Identification of genes affecting selenite toxicity and resistance in <i>Saccharomyces cerevisiae</i>

Pinson, Benoı̂t; Sagot, Isabelle; Daignan‐Fornier, Bertrand

doi:10.1046/j.1365-2958.2000.01890.x

Cited by 64 publications

(82 citation statements)

References 35 publications

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“…2(b) for the respective W303 background strains (data not shown). As expected from Pinson et al (2000), the proportion of wild-type viable cells which became can R increased with the duration of selenite treatment, confirming the mutagenicity of selenite under our experimental conditions (Fig. 7a).…”

Section: Selenite Provokes An Increase Of Protein Carbonylationsupporting

confidence: 87%

“…In fact, S. cerevisiae, and fungi in general, do not contain selenoproteins and therefore Se is not essential for these organisms (Lu & Holmgren, 2009). High concentrations of Se cause DNA double-strand breaks in exponentially growing S. cerevisiae cells (Letavayová et al, 2008) and RAD9-dependent cell cycle arrest (Pinson et al, 2000). Accordingly, yeast mutants defective in the RAD9-mediated DNA repair pathway or the RAD6/RAD18-mediated DNA damage tolerance pathway are hypersensitive to sodium selenite (Seitomer et al, 2008), pointing to the importance of DNA damage in explaining Se toxicity to yeast cells.…”

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confidence: 99%

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Selenite-induced cell death in Saccharomyces cerevisiae: protective role of glutaredoxins

2010

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Unlike in higher organisms, selenium is not essential for growth in Saccharomyces cerevisiae. In this species, it causes toxic effects at high concentrations. In the present study, we show that when supplied as selenite to yeast cultures growing under fermentative metabolism, its effects can be dissected into two death phases. From the time of initial treatment, it causes loss of membrane integrity and genotoxicity. Both effects occur at higher levels in mutants lacking Grx1p and Grx2p than in wild-type cells, and are reversed by expression of a cytosolic version of the membrane-associated Grx7p glutaredoxin. Grx7p can also rescue the high levels of protein carbonylation damage that occur in selenite-treated cultures of the grx1 grx2 mutant. After longer incubation times, selenite causes abnormal nuclear morphology and the appearance of TUNELpositive cells, which are considered apoptotic markers in yeast cells. This effect is independent of Grx1p and Grx2p. Therefore, the protective role of the two glutaredoxins is restricted to the initial stages of selenite treatment. Lack of Yca1p metacaspase or of a functional mitochondrial electron transport chain only moderately diminishes apoptotic-like death by selenite. In contrast, seleniteinduced apoptosis is dependent on the apoptosis-inducing factor Aif1p. In the absence of the latter, intracellular protein carbonylation is reduced after prolonged selenite treatment, supporting the supposition that part of the oxidative damage is contributed by apoptotic cells. INTRODUCTIONSelenium (Se) is a trace element which may have anticarcinogenic action at low concentrations (Letavayová et al., 2006). The essential character of Se in the mammalian diet is related to its presence as selenocysteine in a number of selenoproteins, such as thioredoxin reductases and glutathione peroxidases (Lu & Holmgren, 2009). These enzymes act in the defence against oxidative stress. In contrast, at high concentrations, Se is toxic because it generates oxidative stress and provokes DNA damage (Hatfield et al., 2006;Letavayová et al., 2006). Among the Se compounds that may come into contact with cells, selenite is a prooxidant because it undergoes glutathionemediated reduction to hydrogen selenide with the subsequent formation of superoxide radicals, which can undergo conversion into other reactive oxygen species (ROS) Spallholz, 1997;Tarze et al., 2007). Saccharomyces cerevisiae is a suitable organism to study the toxic properties of Se and the cellular mechanisms which prevent or repair its effects, without the interference due to an Se requirement for selenoproteins. In fact, S. cerevisiae, and fungi in general, do not contain selenoproteins and therefore Se is not essential for these organisms (Lu & Holmgren, 2009). High concentrations of Se cause DNA double-strand breaks in exponentially growing S. cerevisiae cells (Letavayová et al., 2008) and RAD9-dependent cell cycle arrest (Pinson et al., 2000). Accordingly, yeast mutants defective in the RAD9-mediated DNA repair pathway or the RAD6/RAD...

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Section: Selenite Provokes An Increase Of Protein Carbonylationsupporting

confidence: 87%

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confidence: 99%

Selenite-induced cell death in Saccharomyces cerevisiae: protective role of glutaredoxins

2010

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“…Toxicity-The toxicity of selenite in yeast is well documented, although the mechanisms of toxicity are less well understood (24,25). Selenite uptake is the first step in selenium metabolism that ultimately leads to toxicity.…”

Section: Effect Of Phosphate On Selenitementioning

confidence: 99%

Uptake of Selenite by Saccharomyces cerevisiae Involves the High and Low Affinity Orthophosphate Transporters

