Cloning chromosomal lac genes of Klebsiella pneumoniae.

The chromosomal gene for beta-galactosidase from Klebsiella pneumoniae strain T17R1 and associated regulatory genes have been cloned as a 5-kb HindIII fragment in the pBR322 plasmid vector. The beta-galactoside permease gene is not present in a functional form in the 5-kb fragment. The K. pneumoniae genes are expressed in an Escherichia coli host. The synthesis of beta-galactosidase is inducible by isopropyl-beta-D-galactosidase (IPTG) and is sensitive to catabolite repression. There appears to be greater homology between the K. pneumoniae and E. coli structural genes for beta-galactosidase than there is between the respective repressor genes.