Association of reovirus outer capsid proteins sigma 3 and mu 1 causes a conformational change that renders sigma 3 protease sensitive.
Association of the reovirus proteins sigma 3 and mu 1 influences viral entry, initiation of outer capsid assembly, and modulation of the effect of sigma 3 on cellular translation. In this study, we have addressed whether structural changes occur in sigma 3 as a result of its interaction with mu 1. Using differences in protease sensitivity to detect conformationally distinct forms of sigma 3, we showed that association of sigma 3 with mu 1 caused a conformational change in sigma 3 that converted it from a protease-resistant to a protease-sensitive structure and occurred posttranslationally. The effect of mu 1 on the structure of sigma 3 was stoichiometric. Our results are consistent with a model in which sigma 3's association with mu 1 shifts its function from translational control to assembly of an outer capsid in which sigma 3 is folded into the protease-sensitive conformation that is required for its cleavage during the next round of infection.
D000818:Animals; D002213:Capsid / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D036022:Capsid Proteins; D019286:Endopeptidase K; D007700:Kinetics; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D011485:Protein Binding; D014176:Protein Biosynthesis; D011487:Protein Conformation; D017510:Protein Folding; D016601:RNA-Binding Proteins; D011817:Rabbits; D012087:Reoviridae / Q000378:metabolism*; D012156:Reticulocytes / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism*; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D014771:Virion / Q000378:metabolism
D036022:Capsid Proteins; D010446:Peptide Fragments; D016601:RNA-Binding Proteins; D014764:Viral Proteins; C055356:mu1 protein, Reovirus; C053179:sigma protein 3, Reovirus; D012697:Serine Endopeptidases; D019286:Endopeptidase K