A 3,466-bp nucleotide sequence containing the katE gene of Escherichia coli has been determined. An open reading frame of 2,259 bp was found and was preceded by a potential ribosome-binding site. The predicted N-terminal sequence agreed with the sequence determined by direct amino acid sequencing, and the predicted direction of transcription was confirmed by expression of the gene cloned in both directions behind a T7 promoter. The start site of transcription was determined to be 127 bp upstream from the start of the open reading frame, and a potential RNA polymerase-binding site similar to a sequence preceding the xthA gene, which is also controlled by the KatF protein, was identified. The predicted sequence of the 753-amino-acid protein was compared with known sequences of other catalases, revealing significant similarity to the shorter catalases, including the residues in the putative active site and residues involved in heme binding.