Transcriptional effect of aft1 and aft2 mutation in iron depleted conditions
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ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
PROVIDER: GSE1763 | GEO | 2005/07/15
SECONDARY ACCESSION(S): PRJNA90305
REPOSITORIES: GEO
Similar Datasets
Project description:The paralogous transcription factors Aft1p and Aft2p activate the expression of genes involved in iron metabolism under iron depleted conditions. Both are able to bind to the same DNA consensus sequence in vitro. We used DNA microarrays and loss of function mutant strains to better understand the respective roles of Aft1p and Aft2p in the regulation of gene expression
2010-06-09 | E-GEOD-1763 | biostudies-arrayexpress
Project description:Iron homeostasis in the yeast Saccharomyces cerevisiae is regulated at the transcriptional level by Aft1p, which activates the expression of its target genes in response to low-iron conditions. The yeast genome contains a paralog of AFT1, which has been designated AFT2. To establish whether AFT1 and AFT2 have overlapping functions, a mutant containing a double aft1aft2 deletion was generated. Growth assays established that the single aft2 strain exhibited no iron-dependent phenotype. However, the double-mutant aft1aft2 strain was more sensitive to low-iron growth conditions than the single-mutant aft1 strain. A mutant allele of AFT2 (AFT2-1up), or overexpression of the wild-type AFT2 gene, led to partial complementation of the respiratory- deficient phenotype of the aft1 strain. The AFT2-1up allele also increased the uptake of 59Fe in an aft1 strain. DNA microarrays were used to identify genes regulated by AFT2. Some of the AFT2-regulated genes are known to be regulated by Aft1p; however, AFT2-1up-dependent activation was independent of Aft1p. The kinetics of induction of two genes activated by the AFT2-1up allele are consistent with Aft2p acting as a direct transcriptional factor. Truncated forms of Aft1p and Aft2p bound to a DNA duplex containing the Aft1p binding site in vitro. The wild-type allele of AFT2 activated transcription in response to growth under low-iron conditions. Together, these data suggest that yeast has a second regulatory pathway for the iron regulon, with AFT1 and AFT2 playing partially redundant roles. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set
2005-08-13 | GSE3122 | GEO
Project description:Iron homeostasis in the yeast Saccharomyces cerevisiae is regulated at the transcriptional level by Aft1p, which activates the expression of its target genes in response to low-iron conditions. The yeast genome contains a paralog of AFT1, which has been designated AFT2. To establish whether AFT1 and AFT2 have overlapping functions, a mutant containing a double aft1aft2 deletion was generated. Growth assays established that the single aft2 strain exhibited no iron-dependent phenotype. However, the double-mutant aft1aft2 strain was more sensitive to low-iron growth conditions than the single-mutant aft1 strain. A mutant allele of AFT2 (AFT2-1up), or overexpression of the wild-type AFT2 gene, led to partial complementation of the respiratory- deficient phenotype of the aft1 strain. The AFT2-1up allele also increased the uptake of 59Fe in an aft1 strain. DNA microarrays were used to identify genes regulated by AFT2. Some of the AFT2-regulated genes are known to be regulated by Aft1p; however, AFT2-1up-dependent activation was independent of Aft1p. The kinetics of induction of two genes activated by the AFT2-1up allele are consistent with Aft2p acting as a direct transcriptional factor. Truncated forms of Aft1p and Aft2p bound to a DNA duplex containing the Aft1p binding site in vitro. The wild-type allele of AFT2 activated transcription in response to growth under low-iron conditions. Together, these data suggest that yeast has a second regulatory pathway for the iron regulon, with AFT1 and AFT2 playing partially redundant roles. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Computed
2005-08-13 | E-GEOD-3122 | biostudies-arrayexpress
Project description:Analysis of iron-regulated gene expression in Saccharomyces cerevisiae using cDNA microarrays has identified three putative cell wall proteins that are directly regulated by Aft1p, the major iron-dependent transcription factor in yeast. FIT1, FIT2, and FIT3 (for facilitator of iron transport) were more highly expressed in strains grown in low concentrations of iron and in strains in which AFT1-1(up), a constitutively active allele of AFT1, was expressed. Northern blot analysis confirmed that FIT1, FIT2, and FIT3 mRNA transcript levels were increased 60-230-fold in response to iron deprivation in an Aft1p-dependent manner. Fit1p was localized exclusively to the cell wall by indirect immunofluorescence. Deletion of the FIT genes, individually or in combination, resulted in diminished uptake of iron bound to the siderophores ferrioxamine B and