Nucleotide sequence of the respiratory D-lactate dehydrogenase gene of Escherichia coli.

The structural gene for the respiratory D-lactate dehydrogenase of Escherichia coli, a membrane-bound flavoenzyme, has been subcloned from a 7 X 10(3)-base-pair chromosomal HindIII fragment containing the gene [Young, I. G., Jaworowski, A., and Poulis, M. (1982) Biochemistry 21, 2092-2095]. The complete nucleotide sequence of the 2340-base-pair PstI-SmaI subclone has been determined on both strands by the dideoxy chain termination method. A single large open reading frame is present in the nucleotide sequence. The reading frame is preceded by a good ribosome binding site and numerous possible promoter sequences, and is followed by a typical rho-independent termination sequence. The reading frame predicts that the D-lactate dehydrogenase polypeptide consists of 571 amino acids (including the initiating methionine residue) with Mr = 64613. The protein does not have a low overall polarity, nor does it contain unusually hydrophobic stretches. It appears to contain a short repeat which is homologous with the well characterized L-lactate dehydrogenases in the vicinity of the 'essential' cysteine residue. Apart from this, homology with other proteins of known sequence has not been detected.