Reduction of Selenite to Elemental Red Selenium by Pseudomonas sp. Strain CA5

Hunter, William J.; Manter, Daniel K.

doi:10.1007/s00284-009-9358-2

Cited by 97 publications

(63 citation statements)

References 33 publications

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“…Whereas, protein presented in the redox system could affect the aggregation of red elemental Se and the size of red elemental Se formed was dependent on the amount of protein in the redox system as reviewed by El-Ramady et al ( 2015b ). Furthermore, Se 0 has a very low biological availability and therefore a low toxicity (Hunter and Manter 2009 ).…”

Section: Red Elemental Selenium Nanoparticles In Higher Plantsmentioning

confidence: 98%

“…It is found that, Se-tolerant diamond back moth feed on S. pinnata containing 0.2 % Se dry weight without ill effects and it accumulated MeSeCys, like its host, explaining its tolerance. Mechanisms of Se-tolerant microbes include: Se reduction to insoluble, non-toxic elemental Se (Se 0 ), volatilization, or conversion to MeSe-Cys (Hunter and Manter 2009 ). Whereas, some plant-associated microbes have been shown to affect plant Se accumulation and volatilization (de Souza et al 1998 ).…”

Section: Selenium Hyperaccumulator Plantsmentioning

confidence: 99%

See 1 more Smart Citation

Selenium and its Role in Higher Plants

El-Ramady¹,

Abdalla²,

Alshaal³

et al. 2015

Pollutants in Buildings, Water and Living Organisms

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Section: Red Elemental Selenium Nanoparticles In Higher Plantsmentioning

confidence: 98%

Section: Selenium Hyperaccumulator Plantsmentioning

confidence: 99%

Selenium and its Role in Higher Plants

El-Ramady¹,

Abdalla²,

Alshaal³

et al. 2015

Pollutants in Buildings, Water and Living Organisms

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“…GSHR was responsible for reducing selenite and tellurite to insoluble NP's using the O-2 strain of Pseudomonas maltophilia; 39 GSHR and thioredoxin reductase are responsible for selenite and selenate reduction in Pseudomonas seleniipraecipitansI. [40][41][42][43] The highly conserved sequence across species within the Pseudomonas genus, including conservation in the product/substrate binding pocket, is suggestive that the ability to handle normally toxic amounts of SeO 3 2-may be a general feature of the Pseudomonas genus. This Se tolerance may arise from the nature of GSHRs in this genus.…”

Section: Resultsmentioning

confidence: 99%

The Metalloid Reductase of Pseudomonas Moravenis Stanleyae Conveys Nanoparticle Mediated Metalloid Tolerance

Nemeth

Neubert²,

Ni³

et al. 2018

Preprint

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When cultured independently in liquid media, it tolerates SeO 3 2-supplementation in liquid culture up to 10mM. This is 10-fold more than the SeO 3 2-tolerance of most other microbes. We attributed the observed selenite reduction activity of P. moravenis to a GSHR-like enzyme on the basis of proteomic mass spectrometry of an in-gel in situ selenium reductase activity.GSHRs generally belong to the family of pyridine nucleoside dependent oxidoreductases.This enzyme family also, notably, includes another well-characterized metal reducing enzyme -- 4In prior study, we characterized commercially sourced Saccharomyces Cervisiae (S. Cervisiae) GSHR for selenite reductase activity, showing the ability of the enzyme to oxidize NADPH while reducing SeO 3 2-to Se(0) nanoparticles. 13 In the present study, we characterize a homologous metalloid reductase from the seleno-specialist P. moravenis. We find that the substrate selectivity of the metalloid reductase (K M ) shows a substantially larger preference for GS-Se-SG relative to all other reported glutathione reductase enzymes. These enzymatic properties can be partially rationalized in terms of sequence and corresponding homologymodeled structure of the enzyme. We also observe that expressing this enzyme in laboratory strains of E. Coli (BL21, SS320) results in increased tolerance to SeO 3 2-, as well as the presence of Se nanoparticles in these cells. Overall, our data suggests that the enzyme may be best described as a glutathione reductase-like-metalloid reductase (GRLMR). RESULTS AND DISCUSSIONAltered substrate specificity of GRLMR enzymes, favoring selenodiglutathione (GS-Se-SG) over oxidized glutathione (GSSG) as a substrate could underlie the remarkable SeO 3 2-tolerance of P. Moravenis stanleyae. We therefore characterized the P. Moravenis stanleyae GRLMR enzyme identified previously. The DNA sequence of the enzyme was acquired through a fullgenome sequencing (ACGT Inc,Wheeling, IL). Sequencing was conducted using de novo paired end sequencing. 21 This revealed a genome where 70.3% of the nucleobases have, at the most, a 1:1000 probability of mis-assignment. Figure S1 shows the "Quality Score" (Q score) for each sequenced base with Q=-log10(e). Q scores, are derived from a phred-like error probability assessment of each individual nucleotide. 5A BLAST search of the genomic sequence, using the Pseudomonas R-28S GSHR as a reference, identified one GSHR-like sequence, with 93% sequence homology. Sequence alignment of this GRLMR DNA using Serial Cloner show high similarity (98.00%) toPseudomonas fluorescines (P. fluorescines) GSHR and modest similarity (67 -71%) to E. coli, S. cervisiae, and Homo sapiens (H. sapiens) GSHR DNA. The sequence similarities are summarized in Table 1, and full alignments are shown in the supporting information, Figure S2.The DNA sequence, combined with homology modeling of the structure suggest that all of the

