The receptor-binding domain of influenza virus hemagglutinin produced in Escherichia coli folds into its native, immunogenic structure.

TitleThe receptor-binding domain of influenza virus hemagglutinin produced in Escherichia coli folds into its native, immunogenic structure.
Publication TypeJournal Article
Year of Publication2011
AuthorsDuBois, Rebecca M., Aguilar-Yañez José Manuel, Mendoza-Ochoa Gonzalo I., Oropeza-Almazán Yuriana, Schultz-Cherry Stacey, Alvarez Mario Moisés, White Stephen W., and Russell Charles J.
JournalJ Virol
Volume85
Issue2
Pagination865-72
Date Published2011 Jan
ISSN1098-5514
KeywordsAnimals, Antibodies, Viral, Binding Sites, Crystallography, X-Ray, Dimerization, Escherichia coli, Ferrets, Hemagglutinins, Viral, Humans, Influenza Vaccines, Models, Molecular, Orthomyxoviridae Infections, Protein Folding, Protein Structure, Quaternary, Protein Structure, Tertiary, Recombinant Proteins
Abstract

The hemagglutinin (HA) surface glycoprotein promotes influenza virus entry and is the key protective antigen in natural immunity and vaccines. The HA protein is a trimeric envelope glycoprotein consisting of a globular receptor-binding domain (HA-RBD) that is inserted into a membrane fusion-mediating stalk domain. Similar to other class I viral fusion proteins, the fusogenic stalk domain spontaneously refolds into its postfusion conformation when expressed in isolation, consistent with this domain being trapped in a metastable conformation. Using X-ray crystallography, we show that the influenza virus HA-RBD refolds spontaneously into its native, immunogenic structure even when expressed in an unglycosylated form in Escherichia coli. In the 2.10-Å structure of the HA-RBD, the receptor-binding pocket is intact and its conformational epitopes are preserved. Recombinant HA-RBD is immunogenic and protective in ferrets, and the protein also binds with specificity to sera from influenza virus-infected humans. Overall, the data provide a structural basis for the rapid production of influenza vaccines in E. coli. From an evolutionary standpoint, the ability of the HA-RBD to refold spontaneously into its native conformation suggests that influenza virus acquired this domain as an insertion into an ancestral membrane-fusion domain. The insertion of independently folding domains into fusogenic stalk domains may be a common feature of class I viral fusion proteins.

DOI10.1128/JVI.01412-10
Alternate JournalJ. Virol.
PubMed ID21068239
PubMed Central IDPMC3020035
Grant ListCA21765 / CA / NCI NIH HHS / United States
HHSN266200700005C / / PHS HHS / United States