Initial steps in the degradation of benzene sulfonic acid, 4-toluene sulfonic acids,and orthanilic acid in Alcaligenes sp. strain O-1 |
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Authors: | Thomas Thurnheer Daniel Zürrer Otmar Höglinger Thomas Leisinger Alasdair M. Cook |
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Affiliation: | (1) Microbiology Institute, Swiss Federal Institute of Technology, ETH-Zentrum, CH-8092 Zürich, Switzerland;(2) Division of Biosphere Sciences, King's College London, W8 7AH London, UK |
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Abstract: | Alcaligenes sp. strain O-1 grew with benzene sulfonate (BS) as sole carbon source for growth with either NH4+ or NH4+ plus orthanilate (2-aminobenzene sulfonate, OS) as the source(s) of nitrogen. The intracellular desulfonative enzyme did not degrade 3- or 4-aminobenzene sulfonates in the medium, although the enzyme in cell extracts degraded these compounds. We deduce the presence of a selective permeability barrier to sulfonates and conclude that the first step in sulfonate metabolism is transport into the cell. Cell-free desulfonation of BS in standard reaction mixtures required 2 mol of O2 per mol. One mol of O2 was required for a catechol 2,3-dioxygenase. When meta ring cleavage was inhibited with 3-chlorocatechol in desalted extracts, about 1 mol each of O2 and of NAD(P)H per mol of BS were required for the reaction, and SO32- and catechol were recovered in high yield. Catechol was shown to be formed by dioxygenation in an experiment involving 18O2. 4-Toluene sulfonate was subject to NAD(P)H-dependent dioxygenation to yield SO32- and 4-methylcatechol, which was subject to meta cleavage. OS also required 2 mol of O2 per mol and NAD(P)H for degradation, and SO32- and NH4+ were recovered quantitatively. Inhibition of ring cleavage with 3-chrorocatechol reduced the oxygen requirement to 1 mol per mol of OS SO32- (1 mol) and an unidentified organic intermediate, but no NH4+, were observed. |
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Keywords: | catechol from benzene sulfonate desulfonation and dioxygenation dioxygenase and desulfonation quantification of cell-free desulfonation transport of aromatic sulfonates |
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