Crystal structure of the receptor binding domain of the spike glycoprotein of human betacoronavirus HKU1.

ABSTRACT: Human coronavirus (CoV) HKU1 is a pathogen causing acute respiratory illnesses and so far little is known about its biology. HKU1 virus uses its S1 subunit C-terminal domain (CTD) and not the N-terminal domain like other lineage A ?-CoVs to bind to its yet unknown human receptor. Here we present the crystal structure of HKU1 CTD at 1.9?Å resolution. The structure consists of three subdomains: core, insertion and subdomain-1 (SD-1). While the structure of the core and SD-1 subdomains of HKU1 are highly similar to those of other ?-CoVs, the insertion subdomain adopts a novel fold, which is largely invisible in the cryo-EM structure of the HKU1 S trimer. We identify five residues in the insertion subdomain that are critical for binding of neutralizing antibodies and two residues essential for receptor binding. Our study contributes to a better understanding of entry, immunity and evolution of CoV S proteins.

SUBMITTER: Ou X 

PROVIDER: S-EPMC5529671 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature