Reductive dehalogenases
Reductive dehaholagenses (EC 1.97.1.8) are a group of enzymes utilized in organohalide respiring bacteria.[1][2] These enzymes are mostly attached to the periplasmic side of the cytoplasmic membrane and play a central role in energy-conserving respiratory process for organohalide respiring bacteria by reducing organohalides. During such reductive dehalogenation reaction, organohalides are used as terminal electron acceptors. They catalyze the following general reactions:
- R-X + 2 e− + 2 H+ → R-H + H-X
- X-RR-X + 2 e− + 2 H+ → R=R + 2X−
These membrane-associated enzymes have attracted great interest for the detoxification of organohalide pollutants. Organohalide pollution is a serious global environmental issue affecting soil and groundwater; and reductive dehalogenases offer a promising natural tool for bioremediation.
Structure and mechanism
[edit]Reductive dehalogenases are related to the cobamide (or vitamin B12) family of enzymes. They contain a cobalamin at its catalytic active site, where actual reductive reaction occurs. They also harbor iron− sulfur clusters that supply the reducing equivalents.[1][3] All membrane-associated dehalogenases harbor a N-terminal twin-arginine (TAT) signal sequence (RRXFXK), which is a conserved signal peptide for membrane protein translocation. Monomeric as well as dimeric forms were previously reported.
Enzymatic mechanism is still understudied; however, several studies reported various mechanisms involving an organocobalt adduct, a single-electron transfer, and a halogen–cobalt bond.[1]
Common reductive dehalogenases studied
[edit]Reductive dehalogenases from Dehalobacter species
[edit]- Chloroform reductive dehalogenases: TmrA[4][5] and CfrA[6]
Reductive dehalogenases from Dehalococcoides species
[edit]- Vinyl chloride reducing VcrA[7]
- Hexachlorobenzene degrading CbrA[8]
Reductive dehalogenases from Desulfitobacterium species
[edit]- Perchloroethene and trichloroethene degrading PceA[9]
Production methods
[edit]Native enzymes
[edit]The examples are those that can dechlorinate chloroform (TmrA), PCE (PceA), TCE (TceA), and VC (VcrA).[2] Purification of such enzymes in native forms are reportedly difficult; however, a few such enzymes were purified to near homogeneity.[10][11] Ultracentrifugation, membrane solubilization and a series of liquid chromatography are the commonly employed techniques to the isolation and purification. A chloroform reducing dehalogenase is the latest reductive dehalogenase that was successfully produced and purified.[4]
Heterologous expressions
[edit]The researchers in the field had turned their interest to heterologous expression of the same enzymes due to difficulties in obtaining these enzymes in the native form. Only have recently a few recombinant reductive dehalogenases been functionally expressed, bringing the dehalogenase research into next levels.[12][7][3][5] Those successful efforts facilitate further investigations on their biochemical and structural properties.
The first membrane-associated respiratory reductive dehalogenase was heterologously expressed in a soluble and active form and purified using Bacillus megaterium.[5]
Uses in bioremediation
[edit]In recent years, research on reductive dehalogenases have attracted great interest from both academic and industrial researchers for their potential application in bioremediation of organohalide contamination.
References
[edit]- ^ a b c Jugder, Bat-Erdene; Ertan, Haluk; Lee, Matthew; Manefield, Michael; Marquis, Christopher P. (2015). "Reductive Dehalogenases Come of Age in Biological Destruction of Organohalides". Trends in Biotechnology. 33 (10): 595–610. doi:10.1016/j.tibtech.2015.07.004. ISSN 0167-7799. PMID 26409778.
- ^ a b Jugder, Bat-Erdene; Ertan, Haluk; Bohl, Susanne; Lee, Matthew; Marquis, Christopher P.; Manefield, Michael (2016). "Organohalide Respiring Bacteria and Reductive Dehalogenases: Key Tools in Organohalide Bioremediation". Frontiers in Microbiology. 7: 249. doi:10.3389/fmicb.2016.00249. ISSN 1664-302X. PMC 4771760. PMID 26973626.
