A single-stranded loop in the 5′ untranslated region of cucumber mosaic virus RNA 4 contributes to competitive translational activity

ABSTRACT Red clover necrotic mosaic virus (RCNMV) is a member of the genus Dianthovirus and has a bipartite positive-sense genomic RNA with 3′ ends that are not polyadenylated. In this study, we show that both genomic RNA1 and RNA2 lack a 5′ cap structure and that uncapped in vitro transcripts of RCNMV RNA1 replicated to a level comparable to that for capped transcripts in cowpea protoplasts. Because the 5′ cap and 3′ poly(A) tail play important roles in the translation of many eukaryotic mRNAs, genomic RNAs of RCNMV should contain an element(s) responsible for 5′ cap- and poly(A) tail-independent translation of viral protein. By using a luciferase reporter assay system in vivo, we showed that the 3′ untranslated region (UTR) of RNA1 alone significantly enhanced translation of the luciferase reporter gene in the absence of the 5′ cap structure. Deletion studies revealed that the middle region (between nucleotides 3596 and 3732) in the 3′ UTR, designated the 3′ translation element of Dianthovirus RNA1 (3′TE-DR1), plays an important role in cap-independent translation. This region contained a stem-loop structure conserved among members of the genera Dianthovirus and Luteovirus. A five-base substitution in the loop abolished cap-independent translational activity, as reported for a luteovirus, indicating that this stem-loop is one of the functional structures in the 3′TE-DR1 involved in cap-independent translation. Finally, we suggest that cap-independent translational activity is required for RCNMV RNA1 replication in protoplasts.

Download Full-text

Enhancing effect of the 3′-untranslated region of tobacco mosaic virus RNA on protein synthesis in vitro

FEBS Letters ◽

10.1016/0014-5793(94)01126-5 ◽

1994 ◽

Vol 354 (3) ◽

pp. 271-273 ◽

Cited By ~ 19

Author(s):

Vladimir V. Zeyenko ◽

Lyubov A. Ryabova ◽

Daniel R. Gallie ◽

Alexander S. Spirin

Keyword(s):

Protein Synthesis ◽

Tobacco Mosaic Virus ◽

Mosaic Virus ◽

Untranslated Region ◽

Enhancing Effect ◽

Virus Rna

Download Full-text

Eukaryotic Elongation Factor 1A Interacts with the Upstream Pseudoknot Domain in the 3′ Untranslated Region of Tobacco Mosaic Virus RNA

Journal of Virology ◽

10.1128/jvi.76.11.5678-5691.2002 ◽

2002 ◽

Vol 76 (11) ◽

pp. 5678-5691 ◽

Cited By ~ 75

Author(s):

Vladimir V. Zeenko ◽

Lyubov A. Ryabova ◽

Alexander S. Spirin ◽

Helen M. Rothnie ◽

Daniel Hess ◽

...

Keyword(s):

Tobacco Mosaic Virus ◽

Mosaic Virus ◽

Untranslated Region ◽

Mutational Analysis ◽

Specific Binding ◽

Elongation Factor ◽

Virus Rna ◽

Eukaryotic Elongation Factor ◽

Sequence Elements ◽

Positive Strand Rna

ABSTRACT The genomic RNA of tobacco mosaic virus (TMV), like that of other positive-strand RNA viruses, acts as a template for both translation and replication. The highly structured 3′ untranslated region (UTR) of TMV RNAs plays an important role in both processes; it is not polyadenylated but ends with a tRNA-like structure (TLS) preceded by a conserved upstream pseudoknot domain (UPD). The TLS of tobamoviral RNAs can be specifically aminoacylated and, in this state, can interact with eukaryotic elongation factor 1A (eEF1A)/GTP with high affinity. Using a UV cross-linking assay, we detected another specific binding site for eEF1A/GTP, within the UPDs of TMV and crucifer-infecting tobamovirus (crTMV), that does not require aminoacylation. A mutational analysis revealed that UPD pseudoknot conformation and some conserved primary sequence elements are required for this interaction. Its possible role in the regulation of tobamovirus gene expression and replication is discussed.

Download Full-text