Publications

• Anaerobic oxidation of p-cresol mediated by a partially purified methylhydroxylase from a denitrifying bacterium.

  Bossert I.D., Whited G., Gibson D.T., Young L.Y.

  Anoxic cell extracts of a denitrifying bacterial isolate (PC-07) were shown to oxidize p-cresol to p-hydroxybenzoate. Oxidation of the substrate was independent of molecular oxygen and required nitrate as the natural terminal electron acceptor. Two enzyme activities were implicated in the pathway ... >> More

  Anoxic cell extracts of a denitrifying bacterial isolate (PC-07) were shown to oxidize p-cresol to p-hydroxybenzoate. Oxidation of the substrate was independent of molecular oxygen and required nitrate as the natural terminal electron acceptor. Two enzyme activities were implicated in the pathway utilized by PC-07. A p-cresol methylhydroxylase mediated the oxidation of p-cresol to p-hydroxybenzaldehyde, which was further oxidized to p-hydroxybenzoate by an NAD+-dependent dehydrogenase. The PC-07 methylhydroxylase was partially purified by anion-exchange chromatography. The protein appeared to be a multifunctional flavocytochrome, which first oxidized p-cresol to p-hydroxybenzyl alcohol, which was then oxidized to p-hydroxybenzaldehyde. The identity of the aldehyde was confirmed by mass spectroscopy. The PC-07 methylhydroxylase had a limited substrate range and required an alkyl-substituted phenolic ring with a hydroxyl group in the para position. From the available evidence, p-cresol, a naturally occurring phenol, exhibited the greatest affinity to the enzyme and therefore may be its natural substrate. << Less

  J Bacteriol 171:2956-2962(1989) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Functional characterization of a vanillin dehydrogenase in Corynebacterium glutamicum.

  Ding W., Si M., Zhang W., Zhang Y., Chen C., Zhang L., Lu Z., Chen S., Shen X.

  Vanillin dehydrogenase (VDH) is a crucial enzyme involved in the degradation of lignin-derived aromatic compounds. Herein, the VDH from Corynebacterium glutamicum was characterized. The relative molecular mass (Mr) determined by SDS-PAGE was ~51 kDa, whereas the apparent native Mr values revealed ... >> More

  Vanillin dehydrogenase (VDH) is a crucial enzyme involved in the degradation of lignin-derived aromatic compounds. Herein, the VDH from Corynebacterium glutamicum was characterized. The relative molecular mass (Mr) determined by SDS-PAGE was ~51 kDa, whereas the apparent native Mr values revealed by gel filtration chromatography were 49.5, 92.3, 159.0 and 199.2 kDa, indicating the presence of dimeric, trimeric and tetrameric forms. Moreover, the enzyme showed its highest level of activity toward vanillin at pH 7.0 and 30°C, and interestingly, it could utilize NAD(+) and NADP(+) as coenzymes with similar efficiency and showed no obvious difference toward NAD(+) and NADP(+). In addition to vanillin, this enzyme exhibited catalytic activity toward a broad range of substrates, including p-hydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde, o-phthaldialdehyde, cinnamaldehyde, syringaldehyde and benzaldehyde. Conserved catalytic residues or putative cofactor interactive sites were identified based on sequence alignment and comparison with previous studies, and the function of selected residues were verified by site-directed mutagenesis analysis. Finally, the vdh deletion mutant partially lost its ability to grow on vanillin, indicating the presence of alternative VDH(s) in Corynebacterium glutamicum. Taken together, this study contributes to understanding the VDH diversity from bacteria and the aromatic metabolism pathways in C. glutamicum. << Less

  Sci. Rep. 5:8044-8044(2015) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.

• Evidence for p-hydroxybenzoate formation involving enzymatic phenylpropanoid side-chain cleavage in hairy roots of Daucus carota.

  Sircar D., Mitra A.

  In this study, methyl jasmonate (MJ)-elicited hairy root cultures of Daucus carota were explored to study the enzymatic route to p-hydroxybenzoic acid (p-HBA) biosynthesis. Treatment with 100microM MJ caused an enhanced accumulation of p-HBA as well as total phenolic content in elicited root lines ... >> More

  In this study, methyl jasmonate (MJ)-elicited hairy root cultures of Daucus carota were explored to study the enzymatic route to p-hydroxybenzoic acid (p-HBA) biosynthesis. Treatment with 100microM MJ caused an enhanced accumulation of p-HBA as well as total phenolic content in elicited root lines as compared to untreated (controls) lines. Using cell-free extract as the source of crude enzymes, attempt was made to reveal the enzymatic route to p-HBA formation. The accumulation of p-HBA was preceded by a substantial upliftment of p-hydroxybenzaldehyde dehydrogenase (HBD) activity in elicited lines as compared to controls. A rapid 6-fold enhancement of phenylalanine ammonia-lyase (PAL) activity, the first enzyme of the phenylpropanoid pathway was also observed. Finally, we demonstrated here for the first time, in D. carota, the evidence of a quite unusual p-hydroxybenzaldehyde synthase (HBS)-type enzyme, which catalyzes the penultimate step of p-HBA biosynthesis by making phenylpropanoid side-chain cleavage of p-coumaric acid without involvement of any cofactor(s), but uplifted by supplementation of a thiol reagent such as DTT in the reaction buffer. This enzyme showed activity in a relatively broad pH range (7-8.4) and the temperature optimum was found to be at 34 degrees C. The MJ-treated roots showed highest HBS activity at 24h (52nkat/mg protein), which was nearly 5-fold higher than that in the control lines. << Less

  J Plant Physiol 165:407-414(2008) [PubMed] [EuropePMC]