Translation of the leader region of the Escherichia coli tryptophan operon.

When the trp operon of Escherichia coli contains either of two deletions that fuse the initial portion of the leader region to the distal segments of the trpE gene, novel fusion polypeptides are produced. The new polypeptides are synthesized efficiently both in vivo and in vitro, and their synthesis is subject to repression by trp repressor. Fingerprint analyses of tryptic and chymotryptic digests of the new polypeptides show that both contain trpE polypeptide sequences and, despite their different sizes, share the same N-terminal sequence. Our results suggest that synthesis of the new polypeptides is initiated at the AUG-centered ribosome-binding site in the leader region and proceeds in phase to the region coding for the C-terminal end of the trpE polypeptide.     

Correction of the nucleotide sequence of the Citrobacter freundii tryptophan operon regulatory region.

We present a correction of the previously reported nucleotide sequence of the Citrobacter freundii trp operon regulatory region. The original sequence analyses were performed with a plasmid designated pCF2. We repeated the cloning of the trp regulatory region of C. freundii and concluded from the determined sequence that a DNA rearrangement had occurred within the leader region of the cloned trp DNA of pCF2. The correct sequence is homologous to the Escherichia coli sequence.     

Primary structure of the E. coli DNA region preceding the tryptophan operon genes

The nucleotide sequence of 1179 b.p. preceding the trp operon genes has been established. There are no open reading frames large enough to code for proteins containing more than 97 amino acid residues. In all cases the coding sequences do not contain the initiation codons. The determined sequence is concluded to represent an intercistronic region.