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Applied and Environmental Microbiology, November 1999, p. 4837-4847, Vol. 65, No. 11
Institut für Mikrobiologie der
Westfälischen Wilhelms-Universität Münster, D-48149
Münster, Germany
Received 12 May 1999/Accepted 23 August 1999
The gene loci fcs, encoding feruloyl coenzyme A
(feruloyl-CoA) synthetase, ech, encoding enoyl-CoA
hydratase/aldolase, and aat, encoding
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Copyright © 1999, American Society for Microbiology. All rights reserved.
Biochemical and Genetic Analyses of Ferulic Acid
Catabolism in Pseudomonas sp. Strain HR199
-ketothiolase,
which are involved in the catabolism of ferulic acid and eugenol in
Pseudomonas sp. strain HR199 (DSM7063), were localized on a
DNA region covered by two EcoRI fragments (E230 and E94),
which were recently cloned from a Pseudomonas sp. strain
HR199 genomic library in the cosmid pVK100. The nucleotide sequences of
parts of fragments E230 and E94 were determined, revealing the
arrangement of the aforementioned genes. To confirm the function of the
structural genes fcs and ech, they were cloned and expressed in Escherichia coli. Recombinant strains
harboring both genes were able to transform ferulic acid to vanillin.
The feruloyl-CoA synthetase and enoyl-CoA hydratase/aldolase activities of the fcs and ech gene products,
respectively, were confirmed by photometric assays and by
high-pressure liquid chromatography analysis. To prove the
essential involvement of the fcs, ech, and
aat genes in the catabolism of ferulic acid and eugenol in Pseudomonas sp. strain HR199, these genes were inactivated
separately by the insertion of omega elements. The corresponding
mutants Pseudomonas sp. strain HRfcs
Gm and
Pseudomonas sp. strain HRech
Km were not able
to grow on ferulic acid or on eugenol, whereas the mutant
Pseudomonas sp. strain HRaat
Km exhibited a
ferulic acid- and eugenol-positive phenotype like the wild type. In
conclusion, the degradation pathway of eugenol via ferulic acid and the
necessity of the activation of ferulic acid to the corresponding CoA
ester was confirmed. The aat gene product was shown not to
be involved in this catabolism, thus excluding a
-oxidation
analogous degradation pathway for ferulic acid. Moreover, the function
of the ech gene product as an enoyl-CoA hydratase/aldolase
suggests that ferulic acid degradation in Pseudomonas sp.
strain HR199 proceeds via a similar pathway to that recently described
for Pseudomonas fluorescens AN103.
*
Corresponding author. Mailing address: Institut
für Mikrobiologie, Westfälische Wilhelms-Universität
Münster, Corrensstraße 3, D-48149 Münster, Germany.
Phone: 49-251-8339829. Fax: 49-251-8338388. E-mail:
priefer{at}uni-muenster.de.
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