Inducible dissociation of SCFMet30 ubiquitin ligase mediates a rapid transcriptional response to cadmium

Barbey, Régine; Baudouin‐Cornu, Peggy; Lee, Traci A.; Rouillon, Astrid; Zarzov, Patrick; Tyers, Mike; Thomas, Dominique

doi:10.1038/sj.emboj.7600556

Cited by 74 publications

(120 citation statements)

References 52 publications

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“…This putative pathway would activate the transcriptional activator Met4 since all the genes of the sulfur amino acid pathway are induced by cadmium in a Met4-dependent way (7). Consistent with our data, recent work showed that Met4, which is normally inactivated following methionine supplementation (through the increased pool of cysteine), remains active when methionine-supplemented cells are treated with cadmium (28,29). Under cadmium conditions, Met4 is stabilized as a result of the dissociation of the Skp1-Met-30 interaction in the SCF Met30 ubiquitin ligase complex (28) that targets the ubiquitylation and the degradation of Met-4 upon methionine addition (30).…”

Section: Protein and Metabolite Levels Can Be Positively Or Negativelsupporting

confidence: 78%

Combined Proteome and Metabolite-profiling Analyses Reveal Surprising Insights into Yeast Sulfur Metabolism

Lafaye

Junot

Pereira

et al. 2005

Journal of Biological Chemistry

121

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Metabolomics is considered as an emerging new tool for functional proteomics in the identification of new protein function or in projects aiming at modeling whole cell metabolism. When combined with proteome studies, metabolite-profiling analyses revealed unanticipated insights into the yeast sulfur pathway. In response to cadmium, the observed overproduction of glutathione, essential for the detoxification of the metal, can be entirely accounted for by a marked drop in sulfur-containing protein synthesis and a redirection of sulfur metabolite fluxes to the glutathione pathway. A kinetic analysis showed sequential and dramatic changes in intermediate sulfur metabolite pools within the first hours of the treatment. Strikingly, whereas proteome and metabolic data were positively correlated under cadmium conditions, proteome and metabolic data were negatively correlated during other growth conditions, i.e. methionine supplementation or sulfate starvation. These differences can be explained by alternative mechanisms in the regulation of Met4, the activator of the sulfur pathway. Whereas Met4 activity is controlled by the cellular cysteine content in response to sulfur source and availability, the present study suggests that Met4 activation under cadmium conditions is cysteine-independent. The results clearly indicate that the metabolic state of a cell cannot be safely predicted based solely on proteomic and/or gene expression data. Combined metabolome and proteome studies are necessary to draw a comprehensive and integrated view of cell metabolism.Assimilable sulfur is essential for all living organisms. The cell requirement for sulfur can be fulfilled by the uptake of sulfur-containing amino acids or by assimilation of inorganic sulfur into organic compounds such as cysteine or homocysteine (1, 2). In yeast, homocysteine is the precursor of methionine through the methyl cycle and of cysteine through the transsulfuration pathway ( Fig. 1) (3). Cysteine is the sensor of the metabolic state in the sulfur amino acid pathway (4) and is required for the synthesis of GSH, an essential antioxidant molecule also important for detoxification.The yeast sulfur pathway has been extensively investigated at the genetic, enzymatic, and regulatory levels (3). The pools of most metabolites of the pathway have been analyzed (5, 6), and the K m values of many enzymes have been measured (3). However, some metabolic data such as the metabolite fluxes in the pathway and the concentration of the metabolites of the transsulfuration pathway (homocysteine and cystathionine) are lacking. Moreover, the levels of some sulfur metabolites are presumed to be modified in different mutants and under different physiological conditions (i.e. sulfur starvation, the presence of a sulfur metabolite, or a toxic metal in the medium), but the few quantitative data that are available are restricted to a small part of the pathway (5). Thus, it has been shown that cadmium (Cd 2ϩ ) strongly increases GSH synthesis (7), which is consistent with the primary impor...

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Section: Protein and Metabolite Levels Can Be Positively Or Negativelsupporting

confidence: 78%

Combined Proteome and Metabolite-profiling Analyses Reveal Surprising Insights into Yeast Sulfur Metabolism

Lafaye

Junot

Pereira

et al. 2005

Journal of Biological Chemistry

121

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“…This regulation of the Met30/Skp1 interaction seems to be unique for the cadmium response because Rouillon et al (2000) demonstrated that methionine starvation, which also blocks Met4 ubiquitination, did not disrupt the Met30/Skp1 complex. While this manuscript was in press, similar results on cadmium-mediated regulation of SCF Met30 were reported (Barbey et al, 2005). Moreover, using an in vitro Met4 ubiquitination system, the authors excluded a direct effect of cadmium on SCF Met30 activity, suggesting that cadmium induces modification of Met30 or association with a putative inhibitor (Barbey et al, 2005).…”

Section: Discussionsupporting

confidence: 49%

“…While this manuscript was in press, similar results on cadmium-mediated regulation of SCF Met30 were reported (Barbey et al, 2005). Moreover, using an in vitro Met4 ubiquitination system, the authors excluded a direct effect of cadmium on SCF Met30 activity, suggesting that cadmium induces modification of Met30 or association with a putative inhibitor (Barbey et al, 2005). Interestingly, studies with the mammalian Cul3-containing ubiquitin ligase SCF3 Keap1 suggested that its substrate recognition subunit Keap1 dissociates from Cul3 in response to oxidative stress (Zhang et al, 2004).…”

