Generation of Subgenomic RNA Directed by a Satellite RNA Associated with Bamboo Mosaic Potexvirus: Analyses of Potexvirus Subgenomic RNA Promoter

AUTOR(ES)

Lee, Yun-Shien

FONTE

American Society for Microbiology

RESUMO

Satellite RNA of bamboo mosaic potexvirus (satBaMV), a single-stranded positive-sense RNA encoding a nonstructural protein of 20 kDa (P20), depends on bamboo mosaic potexvirus (BaMV) for replication and encapsidation. A full-length cDNA clone of satBaMV was used to examine the sequences required for the synthesis of potexvirus subgenomic RNAs (sgRNAs). Subgenomic promoter-like sequences (SGPs), 107 nucleotides (nt) upstream from the capsid protein (CP) gene of BaMV-V, were inserted upstream of the start codon of the P20 gene of satBaMV. Insertion of SGPs gave rise to the synthesis of sgRNA of satBaMV in protoplasts of Nicotiana benthamiana and leaves of Chenopodium quinoa when coinoculated with BaMV-V genomic RNA. Moreover, both the satBaMV cassette and its sgRNA were encapsidated. From analysis of the SGPs by deletion mutation, we concluded that an SGP contains one core promoterlike sequence (nt −30 through +16), two upstream enhancers (nt −59 through −31 and −91 through −60), and one downstream enhancer (nt +17 through +52), when the transcription initiation site is taken as +1. Site-directed mutagenesis and compensatory mutation to disrupt and restore potential base pairing in the core promoter-like sequence suggest that the stem-loop structure is important for the function of SGP in vivo. Likewise, the insertion of a putative SGP of the BaMV open reading frame 2 gene or a heterologous SGP of potato virus X resulted in generation of an sgRNA. The satBaMV cassette should be a useful tool to gain insight into sequences required for the synthesis of potexvirus sgRNAs.

Documentos Relacionados

• Bamboo Mosaic Potexvirus Satellite RNA (satBaMV RNA)-Encoded P20 Protein Preferentially Binds to satBaMV RNA
• The open reading frame of bamboo mosaic potexvirus satellite RNA is not essential for its replication and can be replaced with a bacterial gene.
• Sequences at the 3′ Untranslated Region of Bamboo Mosaic Potexvirus RNA Interact with the Viral RNA-Dependent RNA Polymerase
• The Synthesis of Minus-Strand RNA of Bamboo Mosaic Potexvirus Initiates from Multiple Sites within the Poly(A) Tail
• Characterization of a satellite RNA associated with strain K8 of cucumber mosaic virus.