Cellular Response of &lt;i&gt;Sinorhizobium&lt;/i&gt; sp. Strain A2 during Arsenite Oxidation

Fukushima, Kazuhiro; Huang, He; Hamamura, Natsuko

doi:10.1264/jsme2.me15096

Cited by 2 publications

(2 citation statements)

References 29 publications

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“…grown on acetate (49)(50)(51), it is possible that TCA cycle in the strain OR-1 is, at least in part, defective during As(V) respiration. In several bacteria, it is known that As(III) significantly inhibited the TCA cycle and resulted in a shift in carbon metabolism from the citric acid pathway to the glyoxylate pathway in order to compensate for the enzymes disrupted by As(III) (47,52,53). However, strain OR-1 lacks key enzymes of the glyoxylate pathway (isocitrate lyase and malate synthase) and is unable to bypass the TCA cycle for carrying out anaplerosis and gluconeogenesis.…”

Section: Resultsmentioning

confidence: 99%

Expression of Genes and Proteins Involved in Arsenic Respiration and Resistance in Dissimilatory Arsenate-Reducing Geobacter sp. Strain OR-1

Tsuchiya

Ehara

Kasahara

et al. 2019

Appl Environ Microbiol

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The reduction of arsenate [As(V)] to arsenite [As(III)] by dissimilatory As(V)-reducing bacteria, such as Geobacter spp., may play a significant role in arsenic release from anaerobic sediments into groundwater. The biochemical and molecular mechanisms by which these bacteria cope with this toxic element remain unclear. In this study, the expression of several genes involved in arsenic respiration (arr) and resistance (ars) was determined using Geobacter sp. strain OR-1, the only cultured Geobacter strain capable of As(V) respiration. In addition, proteins expressed differentially under As(V)-respiring conditions were identified by semiquantitative proteomic analysis. Dissimilatory As(V) reductase (Arr) of strain OR-1 was localized predominantly in the periplasmic space, and the transcription of its gene (arrA) was upregulated under As(V)-respiring conditions. The transcription of the detoxifying As(V) reductase gene (arsC) was also upregulated, but its induction required 500 times higher concentration of As(III) (500 M) than did the arrA gene. Comparative proteomic analysis revealed that in addition to the Arr and Ars proteins, proteins involved in the following processes were upregulated under As(V)-respiring conditions: (i) protein folding and assembly for rescue of proteins with oxidative damage, (ii) DNA replication and repair for restoration of DNA breaks, (iii) anaplerosis and gluconeogenesis for sustainable energy production and biomass formation, and (iv) protein and nucleotide synthesis for the replacement of damaged proteins and nucleotides. These results suggest that strain OR-1 copes with arsenic stress by orchestrating pleiotropic processes that enable this bacterium to resist and actively metabolize arsenic. IMPORTANCE Dissimilatory As(V)-reducing bacteria, such as Geobacter spp., play significant roles in arsenic release and contamination in groundwater and threaten the health of people worldwide. However, the biochemical and molecular mechanisms by which these bacteria cope with arsenic toxicity remain unclear. In this study, it was found that both respiratory and detoxifying As(V) reductases of a dissimilatory As(V)-reducing bacterium, Geobacter sp. strain OR-1, were upregulated under As(V)respiring conditions. In addition, various proteins expressed specifically or more abundantly in strain OR-1 under arsenic stress were identified. Strain OR-1 actively metabolizes arsenic while orchestrating various metabolic processes that repair oxidative damage caused by arsenic. Such information is useful in assessing and identifying possible countermeasures for the prevention of microbial arsenic release in nature.

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Section: Resultsmentioning

confidence: 99%

Expression of Genes and Proteins Involved in Arsenic Respiration and Resistance in Dissimilatory Arsenate-Reducing Geobacter sp. Strain OR-1

Tsuchiya

Ehara

Kasahara

et al. 2019

Appl Environ Microbiol

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“…Antimony toxicity is known to induce oxidative stress via a similar mechanism to that of As ( 2 , 16 ). Since As(III)-oxidizing bacteria are capable of tolerating As toxicity ( 14 ), they may also tolerate Sb toxicity using similar mechanisms. Indeed, the ars genes, coding for arsenic resistance, are also considered to be involved in antimony resistance ( 13 ).…”

Section: Resultsmentioning

confidence: 99%

Influence of the Chemical Form of Antimony on Soil Microbial Community Structure and Arsenite Oxidation Activity

Kataoka

Mitsunobu

Hamamura

2018

Microbes and environments

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In the present study, the influence of the co-contamination with various chemical forms of antimony (Sb) with arsenite (As[III]) on soil microbial communities was investigated. The oxidation of As(III) to As(V) was monitored in soil columns amended with As(III) and three different chemical forms of Sb: antimony potassium tartrate (Sb[III]-tar), antimony(III) oxide (Sb2O3), and potassium antimonate (Sb[V]). Soil microbial communities were examined qualitatively and quantitatively using 16S rDNA- and arsenite oxidase gene (aioA)-targeted analyses. Microbial As(III) oxidation was detected in all soil columns and 90–100% of added As(III) (200 μmol L−1) was oxidized to As(V) in 9 d, except in the Sb(III)-tar co-amendments that only oxidized 30%. 16S rDNA- and aioA-targeted analyses showed that the presence of different Sb chemical forms significantly affected the selection of distinct As(III)-oxidizing bacterial populations. Most of the 16S rRNA genes detected in soil columns belonged to Betaproteobacteria and Gammaproteobacteria, and some sequences were closely related to those of known As(III) oxidizers. Co-amendments with Sb(III)-tar and high concentrations of Sb2O3 significantly increased the ratios of aioA-possessing bacterial populations, indicating the enrichment of As(III) oxidizers resistant to As and Sb toxicity. Under Sb co-amendment conditions, there was no correlation between aioA gene abundance and the rates of As(III) oxidation. Collectively, these results demonstrated that the presence of different Sb chemical forms imposed a strong selective pressure on the soil bacterial community and, thus, the co-existing metalloid is an important factor affecting the redox transformation of arsenic in natural environments.

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Cellular Response of <i>Sinorhizobium</i> sp. Strain A2 during Arsenite Oxidation

Cited by 2 publications

References 29 publications

Expression of Genes and Proteins Involved in Arsenic Respiration and Resistance in Dissimilatory Arsenate-Reducing Geobacter sp. Strain OR-1

Expression of Genes and Proteins Involved in Arsenic Respiration and Resistance in Dissimilatory Arsenate-Reducing Geobacter sp. Strain OR-1

Influence of the Chemical Form of Antimony on Soil Microbial Community Structure and Arsenite Oxidation Activity

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