ジャーナル: J Virol / 年: 2015 タイトル: A cryo-electron microscopy study identifies the complete H16.V5 epitope and reveals global conformational changes initiated by binding of the neutralizing antibody fragment. 著者: Hyunwook Lee / Sarah A Brendle / Stephanie M Bywaters / Jian Guan / Robert E Ashley / Joshua D Yoder / Alexander M Makhov / James F Conway / Neil D Christensen / Susan Hafenstein / 要旨: Human papillomavirus 16 (HPV16) is a worldwide health threat and an etiologic agent of cervical cancer. To understand the antigenic properties of HPV16, we pursued a structural study to elucidate HPV ...Human papillomavirus 16 (HPV16) is a worldwide health threat and an etiologic agent of cervical cancer. To understand the antigenic properties of HPV16, we pursued a structural study to elucidate HPV capsids and antibody interactions. The cryo-electron microscopy (cryo-EM) structures of a mature HPV16 particle and an altered capsid particle were solved individually and as complexes with fragment of antibody (Fab) from the neutralizing antibody H16.V5. Fitted crystal structures provided a pseudoatomic model of the virus-Fab complex, which identified a precise footprint of H16.V5, including previously unrecognized residues. The altered-capsid-Fab complex map showed that binding of the Fab induced significant conformational changes that were not seen in the altered-capsid structure alone. These changes included more ordered surface loops, consolidated so-called "invading-arm" structures, and tighter intercapsomeric connections at the capsid floor. The H16.V5 Fab preferentially bound hexavalent capsomers likely with a stabilizing effect that directly correlated with the number of bound Fabs. Additional cryo-EM reconstructions of the virus-Fab complex for different incubation times and structural analysis provide a model for a hyperstabilization of the capsomer by H16.V5 Fab and showed that the Fab distinguishes subtle differences between antigenic sites. IMPORTANCE: Our analysis of the cryo-EM reconstructions of the HPV16 capsids and virus-Fab complexes has identified the entire HPV.V5 conformational epitope and demonstrated a detailed neutralization ...IMPORTANCE: Our analysis of the cryo-EM reconstructions of the HPV16 capsids and virus-Fab complexes has identified the entire HPV.V5 conformational epitope and demonstrated a detailed neutralization mechanism of this clinically important monoclonal antibody against HPV16. The Fab bound and ordered the apical loops of HPV16. This conformational change was transmitted to the lower region of the capsomer, resulting in enhanced intercapsomeric interactions evidenced by the more ordered capsid floor and "invading-arm" structures. This study advances the understanding of the neutralization mechanism used by H16.V5.
The particles were selected using semi-automatic program e2boxer.py (EMAN2).
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: 12.6 Å / 解像度の算出法: OTHER / ソフトウェア - 名称: Auto3dem 詳細: 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 ...詳細: 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 13 A resolution estimated at a Fourier Shell Correlation (FSC) of 0.5. For the last step of refinement, the final maps were CTF-corrected using a B factor of 200 A2. 使用した粒子像数: 4737