The in vitro translation of Pea enation mosaic virus RNA

Pea enation mosaic virus (PEMV) RNA was isolated from virions and then translated in rabbit reticulocyte lysates and in wheat germ extracts. RNA 1 (apparent molecular weight, Mr 1.77 x 106) was shown to code for two major translation products, vp2 (Mr 88,000) and vp4 (Mr 36,000) plus a high-molecular-weight minor product vp1 (Mr 147,000). Tryptic peptide comparisons of vp2 and vp4 revealed unique amino acid sequences for each product indicating that vp2 was not a read through protein of vp4. The in vitro translation products were synthesized in the order of their molecular weight, with vp4 appearing first. Therefore, vp4 and vp2 were not produced from a slowly processed precursor. RNA 2 (Mr 1.2 x 106) was shown to code for one product, vp3 (Mr 45,000). Northern analysis of total virion RNA, which was hybridized to cDNA transcribed from total virion RNA, did not detect additional RNA species. Therefore, gene products, vp2, vp3, and vp4, appear to be translated from the two genomic RNAs rather than from encapsidated subgenomic RNAs. PEMV antiserum specifically immunoprecipitated vp2, indicating that vp2 has amino acid sequences that are related to those of capsid protein.