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Detoxification of Indole by an Indole-Induced Flavoprotein Oxygenase from Acinetobacter baumannii

Lin, Guang-Huey ; Chen, Hao-Ping ; Shu, Hung-Yu Lee, Seon-Woo (editor)

PLoS ONE, 2015, Vol.10(9) [Peer Reviewed Journal]

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  • Title:
    Detoxification of Indole by an Indole-Induced Flavoprotein Oxygenase from Acinetobacter baumannii
  • Author: Lin, Guang-Huey ; Chen, Hao-Ping ; Shu, Hung-Yu
  • Lee, Seon-Woo (editor)
  • Subjects: Research Article
  • Is Part Of: PLoS ONE, 2015, Vol.10(9)
  • Description: Indole, a derivative of the amino acid tryptophan, is a toxic signaling molecule, which can inhibit bacterial growth. To overcome indole-induced toxicity, many bacteria have developed enzymatic defense systems to convert indole to non-toxic, water-insoluble indigo. We previously demonstrated that, like other aromatic compound-degrading bacteria, Acinetobacter baumannii can also convert indole to indigo. However, no work has been published investigating this mechanism. Here, we have shown that the growth of wild-type A . baumannii is severely inhibited in the presence of 3.5 mM indole. However, at lower concentrations, growth is stable, implying that the bacteria may be utilizing a survival mechanism to oxidize indole. To this end, we have identified a flavoprotein oxygenase encoded by the iifC gene of A . baumannii . Further, our results suggest that expressing this recombinant oxygenase protein in Escherichia coli can drive indole oxidation to indigo in vitro . Genome analysis shows that the iif operon is exclusively present in the genomes of A . baumannii and Pseudomonas syringae pv. actinidiae . Quantitative PCR and Western blot analysis also indicate that the iif operon is activated by indole through the AraC-like transcriptional regulator IifR. Taken together, these data suggest that this species of bacteria utilizes a novel indole-detoxification mechanism that is modulated by IifC, a protein that appears to be, at least to some extent, regulated by IifR.
  • Identifier: E-ISSN: 1932-6203 ; DOI: 10.1371/journal.pone.0138798 ; PMCID: 4577076 ; PMID: 26390211

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