New bacterial pathway for 4- and 5-chlorosalicylate degradation via 4-chlorocatechol and maleylacetate in Pseudomonas sp. strain MT1

Pseudomonas sp. strain MT1 is capable of degrading 4- and 5-chlorosalicylates via 4-chlorocatechol, 3-chloromuconate, and maleylacetate by a novel pathway. 3-Chloromuconate is transformed by muconate cycloisomerase of MT1 into protoanemonin, a dominant reaction product, as previously shown for other...

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Bibliographic Details
Published in:Journal of bacteriology Vol. 185; no. 23; p. 6790
Main Authors: Nikodem, Patricia, Hecht, Volker, Schlömann, Michael, Pieper, Dietmar H
Format: Journal Article
Language:English
Published: United States 01.12.2003
Subjects:
Amino Acid Sequence
Carboxylic Ester Hydrolases - antagonists & inhibitors
Carboxylic Ester Hydrolases - metabolism
Catechol 1,2-Dioxygenase
Catechols - metabolism
Dioxygenases
Furans - analysis
Furans - metabolism
Genome, Bacterial
Intramolecular Lyases - metabolism
Maleates - analysis
Maleates - metabolism
Molecular Sequence Data
Multienzyme Complexes - metabolism
Oxidoreductases Acting on CH-CH Group Donors - metabolism
Oxygenases - metabolism
Pseudomonas - genetics
Pseudomonas - metabolism
Salicylates - metabolism
Sequence Homology, Amino Acid
Xenobiotics - metabolism
ISSN:0021-9193
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Summary:Pseudomonas sp. strain MT1 is capable of degrading 4- and 5-chlorosalicylates via 4-chlorocatechol, 3-chloromuconate, and maleylacetate by a novel pathway. 3-Chloromuconate is transformed by muconate cycloisomerase of MT1 into protoanemonin, a dominant reaction product, as previously shown for other muconate cycloisomerases. However, kinetic data indicate that the muconate cycloisomerase of MT1 is specialized for 3-chloromuconate conversion and is not able to form cis-dienelactone. Protoanemonin is obviously a dead-end product of the pathway. A trans-dienelactone hydrolase (trans-DLH) was induced during growth on chlorosalicylates. Even though the purified enzyme did not act on either 3-chloromuconate or protoanemonin, the presence of muconate cylcoisomerase and trans-DLH together resulted in considerably lower protoanemonin concentrations but larger amounts of maleylacetate formed from 3-chloromuconate than the presence of muconate cycloisomerase alone resulted in. As trans-DLH also acts on 4-fluoromuconolactone, forming maleylacetate, we suggest that this enzyme acts on 4-chloromuconolactone as an intermediate in the muconate cycloisomerase-catalyzed transformation of 3-chloromuconate, thus preventing protoanemonin formation and favoring maleylacetate formation. The maleylacetate formed in this way is reduced by maleylacetate reductase. Chlorosalicylate degradation in MT1 thus occurs by a new pathway consisting of a patchwork of reactions catalyzed by enzymes from the 3-oxoadipate pathway (catechol 1,2-dioxygenase, muconate cycloisomerase) and the chlorocatechol pathway (maleylacetate reductase) and a trans-DLH.
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ISSN:0021-9193
DOI:10.1128/JB.185.23.6790-6800.2003