Metabolism of isovanillate, vanillate, and veratrate by Comamonas testosteroni strain BR6020.
In Comamonas testosteroni strain BR6020, metabolism of isovanillate (iVan; 3-hydroxy-4-methoxybenzoate), vanillate (Van; 4-hydroxy-3-methoxybenzoate), and veratrate (Ver; 3,4-dimethoxybenzoate) proceeds via protocatechuate (Pca; 3,4-dihydroxybenzoate). A 13.4-kb locus coding for the catabolic enzymes that channel the three substrates to Pca was cloned. O demethylation is mediated by the phthalate family oxygenases IvaA (converts iVan to Pca and Ver to Van) and VanA (converts Van to Pca and Ver to iVan). Reducing equivalents from NAD(P)H are transferred to the oxygenases by the class IA oxidoreductase IvaB. Studies using whole cells, cell extracts, and reverse transcriptase PCR showed that degradative activity and expression of vanA, ivaA, and ivaB are inducible. In succinate- and Pca-grown cells, there is negligible degradative activity towards Van, Ver, and iVan and little to no expression of vanA, ivaA, and ivaB. Growth on Van or Ver results in production of oxygenases with activity towards Van, Ver, and iVan and expression of vanA, ivaA, and ivaB. With iVan-grown cultures, ivaA and ivaB are expressed, and in assays with whole cells, production of the iVan oxygenase is observed, but there is little activity towards Van or Ver. In cell extracts, though, Ver metabolism is observed, which suggests that the system mediating iVan uptake in whole cells does not mediate Ver uptake.
Providenti
Miguel A
MA
Institute of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6. miguel_providenti@carleton.ca
O'Brien
Jason M
JM
Ruff
Jürgen
J
Cook
Alasdair M
AM
Lambert
Iain B
IB
D020604:Comamonas testosteroni / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D005838:Genotype; D062385:Hydroxybenzoates / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010641:Phenotype; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D014641:Vanillic Acid / Q000031:analogs & derivatives* / Q000378:metabolism*
D017931:DNA Primers; D062385:Hydroxybenzoates; C009333:veratric acid; C009091:protocatechuic acid; C045317:isovanillic acid; D014641:Vanillic Acid