title: A putative azoreductase gene is involved in the Shewanella oneidensis response to heavy metal stress.
abstract: The Shewanella oneidensis MR-1 gene SO3585, which is annotated as a putative flavin mononucleotide-dependent azoreductase, shares 28% sequence identity with Bacillus subtilis azoreductase and Pseudomonas putida ChrR, a soluble flavoprotein exhibiting chromate reductase activity. Reverse transcription polymerase chain reaction demonstrated that the SO3585 gene is co-transcribed with two downstream open reading frames: SO3586 (a glyoxalase family protein) and SO3587 (a predicted membrane-associated hypothetical protein). The transcriptional start site of the so3585 transcript was localized using 5' rapid amplification of complementary DNA ends analysis. To investigate the cellular function of SO3585, an in-frame deletion of the so3585 locus was generated in MR-1, and the phenotype of the resulting mutant was characterized. The so3585 deletion mutant was comparable to the parental strain in its ability to decolorize two sulfonated azo dyes (Orange II, Direct Blue 15) under aerobic conditions. By contrast, growth of the so3585 deletion mutant was sensitive to different exogenous transition heavy metals [Cr(VI), Cd(II), Cu(II), and Zn(II)], while the most severe growth deficiencies were observed in the presence of Cd(II) and Cu(II). In addition, the rate of extracellular chromate disappearance by the deletion strain was initially impaired, although both the so3585 mutant and MR-1 wild type reduced Cr(VI) within the same time period.
authors.affiliation: Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA.
authors.forename: Irina
authors.initials: I
authors.lastname: Mugerfeld
authors.forename: Brittany A
authors.initials: BA
authors.lastname: Law
authors.forename: Gene S
authors.initials: GS
authors.lastname: Wickham
authors.forename: Dorothea K
authors.initials: DK
authors.lastname: Thompson
mesh_terms: D000332:Aerobiosis; D000595:Amino Acid Sequence; D001391:Azo Compounds / Q000378:metabolism; D001483:Base Sequence; D002840:Chromates / Q000378:metabolism; D004396:Coloring Agents / Q000378:metabolism; D017353:Gene Deletion; D023061:Gene Order; D005798:Genes, Bacterial; D019216:Metals, Heavy / Q000633:toxicity*; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D009601:Nitroreductases; D009876:Operon; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D020592:Shewanella / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D001391:Azo Compounds; D002840:Chromates; D004396:Coloring Agents; D019216:Metals, Heavy; D009247:NADH, NADPH Oxidoreductases; D009601:Nitroreductases; C021106:azoreductase