Exogenous 5, 6‐dimethylbenzimidazole caused production of a non‐functional tetrachloroethene reductive dehalogenase in Sulfurospirillum multivorans. (6th October 2013)

• Record Type: Journal Article
• Authors: Keller, Sebastian; Ruetz, Markus; Kunze, Cindy; Kräutler, Bernhard; Diekert, Gabriele; Schubert, Torsten
• Is Part Of: Environmental microbiology. Volume 16:Number 11(2014:Nov.)
• Page Start: 3361
• Page End: 3369
• Publication Date: 2013-10-06
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12268
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Corrinoid‐dependent reductive dehalogenation is mediated by phylogenetically diverse anaerobic bacteria that either synthesize corrinoids <italic>de novo</italic> or are dependent on corrinoid salvaging from the environment. The tetrachloroethene (PCE) reductive dehalogenase (PceA) of the Gram‐negative Epsilonproteobacterium <italic>Sulfurospirillum multivorans</italic> harbours a norpseudo‐B<sub>12</sub> as corrinoid cofactor. Norpseudo‐B<sub>12</sub> differs from coenzyme B<sub>12</sub> in the nucleotide loop structure. Adenine instead of 5, 6‐dimethylbenzimidazole (DMB) serves as lower ligand base of the central cobalt ion, and the nucleotide loop of norpseudo‐B<sub>12</sub> lacks a methyl group at position 176. In this study, <italic>S. multivorans</italic> was grown anaerobically with PCE in the presence of DMB. At a DMB concentration of 25 μM, the adenine moiety in the nucleotide loop of norpseudo‐B<sub>12</sub> was quantitatively replaced by DMB. The formation of the DMB‐containing nor‐B<sub>12</sub> severely affected PCE‐dependent growth and the PceA activity. In DMB‐treated cells processing of the cytoplasmic PceA precursor was impeded, a result pointing to retarded cofactor incorporation. PceA enriched from cells cultivated with DMB contained nor‐B<sub>12</sub>. Nor‐B<sub>12</sub> purified from cells grown in the presence of DMB mediated the abiotic reductive dehalogenation of trichloroacetate to dichloroacetate at a 25‐fold lower rate in comparison with norpseudo‐B<sub>12</sub>, a fact underpinning the relevance of norpseudo‐B<sub>12</sub> as efficient catalyst for reductive dehalogenation in general.</p> </abstract>