ferrichrome, without diminishing the uptake of ferric iron salts, or the siderophores triacetylfusarinine C and enterobactin. FIT-deletion strains exhibited increased expression of Aft1p target genes as measured by a FET3-lacZ reporter gene or by Arn1p Western blotting, indicating that cells respond to the absence of FIT genes by up-regulating systems of iron uptake. Aft1p activation in FIT-deleted strains occurred when either ferrichrome or ferric salts were used as sources of iron during growth, suggesting that the FIT genes enhance uptake of iron from both sources. Enzymatic digestion of the cell wall resulted in the release of significant amounts of iron from cells, and the relative quantity of iron released was reduced in FIT-deletion strains. Fit1p, Fit2p, and Fit3p may function by increasing the amount of iron associated with the cell wall and periplasmic space. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set
2005-10-22 | GSE3496 | GEO
Project description:Analysis of iron-regulated gene expression in Saccharomyces cerevisiae using cDNA microarrays has identified three putative cell wall proteins that are directly regulated by Aft1p, the major iron-dependent transcription factor in yeast. FIT1, FIT2, and FIT3 (for facilitator of iron transport) were more highly expressed in strains grown in low concentrations of iron and in strains in which AFT1-1(up), a constitutively active allele of AFT1, was expressed. Northern blot analysis confirmed that FIT1, FIT2, and FIT3 mRNA transcript levels were increased 60-230-fold in response to iron deprivation in an Aft1p-dependent manner. Fit1p was localized exclusively to the cell wall by indirect immunofluorescence. Deletion of the FIT genes, individually or in combination, resulted in diminished uptake of iron bound to the siderophores ferrioxamine B and ferrichrome, without diminishing the uptake of ferric iron salts, or the siderophores triacetylfusarinine C and enterobactin. FIT-deletion strains exhibited increased expression of Aft1p target genes as measured by a FET3-lacZ reporter gene or by Arn1p Western blotting, indicating that cells respond to the absence of FIT genes by up-regulating systems of iron uptake. Aft1p activation in FIT-deleted strains occurred when either ferrichrome or ferric salts were used as sources of iron during growth, suggesting that the FIT genes enhance uptake of iron from both sources. Enzymatic digestion of the cell wall resulted in the release of significant amounts of iron from cells, and the relative quantity of iron released was reduced in FIT-deletion strains. Fit1p, Fit2p, and Fit3p may function by increasing the amount of iron associated with the cell wall and periplasmic space.
2005-09-27 | E-SMDB-1593 | biostudies-arrayexpress
Project description:The budding yeast S. cerevisiae responds to depletion of iron in the environment by activating Aft1p, the major iron-dependent transcription factor, and by transcribing systems involved in the uptake of iron. Here we have studied the transcriptional response to iron deprivation, and have identified new Aft1p target genes. We find that other metabolic pathways are regulated by iron: biotin uptake and biosynthesis, nitrogen assimilation, and purine biosynthesis. Two enzymes active in these pathways, biotin synthase and glutamate synthase, require an iron-sulfur cluster for activity. Iron deprivation activates transcription of the biotin importer and simultaneously represses transcription of the entire biotin biosynthetic pathway. Multiple genes involved in nitrogen assimilation and amino acid metabolism are induced by iron deprivation, while glutamate synthase, a key enzyme in nitrogen assimilation, is repressed. A CGG palindrome within the promoter of glutamate synthase confers iron-regulated expression, suggesting control by a transcription factor of the binuclear zinc cluster family. We provide evidence that yeast subjected to iron deprivation undergo a transcriptional remodeling, resulting in a shift from iron-dependent to parallel, but iron-independent, metabolic pathways. A dose response design type examines the relationship between the size of the administered dose and the extent of the response of the organism(s). Keywords: dose_response_design
2006-02-08 | GSE4196 | GEO
