Towards understanding of human betacoronavirus HKU1 life cycle

Coronaviruses are positive single-stranded RNA viruses, which cause significant percentage of acute respiratory illnesses in humans. In recent years SARS and MERS were responsible for two pandemics of deadly pneumonia. Currently, there is no vaccines or specific antiviral treatment available against coronaviruses. Structural characterization of proteins essential in virus life cycle provides valid functional information and is basis for structure-based drug design. Recent publication on human coronavirus HKU1 including structure determination of the protein S1, which binds to yet unknown human receptor and initiates virus entry into host, brings possibility of finding effective treatment against coronavirus closer [1].

Human coronavirus HKU1 is a pathogen causing acute respiratory illness. HKU1 infection generally results in mild 
upper respiratory tract disease, but can occasionally cause severe respiratory diseases 
including pneumonia in very young children, the elderly, and immunocompromised 
patients. Research published in Nature Communications [1] was assisted by SLS beamline scientists Justyna Wojdyla and Meitian Wang, who applied an experimental phasing technique called native-SAD to fully exploit the unique features of the SLS MX beamline X06DA [2,3]. This phasing method enabled de novo structure determination of native S1 protein without additional labeling. Native-SAD is particularly convenient for viral proteins produced in sophisticated eukaryotic expression systems, where introduction of non-standard amino acids, such as selenomethionine, is tedious or not possible. Structural characterization of HKU1 S1 protein contributed to better understanding of entry, immunity and evolution of coronavirus S proteins and allowed determination of residues critical for receptor binding and neutralizing antibody binding.