Dehalogenimonas sp. Strain WBC-2 Genome and Identification of Its trans -Dichloroethene Reductive Dehalogenase, TdrA

TheDehalogenimonas population in a dechlorinating enrichment culture referred to as WBC-2 was previously shown to be responsible fortrans -dichloroethene (tDCE) hydrogenolysis to vinyl chloride (VC). In this study, blue native polyacrylamide gel electrophoresis (BN-PAGE) followed by enzymatic assays and protein identification using liquid chromatography coupled with mass spectrometry (LC-MS/MS) led to the functional characterization of a novel dehalogenase, TdrA. This new reductive dehalogenase (RDase) catalyzes the dechlorination of tDCE to VC. A metagenome of the WBC-2 culture was sequenced, and a completeDehalogenimonas genome, only the secondDehalogenimonas genome to become publicly available, was closed. ThetdrA dehalogenase found within theDehalogenimonas genome appears to be on a genomic island similar to genomic islands found inDehalococcoides . TdrA itself is most similar to TceA fromDehalococcoides sp. strain FL2 with 76.4% amino acid pairwise identity. It is likely that the horizontal transfer ofrdhA genes is not only a feature ofDehalococcoides but also a feature of otherDehalococcoidia , includingDehalogenimonas. A set of primers was developed to tracktdrA in WBC-2 subcultures maintained on different electron acceptors. This newest dehalogenase is an addition to the short list of functionally defined RDases sharing the usual characteristic motifs (including an AB operon, a TAT export sequence, two iron-sulfur clusters, and a corrinoid binding domain), substrate flexibility, and evidence for horizontal gene transfer within theDehalococcoidia .