Structural homology between bamboo mosaic virus and its satellite RNAs in the 5′ untranslated region

A structural element was identified in the 5'-proximal sequence of the bamboo mosaic virus (BaMV) RNA. Mutational analysis of the hairpin showed that disruptions of the secondary structure or substitutions of the loop sequences resulted in reduced accumulation of BaMV genomic RNA. Phylogenetic analysis further suggested the presence of structural homologues of this hairpin in all other potexviruses. In addition, remarkable structural homology was discovered between the BaMV hairpin and a stem-loop in the 5' untranslated region of satellite RNAs responsible for attenuation of BaMV in co-infected plants. The role of this homology in the helper-satellite interaction is discussed.