Mechanism of Reduction of Aqueous U(V)-dpaea and Solid-Phase U(VI)-dpaea Complexes: The Role of Multiheme c -Type Cytochromes
| Autor: | Molinas, Margaux, Lederballe Meibom, Karin, Faizova, Radmila, Mazzanti, Marinella, Bernier-Latmani, Rizlan |
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| Jazyk: | angličtina |
| Předmět: | |
| Zdroj: | Environmental Science & Technology. 57(19):7537-7546 |
| ISSN: | 1520-5851 0013-936X |
| DOI: | 10.1021/acs.est.3c00666 |
| Popis: | The biological reduction of soluble U(VI) complexes to form immobile U(IV) species has been proposed to remediate contaminated sites. It is well established that multiheme c-type cytochromes (MHCs) are key mediators of electron transfer to aqueous phase U(VI) complexes for bacteria such as Shewanella oneidensis MR-1. Recent studies have confirmed that the reduction proceeds via a first electron transfer forming pentavalent U(V) species that readily disproportionate. However, in the presence of the stabilizing aminocarboxylate ligand, dpaea2– (dpaeaH2═bis(pyridyl-6-methyl-2-carboxylate)-ethylamine), biologically produced U(V) persisted in aqueous solution at pH 7. We aim to pinpoint the role of MHC in the reduction of U(V)-dpaea and to establish the mechanism of solid-phase U(VI)-dpaea reduction. To that end, we investigated U-dpaea reduction by two deletion mutants of S. oneidensis MR-1–one lacking outer membrane MHCs and the other lacking all outer membrane MHCs and a transmembrane MHC–and by the purified outer membrane MHC, MtrC. Our results suggest that solid-phase U(VI)-dpaea is reduced primarily by outer membrane MHCs. Additionally, MtrC can directly transfer electrons to U(V)-dpaea to form U(IV) species but is not strictly necessary, underscoring the primary involvement of outer membrane MHCs in the reduction of this pentavalent U species but not excluding that of periplasmic MHCs. |
| Databáze: | OpenAIRE |
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