The structural gene encoding cyclodextrin-glycosyltransferase of Klebsiella pneumoniae strain M5a1 was cloned; it is expressed both in Escherichia coli and in K. pneumoniae and the gene product is secreted into the extracellular space. Determination of the nucleotide sequence revealed an open reading frame coding for a single polypeptide of 655 amino acid (aa) residues. The enzyme is synthesized as a precursor with an N-terminal signal peptide of 30 aa residues, which is proteolytically processed between two alanine residues during export. The primary structure of CGT bears homology with the sequences of amylases from both prokaryotic and eukaryotic origins.