title: Aniline is an inducer, and not a precursor, for indole derivatives in Rubrivivax benzoatilyticus JA2.
abstract: Rubrivivax benzoatilyticus JA2 and other anoxygenic photosynthetic bacteria produce indole derivatives when exposed to aniline, a xenobiotic compound. Though this phenomenon has been reported previously, the role of aniline in the production of indoles is still a biochemical riddle. The present study aims at understanding the specific role of aniline (as precursor or stimulator) in the production of indoles and elucidating the biochemical pathway of indoles in aniline-exposed cells by using stable isotope approaches. Metabolic profiling revealed tryptophan accumulation only in aniline exposed cells along with indole 3-acetic acid (IAA) and indole 3-aldehyde (IAld), the two major catabolites of tryptophan. Deuterium labelled aniline feeding studies revealed that aniline is not a precursor of indoles in strain JA2. Further, production of indoles only in aniline-exposed cells suggests that aniline is an indoles stimulator. In addition, production of indoles depended on the presence of a carbon source, and production enhanced when carbon sources were added to the culture. Isotope labelled fumarate feeding identified, fumarate as the precursor of indole, indicating de novo synthesis of indoles. Glyphosate (shikimate pathway inhibitor) inhibited the indoles production, accumulation of tryptophan, IAA and IAld indicating that indoles synthesis in strain JA2 occurs via the de novo shikimate pathway. The up-regulation of anthranilate synthase gene and induction of anthranilate synthase activity correlated well with tryptophan production in strain JA2. Induction of tryptophan aminotransferase and tryptophan 2-monooxygenase activities corroborated well with IAA levels, suggesting that tryptophan catabolism occurs simultaneously in aniline exposed cells. Our study demonstrates that aniline (stress) stimulates tryptophan/indoles synthesis via the shikimate pathway by possibly modulating the metabolic pathway.
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, India.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Mujahid
authors.affiliation: Bacterial Discovery Laboratory, Centre for Environment, IST, J NT University Hyderabad, Kukatpally, Hyderabad, India.
authors.forename: Ch
authors.initials: Ch
authors.lastname: Sasikala
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, India.
authors.forename: Ch V
authors.initials: ChV
authors.lastname: Ramana
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D020562:Betaproteobacteria / Q000378:metabolism*; D002474:Cell-Free System; D004952:Esters / Q000737:chemistry; D005650:Fumarates / Q000737:chemistry; D007210:Indoleacetic Acids / Q000737:chemistry; D007211:Indoles / Q000737:chemistry*; D006899:Mixed Function Oxygenases / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D014364:Tryptophan / Q000737:chemistry; D051279:Tryptophan Transaminase / Q000378:metabolism; D015262:Xenobiotics / Q000737:chemistry*
chemical_list: D000814:Aniline Compounds; D004952:Esters; D005650:Fumarates; D007210:Indoleacetic Acids; D007211:Indoles; D015262:Xenobiotics; C001655:indole-3-acetaldehyde; C030737:indoleacetic acid; D014364:Tryptophan; D006899:Mixed Function Oxygenases; C023204:tryptophan 2-monooxygenase; D051279:Tryptophan Transaminase; C023650:aniline