Cobamide-mediated enzymatic reductive dehalogenation via long-range electron transfer

Cindy Kunze, Martin Bommer, Wilfred R. Hagen, Marie Uksa, Holger Dobbek, Torsten Schubert, Gabriele Diekert

Research output: Contribution to journalArticleScientificpeer-review

28 Citations (Scopus)
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Abstract

The 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.

Original languageEnglish
Article number15858
Number of pages11
JournalNature Communications
Volume8
DOIs
Publication statusPublished - 3 Jul 2017

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