Project description:In this study, we combined metabolic reconstruction, growth assays, metabolome and transcriptome analyses to obtain a global view of the sulfur metabolic network and of the response to sulfur availability in Brevibacterium aurantiacum. In agreement with the growth of B. aurantiacum in the presence of sulfate and cystine, the metabolic reconstruction showed the presence of a sulfate assimilation pathway and of thiolation pathways that produce cysteine (cysE and cysK) or homocysteine (metX and metY) from sulfide, of at least one gene of the transsulfuration pathway (aecD) and of genes encoding three MetE-type methionine synthases. We also compared the expression profiles of B. aurantiacum ATCC9175 during sulfur starvation and in the presence of sulfate, cystine or methionine plus cystine. In sulfur starvation, 690 genes including 21 genes involved in sulfur metabolism and 29 genes encoding amino acids and peptide transporters were differentially expressed. We also investigated changes in pools of sulfur-containing metabolites and in expression profiles after growth in the presence of sulfate, cystine or methionine plus cystine. The expression of genes involved in sulfate assimilation and cysteine synthesis was repressed in presence of cysteine, while the expression of metX, metY, metE1, metE2 and BL613 encoding a probable cystathionine-γ-synthase decreased in the presence of methionine. We identified three ABC transporters: two stronger transcribed during cysteine limitation and one during methionine depletion. Finally, the expression of genes encoding a methionine γ-lyase, BL929, and a methionine transporter (metPS) was induced in the presence of methionine, in conjunction with a significant increase of volatile sulfur compounds production. Refer to individual Series. This SuperSeries is composed of the following subset Series: GSE25418: BA-Methionine plus Cystine vs Cystine GSE25419: BA-Sulfate vs Cystine GSE25420: BA-Methionine plus Cystine vs Sulfate GSE25421: BA-Sulfate vs Sulfate starvation
Project description:In this study, we combined metabolic reconstruction, growth assays, metabolome and transcriptome analyses to obtain a global view of the sulfur metabolic network and of the response to sulfur availability in Brevibacterium aurantiacum. In agreement with the growth of B. aurantiacum in the presence of sulfate and cystine, the metabolic reconstruction showed the presence of a sulfate assimilation pathway and of thiolation pathways that produce cysteine (cysE and cysK) or homocysteine (metX and metY) from sulfide, of at least one gene of the transsulfuration pathway (aecD) and of genes encoding three MetE-type methionine synthases. We also compared the expression profiles of B. aurantiacum ATCC9175 during sulfur starvation and in the presence of sulfate, cystine or methionine plus cystine. In sulfur starvation, 690 genes including 21 genes involved in sulfur metabolism and 29 genes encoding amino acids and peptide transporters were differentially expressed. We also investigated changes in pools of sulfur-containing metabolites and in expression profiles after growth in the presence of sulfate, cystine or methionine plus cystine. The expression of genes involved in sulfate assimilation and cysteine synthesis was repressed in presence of cysteine, while the expression of metX, metY, metE1, metE2 and BL613 encoding a probable cystathionine-γ-synthase decreased in the presence of methionine. We identified three ABC transporters: two stronger transcribed during cysteine limitation and one during methionine depletion. Finally, the expression of genes encoding a methionine γ-lyase, BL929, and a methionine transporter (metPS) was induced in the presence of methionine, in conjunction with a significant increase of volatile sulfur compounds production. This SuperSeries is composed of the SubSeries listed below.
Project description:Responses of photosynthetic organisms to sulfur starvation include (i) increasing the capacity of the cell for transporting and/or assimilating exogenous sulfate, (ii) restructuring cellular features to conserve sulfur resources, and (iii) modulating metabolic processes and rates of cell growth and division. We used microarray analyses to obtain a genome-level view of changes in mRNA abundances in the green alga Chlamydomonas reinhardtii during sulfur starvation. The work confirms and extends upon previous findings showing that sulfur deprivation elicits changes in levels of transcripts for proteins that help scavenge sulfate and economize on the use of sulfur resources. Changes in levels of transcripts encoding members of the light-harvesting polypeptide family, such as LhcSR2, suggest restructuring of the photosynthetic apparatus during sulfur deprivation. There are also significant changes in levels of transcripts encoding enzymes involved in metabolic processes (e.g., carbon metabolism), intracellular proteolysis, and the amelioration of oxidative damage; a marked and sustained increase in mRNAs for a putative vanadium chloroperoxidase and a peroxiredoxin may help prolong survival of C. reinhardtii during sulfur deprivation. Furthermore, many of the sulfur stress-regulated transcripts (encoding polypeptides associated with sulfate uptake and assimilation, oxidative stress, and photosynthetic function) are not properly regulated in the sac1 mutant of C. reinhardtii, a strain that dies much more rapidly than parental cells during sulfur deprivation. Interestingly, sulfur stress elicits dramatic changes in levels of transcripts encoding putative chloroplast-localized chaperones in the sac1 mutant but not in the parental strain. These results suggest various strategies used by photosynthetic organisms during acclimation to nutrient-limited growth.
