Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The high affinity uptake systems for iron and copper ions in Saccharomyces cerevisiae involve metal-specific permeases and two known cell surface Cu(II) and Fe(III) metalloreductases, Fre1 and Fre2. Five novel genes found in the S. cerevisiae genome exhibit marked sequence similarity to Fre1 and Fre2, suggesting that the homologs are part of a family of proteins related to Fre1 and Fre2. The homologs are expressed genes in S. cerevisiae, and their expression is metalloregulated as is true with FRE1 and FRE2. Four of the homologs (FRE3-FRE6) are specifically iron-regulated through the Aft1 transcription factor. These genes are expressed either in cells limited for iron ion uptake by treatment with a chelator or in cells lacking the high affinity iron uptake system. Expression of FRE3-FRE6 is elevated in AFT1-1 cells and attenuated in aft1 null cells, showing that iron modulation occurs through the Aft1 transcriptional activator. The fifth homolog FRE7 is specifically copper-metalloregulated. FRE7 is expressed in cells limited in copper ion uptake by a Cu(I)-specific chelator or in cells lacking the high affinity Cu(I) permeases. The constitutive expression of FRE7 in MAC1 cells and the lack of expression in mac1-1 cells are consistent with Mac1 being the critical transcriptional activator of FRE7 expression. The 5' promoter sequence of FRE7 contains three copper-responsive promoter elements. Two elements are critical for Mac1-dependent FRE7 expression. Combinations of either the distal and central elements or the central and proximal elements result in copper-regulated FRE7 expression. Spacing between Mac1-responsive sites is important as shown by the attenuated expression of FRE7 and CTR1 when two elements are separated by over 100 base pairs. From the three Mac1-responsive elements in FRE7, a new consensus sequence for Mac1 binding can be established as TTTGC(T/G)C(A/G).
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PMID:Metalloregulation of FRE1 and FRE2 homologs in Saccharomyces cerevisiae. 972 78

Inducible high-affinity copper uptake is key to copper homeostasis in Chlamydomonas reinhardtii. We generated cDNAs and updated gene models for four genes, CTR1, CTR2, CTR3, and COPT1, encoding CTR-type copper transporters in Chlamydomonas. The expression of CTR1, CTR2, and CTR3 increases in copper deficient cells and in response to hypoxia or Ni(2+) supplementation; this response depends on the transcriptional activator CRR1. A copper response element was identified by mutational analysis of the 5' upstream region of CTR1. Functional analyses identify CTR1 and CTR2 as the assimilatory transporters of Chlamydomonas based on localization to the plasma membrane and ability to rescue a Saccharomyces cerevisiae mutant defective in high-affinity copper transport. The Chlamydomonas CTRs contain a novel Cys-Met motif (CxxMxxMxxC-x(5/6)-C), which occurs also in homologous proteins in other green algae, amoebae, and pathogenic fungi. CTR3 appears to have arisen by duplication of CTR2, but CTR3 lacks the characteristic transmembrane domains found in the transporters, suggesting that it may be a soluble protein. Thus, Chlamydomonas CTR genes encode a distinct subset of the classical CTR family of Cu(I) transporters and represent new targets of CRR1-dependent signaling.
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PMID:Two Chlamydomonas CTR copper transporters with a novel cys-met motif are localized to the plasma membrane and function in copper assimilation. 1931 9

Cadmium is a toxic metal and the mechanism of its toxicity has been studied in various model systems from bacteria to mammals. We employed Saccharomyces cerevisiae as a model system to study cadmium toxicity at the molecular level because it has been used to identify the molecular mechanisms of toxicity found in higher organisms. cDNA microarray and Northern blot analyses revealed that cadmium salts inhibited the expression of genes related to copper metabolism. Western blotting, Northern blotting and chromatin immunoprecipitation experiments indicated that CTR1 expression was inhibited at the transcriptional level through direct inhibition of the Mac1 transcriptional activator. The decreased expression of CTR1 results in cellular copper deficiency and inhibition of Fet3 activity, which eventually impairs iron uptake. In this way, cadmium exhibits a negative effect on both iron and copper homoeostasis.
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PMID:Cadmium regulates copper homoeostasis by inhibiting the activity of Mac1, a transcriptional activator of the copper regulon, in Saccharomyces cerevisiae. 2067 Feb 16

To gain insights on the transcriptional switches that modulate proper copper homeostasis in yeast, we have examined in detail functional interactions of the relevant transcriptional activator Mac1. We identified Hir1 transcriptional repressor and histone chaperone as a Mac1-interacting protein. This association directly recruits Hir1 on a Mac1 target, CTR1 promoter, quantitatively under induction conditions. We also found Hir1 interacting directly with a previously unknown partner, the Ssn6 (Cyc8) co-regulator. On the non-induced CTR1 promoter, a Hir1 transcriptional activation function was revealed, in the absence of Ssn6, which was dependent on the presence of Snf2 (Swi2) nucleosome remodeler. Moreover, Ssn6 was identified as a Mac1-dependent prominent repressor of CTR1 transcription, antagonizing Snf2 occupancy. Transcriptional induction by copper depletion was effected by the quantitative recruitment of Snf2 directed mainly by Mac1 and redundantly by the quantitatively accumulated Hir1 and Ssn6 pair. Our analysis showed that the activation-effecting chromatin remodeling of CTR1 was due to Snf2 and not to the Hir1 histone chaperone activity or ability to regulate histone levels and stoichiometry. Following initiation, Hir1 and Snf2, but not Ssn6, were found to associate also with the actively transcribing CTR1 coding region, where Hir1 followed the pattern of the elongating RNA polymerase II. Therefore, we have shown that, at the CTR1 gene, in association with Mac1 DNA-binding transcriptional activator, the distinct and alternate genetic and physical collaboration of three global regulators modulates the transcriptional state of a switch involved in copper homeostasis.
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PMID:Synergy of Hir1, Ssn6, and Snf2 global regulators is the functional determinant of a Mac1 transcriptional switch in S. cerevisiae copper homeostasis. 3068 22

While it is known that ScRad9 DNA damage checkpoint protein is recruited to damaged DNA by recognizing specific histone modifications, here we report a different way of Rad9 recruitment on chromatin under non DNA damaging conditions. We found Rad9 to bind directly with the copper-modulated transcriptional activator Mac1, suppressing both its DNA binding and transactivation functions. Rad9 was recruited to active Mac1-target promoters (CTR1, FRE1) and along CTR1 coding region following the association pattern of RNA polymerase (Pol) II. Hir1 histone chaperone also interacted directly with Rad9 and was partly required for its localization throughout CTR1 gene. Moreover, Mac1-dependent transcriptional initiation was necessary and sufficient for Rad9 recruitment to the heterologous ACT1 coding region. In addition to Rad9, Rad53 kinase also localized to CTR1 coding region in a Rad9-dependent manner. Our data provide an example of a yeast DNA-binding transcriptional activator that interacts directly with a DNA damage checkpoint protein in vivo and is functionally restrained by this protein, suggesting a new role for Rad9 in connecting factors of the transcription machinery with the DNA repair pathway under unchallenged conditions.
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PMID:Distinct associations of the Saccharomyces cerevisiae Rad9 protein link Mac1-regulated transcription to DNA repair. 3178 68