Base-pairing between untranslated regions facilitates translation of uncapped, nonpolyadenylated viral RNA


Publication Type:

Journal Article


Mol Cell, Volume 7, Number 5, p.1103-9 (2001)


1097-2765 (Print)<br/>1097-2765 (Linking)

Accession Number:



3' Untranslated Regions/ metabolism, 5' Untranslated Regions/ metabolism, Amino Acid Sequence, Base Pairing, Conserved Sequence, Luteovirus/genetics, Molecular Sequence Data, Mutagenesis, Site-Directed, Nucleic Acid Conformation, Poly A/ genetics, Protein Biosynthesis, Ribosomes/metabolism, RNA, Messenger/chemistry/genetics, RNA, Viral/chemistry/ genetics/metabolism, Sequence Alignment


Translationally competent mRNAs form a closed loop via interaction of initiation factors with the 5' cap and poly(A) tail. However, many viral mRNAs lack a cap and/or a poly(A) tail. We show that an uncapped, nonpolyadenylated plant viral mRNA forms a closed loop by direct base-pairing (kissing) of a stem loop in the 3' untranslated region (UTR) with a stem loop in the 5' UTR. This allows a sequence in the 3' UTR to confer translation initiation at the 5'-proximal AUG. This base-pairing is also required for replication. Unlike other cap-independent translation mechanisms, the ribosome enters at the 5' end of the mRNA. This remarkably long-distance base-pairing reveals a novel mechanism of cap-independent translation and means by which mRNA UTRs can communicate.


Guo, L<br/>Allen, E M<br/>Miller, W A<br/>Research Support, Non-U.S. Gov't<br/>Research Support, U.S. Gov't, Non-P.H.S.<br/>United States<br/>Mol Cell. 2001 May;7(5):1103-9.