The Molecular Geomicrobiology of Bacterial Manganese(II) Oxidation

Tebo, Bradley M.; Geszvain, Kati; Lee, Sung Woo

doi:10.1007/978-90-481-9204-5_13

Cited by 60 publications

(26 citation statements)

References 120 publications

(154 reference statements)

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“…Mn(II) oxidation occurs on the outside surface of the cell, coating the cell with Mn oxides (8). The Mn(II) oxidase enzymes that have been identified so far are found loosely bound to the exosporium (40) or the outer membrane (15) or are secreted from the cell into the culture milieu (17).…”

Section: Discussionmentioning

confidence: 99%

“…The ability to form Mn(III, IV) minerals through the oxidation of Mn(II) is found in a diverse array of bacteria, including Grampositive and Gram-negative species, and can be found in many environments, including deep-sea vents, freshwater lakes, rivers, and soil (8,9). There are, however, common themes among Mn(II)-oxidizing bacteria.…”

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confidence: 99%

“…The Mn(II) oxidase activity is localized to the outer surface of the cell, for example, the exosporium of Bacillus sp. SG-1 or the sheath of Leptothrix discophora SS-1 (8). As a consequence, the cells become covered in Mn minerals.…”

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confidence: 99%

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Identification of a Third Mn(II) Oxidase Enzyme in Pseudomonas putida GB-1

Geszvain

Smesrud

Tebo

2016

Appl Environ Microbiol

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The oxidation of soluble Mn(II) to insoluble Mn(IV) is a widespread bacterial activity found in a diverse array of microbes. In the Mn(II)-oxidizing bacterium Pseudomonas putida GB-1, two Mn(II) oxidase genes, named mnxG and mcoA, were previously identified; each encodes a multicopper oxidase (MCO)-type enzyme. Expression of these two genes is positively regulated by the response regulator MnxR. Preliminary investigation into putative additional regulatory pathways suggested that the flagellar regulators FleN and FleQ also regulate Mn(II) oxidase activity; however, it also revealed the presence of a third, previously uncharacterized Mn(II) oxidase activity in P. putida GB-1. A strain from which both of the Mn(II) oxidase genes and fleQ were deleted exhibited low levels of Mn(II) oxidase activity. The enzyme responsible was genetically and biochemically identified as an animal heme peroxidase (AHP) with domain and sequence similarity to the previously identified Mn(II) oxidase MopA. In the ⌬fleQ strain, P. putida GB-1 MopA is overexpressed and secreted from the cell, where it actively oxidizes Mn. Thus, deletion of fleQ unmasked a third Mn(II) oxidase activity in this strain. These results provide an example of an Mn(II)-oxidizing bacterium utilizing both MCO and AHP enzymes. IMPORTANCEThe identity of the Mn(II) oxidase enzyme in Pseudomonas putida GB-1 has been a long-standing question in the field of bacterial Mn(II) oxidation. In the current work, we demonstrate that P. putida GB-1 employs both the multicopper oxidase-and animal heme peroxidase-mediated pathways for the oxidation of Mn(II), rendering this model organism relevant to the study of both types of Mn(II) oxidase enzymes. The presence of three oxidase enzymes in P. putida GB-1 deepens the mystery of why microorganisms oxidize Mn(II) while providing the field with the tools necessary to address this question. The initial identification of MopA as a Mn(II) oxidase in this strain required the deletion of FleQ, a regulator involved in both flagellum synthesis and biofilm synthesis in Pseudomonas aeruginosa. Therefore, these results are also an important step toward understanding the regulation of Mn(II) oxidation.

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Section: Discussionmentioning

confidence: 99%

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Identification of a Third Mn(II) Oxidase Enzyme in Pseudomonas putida GB-1

Geszvain

Smesrud

Tebo

2016

Appl Environ Microbiol

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“…3). Because Mn(II) oxidation occurs in stationary phase (7,44), one explanation for this delay in oxidation could be delayed entry into stationary phase. However, growth curves obtained with cultures in liquid media indicated that both single mutants and the ⌬mcoA ⌬mnxG double mutant entered stationary phase at the same time as the wild type (data not shown).…”

Section: Discussionmentioning

confidence: 99%

“…Other fungi may produce a Mn(IV) oxide (4)(5)(6). In bacteria, Mn(II) oxidation leads primarily to the formation of Mn(IV) oxides, the function and benefit of which remain speculative (7).…”

