IDENTIFICATION OF 5 RHODOBACTER-CAPSULATUS GENES ENCODING THE EQUIVALENT OF ND SUBUNITS OF THE MITOCHONDRIAL NADH-UBIQUINONE OXIDOREDUCTASE

We previously reported the sequencing of two genes (ndhA and ndhI) enc oding two of the subunits of the type-I NADH-ubiquinone oxidoreductase from Rhodobacter capsulatus (Rc). The present paper deals with the cl oning and characterization of a chromosomal fragment clustering five n ew Rc genes which encode subunits of this enzyme. This gene cluster is located immediately downstream from ndhA and ndhI, and also contains two unidentified open reading frames (urf2, urf3). The five genes, nuo J, nuoK, nuoL, nuoM and nuoN, encode proteins related, respectively, t o mitochondrial (mt) subunits ND6, ND4L, ND5, ND4 and ND2. The overall organization of the nuo genes identified in Reshows similarity to tha t of the Paracoccus denitrificans (Pd) nqo gene cluster.