 20 mM Hepes, 150 mM NaCl and 0.1 mM EDTA
染色
タイプ: NEGATIVE / 詳細: cryo-EM
グリッド
詳細: 300 mesh copper grid with thin carbon support
凍結
凍結剤: ETHANE / チャンバー内湿度: 100 % / 装置: FEI VITROBOT MARK III / 手法: wait 25 sec and blot for 4 sec before plunging
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電子顕微鏡法
顕微鏡
JEOL 3200FS
温度
平均: 100 K
アライメント法
Legacy - 非点収差: Objective lens astigmatism was corrected at 60,000 times magnification
特殊光学系
エネルギーフィルター - 名称: omega filter エネルギーフィルター - エネルギー下限: 0.0 eV エネルギーフィルター - エネルギー上限: 20.0 eV