title: An additional ribosome-binding site on mRNA of highly expressed genes and a bifunctional site on the colicin fragment of 16S rRNA from Escherichia coli: important determinants of the efficiency of translation-initiation.
abstract: For various genes of E. coli, three regions (-55 to -1; -35 to -1; -21 to -1) 5' to AUG codon on mRNA were searched for sites of interaction with colicin fragment of 16S rRNA. The detailed sequence comparison points out that apart from Shine-Dalgarno base pairing, an additional ribosome-binding site, a subsequence of 5'-UGAUCC-3' invariably exists in mRNA for highly expressed genes. Poorly expressed genes appear to be controlled by only Shine-Dalgarno base pairing. The analysis indicates that in the initiator region, the -55 to -1 region contains the signal which decides the efficiency of the translation-initiation. The site on 16S rRNA, 5'-GGAUCA-3' at position 1529, that can base pair to the above site, has a recognition site on 23S rRNA at position 2390. In the light of the conserved nature and accessibility of these sites, it is proposed that the site on 16S rRNA plays a bifunctional role--initially it binds to mRNA from highly expressed genes to form a stable 30S initiation complex, and upon association with 50S subunit it exchanges base pairing with 23S rRNA, thus leaving the site on mRNA free.
authors.affiliation: Centre for Cellular and Molecular Biology, Hyderabad, India.
authors.forename: T A
authors.initials: TA
authors.lastname: Thanaraj
authors.forename: M W
authors.initials: MW
authors.lastname: Pandit
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002736:Chloroplasts / Q000502:physiology; D003087:Colicins; D004926:Escherichia coli / Q000235:genetics*; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D006860:Hydrogen Bonding; D009690:Nucleic Acid Conformation; D010442:Peptide Chain Initiation, Translational; D010957:Plasmids; D012333:RNA, Messenger / Q000235:genetics*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D012270:Ribosomes / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D003087:Colicins; D012333:RNA, Messenger; D012336:RNA, Ribosomal, 16S