The nature of the polypeptide encoded by each of the 10 double-stranded RNA segments of reovirus type 3

Abstract

Under suitable conditions of denaturation, the double-stranded (ds) RNA segments of reovirus can be translated in cell-free protein synthesizing systems. Since all 10 segments of reovirus ds RNA can be isolated in virtually pure form, this provides a means for determining the nature of the polypeptide encoded by each individual segment. The complete coding assignment set was determined for the Dearing strain of reovirus serotype 3. Polypeptide identification was made not only on the basis of electrophoretic migration rates in both the phosphate- and Tri-glycine (Laemmli)-based polyacrylamide gel systems, but also on the basis of comparing peptide profiles of in vitro translation products and authentic reovirus polypeptides after digestion with staphylococcal V8 protease. The latter method provides absolute identification. The assignment set is (using the commonly accepted designation for the ds RNA segments, but a newly proposed nomenclature for the polypeptides): Segment L1 codes for the minor virion component λ3, and segments L2 and L3 code for the two major virion core components λ2 and λ1, respectively; segment M1 codes for a minor virion component μ2, segment M2 codes for the polypeptide that is present in virions both in the form of the minor component μ1 and as the major component μ1C which is derived from it by cleavage, and segment M3 codes for the nonstructural polypeptide μNS; and segment S1 codes for the minor outer capsid shell component σ1, segment S2 codes for the core component σ2, segment S3 codes for the nonstructural polypeptide σNS, and segment S4 codes for the major outer capsid shell component σ3.