Chaperone-mediated in vitro disassembly of polyoma- and papillomaviruses.

Hsp70 chaperones play a role in polyoma- and papillomavirus assembly, as evidenced by their interaction in vivo with polyomavirus capsid proteins at late times after virus infection and by their ability to assemble viral capsomeres into capsids in vitro. We studied whether Hsp70 chaperones might also participate in the uncoating reaction. In vivo, Hsp70 co-immunoprecipitated with polyomavirus virion VP1 at 3 h after infection of mouse cells.

Chaperone-mediated in vitro assembly of Polyomavirus capsids.

The polyomavirus coat protein viral protein 1 (VP1) has the intrinsic ability to self-assemble in vitro into polymorphic capsid-like structures on addition of calcium. In contrast, polyomavirus assembly in vivo is rigorously controlled, such that virions of uniform size are formed only in the cell nucleus. During viral infection, the 72 kDa cellular chaperone heat shock cognate protein (hsc70) binds VP1 posttranslation and colocalizes with VP1 to the nucleus, thereby suggesting a role for approximately 70-kDa heat shock protein (hsp70) family chaperones in regulating the quality and location of capsid assembly.