An Internally Located RNA Hairpin Enhances Replication of Tomato Bushy Stunt Virus RNAs
AUTOR(ES)
Ray, Debashish
FONTE
American Society for Microbiology
RESUMO
Defective interfering (DI) RNAs of Tomato bushy stunt virus (TBSV), a plus-sense RNA virus, comprise four conserved noncontiguous regions (I through IV) derived from the viral genome. Region III, a 70-nucleotide-long sequence corresponding to a genomic segment located 378 nucleotides upstream of the 3′ terminus of the genome, has been found to enhance DI RNA accumulation by approximately 10-fold in an orientation-independent manner (D. Ray and K. A. White, Virology 256:162-171, 1999). In this study, a more detailed structure-function analysis of region III was conducted. RNA secondary-structure analyses indicated that region III contains stem-loop structures in both plus and minus strands. Through deletion analyses of a DI RNA, a primary determinant of region III activity was mapped to the 5′-proximal 35-nucleotide segment. Compensatory-type mutational analyses showed that a stem-loop structure in the minus strand of this subregion was required for enhanced DI RNA replication. The same stem-loop structure was also found to function in a position-independent manner in a DI RNA (albeit at reduced levels) and to be important for efficient accumulation within the context of the TBSV genome. Taken together, these observations suggest that the 5′-proximal segment of region III is a modular RNA replication element that functions primarily through the formation of an RNA hairpin structure in the minus strand.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=140596Documentos Relacionados
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