Identification of six subunits constituting Na+-translocating NADH-quinone reductase from the marine Vibrio alginolyticus

We previously reported that the purified Na+-translocating NADH-quinone reductase (NQR) from the marine Vibrio alginolyticus ss composed of three major subunits, alpha, beta and gamma. NQR operon was sequenced and was found to be composed af 6 structural genes. Among these genes, nqr1, nqr3 and nqr6 were identified to cods for alpha-, gamma- and beta-subunits, respectively. The protein produces from nqr2, nqr4 and nqr5, however, were not reported. The sequence data predicted that these three proteins are very hydrophobic and mat be unusual in mobility and staining on SDS-PAGE. By modifying the detection method of proteins on SDS-PAGE, we could detect all six subunits encoded by NQR operon in the purified NQR complex. The open reading frame of each subunit was identified from its N-terminal amino acid sequence. (C) 1998 Federation of European Biochemical Societies.