%0 Journal Article
%A Gabriel, F.
%A Heidelberger, A.
%A Rentsch, D.
%A Giger, W.
%A Günther, K.
%A Kohler, H.-P.
%T A novel metabolic pathway for degradation of 4-nonylphenol environmental contaminants by Sphingomonas xenophaga Bayram
%J The journal of biological chemistry
%V 280
%@ 0021-9258
%C Bethesda, Md.
%I Soc.
%M PreJuSER-47189
%P 15526 - 15533
%D 2005
%Z Record converted from VDB: 12.11.2012
%X Several nonylphenol isomers with alpha-quaternary carbon atoms serve as growth substrates for Sphingomonas xenophaga Bayram, whereas isomers containing hydrogen atoms at the alpha-carbon do not. Three metabolites of 4-(1-methyloctyl)-phenol were isolated in mg quantities from cultures of strain Bayram supplemented with the growth substrate isomer 4-(1-ethyl-1,4-dimethyl-pentyl)-phenol. They were unequivocally identified as 4-hydroxy-4-(1-methyl-octyl)-cyclohexa-2,5-dienone, 4-hydroxy-4-(1-methyl-octyl)-cyclohex-2-enone, and 2-(1-methyl-octyl)-benzene-1,4-diol by high pressure liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. Furthermore, two metabolites originating from 4-n-nonylphenol were identified as 4-hydroxy-4-nonyl-cyclohexa-2,5-dienone and 4-hydroxy-4-nonyl-cyclohex-2-enone by high pressure liquid chromatography-mass spectrometry. We conclude that nonylphenols were initially hydroxylated at the ipso-position forming 4-alkyl-4-hydroxy-cyclohexa-2,5-dienones. Dienones originating from growth substrate nonylphenol isomers underwent a rearrangement that involved a 1,2-C,O shift of the alkyl moiety as a cation to the oxygen atom of the geminal hydroxy group yielding 4-alkoxyphenols, from which the alkyl moieties can be easily detached as alcohols by known mechanisms. Dienones originating from nongrowth substrates did not undergo such a rearrangement because the missing alkyl substituents at the alpha-carbon atom prevented stabilization of the putative alpha-carbocation. Instead they accumulated and subsequently underwent side reactions, such as 1,2-C,C shifts and dihydrogenations. The ipso-hydroxylation and the proposed 1,2-C,O shift constitute key steps in a novel pathway that enables bacteria to detach alpha-branched alkyl moieties of alkylphenols for utilization of the aromatic part as a carbon and energy source.
%K Carbon Isotopes
%K Carbon Radioisotopes
%K Environmental Pollutants: metabolism
%K Isomerism
%K Magnetic Resonance Spectroscopy
%K Mass Spectrometry
%K Phenols: metabolism
%K Sphingomonas: metabolism
%K Time Factors
%K Carbon Isotopes (NLM Chemicals)
%K Carbon Radioisotopes (NLM Chemicals)
%K Environmental Pollutants (NLM Chemicals)
%K Phenols (NLM Chemicals)
%K 4-nonylphenol (NLM Chemicals)
%K J (WoSType)
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:15665329
%U <Go to ISI:>//WOS:000228444800010
%R 10.1074/jbc.M413446200
%U https://juser.fz-juelich.de/record/47189