title: Two different respiratory Rieske proteins are expressed in the extreme thermoacidophilic crenarchaeon Sulfolobus acidocaldarius: cloning and sequencing of their genes.
abstract: We have isolated two genes encoding Rieske iron sulfur proteins from the genomic DNA of the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius (DSM 639). One of the genes, named soxL, codes for the previously isolated novel Rieske-I protein. The second gene (soxF) 121 codes for the Rieske-II protein associated with the second terminal oxidase of Sulfolobus. Both proteins exhibit only 24% identical residues. The Rieske-I protein shows a number of unusual features. (i) The distance between the two cluster binding sites is significantly larger than in all known proteins. (ii) An unexpected Pro --> Asp exchange in one of the cluster binding sites. (iii) It shows some resemblance to the mitochondrial and plastidic Rieske proteins insofar as the soxL gene codes for a pre-sequence which is no longer present in the mature Rieske-I protein. Both proteins cluster together on a separate branch of the phylogenetic tree. To our knowledge this is the first proven case of two significantly different Rieske proteins in a prokaryote.
authors.affiliation: Institut für Biochemie, Medizinische Universität zu Lübeck, Germany.
authors.forename: C L
authors.initials: CL
authors.lastname: Schmidt
authors.forename: S
authors.initials: S
authors.lastname: Anemüller
authors.forename: G
authors.initials: G
authors.lastname: Schäfer
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence / Q000235:genetics; D014450:Electron Transport Complex III; D005798:Genes, Bacterial / Q000235:genetics*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D016945:Sulfolobus acidocaldarius / Q000737:chemistry / Q000235:genetics*
chemical_list: D007506:Iron-Sulfur Proteins; C037989:Rieske iron-sulfur protein; D014450:Electron Transport Complex III