Phosphate transport and arsenate resistance in the cyanobacterium Anabaena variabilis

Thiel, Teresa

doi:10.1128/jb.170.3.1143-1147.1988

Cited by 71 publications

(48 citation statements)

References 26 publications

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“…However, elevated levels of Pi increased the uptake rate of phosphorus (p , 0.05) (Fig. 4B), which is inconsistent with the report of Thiel (1988), who found that cyanobacteria showed higher rates of phosphate uptake under phosphate-limited conditions. Previous data had indicated that Cylindrospermopsis raciborskii was opportunistic with respect to Pi (Istvá novics et al 2000) and had rapid DIC uptake and storage capacity (Posselt et al 2009).…”

Section: Discussioncontrasting

confidence: 56%

Combined effects of carbon and phosphorus levels on the invasive cyanobacterium, Cylindrospermopsis raciborskii

Zeng

et al. 2012

Phycologia

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The invasive cyanobacterium, Cylindrospermopsis raciborskii, was cultured semicontinuously for 18 days at different carbon and phosphorus levels. Growth and photosynthesis were measured to study the combined effects of CO 2 and phosphorus availabilities. The results showed that enrichment of CO 2 or inorganic phosphorus (Pi) levels in the culture medium significantly increased specific growth rate (m), light-saturated photosynthesis (P m ) and photosynthetic efficiency (a), but tended to decrease dark respiratory rate (R d ), saturating irradiance for photosynthesis (E k ) and the light compensation point (E c ). However, photosynthetic responses to inorganic carbon concentration in C. raciborskii were affected by interactions between CO 2 and Pi. At high Pi concentration, elevated CO 2 significantly increased the inorganic carbon-saturated photosynthesis rate (V max ) and substrate concentration giving half-maximal photosynthetic rate [K 0.5 (DIC)], whereas at low Pi levels, elevated CO 2 slightly decreased the values of V max and K 0.5 (DIC). Additionally, enrichment with Pi significantly increased K 0.5 (DIC) and V max regardless of the CO 2 level, suggesting that Pi plays a role in photosynthetic carbon fixation in C. raciborskii. Furthermore, when C. raciborskii was batch cultured in different carbon and phosphorus concentrations for 72 h, the uptake rate of nitrogen increased with enrichment of both CO 2 and Pi, while the uptake rate of phosphorus was enhanced only by increases in Pi concentration. The results suggest that the availability of CO 2 and phosphorus have combined and independent effects on photosynthesis and nutrient uptake in C. raciborskii, reflecting that changes in environmental factors could influence the dominance of this invasive cyanobacterium. These combined effects need to be considered when generalizing this species response to changing CO 2 levels.

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Section: Discussioncontrasting

confidence: 56%

Combined effects of carbon and phosphorus levels on the invasive cyanobacterium, Cylindrospermopsis raciborskii

Zeng

et al. 2012

Phycologia

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“…We have previously studied arsenate toxicity in media with reduced amounts of phosphate (23) (a condition that does not affect the growth of any of the strains tested [ Fig. 3]), since this compound has a protective effect against arsenate toxicity, probably affecting arsenate transport (37,48) (Fig. 3).…”

Section: Resultsmentioning

confidence: 99%

The Glutathione/Glutaredoxin System Is Essential for Arsenate Reduction in Synechocystis sp. Strain PCC 6803