- ^ a b Quezada, C.P.; Payne, K.A.P.; Leys, D. (2014). "Reductive dehalogenase structure suggests a mechanism for B12-dependent dehalogenation". Nature. 517 (7535): 513–516. doi:10.1038/nature13901. PMC 4968649. PMID 25327251.
- ^ a b Jugder, Bat-Erdene; Bohl, Susanne; Lebhar, Helene; Healey, Robert D.; Manefield, Mike; Marquis, Christopher P.; Lee, Matthew (2017-06-20). "A bacterial chloroform reductive dehalogenase: purification and biochemical characterization". Microbial Biotechnology. 10 (6): 1640–1648. doi:10.1111/1751-7915.12745. ISSN 1751-7915. PMC 5658581. PMID 28631300.
- ^ a b c Jugder, Bat-Erdene; Payne, Karl A. P.; Fisher, Karl; Bohl, Susanne; Lebhar, Helene; Manefield, Mike; Lee, Matthew; Leys, David; Marquis, Christopher P. (2018-01-24). "Heterologous Production and Purification of a Functional Chloroform Reductive Dehalogenase". ACS Chemical Biology. 13 (3): 548–552. doi:10.1021/acschembio.7b00846. ISSN 1554-8929. PMID 29363941.
- ^ Tang, S.; Edwards, E. A. (2013-03-11). "Identification of Dehalobacter reductive dehalogenases that catalyse dechlorination of chloroform, 1,1,1-trichloroethane and 1,1-dichloroethane". Philosophical Transactions of the Royal Society B: Biological Sciences. 368 (1616): 20120318. doi:10.1098/rstb.2012.0318. ISSN 0962-8436. PMC 3638459. PMID 23479748.
- ^ a b Parthasarathy, Anutthaman; Stich, Troy A.; Lohner, Svenja T.; Lesnefsky, Ann; Britt, R. David; Spormann, Alfred M. (2015-03-04). "Biochemical and EPR-Spectroscopic Investigation into Heterologously Expressed Vinyl Chloride Reductive Dehalogenase (VcrA) from Dehalococcoides mccartyi Strain VS". Journal of the American Chemical Society. 137 (10): 3525–3532. doi:10.1021/ja511653d. ISSN 0002-7863. PMC 4516053. PMID 25686300.
- ^ Wagner, A. Segler, L. Kleinsteuber, S. Sawers, G. Smidt, H. Lechner, U. (2013). Regulation of reductive dehalogenase gene transcription in Dehalococcoides mccartyi. OCLC 1018969275.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Suyama, A.; Yamashita, M.; Yoshino, S.; Furukawa, K. (2002-07-01). "Molecular Characterization of the PceA Reductive Dehalogenase of Desulfitobacterium sp. Strain Y51". Journal of Bacteriology. 184 (13): 3419–3425. doi:10.1128/jb.184.13.3419-3425.2002. ISSN 0021-9193. PMC 135124. PMID 12057934.
- ^ Neumann, Anke; Wohlfarth, Gert; Diekert, Gabriele (1996-07-12). "Purification and Characterization of Tetrachloroethene Reductive Dehalogenase fromDehalospirillum multivorans". Journal of Biological Chemistry. 271 (28): 16515–16519. doi:10.1074/jbc.271.28.16515. ISSN 0021-9258. PMID 8663199.
- ^ Ni, S; Fredrickson, J K; Xun, L (1995). "Purification and characterization of a novel 3-chlorobenzoate-reductive dehalogenase from the cytoplasmic membrane of Desulfomonile tiedjei DCB-1". Journal of Bacteriology. 177 (17): 5135–5139. doi:10.1128/jb.177.17.5135-5139.1995. ISSN 0021-9193. PMC 177294. PMID 7665493.
- ^ Mac Nelly, Anita; Kai, Marco; Svatoš, Aleš; Diekert, Gabriele; Schubert, Torsten (2014-05-09). "Functional Heterologous Production of Reductive Dehalogenases from Desulfitobacterium hafniense Strains". Applied and Environmental Microbiology. 80 (14): 4313–4322. Bibcode:2014ApEnM..80.4313M. doi:10.1128/aem.00881-14. ISSN 0099-2240. PMC 4068680. PMID 24814779.