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Elimination of Manganese(II,III) Oxidation in Pseudomonas putida GB-1 by a Double Knockout of Two Putative Multicopper Oxidase Genes

Geszvain

McCarthy

Tebo

2013

Appl Environ Microbiol

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bBacterial manganese(II) oxidation impacts the redox cycling of Mn, other elements, and compounds in the environment; therefore, it is important to understand the mechanisms of and enzymes responsible for Mn(II) oxidation. In several Mn(II)-oxidizing organisms, the identified Mn(II) oxidase belongs to either the multicopper oxidase (MCO) or the heme peroxidase family of proteins. However, the identity of the oxidase in Pseudomonas putida GB-1 has long remained unknown. To identify the P. putida GB-1 oxidase, we searched its genome and found several homologues of known or suspected Mn(II) oxidase-encoding genes (mnxG, mofA, moxA, and mopA). To narrow this list, we assumed that the Mn(II) oxidase gene would be conserved among Mn(II)-oxidizing pseudomonads but not in nonoxidizers and performed a genome comparison to 11 Pseudomonas species. We further assumed that the oxidase gene would be regulated by MnxR, a transcription factor required for Mn(II) oxidation. Two loci met all these criteria: PputGB1_2447, which encodes an MCO homologous to MnxG, and PputGB1_2665, which encodes an MCO with very low homology to MofA. In-frame deletions of each locus resulted in strains that retained some ability to oxidize Mn(II) or Mn(III); loss of oxidation was attained only upon deletion of both genes. These results suggest that PputGB1_2447 and PputGB1_2665 encode two MCOs that are independently capable of oxidizing both Mn(II) and Mn(III). The purpose of this redundancy is unclear; however, differences in oxidation phenotype for the single mutants suggest specialization in function for the two enzymes.

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Control of particulate manganese (Mn) cycling in halocline Arctic Ocean waters by putative Mn‐oxidizing bacterial dynamics

Colombo

LaRoche

Desai

et al. 2023

Limnology & Oceanography

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Particulate Mn, given its high adsorptive capacity and oxidation potential, has profound impacts on the cycling of various trace elements and organic matter in the ocean. Moreover, particulate Mn acts as a sink (via oxidation and adsorption) or as a source (via remineralization and photoreduction) term of bioactive dissolved Mn(II). In the Canadian Arctic Ocean, particulate Mn distributions in the water column revealed the presence of distinctively high particulate Mn concentrations and an overwhelming dominance of the non‐lithogenic component to the bulk particulate Mn pool. This phenomenon is of particular importance in halocline waters in the Canada Basin, the Canadian Arctic Archipelago and Baffin Bay, and near‐bottom samples in Baffin Bay. Enhanced microbially‐mediated Mn oxidation in the water column is suggested as the main mechanism driving the non‐lithogenic dominance. Indeed, the microbial community composition data associated with high non‐lithogenic particulate Mn (i.e., Mn oxides) display a high relative abundance of taxa (e.g., f.Pirellulaceae, o.Phycisphaerales, f.Cryomorphaceae, g. Moritella) that have been identified in Mn oxide enriched environments. Furthermore, numerous taxa identified in the Canada Basin halocline water, where non‐lithogenic particulate Mn peaked, are phylogenetically related to known (cultured) Mn‐oxidizing bacteria (MnOB; e.g., Rhodobacteraceae, Oceanospirillaceae, Rhizobiaceae, and other Alphaproteobacteria). Putative MnOB appears to proliferate in certain water masses having a unique set of environmental conditions: low light intensity—alleviating photoinhibition—and high dissolved Mn concentrations, the main drivers known to influence MnOB dynamic, and hence, Mn oxidation.

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The Molecular Geomicrobiology of Bacterial Manganese(II) Oxidation

Cited by 60 publications

References 120 publications

Identification of a Third Mn(II) Oxidase Enzyme in Pseudomonas putida GB-1

Identification of a Third Mn(II) Oxidase Enzyme in Pseudomonas putida GB-1

Elimination of Manganese(II,III) Oxidation in Pseudomonas putida GB-1 by a Double Knockout of Two Putative Multicopper Oxidase Genes

Control of particulate manganese (Mn) cycling in halocline Arctic Ocean waters by putative Mn‐oxidizing bacterial dynamics

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