Trichloroethene reductive dehalogenase from Dehalococcoides ethenogenes : Sequence of tceA and substrate range characterization

• Published in: Applied and environmental microbiology 2000-12, Vol.66 (12), p.5141-5147
• Main Authors: MAGNUSON, Jon K, ROMINE, Margaret F, BURRIS, David R, KINGSLEY, Mark T
• Format: Article
• Language: English
• Subjects: 1,2-dibromoethane; 1,2-Dichloroethane; 2-dichloroethane; Amino Acid Sequence; Bacteria; Bacteria, Anaerobic - enzymology; Bacteria, Anaerobic - genetics; Base Sequence; Biodegradation, Environmental; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Cloning; Dehalococcoides ethenogenes; dehalorespiration; DNA Primers - genetics; Enzymes; Enzymology and Protein Engineering; ethene; Fundamental and applied biological sciences. Psychology; Genes; Genes, Bacterial; Hydrocarbons, Halogenated - metabolism; Hydrolases - genetics; Hydrolases - metabolism; Membranes - enzymology; Microbiology; Miscellaneous; Mission oriented research; Molecular Sequence Data; Oxidoreductases; Sequence Homology, Amino Acid; Substrate Specificity; tceA gene; tceB gene; tetrachloroethene; trichloroethene; trichloroethene reductive dehalogenase
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.66.12.5141-5147.2000

The anaerobic bacterium Dehalococcoides ethenogenes is the only known organism that can completely dechlorinate tetrachloroethene or trichloroethene (TCE) to ethene via dehalorespiration. One of two corrinoid-containing enzymes responsible for this pathway, TCE reductive dehalogenase (TCE-RDase) catalyzes the dechlorination of TCE to ethene. TCE-RDase dehalogenated 1,2-dichloroethane and 1, 2-dibromoethane to ethene at rates of 7.5 and 30 micromol/min/mg, respectively, similar to the rates for TCE, cis-dichloroethene (DCE), and 1,1-DCE. A variety of other haloalkanes and haloalkenes containing three to five carbon atoms were dehalogenated at lower rates. The gene encoding TCE-RDase, tceA, was cloned and sequenced via an inverse PCR approach. Sequence comparisons of tceA to proteins in the public databases revealed weak sequence similarity confined to the C-terminal region, which contains the eight-iron ferredoxin cluster binding motif, (CXXCXXCXXXCP)(2). Direct N-terminal sequencing of the mature enzyme indicated that the first 42 amino acids constitute a signal sequence containing the twin-arginine motif, RRXFXK, associated with the Sec-independent membrane translocation system. This information coupled with membrane localization studies indicated that TCE-RDase is located on the exterior of the cytoplasmic membrane. Like the case for the two other RDases that have been cloned and sequenced, a small open reading frame, tceB, is proposed to be involved with membrane association of TCE-RDase and is predicted to be cotranscribed with tceA.