CLONING AND SEQUENCING OF 4 STRUCTURAL GENES FOR THE NA+-TRANSLOCATING NADH-UBIQUINONE OXIDOREDUCTASE OF VIBRIO-ALGINOLYTICUS

Oligonucleotide probes based on the N-terminal amino acid sequences of the NqrA and NqrC subunits were used to clone genes for the Na+-dependent NADH-ubiquinone oxidoreductase complex from Vibrio alginolyticus. Four consecutive ORFs were identified encoding subunit proteins of 48.6, 46.8, 27.7 and 22.6 kDa, respectively (NqrA-D). A further ORF, showing 71% homology to the BolA protein of Escherichia coli, was located upstream. From sequence comparisons, we conclude that the Na+-dependent NADH-ubiquinone oxidoreductase complex of V. alginolyticus is clearly distinct from the corresponding H+-dependent enzymes of both prokaryotes and eukaryotes.