Nucleotide sequence of the 5' end of tryptophan messenger RNA of Escherichia coli.

Abstract

Abstract The 5′-terminal sequence of the tryptophan (trp) operon messenger RNA of Escherichia coli was determined by a combination of in vivo and in vitro 32P-labeling techniques. A leader sequence of approximately 166 nucleotides precedes the start codon for the polypeptide specified by the operator-proximal structural gene, trpE. The leader sequence contains an AUG codon (positions 27 to 29) in a region which binds ribosomes (Platt et al., 1976) and is followed in phase by the tandem chain termination codons, U-A-A-U-G-A (positions 120 to 125). The inferred DNA sequence has a region of high G + C content (positions 126 to 137) followed by a region of high A + T content (positions 138 to 156). Studies in vivo (Bertrand et al., 1976) and in vitro (Lee et al., 1976) suggest that transcription termination occurs in the vicinity of these G + C and A + T-rich regions and that termination may be regulated (Bertrand & Yanofsky, 1976).