Recombinant Murine polyomavirus Major capsid protein VP1

Function

Forms an icosahedral capsid with a T=7 symmetry and a 40 nm diameter. The capsid is composed of 72 pentamers linked to each other by disulfide bonds and associated with VP2 or VP3 proteins. Interacts with terminal alpha(2,3)-linked sialic acids on the cell surface to provide virion attachment to target cell. This attachment induces virion internalization predominantly through caveolin-mediated endocytosis. Once attached, the virion is internalized by caveolin-mediated endocytosis and traffics to the endoplasmic reticulum. Inside the endoplasmic reticulum, the protein folding machinery isomerizes VP1 interpentamer disulfide bonds, thereby triggering initial uncoating. Next, the virion uses the endoplasmic reticulum-associated degradation machinery to probably translocate in the cytosol before reaching the nucleus. Nuclear entry of the viral DNA involves the selective exposure and importin recognition of VP2/Vp3 nuclear localization signal. In late phase of infection, neo-synthesized VP1 encapsulates replicated genomic DNA in the nucleus, and participates in rearranging nucleosomes around the viral DNA

Subcellular Location

Virion; Host nucleus

Subunit

Homomultimer; disulfide-linked. The virus capsid is composed of 72 icosahedral units, each one composed of five disulfide-linked copies of VP1. Interacts with minor capsid proteins VP2 and VP3

• Mayer M. et al. Nucleotide sequence and genome organization of the murine polyomavirus, Kilham strain. — Virology (1991)
• Neu U. et al. The Polyomaviridae: Contributions of virus structure to our understanding of virus receptors and infectious entry. — Virology (2009)