Lazard

Blanquet

Fisicaro

et al. 2010

Journal of Biological Chemistry

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Although the general cytotoxicity of selenite is well established, the mechanism by which this compound crosses cellular membranes is still unknown. Here, we show that in Saccharomyces cerevisiae, the transport system used opportunistically by selenite depends on the phosphate concentration in the growth medium. Both the high and low affinity phosphate transporters are involved in selenite uptake. When cells are grown at low P i concentrations, the high affinity phosphate transporter Pho84p is the major contributor to selenite uptake. When phosphate is abundant, selenite is internalized through the low affinity P i transporters (Pho87p, Pho90p, and Pho91p). Accordingly, inactivation of the high affinity phosphate transporter Pho84p results in increased resistance to selenite and reduced uptake in low P i medium, whereas deletion of SPL2, a negative regulator of low affinity phosphate uptake, results in exacerbated sensitivity to selenite. Measurements of the kinetic parameters for selenite and phosphate uptake demonstrate that there is a competition between phosphate and selenite ions for both P i transport systems. In addition, our results indicate that Pho84p is very selective for phosphate as compared with selenite, whereas the low affinity transporters discriminate less efficiently between the two ions. The properties of phosphate and selenite transport enable us to propose an explanation to the paradoxical increase of selenite toxicity when phosphate concentration in the growth medium is raised above 1 mM.Although toxic at high concentrations, selenium is required in many cells, because it is translationally incorporated as selenocysteine into selenoproteins that perform specific and essential functions (1). Cells must ensure selenium uptake to sustain this metabolism. However, little is known about selenium transport. Because selenium and sulfur are chalcogen elements that have many chemical properties in common, selenium shares metabolic pathways with sulfur. Accordingly, selenate was shown to be taken up by the yeast Saccharomyces cerevisiae sulfate permeases (2). Similarly, in plants, selenate is taken up by roots via the high affinity sulfate transporters (3).On the other hand, specific selenite transporters have never been identified so far. The sulfate ABC transporter of Escherichia coli mediates selenite uptake in addition to that of selenate (4). However, repression of the expression of that transporter does not quench selenite uptake completely, indicating that an alternative entry pathway exists for selenite (5). In S. cerevisiae, which does not possess selenoproteins, an energy-dependent uptake of selenite, distinct from that of selenate, was reported. Characterization of the kinetics of selenite uptake suggested the existence of two transport systems: a high affinity system at low selenite concentration and a low affinity system at higher concentration (6). Recently, a study of selenite uptake by wheat (Triticum aestivum) roots showed it to be an active process competitively inhibited by phosph...

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“…Although classic studies revealed that SeMet was efficiently incorporated into the Met pathway (7), the toxicity of SeMet has not been examined in yeast. In contrast, the effects of selenite have been studied by several groups spanning several decades (15,(22)(23)(24)(25), underscoring the importance of yeast as a model system for deciphering the mechanisms of selenium toxicity. Indeed, recent data analyzing the role of genes in the RAD9-dependent DNA repair pathway, the RAD6/RAD18 DNA damage tolerance pathway, and the oxidative stress pathway DNA damage tolerance pathway in S. cerevisiae suggest that both selenite and SeMet are likely inducing DNA damage by generating reactive species (19).…”

Section: Semet Incorporation Into Proteins In a Cys3⌬ Null Strain By mentioning

confidence: 99%

Genome-wide screen of Saccharomyces cerevisiae null allele strains identifies genes involved in selenomethionine resistance

Bockhorn¹,

Balar²,

He³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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Selenomethionine (SeMet) is a potentially toxic amino acid, and yet it is a valuable tool in the preparation of labeled proteins for multiwavelength anomalous dispersion or single-wavelength anomalous dispersion phasing in X-ray crystallography. The mechanism by which high levels of SeMet exhibits its toxic effects in eukaryotic cells is not fully understood. Attempts to use Saccharomyces cerevisiae for the preparation of fully substituted SeMet proteins for X-ray crystallography have been limited. A screen of the viable S. cerevisiae haploid null allele strain collection for resistance to SeMet was performed. Deletion of the CYS3 gene encoding cystathionine gamma-lyase resulted in the highest resistance to SeMet. In addition, deletion of SSN2 resulted in both increased resistance to SeMet as well as reduced levels of Cys3p. A methionine auxotrophic strain lacking CYS3 was able to grow in media with SeMet as the only source of Met, achieving essentially 100% occupancy in total proteins. The CYS3 deletion strain provides advantages for an easy and cost-effective method to prepare SeMet-substituted protein in yeast and perhaps other eukaryotic systems.CYS3 ͉ SSN2

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Identification of genes affecting selenite toxicity and resistance in Saccharomyces cerevisiae

Cited by 64 publications

References 35 publications

Selenite-induced cell death in Saccharomyces cerevisiae: protective role of glutaredoxins

Selenite-induced cell death in Saccharomyces cerevisiae: protective role of glutaredoxins

Uptake of Selenite by Saccharomyces cerevisiae Involves the High and Low Affinity Orthophosphate Transporters

Genome-wide screen of Saccharomyces cerevisiae null allele strains identifies genes involved in selenomethionine resistance

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