Abstract
A segment of corynephage omega (tox+) DNA, containing the gene for diphtheria toxin (tox) was fragmented with restriction enzymes and the fragments cloned into M13 vectors for nucleotide sequence determination. A long open reading frame was shown to encode the tox gene by comparing the predicted amino acid sequence with that of peptides derived from the mature toxin molecule. Analysis of the nucleotide sequence shows RNA polymerase and ribosome binding signals preceding a GTG codon in the open reading frame: if this is the correct starting signal for translation, then a 25 amino acid signal peptide can be predicted for the toxin molecule.