Base-paired structure in the 5' untranslated region is required for the efficient amplification of negative-strand RNA3 in the bromovirus melandrium yellow fleck virus.
Melandrium yellow fleck virus belongs to the genus Bromovirus, which is a group of tripartite plant RNA viruses. This virus has an approximately 200-nucleotide direct repeat sequence in the 5' untranslated region (UTR) of RNA3 that encodes the 3a movement protein. In the present study, protoplast assays suggested that the duplicated region contains amplification-enhancing elements. Deletion analyses of the 5' UTR of RNA3 showed that mutations in the short base-paired region, which is located dozens of bases upstream of the initiation codon of the 3a gene, greatly reduced the accumulation of RNA3. Disruption and restoration of the base-paired structure caused the accumulation of RNA3 to be decreased and restored, respectively. In vitro translation/replication assays demonstrated that the base-paired structure is important for the efficient amplification of negative-stand RNA3. A similar base-paired structure in RNA3 of another bromovirus, brome mosaic virus (BMV), also facilitated the efficient amplification of BMV RNA3, but only in combination with melandrium yellow fleck virus (MYFV) replicase and not with BMV replicase, thereby suggesting specific interactions between base-paired structures and MYFV replicase.
Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
Taiki
T
Narabayashi
Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
Masanori
M
Kaido
Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
Tetsuro
T
Okuno
Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan. Electronic address: kmise@kais.kyoto-u.ac.jp.
Kazuyuki
K
Mise
D020121:5' Untranslated Regions; D020029:Base Pairing; D017795:Bromovirus / Q000502:physiology*; D004252:DNA Mutational Analysis; D011485:Protein Binding; D012367:RNA, Viral / Q000096:biosynthesis* / Q000235:genetics*; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism; D017384:Sequence Deletion; D014779:Virus Replication
D020121:5' Untranslated Regions; D012367:RNA, Viral; D012324:RNA-Dependent RNA Polymerase
5′ untranslated region; Bromovirus; Positive-strand RNA virus; Protoplast; RNA replication; RNA structure