Nucleotide sequence of the respiratory d‐lactate dehydrogenase gene of Escherichia coli

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Abstract
The structural gene for the respiratory d-lactate dehydrogenase of Escherichia coli, a membrane-bound flavoenzyme, has been subcloned from a 7 × 103-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.