et al. 2009

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Arsenic resistance in Synechocystis sp. strain PCC 6803 is mediated by an operon of three genes in which arsC codes for an arsenate reductase with unique characteristics. Here we describe the identification of two additional and nearly identical genes coding for arsenate reductases in Synechocystis sp. strain PCC 6803, which we have designed arsI1 and arsI2, and the biochemical characterization of both ArsC (arsenate reductase) and ArsI. Functional analysis of single, double, and triple mutants shows that both ArsI enzymes are active arsenate reductases but that their roles in arsenate resistance are essential only in the absence of ArsC. Based on its biochemical properties, ArsC belongs to a family that, though related to thioredoxin-dependent arsenate reductases, uses the glutathione/glutaredoxin system for reduction, whereas ArsI belongs to the previously known glutaredoxin-dependent family. We have also analyzed the role in arsenate resistance of the three glutaredoxins present in Synechocystis sp. strain PCC 6803 both in vitro and in vivo. Only the dithiolic glutaredoxins, GrxA (glutaredoxin A) and GrxB (glutaredoxin B), are able to donate electrons to both types of reductases in vitro, while GrxC (glutaredoxin C), a monothiolic glutaredoxin, is unable to donate electrons to either type. Analysis of glutaredoxin mutant strains revealed that only those lacking the grxA gene have impaired arsenic resistance.Arsenic is a ubiquitous pollutant that can produce cancer and cause serious health problems in certain parts of the world (36). Because of the wide distribution of arsenic compounds, arsenic resistance is widespread among living organisms (47). Most resistance systems reduce arsenate to arsenite and export the latter to the outside of the cell or transport it to a vacuole (31). Arsenate reduction to arsenite is catalyzed by arsenate reductase, an enzyme at least three families of which have been described (25,30,43). The first family is exemplified by Escherichia coli ArsC, a protein that uses the glutathione (GSH)/ glutaredoxin system as a reducing system and has a single catalytic cysteine. The second family is represented by Staphylococcus aureus and Bacillus subtilis arsenate reductases (also named ArsC). These enzymes are related to low-molecularweight protein phosphotyrosine phosphatases and use thioredoxin as a reducing system through an intramolecular redox cascade requiring three cysteines for arsenate reduction (25). The last family is present only in eukaryotic organisms and was initially described in Saccharomyces cerevisae and, more recently in Leishmania major and Arabidopsis thaliana (6,32,53). These arsenate reductases also use the GSH/glutaredoxin system as a reductant, but they are related not to the E. coli reductase but rather to the Cdc25 family of protein phosphatases.Arsenic resistance in Synechocystis sp. strain PCC 6803 is mediated by an operon of three genes that is regulated by an unlinked arsR homolog. The operon includes an arsenite transporter gene, arsB; an arsH homolog witho...

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“…Because of the similarity in the uptake pattern between AsO 3À 4 and PO 3À 4 [17], arsenate could enter the cell of cyanobacteria through PST and PIT systems [20,27]. The PST system was slow and 100 times more specific for phosphate than arsenate, but the PIT system was fast and did not discriminate between phosphate and arsenate [20].…”

Section: Aeruginosamentioning

confidence: 99%

Arsenic speciation and effect of arsenate inhibition in a Microcystis aeruginosa culture medium under different phosphate regimes

Guo

Gong

Wang

et al. 2011

Enviro Toxic and Chemistry

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Abstract-To assess the ecological impact of arsenic pollution during cyanobacterial blooms, As speciation and cyanobacterial growth in phosphate-modified Microcystis aeruginosa cultures treated with arsenate were investigated under laboratory conditions. Marked growth inhibition was observed when arsenate was added. The inhibition effect of 1 mM arsenate was lower than that of 10 mM arsenate. Increasing phosphate supply (0-175 mM) in the medium decreased the inhibition of As. In the medium, arsenate, arsenite, and dimethylarsenicals (DMA) occurred under phosphate-deprivation (0 mM) and phosphate-excess (175 mM) conditions. However, only arsenate and DMA were detected under phosphate-limited (1 mM) and phosphate-rich (10 mM) conditions. Moreover, arsenite and DMA concentrations had significantly positive correlation with the biomass production of M. aeruginosa in the existence of phosphate. Arsenic speciation was more significantly affected by phosphate levels than arsenate concentrations. Recovery of total As content in M. aeruginosa culture medium increased with the increasing phosphate supply. The duration of arsenate contamination in the culture of M. aeruginosa had no influence on the variation of As species but affected the concentration of them in the medium under the phosphateexcess condition. This demonstrated that the effect of M. aeruginosa on As speciation was not related to the duration of As contamination under the phosphate-excess condition. Environ.

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Phosphate transport and arsenate resistance in the cyanobacterium Anabaena variabilis

Cited by 71 publications

References 26 publications

Combined effects of carbon and phosphorus levels on the invasive cyanobacterium, Cylindrospermopsis raciborskii

Combined effects of carbon and phosphorus levels on the invasive cyanobacterium, Cylindrospermopsis raciborskii

The Glutathione/Glutaredoxin System Is Essential for Arsenate Reduction in Synechocystis sp. Strain PCC 6803

Arsenic speciation and effect of arsenate inhibition in a Microcystis aeruginosa culture medium under different phosphate regimes

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