Structure analysis of the major capsid proteins of human polyomaviruses 6 and 7 reveals an obstructed sialic Acid binding site.
Stroh, L.J., Neu, U., Blaum, B.S., Buch, M.H., Garcea, R.L., Stehle, T.(2014) J Virol 88: 10831-10839
- PubMed: 25008942 
- DOI: https://doi.org/10.1128/JVI.01084-14
- Primary Citation of Related Structures:  
4PCG, 4PCH - PubMed Abstract: 
Human polyomavirus 6 (HPyV6) and HPyV7 are commonly found on human skin. We have determined the X-ray structures of their major capsid protein, VP1, at resolutions of 1.8 and 1.7 Å, respectively. In polyomaviruses, VP1 commonly determines antigenicity as well as cell-surface receptor specificity, and the protein is therefore linked to attachment, tropism, and ultimately, viral pathogenicity. The structures of HPyV6 and HPyV7 VP1 reveal uniquely elongated loops that cover the bulk of the outer virion surfaces, obstructing a groove that binds sialylated glycan receptors in many other polyomaviruses. In support of this structural observation, interactions of VP1 with α2,3- and α2,6-linked sialic acids could not be detected in solution by nuclear magnetic resonance spectroscopy. Single-cell binding studies indicate that sialylated glycans are likely not required for initial attachment to cultured human cells. Our findings establish distinct antigenic properties of HPyV6 and HPyV7 capsids and indicate that these two viruses engage nonsialylated receptors.
Organizational Affiliation: 
Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.