Overproduction and nucleotide sequence of the respiratory D-lactate dehydrogenase of Escherichia coli

Abstract

Recombinant DNA plasmids containing the gene for the membrane-bound D-lactate dehydrogenase (D-LDH) of Escherichia coli linked to the promotor pL from lambda were constructed. After induction, the levels of D-LDH were elevated 300-fold over that of the wild type and amounted to 35% of the total cellular protein. The nucleotide sequence of the D-LDH gene was determined and shown to agree with the amino acid composition and the amino-terminal sequence of the purified enzyme. Removal of the amino-terminal formyl-Met from D-LDH was not inhibited in cells which contained these high levels of D-LDH.