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“…The strain is resistant to selenite at high concentrations (Ͼ150 mM). Two activities capable of reducing selenate were detected by zymography, one of which may correspond to nitrate reductase (70). Analyses of fractions from this strain indicate the presence of two reductases that can reduce SeO 3 2Ϫ to Se 0 in the presence of NADPH and that (based upon proteomics analysis of mixed protein samples) may correspond to glutathione reductase and thioredoxin reductase, both of which are able to reduce SeO 3 2Ϫ to Se 0 when derived from other sources (71).…”

Section: ϫmentioning

confidence: 99%

Microbial Transformations of Selenium Species of Relevance to Bioremediation

Eswayah

Smith

Gardiner

2016

Appl Environ Microbiol

167

102

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b Selenium species, particularly the oxyanions selenite (SeO 3 2؊ ) and selenate (SeO 4 2؊ ), are significant pollutants in the environment that leach from rocks and are released by anthropogenic activities. Selenium is also an essential micronutrient for organisms across the tree of life, including microorganisms and human beings, particularly because of its presence in the 21st genetically encoded amino acid, selenocysteine. Environmental microorganisms are known to be capable of a range of transformations of selenium species, including reduction, methylation, oxidation, and demethylation. Assimilatory reduction of selenium species is necessary for the synthesis of selenoproteins. Dissimilatory reduction of selenate is known to support the anaerobic respiration of a number of microorganisms, and the dissimilatory reduction of soluble selenate and selenite to nanoparticulate elemental selenium greatly reduces the toxicity and bioavailability of selenium and has a major role in bioremediation and potentially in the production of selenium nanospheres for technological applications. Also, microbial methylation after reduction of Se oxyanions is another potentially effective detoxification process if limitations with low reaction rates and capture of the volatile methylated selenium species can be overcome. This review discusses microbial transformations of different forms of Se in an environmental context, with special emphasis on bioremediation of Se pollution. Since the discovery in 1954 by Pinsent that the oxidation of formate by cell suspensions of Escherichia coli requires growth medium containing molybdate and selenite, there has been a growing interest in the biochemical role of selenium in microorganisms (1). Se is an essential component of selenoamino acids, such as selenomethionine and selenocysteine (the 21st proteinogenic amino acid), that occur in certain types of prokaryotic enzymes. Indeed, the requirement for selenite in E. coli growing on formate is linked to the fact that formate dehydrogenase contains selenocysteine. Other prokaryotic enzymes that contain selenocysteine include glycine reductase in several clostridia, formate dehydrogenases in diverse prokaryotes, including Salmonella, Clostridium, and Methanococcus, as well as hydrogenases in Methanococcus and other anaerobes. In addition, other bacterial Se-dependent enzymes, in which the selenium is part of the active site molybdenum-containing cofactor, include nicotinic acid dehydrogenase and xanthine dehydrogenase, which is present in certain clostridial species (2-4).Reactions that are involved in the cycling of Se in soil, including those influenced by microbes, are diagrammatically summarized in Fig. 1 2Ϫ and was spatially separated from sulfate reduction in the environment despite the presence of substantial concentrations of sulfate where it occurred. Thus, it can be concluded that Se and S have different reductive biogeochemical cycles and appear to involve distinct populations of microorganisms.With respect to the remediation of sel...

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Reduction of Selenite to Elemental Red Selenium by Pseudomonas sp. Strain CA5

Cited by 97 publications

References 33 publications

Selenium and its Role in Higher Plants

Selenium and its Role in Higher Plants

The Metalloid Reductase of Pseudomonas Moravenis Stanleyae Conveys Nanoparticle Mediated Metalloid Tolerance

Microbial Transformations of Selenium Species of Relevance to Bioremediation

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