Chemical composition and translation products of radish enation mosaic virus isolated in Japan.

Abstract

Radish enation mosaic virus (RMV) is a member of the comovirus group, but a biochemical characterization of the group has been done only with cowpea mosaic virus (CpMV) which is the type member of the group. Therefore, the biochemical properties of other members of the group, such as RMV, are poorly understood. The present study was an attempt to analyze the nucleic acid, coat protein and gene composition of RMV. The purified RMV was fractionated into the three components (T, M and B components). B and M components were composed of two kinds of coat proteins with molecular weights of 47k and 18k daltons and contained single stranded RNAs with molecular weights of 2.0×106 and 1.6×106 daltons respectively, but T did not contain RNAs. The RNAs contained poly (A) sequences. Then, the B-RNA was in vitro translated into one polypeptide with a molecular weight of 200k daltons in the presence of zinc ions, which inhibited the protease activity. M-RNA was in vitro translated into two polypeptides with molecular weights of 115k and 105k daltons. These products in vitro translated from M and B-RNA were cleaved into eight kinds of polypeptides during incubation without the zinc ions. The results indicated that RMV might have essentially the same chemical composition and translation strategy as cowpea mosaic virus, except that the molecular weights of M-RNA and M-RNA translation products of RMV were quite different from those of CpMV.