title: Tetrachloroethene reductive dehalogenase of Dehalospirillum multivorans: substrate specificity of the native enzyme and its corrinoid cofactor.
abstract: The substrate specificity of the tetrachloroethene reductive dehalogenase of Dehalospirillum multivoransand its corrinoid cofactor were studied. Besides reduced methyl viologen, titanium(III) citrate could serve as electron donor for reductive dehalogenation of tetrachloroethene (PCE) and trichloroethene to cis-1,2-dichloroethene. In addition to chlorinated ethenes, chlorinated propenes were reductively dechlorinated solely by the native enzyme. trans-1,3-Dichloropropene, 1,1,3-trichloropropene and 2,3-dichloropropene were reduced to a mixture of mono-chloropropenes, 1,1-dichloropropene, and 2-chloropropene, respectively. Other halogenated compounds that were rapidly reduced by the enzyme were also dehalogenated abiotically by the heat-inactivated enzyme and by commercially available cyanocobalamin. The rate of this abiotic reaction was dependent on the number and type of halogen substituents and on the type of catalyst. The corrinoid cofactor purified from the tetrachloroethene dehalogenase of D. multivorans exhibited an activity about 50-fold higher than that of cyanocobalamin (vitamin B(12)) with trichloroacetate as electron acceptor, indicating that the corrinoid cofactor of the PCE dehalogenase is not cyanocobalamin. Corrinoids catalyzed the rapid dehalogenation of trichloroacetic acid. The rate was proportional to the amount of, e.g. cyanocobalamin; therefore, the reductive dehalogenation assay can be used for the sensitive and rapid quantification of this cofactor.
authors.affiliation: Institut für Mikrobiologie, Lehrstuhl für Angewandte und Okologische Mikrobiologie, FSU Jena, Philosophenweg 12, 07743 Jena, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Neumann
authors.forename: Anke
authors.initials: A
authors.lastname: Siebert
authors.forename: Tina
authors.initials: T
authors.lastname: Trescher
authors.forename: Simone
authors.initials: S
authors.lastname: Reinhardt
authors.forename: Gert
authors.initials: G
authors.lastname: Wohlfarth
authors.forename: Gabriele
authors.initials: G
authors.lastname: Diekert
mesh_terms: D002384:Catalysis; D002713:Chlorine / Q000378:metabolism; D003067:Coenzymes / Q000378:metabolism*; D045728:Corrinoids; D006089:Gram-Negative Anaerobic Bacteria / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism*; D011166:Porphyrins / Q000378:metabolism*; D013379:Substrate Specificity; D013750:Tetrachloroethylene / Q000378:metabolism*
chemical_list: D003067:Coenzymes; D045728:Corrinoids; D011166:Porphyrins; D002713:Chlorine; D010088:Oxidoreductases; C112990:tetrachloroethene dehalogenase; D013750:Tetrachloroethylene