Section: Discussionmentioning

confidence: 55%

The Yeast Ubiquitin Ligase SCF^Met30Regulates Heavy Metal Response

Yen

Kaiser

2005

MBoC

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Cells have developed a variety of mechanisms to respond to heavy metal exposure. Here, we show that the yeast ubiquitin ligase SCF Met30 plays a central role in the response to two of the most toxic environmental heavy metal contaminants, namely, cadmium and arsenic. SCF Met30 inactivates the transcription factor Met4 by proteolysis-independent polyubiquitination. Exposure of yeast cells to heavy metals led to activation of Met4 as indicated by a complete loss of ubiquitinated Met4 species. The association of Met30 with Skp1 but not with its substrate Met4 was inhibited in cells treated with cadmium. Cadmium-activated Met4 induced glutathione biosynthesis as well as genes involved in sulfuramino acid synthesis. Met4 activation was important for the cellular response to cadmium because mutations in various components of the Met4-transcription complex were hypersensitive to cadmium. In addition, cell cycle analyses revealed that cadmium induced a delay in the transition from G 1 to S phase of the cell cycle and slow progression through S phase. Both cadmium and arsenic induced phosphorylation of the cell cycle checkpoint protein Rad53. Genetic analyses demonstrated a complex effect of cadmium on cell cycle regulation that might be important to safeguard cellular and genetic integrity when cells are exposed to heavy metals. INTRODUCTIONHeavy metals are a major environmental hazard and present a danger to human health. The cause of the cytotoxic effects of heavy metals is not completely understood, but it has been suggested that at least part of their toxicity is due to the formation of hydroxyl radicals, which lead to lipid, protein, and DNA damage (Stohs and Bagchi, 1995;Brennan and Schiestl, 1996;Halliwell and Gutteridge, 1984).As with any cytotoxic and genotoxic insults, all organisms have developed strategies to respond to heavy metal exposure to maintain cellular and genetic integrity. These strategies include detoxification, repair, or removal of damaged molecules, and delay of cell division to prevent propagation of damaged cellular components (Jamieson, 1998).The biological effects of cadmium are perhaps better studied than that of other heavy metals. High affinity for sulfhydryl groups, competition with Zn(II) in proteins, nonspecific interaction with DNA, generation of reactive oxygen species, and depletion of glutathione have been shown to contribute to the toxicity of cadmium (Stohs and Bagchi, 1995;Zalups and Ahmad, 2003;McMurray and Tainer, 2003). Recently, it has been demonstrated in yeast that the genotoxic effects of cadmium are indirect (Jin et al., 2003;McMurray and Tainer, 2003). Rather than by direct DNA damage, cadmium leads to genome instability by inhibition of the DNA mismatch repair system (Jin et al., 2003). Although the mechanism of how cadmium inhibits DNA repair is not clear, it has been suggested that damage of sulfhydryl groups containing components of the mismatch repair system might be responsible (Jin et al., 2003).The damaging effect of cadmium on sulfhydryl groups containing pro...

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“…To test whether cells can initiate transcription faster and that the delay is due to delayed induction of gene expression by pre-transcription control mechanisms, we performed a time course experiment using cadmium to induce transcription of the MET genes. Cadmium is a known strong and direct activator of the sulphate assimilation pathway 24,25 . We added cadmium to the medium with methionine and sulphate.…”

Section: Direct Transcription Activation Reduces Delay Time Fourfoldmentioning

confidence: 99%

“…Interestingly, cadmium can be used to bypass this complex regulation. It causes dissociation of the SCF (Skp1-Cullin-F-box) ubiquitin ligase and the substrate recognition protein Met30, thereby inhibiting the ubiquitination of Met4 and activating de-ubiquitination of the existing Met4-ubiquitin 24,25 . Thus, cadmium allows for the direct induction of gene expression by effectively bypassing the cellular decision process.…”

mentioning

confidence: 99%

Single yeast cells vary in transcription activity not in delay time after a metabolic shift

Schwabe¹,

Bruggeman²

2014

Nat Commun

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Individual cells respond very differently to changes in environmental conditions. Stochasticity causes cells to respond at different times, magnitudes or both. Here we disentangle and quantify these two sources of heterogeneity. We track the adaptation dynamics of single Saccharomyces cerevisiae cells exposed to a nutrient shift from methionine to sulphate and back. Using single-molecule RNA fluorescence in situ hybridization, we count the number of transcripts of a methionine-biosynthesis enzyme in single cells during adaptation. The variation of response times between cells is small, yet we find a high transient variability in the messenger RNA copy numbers. Surprisingly, single cells display strongly delayed transcription induction, as we could induce transcription fourfold quicker by direct activation and bypassing the cellular control circuitry. Transcription repression occurs rapidly within several minutes. This study indicates that small variability in response timing combined with high, stochastic transcription activity can cause large cell-to-cell variability in dynamic adaptation responses.

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Inducible dissociation of SCFMet30 ubiquitin ligase mediates a rapid transcriptional response to cadmium

Cited by 74 publications

References 52 publications

Combined Proteome and Metabolite-profiling Analyses Reveal Surprising Insights into Yeast Sulfur Metabolism

Combined Proteome and Metabolite-profiling Analyses Reveal Surprising Insights into Yeast Sulfur Metabolism

The Yeast Ubiquitin Ligase SCF^Met30Regulates Heavy Metal Response

Single yeast cells vary in transcription activity not in delay time after a metabolic shift

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Inducible dissociation of SCFMet30 ubiquitin ligase mediates a rapid transcriptional response to cadmium

Cited by 74 publications

References 52 publications

Combined Proteome and Metabolite-profiling Analyses Reveal Surprising Insights into Yeast Sulfur Metabolism

Combined Proteome and Metabolite-profiling Analyses Reveal Surprising Insights into Yeast Sulfur Metabolism

The Yeast Ubiquitin Ligase SCFMet30Regulates Heavy Metal Response

Single yeast cells vary in transcription activity not in delay time after a metabolic shift

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Product

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The Yeast Ubiquitin Ligase SCF^Met30Regulates Heavy Metal Response