title: Arsenite oxidase aox genes from a metal-resistant beta-proteobacterium.
abstract: The beta-proteobacterial strain ULPAs1, isolated from an arsenic-contaminated environment, is able to efficiently oxidize arsenite [As(III)] to arsenate [As(V)]. Mutagenesis with a lacZ-based reporter transposon yielded two knockout derivatives deficient in arsenite oxidation. Sequence analysis of the DNA flanking the transposon insertions in the two mutants identified two adjacent open reading frames, named aoxA and aoxB, as well as a putative promoter upstream of the aoxA gene. Reverse transcription-PCR data indicated that these genes are organized in an operonic structure. The proteins encoded by aoxA and aoxB share 64 and 72% identity with the small Rieske subunit and the large subunit of the purified and crystallized arsenite oxidase of Alcaligenes faecalis, respectively (P. J. Ellis, T. Conrads, R. Hille, and P. Kuhn, Structure [Cambridge] 9:125-132, 2001). Importantly, almost all amino acids involved in cofactor interactions in both subunits of the A. faecalis enzyme were conserved in the corresponding sequences of strain ULPAs1. An additional Tat (twin-arginine translocation) signal peptide sequence was detected at the N terminus of the protein encoded by aoxA, strongly suggesting that the Tat pathway is involved in the translocation of the arsenite oxidase to its known periplasmic location.
authors.affiliation: Laboratoire de Dynamique, Evolution et Expression des Génomes de Micro-Organismes, FRE2326 Université Louis-Pasteur/CNRS, 67083 Strasbourg cedex, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Muller
authors.forename: Didier
authors.initials: D
authors.lastname: Lièvremont
authors.forename: Diliana Dancheva
authors.initials: DD
authors.lastname: Simeonova
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Hubert
authors.forename: Marie-Claire
authors.initials: MC
authors.lastname: Lett
mesh_terms: D000595:Amino Acid Sequence; D001149:Arsenates / Q000378:metabolism; D001151:Arsenic / Q000378:metabolism / Q000494:pharmacology*; D018053:Arsenites / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D020562:Betaproteobacteria / Q000201:enzymology* / Q000235:genetics; D004251:DNA Transposable Elements / Q000235:genetics; D024881:Drug Resistance, Bacterial; D019216:Metals, Heavy / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D001149:Arsenates; D018053:Arsenites; D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D019216:Metals, Heavy; D010088:Oxidoreductases; C078179:arsenite oxidase; C015001:arsenite; D001151:Arsenic; C025657:arsenic acid