title: New bacterial pathway for 4- and 5-chlorosalicylate degradation via 4-chlorocatechol and maleylacetate in Pseudomonas sp. strain MT1.
abstract: 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.
authors: Department of Environmental Microbiology, GBF-German Research Center for Biotechnology, D-38124 Braunschweig, Germany.
authors: Patricia
authors: P
authors: Nikodem
authors: Volker
authors: V
authors: Hecht
authors: Michael
authors: M
authors: Schlömann
authors: Dietmar H
authors: DH
authors: Pieper
mesh_terms: D000595:Amino Acid Sequence; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism; D050548:Catechol 1,2-Dioxygenase; D002396:Catechols / Q000378:metabolism*; D049308:Dioxygenases; D005663:Furans / Q000032:analysis / Q000378:metabolism; D016680:Genome, Bacterial; D019753:Intramolecular Lyases / Q000378:metabolism; D008298:Maleates / Q000032:analysis / Q000378:metabolism*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism; D010105:Oxygenases / Q000378:metabolism; D011549:Pseudomonas / Q000235:genetics / Q000378:metabolism*; D012459:Salicylates / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D015262:Xenobiotics / Q000378:metabolism
chemical_list: D002396:Catechols; D005663:Furans; D008298:Maleates; D009097:Multienzyme Complexes; D012459:Salicylates; D015262:Xenobiotics; C011905:maleoylacetic acid; C479918:4-chlorosalicylic acid; C037354:protoanemonin; D010105:Oxygenases; D049308:Dioxygenases; D050548:Catechol 1,2-Dioxygenase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C021530:maleylacetate reductase; D002265:Carboxylic Ester Hydrolases; C046130:carboxymethylenebutenolidase; D019753:Intramolecular Lyases; C021811:muconate cycloisomerase; C038861:4-chlorocatechol; C015751:5-chlorosalicylic acid