Project description:volved enabling cells to evade toxicity and acquire tolerance. Herein, we explored how Saccharomyces cerevisiae (budding yeast) respond to trivalent arsenic (arsenite) by quantitative and kinetic transcriptome, proteome and sulfur metabolite profiling. Arsenite exposure affected transcription of genes encoding functions related to protein biosynthesis, arsenic detoxification, oxidative stress defense, redox maintenance and proteolytic activity. Importantly, enzymes involved in sulfate assimilation and glutathione biosynthesis were induced at both gene and protein levels. Kinetic metabolic profiling evidenced a significant increase in the pools of sulfur metabolites as well as elevated glutathione levels. Moreover, the flux in the sulfur assimilation pathway as well as the glutathione synthesis rate strongly increased with a concomitant reduction of sulfur incorporation into proteins. By combining comparative genomics and molecular analyses, we pin-pointed transcription factors that mediate thecore of the transcriptional response to arsenite. Taken together, our data reveals that arsenite-exposed cells channel a large part of assimilated sulfur into glutathione biosynthesis and we provide evidence that the transcriptional regulators Yap1p and Met4p control this response in concert. Keywords: stress
Project description:Responses of photosynthetic organisms to sulfur starvation include (i) increasing the capacity of the cell for transporting and/or assimilating exogenous sulfate, (ii) restructuring cellular features to conserve sulfur resources, and (iii) modulating metabolic processes and rates of cell growth and division. We used microarray analyses to obtain a genome-level view of changes in mRNA abundances in the green alga Chlamydomonas reinhardtii during sulfur starvation. The work confirms and extends upon previous findings showing that sulfur deprivation elicits changes in levels of transcripts for proteins that help scavenge sulfate and economize on the use of sulfur resources. Changes in levels of transcripts encoding members of the light-harvesting polypeptide family, such as LhcSR2, suggest restructuring of the photosynthetic apparatus during sulfur deprivation. There are also significant changes in levels of transcripts encoding enzymes involved in metabolic processes (e.g., carbon metabolism), intracellular proteolysis, and the amelioration of oxidative damage; a marked and sustained increase in mRNAs for a putative vanadium chloroperoxidase and a peroxiredoxin may help prolong survival of C. reinhardtii during sulfur deprivation. Furthermore, many of the sulfur stress-regulated transcripts (encoding polypeptides associated with sulfate uptake and assimilation, oxidative stress, and photosynthetic function) are not properly regulated in the sac1 mutant of C. reinhardtii, a strain that dies much more rapidly than parental cells during sulfur deprivation. Interestingly, sulfur stress elicits dramatic changes in levels of transcripts encoding putative chloroplast-localized chaperones in the sac1 mutant but not in the parental strain. These results suggest various strategies used by photosynthetic organisms during acclimation to nutrient-limited growth. An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Computed
Project description:Plants utilize soil sulfate for production of sulfur-containing amino acids that serve as essential dietary sulfur sources for animals. Despite the global nutritional significance of this fundamental metabolic process in nature, transcription factors regulating the plant sulfur assimilation pathways have never been discovered. We isolated sulfur limitation1 (slim1) mutants from Arabidopsis, showing abnormally low expression of SULTR1;2 sulfate transporter, by screening responsiveness of SULTR1;2 promoter-GFP, as an indicator, to sulfur limitation. SLIM1 encoded an EIL-family transcription factor, EIL3. To clarify the siganificance of SLIM1 function in sulfur responsive gene expression, we analyzed the transcriptome profiles in slim1-1, slim1-2 and the parental line under +S and -S conditions. Keywords: comparison of mutant and wild type, sulfur limitation response, nutritional stress response
Project description:Dimethylsulfide is a volatile organic sulfur compound that provides the largest input of biogenic sulfur from the oceans to the atmosphere, and thence back to land, constituting an important link in the global sulfur cycle. Microorganisms degrading DMS affect fluxes of DMS in the environment, but the underlying metabolic pathways are still poorly understood. Methylophaga thiooxydans is a marine methylotrophic bacterium capable of growth on DMS as sole source of carbon and energy. Using proteomics and transcriptomics we identified genes expressed during growth on dimethylsulfide and methanol to refine our knowledge of the metabolic pathways that are involved in DMS and methanol degradation in this strain. Amongst the most highly expressed genes on DMS were the two methanethiol oxidases driving the oxidation of this reactive and toxic intermediate of DMS metabolism. Growth on DMS also increased expression of the enzymes of the tetrahydrofolate linked pathway of formaldehyde oxidation, in addition to the tetrahydromethanopterin linked pathway. Key enzymes of the inorganic sulfur oxidation pathway included flavocytochrome c sulfide dehydrogenase, sulfide quinone oxidoreductase, and persulfide dioxygenases. A sulP permease was also expressed during growth on DMS. Other enzymes of organic and inorganic sulfur metabolism previously detected in cell extracts of Methylophaga have not been characterised at the genetic level yet; their expression level and regulation could not be analysed. A pan-genome analysis of six available Methylophaga genomes suggests that only two of the six investigated bacteria have the metabolic potential to utilize methanethiol, the degradation product of DMS. These results mirror phenotypic analyses and demonstrate that DMS-utilization and subsequent C1 and sulfur oxidation are not conserved across the entire genus.
