High-resolution asymmetric structure of a Fab–virus complex reveals overlap with the receptor binding site
| Autor: | James F. Conway, Carol M. Bator, Daniel J. Goetschius, Susan Hafenstein, Robert E. Ashley, Alexander M. Makhov, Kai Huang, Lindsey J. Organtini, Samantha R. Hartmann, Colin R. Parrish, Heather M. Callaway |
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| Rok vydání: | 2021 |
| Předmět: |
Parvovirus
Canine Cryo-electron microscopy medicine.drug_class viruses ISECC Antibodies Viral Monoclonal antibody Microbiology Virus Epitope Epitopes Immunoglobulin Fab Fragments 03 medical and health sciences Capsid Dogs Protein Domains medicine Animals Antigens 030304 developmental biology epitope 0303 health sciences Binding Sites Multidisciplinary biology 030306 microbiology Parvovirus Chemistry parvovirus Cryoelectron Microscopy Canine parvovirus Biological Sciences biology.organism_classification virus–fab complex Mutation Biophysics cryo-EM Protein Binding Conformational epitope |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 0027-8424 |
| Popis: | Significance Our study makes significant progress understanding asymmetry in icosahedral viruses that would be otherwise masked by forcing homogeneity through icosahedral averaging. Using an asymmetric approach revealed the atomic-resolution structure of a complex between canine parvovirus and a strain-specific neutralizing antibody. Since species jumping is a rare event in DNA viruses, the emergence of an antibody that binds more avidly to the canine-adapted virus (and not ancestral feline equivalent) is of special interest. The Fab-bound and -unbound epitopes were solved on the same virus capsid with an atomic-resolution asymmetric map. Fab 14 stabilizes a capsid loop within the same binding site used by the receptor, suggesting capsid conformational change or steric competition with the receptor contributes to the mechanism of antibody neutralization. Canine parvovirus is an important pathogen causing severe diseases in dogs, including acute hemorrhagic enteritis, myocarditis, and cerebellar disease. Overlap on the surface of parvovirus capsids between the antigenic epitope and the receptor binding site has contributed to cross-species transmission, giving rise to closely related variants. It has been shown that Mab 14 strongly binds and neutralizes canine but not feline parvovirus, suggesting this antigenic site also controls species-specific receptor binding. To visualize the conformational epitope at high resolution, we solved the cryogenic electron microscopy (cryo-EM) structure of the Fab–virus complex. We also created custom software, Icosahedral Subparticle Extraction and Correlated Classification, to solve a Fab–virus complex with only a few Fab bound per capsid and visualize local structures of the Fab-bound and -unbound antigenic sites extracted from the same complex map. Our results identified the antigenic epitope that had significant overlap with the receptor binding site, and the structures revealed that binding of Fab induced conformational changes to the virus. We were also able to assign the order and position of attached Fabs to allow assessment of complementarity between the Fabs bound to different positions. This approach therefore provides a method for using cryo-EM to investigate complementarity of antibody binding. |
| Databáze: | OpenAIRE |
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