Dataset Information

Theoretical Study of O2 Reduction and Water Oxidation in Multicopper Oxidases.

ABSTRACT: Recent electrochemical experiments have shown that the reduction of O2 can be driven backward to water oxidation, which is the first case that has been successfully demonstrated for an enzyme. To understand this ability of the enzyme, both the forward reduction and backward oxidation have been studied here. For the forward reaction, a mechanism similar to earlier studies was obtained. All steps of the full catalytic cycle were obtained for the first time, and it was shown that the explicit reduction steps contribute significantly to the rate-limiting step of the O-O bond cleavage. For the backward oxidation reaction, it was found that the mechanism of the O-O bond formation is not just the reverse of the reduction step where the O-O bond is cleaved for a protonated peroxide. The formation of two fully deprotonated oxo groups was found to be important, which leads to a large radical character for one of the oxo groups. For this possibility, it is important that the pKa of the water bound to the cofactor is quite high.

SUBMITTER: Siegbahn PEM

PROVIDER: S-EPMC7467714 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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Theoretical Study of O<sub>2</sub> Reduction and Water Oxidation in Multicopper Oxidases.

Siegbahn Per E M PEM

The journal of physical chemistry. A 20200706 28

Recent electrochemical experiments have shown that the reduction of O<sub>2</sub> can be driven backward to water oxidation, which is the first case that has been successfully demonstrated for an enzyme. To understand this ability of the enzyme, both the forward reduction and backward oxidation have been studied here. For the forward reaction, a mechanism similar to earlier studies was obtained. All steps of the full catalytic cycle were obtained for the first time, and it was shown that the exp ...[more]

PMID: 32579359

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Project description:BackgroundCylindrospermopsin is a highly persistent cyanobacterial secondary metabolite toxic to humans and other living organisms. Strain OF001 and A210 are manganese-oxidizing bacteria (MOB) able to transform cylindrospermopsin during the oxidation of Mn2+. So far, the enzymes involved in manganese oxidation in strain OF001 and A210 are unknown. Therefore, we analyze the genomes of two cylindrospermopsin-transforming MOB, Pseudomonas sp. OF001 and Rubrivivax sp. A210, to identify enzymes that could catalyze the oxidation of Mn2+. We also investigated specific metabolic features related to pollutant degradation and explored the metabolic potential of these two MOB with respect to the role they may play in biotechnological applications and/or in the environment.ResultsStrain OF001 encodes two multicopper oxidases and one haem peroxidase potentially involved in Mn2+ oxidation, with a high similarity to manganese-oxidizing enzymes described for Pseudomonas putida GB-1 (80, 83 and 42% respectively). Strain A210 encodes one multicopper oxidase potentially involved in Mn2+ oxidation, with a high similarity (59%) to the manganese-oxidizing multicopper oxidase in Leptothrix discophora SS-1. Strain OF001 and A210 have genes that might confer them the ability to remove aromatic compounds via the catechol meta- and ortho-cleavage pathway, respectively. Based on the genomic content, both strains may grow over a wide range of O2 concentrations, including microaerophilic conditions, fix nitrogen, and reduce nitrate and sulfate in an assimilatory fashion. Moreover, the strain A210 encodes genes which may convey the ability to reduce nitrate in a dissimilatory manner, and fix carbon via the Calvin cycle. Both MOB encode CRISPR-Cas systems, several predicted genomic islands, and phage proteins, which likely contribute to their genome plasticity.ConclusionsThe genomes of Pseudomonas sp. OF001 and Rubrivivax sp. A210 encode sequences with high similarity to already described MCOs which may catalyze manganese oxidation required for cylindrospermopsin transformation. Furthermore, the analysis of the general metabolism of two MOB strains may contribute to a better understanding of the niches of cylindrospermopsin-removing MOB in natural habitats and their implementation in biotechnological applications to treat water.

Dataset Information

Theoretical Study of O2 Reduction and Water Oxidation in Multicopper Oxidases.

Publications

Theoretical Study of O<sub>2</sub> Reduction and Water Oxidation in Multicopper Oxidases.

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