UC Davis

The polypeptides synthesized in an E. coli cell-free system under the direction of the small RNA of the satellite tobacco necrosis virus were compared with the authentic coat protein of this virus. Many of the tryptic peptides obtained from the two types of proteins moved identically upon high-resolution cation exchange column chromatography, but distinct qualitative and quantitative differences between the two peptide patterns were also evident. Gel electrophoresis in 9 M urea at pH 4.0 showed that the biosynthesized material was not homogeneous in regard to charge; some of it showed a mobility similar to that of the authentic coat protein. Gel electrophoresis in the presence of sodium dodecyl sulfate demonstrated the presence of a wide range of molecular weight species in the biosynthesized protein; the largest, representing about 5% of the total, coincided with authentic virus coat protein. It is concluded that much of the information on satellite tobacco necrosis virus RNA is translated into proper amino acid sequences in the E. coli system, but that only very little complete coat protein, and that probably carrying a terminal formyl-methionyl group, is synthesized. © 1973, American Chemical Society. All rights reserved.