Cloning and sequence analysis of the cyclomaltodextrinase gene from Bacillus sphaericus and expression in Escherichia coli cells.

The gene for cyclomaltodextrinase (CDase; EC 3.2.1.54) from Bacillus sphaericus E-244 was cloned in the recombinant plasmid pCD629. Sequencing a portion of pCD629 revealed a unique open reading frame of 1,773 nucleotides coding for a 591-amino-acid polypeptide. The deduced polypeptide sequence showed about 50% homology with that of a neopullulanase, and was slightly homologous to those of the cyclodextrin glucanotransferases and the alpha-amylases. The optimum pH, specific activity and Km value for beta-cyclodextrin of the CDase that has been produced in Escherichia coli cells were 8.0, 16.4 units/mg protein, and 0.41 mM, respectively. These values were almost identical to those from B. sphaericus E-244.