Project description:Arsenic is ubiquitously present in nature and various mechanisms have evolved enabling cells to evade toxicity and acquire tolerance. Herein, we explored how Saccharomyces cerevisiae (budding yeast) respond to trivalent arsenic (arsenite) by quantitative and kinetic transcriptome, proteome and sulfur metabolite profiling. Arsenite exposure affected transcription of genes encoding functions related to protein biosynthesis, arsenic detoxification, oxidative stress defense, redox maintenance and proteolytic activity. Importantly, enzymes involved in sulfate assimilation and glutathione biosynthesis were induced at both gene and protein levels. Kinetic metabolic profiling evidenced a significant increase in the pools of sulfur metabolites as well as elevated glutathione levels. Moreover, the flux in the sulfur assimilation pathway as well as the glutathione synthesis rate strongly increased with a concomitant reduction of sulfur incorporation into proteins. By combining comparative genomics and molecular analyses, we pin-pointed transcription factors that mediate thecore of the transcriptional response to arsenite. Taken together, our data reveals that arsenite-exposed cells channel a large part of assimilated sulfur into glutathione biosynthesis and we provide evidence that the transcriptional regulators Yap1p and Met4p control this response in concert. Keywords: stress
Project description:Arsenic is ubiquitously present in nature and various mechanisms have evolved enabling cells to evade toxicity and acquire tolerance. Herein, we explored how Saccharomyces cerevisiae (budding yeast) respond to trivalent arsenic (arsenite) by quantitative and kinetic transcriptome, proteome and sulfur metabolite profiling. Arsenite exposure affected transcription of genes encoding functions related to protein biosynthesis, arsenic detoxification, oxidative stress defense, redox maintenance and proteolytic activity. Importantly, enzymes involved in sulfate assimilation and glutathione biosynthesis were induced at both gene and protein levels. Kinetic metabolic profiling evidenced a significant increase in the pools of sulfur metabolites as well as elevated glutathione levels. Moreover, the flux in the sulfur assimilation pathway as well as the glutathione synthesis rate strongly increased with a concomitant reduction of sulfur incorporation into proteins. By combining comparative genomics and molecular analyses, we pin-pointed transcription factors that mediate thecore of the transcriptional response to arsenite. Taken together, our data reveals that arsenite-exposed cells channel a large part of assimilated sulfur into glutathione biosynthesis and we provide evidence that the transcriptional regulators Yap1p and Met4p control this response in concert. Keywords: stress, time course
Project description:Arsenic is ubiquitously present in nature and various mechanisms have evolved enabling cells to evade toxicity and acquire tolerance. Herein, we explored how Saccharomyces cerevisiae (budding yeast) respond to trivalent arsenic (arsenite) by quantitative and kinetic transcriptome, proteome and sulfur metabolite profiling. Arsenite exposure affected transcription of genes encoding functions related to protein biosynthesis, arsenic detoxification, oxidative stress defense, redox maintenance and proteolytic activity. Importantly, enzymes involved in sulfate assimilation and glutathione biosynthesis were induced at both gene and protein levels. Kinetic metabolic profiling evidenced a significant increase in the pools of sulfur metabolites as well as elevated glutathione levels. Moreover, the flux in the sulfur assimilation pathway as well as the glutathione synthesis rate strongly increased with a concomitant reduction of sulfur incorporation into proteins. By combining comparative genomics and molecular analyses, we pin-pointed transcription factors that mediate thecore of the transcriptional response to arsenite. Taken together, our data reveals that arsenite-exposed cells channel a large part of assimilated sulfur into glutathione biosynthesis and we provide evidence that the transcriptional regulators Yap1p and Met4p control this response in concert. Keywords: stress