Nucleotide sequence of the structural gene for tryptophanase of Escherichia coli K-12

Abstract

The tryptophanase structural gene, tnaA, of E. coli K-12 was cloned and sequenced. The size, amino acid composition and sequence of the protein predicted from the nucleotide sequence agree with protein structure data previously acquired by others for the tryptophanase of E. coli B. Physiological data indicated that the region controlling expression of tnaA was present in the cloned segment. Sequence data suggested that a 2nd structural gene of unknown function was located distal to tnaA and may be in the same operon. The pattern of codon usage in tnaA was intermediate between codon usage in 4 of the ribosomal protein structural genes and the structural genes for 3 of the tryptophan biosynthetic proteins.