Project description:The budding yeast S. cerevisiae responds to depletion of iron in the environment by activating Aft1p, the major iron-dependent transcription factor, and by transcribing systems involved in the uptake of iron. Here we have studied the transcriptional response to iron deprivation, and have identified new Aft1p target genes. We find that other metabolic pathways are regulated by iron: biotin uptake and biosynthesis, nitrogen assimilation, and purine biosynthesis. Two enzymes active in these pathways, biotin synthase and glutamate synthase, require an iron-sulfur cluster for activity. Iron deprivation activates transcription of the biotin importer and simultaneously represses transcription of the entire biotin biosynthetic pathway. Multiple genes involved in nitrogen assimilation and amino acid metabolism are induced by iron deprivation, while glutamate synthase, a key enzyme in nitrogen assimilation, is repressed. A CGG palindrome within the promoter of glutamate synthase confers iron-regulated expression, suggesting control by a transcription factor of the binuclear zinc cluster family. We provide evidence that yeast subjected to iron deprivation undergo a transcriptional remodeling, resulting in a shift from iron-dependent to parallel, but iron-independent, metabolic pathways. A dose response design type examines the relationship between the size of the administered dose and the extent of the response of the organism(s). Using regression correlation
2006-02-07 | E-GEOD-4196 | biostudies-arrayexpress
Project description:Soilborne fungal pathogens cause devastating yield losses, are highly persistent and difficult to control. To culminate infection, these organisms must cope with limited availability of iron. Here we show that the bZIP protein HapX functions as a key regulator of iron homeostasis and virulence in the vascular wilt fungus Fusarium oxysporum. Deletion of hapX does not affect iron uptake, but causes derepression of genes involved in iron-consuming pathways, leading to impaired growth under iron-depleted conditions. F. oxysporum strains lacking HapX are reduced in their capacity to invade and kill tomato plants and immunodepressed mice. The virulence defect of ΔhapX on tomato plants is exacerbated by coinoculation of roots with a biocontrol strain of Pseudomonas putida, but not with a siderophore-deficient mutant, indicating that HapX contributes to iron competition of F. oxysporum in the tomato rhizosphere. These results establish a conserved role for HapX-mediated iron homeostasis in fungal infection of plants and mammals.
2012-07-14 | GSE39325 | GEO
Project description:Iron homeostasis in the yeast Saccharomyces cerevisiae is regulated at the transcriptional level by Aft1p, which activates the expression of its target genes in response to low-iron conditions. The yeast genome contains a paralog of AFT1, which has been designated AFT2. To establish whether AFT1 and AFT2 have overlapping functions, a mutant containing a double aft1aft2 deletion was generated. Growth assays established that the single aft2 strain exhibited no iron-dependent phenotype. However, the double-mutant aft1aft2 strain was more sensitive to low-iron growth conditions than the single-mutant aft1 strain. A mutant allele of AFT2 (AFT2-1up), or overexpression of the wild-type AFT2 gene, led to partial complementation of the respiratory- deficient phenotype of the aft1 strain. The AFT2-1up allele also increased the uptake of 59Fe in an aft1 strain. DNA microarrays were used to identify genes regulated by AFT2. Some of the AFT2-regulated genes are known to be regulated by Aft1p; however, AFT2-1up-dependent activation was independent of Aft1p. The kinetics of induction of two genes activated by the AFT2-1up allele are consistent with Aft2p acting as a direct transcriptional factor. Truncated forms of Aft1p and Aft2p bound to a DNA duplex containing the Aft1p binding site in vitro. The wild-type allele of AFT2 activated transcription in response to growth under low-iron conditions. Together, these data suggest that yeast has a second regulatory pathway for the iron regulon, with AFT1 and AFT2 playing partially redundant roles.
2005-06-29 | E-SMDB-1517 | biostudies-arrayexpress
Project description:Soilborne fungal pathogens cause devastating yield losses, are highly persistent and difficult to control. To culminate infection, these organisms must cope with limited availability of iron. Here we show that the bZIP protein HapX functions as a key regulator of iron homeostasis and virulence in the vascular wilt fungus Fusarium oxysporum. Deletion of hapX does not affect iron uptake, but causes derepression of genes involved in iron-consuming pathways, leading to impaired growth under iron-depleted conditions. F. oxysporum strains lacking HapX are reduced in their capacity to invade and kill tomato plants and immunodepressed mice. The virulence defect of M-NM-^ThapX on tomato plants is exacerbated by coinoculation of roots with a biocontrol strain of Pseudomonas putida, but not with a siderophore-deficient mutant, indicating that HapX contributes to iron competition of F. oxysporum in the tomato rhizosphere. These results establish a conserved role for HapX-mediated iron homeostasis in fungal infection of plants and mammals. Iron dependent gene expression in Fusarium oxysporum wt and M-NM-^ThapX mutant was measured 1 hour after shifting the mycelia to minimal medium with or without 50 M-NM-<M Fe2(SO4)3. Three independent experiments were performed.
2012-07-13 | E-GEOD-39325 | biostudies-arrayexpress