Inhibition of Cell-Free Translation and Replication of Tobacco Mosaic Virus RNA by Exogenously Added 5'-Proximal Fragments of the Genomic RNA.

Replication proteins of tobacco mosaic virus (TMV), a positive-sense RNA virus, co-translationally bind to a 5'-proximal ~70-nucleotide (nt) region of the genomic RNA, referred to as the nuclease-resistant (NR) region for replication template selection. Therefore, disruption of the interaction between the viral replication proteins and viral genomic RNA is expected to inhibit the replication of TMV. In this study, we demonstrate that the addition of small RNA fragments (18-33 nts in length) derived from different regions within the NR region inhibit the binding of TMV replication proteins to viral RNA and TMV RNA replication in a cell-free system. Intriguingly, some of the small RNA fragments also inhibited the translation of mRNA in a sequence-nonspecific manner. These results highlight the pleiotropic roles of the 5'-proximal region of the TMV genome.