ジャーナル: Proc Natl Acad Sci U S A / 年: 2010 タイトル: Subunits fold at position-dependent rates during maturation of a eukaryotic RNA virus. 著者: Tsutomu Matsui / Gabriel C Lander / Reza Khayat / John E Johnson / 要旨: Effective antiviral agents are difficult to develop because of the close relationship between the cell biology of the virus and host. However, viral capsid maturation, the in vivo process where the ...Effective antiviral agents are difficult to develop because of the close relationship between the cell biology of the virus and host. However, viral capsid maturation, the in vivo process where the particle transitions from a noninfectious provirion to an infectious virion, is an ideal process to interrupt because the provirion is usually fragile and the conversion to the virion often involves large conformational changes and autocatalytic chemistry that can be hampered by small molecules. The Nudaurelia capensis omega virus (N omegaV) is one of the few eukaryotic viruses where this process can be investigated in vitro with a variety of biophysical methods, allowing fundamental chemical and structural principles of the maturation to be established. It has a T = 4 quasi-equivalent capsid with a dramatic maturation pathway that includes a particle size reduction of 100 A and an autocatalytic cleavage. Here we use cryo-EM and difference maps, computed at three time points following maturation initiation, to show that regions of N omegaV subunit folding are maturation dependent and occur at rates determined by their quasi-equivalent position in the capsid, explaining the unusual kinetics of the maturation cleavage. This study shows that folding is rapid and peptide chain self-cleavage occurs early for subunits adjacent to 3-fold and 5-fold icosahedral symmetry elements and that folding is slower in regions where molecular switches are required for the formation of the proper interfacial contacts. The results connect viral maturation to the well-studied assembly-dependent folding that occurs in the formation of cellular complexes.
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 90 K / 装置: FEI VITROBOT MARK I / 手法: Blot for 4sec before plunging
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電子顕微鏡法
顕微鏡
FEI TECNAI F20
日付
2008年1月8日
撮影
実像数: 102 / 平均電子線量: 16.5 e/Å2 詳細: Data were collected using the Leginon automated electron microscopy package and data processing was performed using the Appion pipeline.
アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 9.3 Å / 解像度の算出法: FSC 0.5 CUT-OFF / ソフトウェア - 名称: EMAN 詳細: Data processing was performed using the Appion pipeline. 使用した粒子像数: 6087