We previously cloned a part of nqr operon encoding the Na+-translocating NADH-quinone reductase (NQR) from the marine Vibrio alginolyticus (Hayashi et al., FEBS Lett. 356 (1994) 330–332]. From its nucleotide sequences, four consecutive open reading frames (ORF) encoding the γ-subunit (27.7 kDa), two unidentified ORFs of 22.6 kDa and 21.5 kDa, and the β-subunit (45.3 kDa) were recognized. The gene encoding the α-subunit was located upstream, and together with the recent report by Beattie et al. [FEBS Lett. 356 (1994) 333–338], the nqr operon was found to be constructed from six consecutive structural genes, where nqrl, nqr3 and nqr6 correspond to the α-, γ-, and β-subunits, respectively, of the NQR complex.
