A second putative mRNA binding site on the Escherichia coli ribosome.

Translation in bacteria is initiated by a base-pairing interaction between the extreme 3'-end of the small-subunit rRNA and a purine-rich domain (Shine-Dalgarno (SD) sequence) preceding the initiation codon at the 5'-end of most bacterial mRNAs. Here, we describe the identification of a second functional and alternative site on the Escherichia coli ribosome which is capable of interacting with mRNA devoid of SD sequences and initiate the translation. This site is localized between nt 1340 and 1360 of the 16S rRNA in E. coli and is complementary to the untranslated region at the 5'-end of tobacco mosaic virus RNA (omega sequence).