5ma2
PCE reductive dehalogenase from S. multivorans in complex with 4-iodophenol
Structural highlights
FunctionPCEA_SULMU Catalyzes the reductive dechlorination of tetrachloroethene (PCE) to trichloroethene (TCE) and of trichloroethene to cis-1,2-dichloroethene (DCE) (PubMed:8663199, PubMed:11976751, PubMed:12420164, PubMed:24433392, PubMed:28671181). In addition, trans-1,3-dichloropropene, 1,1,3-trichloropropene and 2,3-dichloropropene are reduced to a mixture of mono-chloropropenes, 1,1-dichloropropene, and 2-chloropropene, respectively (PubMed:11976751). Is also able to convert brominated phenols such as 4-bromophenol (4-BP), 2,4-dibromophenol (2,4-DBP) and 2,4,6-tribromophenol (2,4,6-TBP) (PubMed:28671181). Utilizes formate or pyruvate as electron donors (PubMed:16802174, PubMed:24433392). Titanium(III) citrate could also serve as electron donor (PubMed:11976751). Reduced methyl viologen can act as the artificial electron donor (PubMed:8663199, PubMed:11976751, PubMed:12420164).[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedThe capacity of metal-containing porphyrinoids to mediate reductive dehalogenation is implemented in cobamide-containing reductive dehalogenases (RDases), which serve as terminal reductases in organohalide-respiring microbes. RDases allow for the exploitation of halogenated compounds as electron acceptors. Their reaction mechanism is under debate. Here we report on substrate-enzyme interactions in a tetrachloroethene RDase (PceA) that also converts aryl halides. The shape of PceA's highly apolar active site directs binding of bromophenols at some distance from the cobalt and with the hydroxyl substituent towards the metal. A close cobalt-substrate interaction is not observed by electron paramagnetic resonance spectroscopy. Nonetheless, a halogen substituent para to the hydroxyl group is reductively eliminated and the path of the leaving halide is traced in the structure. Based on these findings, an enzymatic mechanism relying on a long-range electron transfer is concluded, which is without parallel in vitamin B12-dependent biochemistry and represents an effective mode of RDase catalysis. Cobamide-mediated enzymatic reductive dehalogenation via long-range electron transfer.,Kunze C, Bommer M, Hagen WR, Uksa M, Dobbek H, Schubert T, Diekert G Nat Commun. 2017 Jul 3;8:15858. doi: 10.1038/ncomms15858. PMID:28671181[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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