SMALL, UNSTABLE RNA MOLECULE OF ESCHERICHIA-COLI - SPOT-42-RNA .1. NUCLEOTIDE-SEQUENCE ANALYSIS

We have determined the structure of an unstable, small RNA of Escherichia coli, called spot 42 RNA (Ikemura & Dahlberg, 1973a,b). Spot 42 RNA is 109 nucleotides long, has no modified nucleotides and is very likely a primary transcription product. The nuoleotide sequence and partial digestion data support a secondary structure with at least one hairpin loop. Contained within this RNA are a possible ribosome binding site, a protein synthesis initiator A-U-G and an in-phase U-G-A terminator, giving spot 42 RNA a messenger RNA-like character. Most of the 14 triplets between the A-U-G and U-G-A are codons for hydrophobic amino acids such as leucine, phenylalanine, valine and isoleucine. The 3′-terminal sequence is -U-U-U-U-U-U-AOH which is preceded by a G + C-rich hairpin looped region. The sequence and structure of spot 42 RNA share many features with other bacterial and bacteriophage RNAs, some of which have been shown to be leader RNAs (Bertrand et al., 1976). © 1979.