Transfer RNA-like Structures in Viral Genomes

Abstract

The occurrence of aminoacylatable transfer RNA (tRNA)-like structures in several groups of plant viruses strongly suggests that they have a biological function. Indeed, in the case of brome mosaic virus (BMV), a relatively simple 3′-specific modification of the RNA results in loss of infectivity. However, currently, no metabolic role for the tRNA-like structures has been demonstrated, and the likelihood of functions related to translation or viral assembly processes seem to be remote. Thus, a role in transcription events currently appears to be the most attractive suggestion. This is despite the fact that other RNA viruses, such as pea enation mosaic virus, which lacks a functional tRNA-like 3′ structure or even a 3′ poly(A) sequence, are efficiently transcribed in their hosts. Because of the analogous levels of specificity for aminoacylation, despite their very different structures, it is possible that comparative studies of viral and tRNAs may yield an insight to the features of RNA, which permit aminoacylation to occur. Comparisons of infective properties of native and chemically modified forms of aminoacylatable viral RNAs may reveal if the tRNA structure is related to transcription or translation events; alternatively, they may reveal a novel metabolic process.