Reovirus protein sigma 1: from cell attachment to protein oligomerization and folding mechanisms.
The reovirus cell attachment protein sigma 1 is a lollipop-shaped structure with the fibrous tail anchored to the virion. Since it interacts with the cell receptor, sigma 1 is a major determinant of reovirus infectivity and tissue tropism. Studies on its structure-function relationships have been facilitated by the fact that protein sigma 1 produced in any expression system is capable of binding to cell receptors. The use of site-specific and deletion mutants has led to the identification and characterization of its virion anchorage and receptor binding domains. Studies on the oligomeric status of sigma 1 have revealed that sigma 1 is a homotrimer and that two independent trimerization events at different loci (the N- and C-terminal halves, respectively) of the protein, are involved in its generation. This also accounts for a clearly demonstrable dominant negative effect by a mutant subunit in a wild-type/mutant sigma 1 heterotrimer. Current efforts are focused on the involvement of chaperones in the generation of sigma 1 and on events that take place upon sigma 1 binding to the cell receptor. Protein sigma 1 has therefore become an excellent model system for the study of both virus attachment and protein oligomerization and folding mechanisms.
Lee
P W
PW
Department of Microbiology and Infectious Diseases, University of Calgary Health Sciences Centre, Alberta, Canada.
Leone
G
G
D000818:Animals; D036022:Capsid Proteins; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances; D008961:Models, Structural; D017510:Protein Folding; D011991:Receptors, Virus / Q000378:metabolism*; D012087:Reoviridae / Q000502:physiology*; D014764:Viral Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D014771:Virion / Q000502:physiology
D036022:Capsid Proteins; D046911:Macromolecular Substances; D011991:Receptors, Virus; D014764:Viral Proteins; C031728:sigma 1 protein, reovirus