Multiple reductive-dehalogenase-homologous genes are simultaneously transcribed during dechlorination by Dehalococcoides-containing cultures.
Degenerate primers were used to amplify 14 distinct reductive-dehalogenase-homologous (RDH) genes from the Dehalococcoides-containing mixed culture KB1. Most of the corresponding predicted proteins were highly similar (97 to >99% amino acid identity) to previously reported Dehalococcoides reductive dehalogenases. To examine the differential transcription of these RDH genes, KB1 was split into five subcultures amended with either trichloroethene, cis-1,2-dichloroethene, vinyl chloride, 1,2-dichlorethane, or no chlorinated electron acceptor. Total RNA was extracted following the onset of reductive dechlorination, and RDH transcripts were reverse transcribed and amplified using degenerate primers. The results indicate that the transcription of RDH genes requires the presence of a chlorinated electron acceptor, and for all treatments, multiple RDH genes were simultaneously transcribed, with transcripts of two of the genes being present under all four electron-accepting conditions. Two of the transcribed sequences were highly similar to reported vinyl chloride reductase genes, namely, vcrA from Dehalococcoides sp. strain VS and bvcA from Dehalococcoides sp. strain BAV1. These findings suggest that multiple RDH genes are induced by a single chlorinated substrate and that multiple reductive dehalogenases contribute to chloroethene degradation in KB1.
Waller
Alison S
AS
Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College St., Toronto, Ontario M5S 3E5, Canada.
Krajmalnik-Brown
Rosa
R
Löffler
Frank E
FE
Edwards
Elizabeth A
EA
D001483:Base Sequence; D002713:Chlorine / Q000378:metabolism*; D041862:Chloroflexi / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D003001:Cloning, Molecular; D017931:DNA Primers; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics*; D010802:Phylogeny; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
D017931:DNA Primers; D002713:Chlorine; D010088:Oxidoreductases