title: RpoN (sigma 54) is required for conversion of phenol to catechol in Acinetobacter calcoaceticus.
abstract: Members of the sigma 54 protein family, encoded by rpoN, are required for the transcription of genes associated with specialized metabolic functions. The ability to grow with phenol appears to be a specialized trait because it is expressed by few of the microorganisms that grow with catechol, the metabolic product of phenol monooxygenase. A mutation preventing the expression of phenol monooxygenase in the bacterial strain Acinetobacter calcoaceticus NCIB8250 was complemented by wild-type DNA segments containing an open reading frame encoding a member of the sigma 54 protein family. DNA sequencing revealed a second open reading frame, designated ORF2, directly downstream of A. calcoaceticus rpoN. The locations of both ORF2 and the 113-residue amino acid sequence of its product are highly conserved in other bacteria. The mutation preventing the expression of rpoN results in an opal codon that terminates the translation of RpoN at a position corresponding to Trp-91 in the 483-residue amino acid sequence of the wild-type protein. Negative autoregulation of rpoN was suggested by the fact that the mutation inactivating RpoN enhanced the transcription of rpoN. Primer extension revealed independent transcription start sites for rpoN and ORF2.
authors.affiliation: Lehrstuhl für Mikrobiologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Ehrt
authors.forename: L N
authors.initials: LN
authors.lastname: Ornston
authors.forename: W
authors.initials: W
authors.lastname: Hillen
mesh_terms: D016954:Acinetobacter calcoaceticus / Q000201:enzymology / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002396:Catechols / Q000378:metabolism*; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases; D005816:Genetic Complementation Test; D006899:Mixed Function Oxygenases / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames / Q000235:genetics; D019800:Phenol; D010636:Phenols / Q000378:metabolism*; D010641:Phenotype; D051877:RNA Polymerase Sigma 54; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012808:Sigma Factor / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D002396:Catechols; D004268:DNA-Binding Proteins; D010636:Phenols; D012808:Sigma Factor; D019800:Phenol; D006899:Mixed Function Oxygenases; C022336:phenol 2-monooxygenase; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54; C034221:catechol