title: Two distinct enzyme systems are responsible for tetrachloroethene and chlorophenol reductive dehalogenation in Desulfitobacterium strain PCE1.
abstract: Desulfitobacterium strain PCE1 is able to use tetrachloroethene and chloroaromatics as terminal electron acceptors for growth. Cell extracts of Desulfitobacterium strain PCE1 grown with tetrachloroethene as electron acceptor showed no dehalogenase activity with 3-chloro-4-hydroxyphenylacetate (Cl-OH-phenylacetate) and other ortho-chlorophenolic compounds in an in vitro assay. Extracts of cells that were grown with Cl-OH-phenylacetate as electron acceptor dechlorinated tetrachloroethene at 10% of the dechlorination rate of Cl-OH-phenylacetate. In both cell extracts dechlorination was inhibited by the addition of 1-iodopropane and dinitrogen oxide, inhibitors of cobalamin-containing enzymes. The enzymes responsible for tetrachloroethene and Cl-OH-phenylacetate dechlorination were partially purified. A 100-fold enriched fraction of chlorophenol reductive dehalogenase was obtained that mainly contained a protein with a subunit size of 48 kDa. The characteristics of this enzyme are similar to that of the chlorophenol reductive dehalogenase of D. dehalogenans. After partial purification of the tetrachloroethene reductive dehalogenase, a fraction was obtained that also contained a 48-kDa protein, but the N-terminal sequence showed no similarity with that of the chlorophenol reductive dehalogenase sequence or with the N-terminal amino acid sequence of tetra- and trichloroethene reductive dehalogenase of Desulfitobacterium strain TCE1. These results provide strong evidence that two different enzymes are responsible for tetrachloroethene and chlorophenol dechlorination in Desulfitobacterium strain PCE1. Furthermore, the characterization of partially purified tetrachloroethene reductive dehalogenase indicated that this enzyme is a novel type of reductive dehalogenase.
authors.affiliation: Laboratory of Microbiology, Wageningen University, Hesselink van Suchtelenweg 4, 6703 CT, Wageningen, The Netherlands.
authors.forename: B A
authors.initials: BA
authors.lastname: van de Pas
authors.forename: J
authors.initials: J
authors.lastname: Gerritse
authors.forename: W M
authors.initials: WM
authors.lastname: de Vos
authors.forename: G
authors.initials: G
authors.lastname: Schraa
authors.forename: A J
authors.initials: AJ
authors.lastname: Stams
mesh_terms: D000595:Amino Acid Sequence; D001421:Bacteria, Anaerobic / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000378:metabolism; D002733:Chlorophenols / Q000378:metabolism*; D003470:Culture Media; D005030:Ethylenes / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010088:Oxidoreductases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011407:Propane; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D002733:Chlorophenols; D003470:Culture Media; D005030:Ethylenes; C036216:ethylene; D010088:Oxidoreductases; C112990:tetrachloroethene dehalogenase; C098849:tetrachloroethene reductase; D011407:Propane