Dehalogenimonas sp. Strain WBC-2 Genome and Identification of Itstrans-Dichloroethene Reductive Dehalogenase, TdrA
ABSTRACTTheDehalogenimonaspopulation 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 completeDehalogenimonasgenome, only the secondDehalogenimonasgenome to become publicly available, was closed. ThetdrAdehalogenase found within theDehalogenimonasgenome appears to be on a genomic island similar to genomic islands found inDehalococcoides. TdrA itself is most similar to TceA fromDehalococcoidessp. strain FL2 with 76.4% amino acid pairwise identity. It is likely that the horizontal transfer ofrdhAgenes is not only a feature ofDehalococcoidesbut also a feature of otherDehalococcoidia, includingDehalogenimonas.A set of primers was developed to tracktdrAin 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.