Format

Send to

Choose Destination
See comment in PubMed Commons below
RNA. 2008 Oct;14(10):2159-69. doi: 10.1261/rna.1089208. Epub 2008 Aug 28.

Ribosomes bind leaderless mRNA in Escherichia coli through recognition of their 5'-terminal AUG.

Author information

  • 1Department of Microbiology, Miami University, Oxford, Ohio 45056, USA.

Abstract

Leaderless mRNAs are translated in the absence of upstream signals that normally contribute to ribosome binding and translation efficiency. In order to identify ribosomal components that interact with leaderless mRNA, a fragment of leaderless cI mRNA from bacteriophage lambda, with a 4-thiouridine (4(S)-U) substituted at the +2 position of the AUG start codon, was used to form cross-links to Escherichia coli ribosomes during binary (mRNA+ribosome) and ternary (mRNA+ribosome+initiator tRNA) complex formation. Ribosome binding assays (i.e., toeprints) demonstrated tRNA-dependent binding of leaderless mRNA to ribosomes; however, cross-links between the start codon and 30S subunit rRNA and r-proteins formed independent of initiator tRNA. Toeprints revealed that a leaderless mRNA's 5'-AUG is required for stable binding. Furthermore, the addition of a 5'-terminal AUG triplet to a random RNA fragment can make it both competent and competitive for ribosome binding, suggesting that a leaderless mRNA's start codon is a major feature for ribosome interaction. Cross-linking assays indicate that a subset of 30S subunit r-proteins, located at either end of the mRNA tunnel, contribute to tRNA-independent contacts and/or interactions with a leaderless mRNA's start codon. The interaction of leaderless mRNA with ribosomes may reveal features of mRNA binding and AUG recognition that are distinct from known signals but are important for translation initiation of all mRNAs.

PMID:
18755843
PMCID:
PMC2553737
DOI:
10.1261/rna.1089208
[PubMed - indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center