ジャーナル: J Virol / 年: 2013 タイトル: Structures of the procapsid and mature virion of enterovirus 71 strain 1095. 著者: Javier O Cifuente / Hyunwook Lee / Joshua D Yoder / Kristin L Shingler / Michael S Carnegie / Jennifer L Yoder / Robert E Ashley / Alexander M Makhov / James F Conway / Susan Hafenstein / 要旨: Enterovirus 71 (EV71) is an important emerging human pathogen with a global distribution and presents a disease pattern resembling poliomyelitis with seasonal epidemics that include cases of severe ...Enterovirus 71 (EV71) is an important emerging human pathogen with a global distribution and presents a disease pattern resembling poliomyelitis with seasonal epidemics that include cases of severe neurological complications, such as acute flaccid paralysis. EV71 is a member of the Picornaviridae family, which consists of icosahedral, nonenveloped, single-stranded RNA viruses. Here we report structures derived from X-ray crystallography and cryoelectron microscopy (cryo-EM) for the 1095 strain of EV71, including a putative precursor in virus assembly, the procapsid, and the mature virus capsid. The cryo-EM map of the procapsid provides new structural information on portions of the capsid proteins VP0 and VP1 that are disordered in the higher-resolution crystal structures. Our structures solved from virus particles in solution are largely in agreement with those from prior X-ray crystallographic studies; however, we observe small but significant structural differences for the 1095 procapsid compared to a structure solved in a previous study (X. Wang, W. Peng, J. Ren, Z. Hu, J. Xu, Z. Lou, X. Li, W. Yin, X. Shen, C. Porta, T. S. Walter, G. Evans, D. Axford, R. Owen, D. J. Rowlands, J. Wang, D. I. Stuart, E. E. Fry, and Z. Rao, Nat. Struct. Mol. Biol. 19:424-429, 2012) for a different strain of EV71. For both EV71 strains, the procapsid is significantly larger in diameter than the mature capsid, unlike in any other picornavirus. Nonetheless, our results demonstrate that picornavirus capsid expansion is possible without RNA encapsidation and that picornavirus assembly may involve an inward radial collapse of the procapsid to yield the native virion.
Semi-automatic particle selection was performed using e2boxer.py to obtain the particle coordinates, followed by particle boxing, linearization, normalization, and apodization of the images using Robem. Defocus and astigmatism values to perform contrast transfer function (CTF) correction were assessed using Robem for the extracted particles. The icosahedrally averaged reconstructions were initiated using a random model generated with setup_rmc and reached better than 10 A resolution estimated at a Fourier Shell Correlation, FSC=0.5. For the last step of refinement, the final maps were CTF corrected using a B factor of 300 A2.
CTF補正
詳細: Each particle
最終 再構成
アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 9.76 Å / 解像度の算出法: FSC 0.5 CUT-OFF / ソフトウェア - 名称: Auto3dem, EMAN2 / 使用した粒子像数: 6168