Transfer RNA Mimicry in a New Group of Positive-Strand RNA Plant Viruses, the Furoviruses: Differential Aminoacylation between the RNA Components of One Genome

Abstract

Recent sequencing of the genomes of several furoviruses—fungus-transmitted rod-shaped positive-strand plant viruses—has suggested the presence of tRNA-like structures (TLSs) at the 3′ ends of the genomic RNAs. We show here that the genomic RNAs of soil-borne wheat mosaic virus (SBWMV), beet soil-borne virus (BSBV), potato mop-top virus (PMTV), peanut clump virus (PCV), and Indian peanut clump virus (IPCV) all possess functional TLSs that are capable of high-efficiency valylation. While the SBWMV, BSBV, and PMTV TLSs are similar to those found in tymoviruses, the PCV and IPCV TLSs harbor an insertion of about 40 nucleotides between the two halves of the TLS. The valylated SBWMV and BSBV RNAs formed tight complexes with wheat germ EF-1α · GTP (Kd= 2 to 11 nM), whereas valylated PMTV, PCV, and IPCV RNAs bound EF-1α · GTP weakly (Kd≥ 50 nM). The TLS of PCV RNA2 differs from PCV RNA1 in lacking the major valine identity nucleotide in the anticodon and consequently is capable of only very inefficient valylation. This is the first case of differential aminoacylation between the RNA components of one genome.