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Leaderless mRNAs in bacteria: surprises in ribosomal recruitment and translational control
Author(s) -
Moll Isabella,
Grill Sonja,
Gualerzi Claudio O.,
Bläsi Udo
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02739.x
Subject(s) - biology , start codon , eukaryotic translation , eukaryotic initiation factor , translational regulation , translation (biology) , ribosome , genetics , translational efficiency , ribosomal binding site , ribosomal rna , internal ribosome entry site , initiation factor , messenger rna , microbiology and biotechnology , computational biology , rna , gene
Summary It is commonly believed that the translational efficiency of prokaryotic mRNAs is intrinsically determined by both primary and secondary structures of their translational initiation regions. However, for leaderless mRNAs starting with the AUG initiating codon occurring in bacteria, archaea and eukaryotes, there is no evidence for ribosomal recruitment signals downstream of the 5 ′ ‐terminal AUG that seems to be the only necessary and constant element. Studies in Escherichia coli have brought to light that the ratio of initiation factors IF2 and IF3 plays a decisive role in translation initiation of leaderless mRNA, indicating that the translational efficiency of this mRNA class can be modulated depending on the availability of components of the translational machinery. Recent data suggested that the start codon of bacterial leaderless mRNAs is recognized by a ribosome‐IF2‐fMet‐tRNA complex, an intermediate equivalent to that obligatorily formed during translation initiation in eukaryotes, which points to a conceptual similarity in all initiation pathways. In fact, the faithful translation of lead‐erless mRNAs in heterologous systems shows that the ability to translate leaderless mRNAs is an evo‐lutionarily conserved function of the translational apparatus.