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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The enzymes of the proline utilization pathway (the products of the PUT1 and PUT2 genes) in Saccharomyces cerevisiae are coordinately regulated by proline and the PUT3 transcriptional activator. To learn more about the control of this pathway, constitutive mutations in PUT3 as well as in other regulators were sought. A scheme using a gene fusion between PUT1 (S. cerevisiae proline oxidase) and galK (Escherichia coli galactokinase) was developed to select directly for constitutive mutations affecting the PUT1 promoter. These mutations were secondarily screened for their effects in trans on the promoter of the PUT2 (delta 1-pyrroline-5-carboxylate dehydrogenase) gene by using a PUT2-lacZ (E. coli beta-galactosidase) gene fusion. Three different classes of mutations were isolated. The major class consisted of semidominant constitutive PUT3 mutations that caused PUT2-lacZ expression to vary from 2 to 22 times the uninduced level. A single dominant mutation in a new locus called PUT5 resulted in low-level constitutive expression of PUT2-lacZ; this mutation was epistatic to the recessive, noninducible put3-75 allele. Recessive constitutive mutations were isolated that had pleiotropic growth defects; it is possible that these mutations are not specific to the proline utilization pathway but may be in genes that control several pathways. Since the PUT3 gene appears to have a major role in the regulation of this pathway, a molecular analysis was undertaken. This gene was cloned by functional complementation of the put3-75 mutation. Strains carrying a complete deletion of this gene are viable, proline nonutilizing, and indistinguishable in phenotype from the original put3-75 allele. The PUT3 gene encodes a 2.8-kilobase-pair transcript that is not regulated by proline at the level of RNA accumulation. The presence of the gene on a high-copy-number plasmid did not alter the regulation of one of its target genes, PUT2-lacZ, suggesting that the PUT3 gene product is not limiting and that a titratable repressor is not involved in the regulation of this pathway.
Mol Cell Biol 1989 Nov
PMID:Isolation of constitutive mutations affecting the proline utilization pathway in Saccharomyces cerevisiae and molecular analysis of the PUT3 transcriptional activator. 268 61

PhoB protein is the transcriptional activator for genes in the phosphate regulon of Escherichia coli, such as phoA and pstS, that are induced by phosphate deprivation. PhoR protein activates PhoB when phosphate is limiting and inactivates it when phosphate is in excess. We constructed a plasmid with a mutant phoR gene (phoR1084), which encoded a PhoR protein (PhoR1084) lacking the amino-terminal hydrophobic region of the intact protein. The cells carrying the plasmid overproduced PhoR1084, which was recovered in the soluble fraction of the cell lysate. We purified the Phor1084 protein and showed that it was autophosphorylated in the presence of ATP, and the phosphate group on the protein was rapidly transferred to PhoB. The phosphorylation of PhoB protein occurred concurrently with the acquisition of the ability to activate transcription from the pstS promoter. On the basis of these findings, we propose that phosphorylated PhoB protein activates transcription from the promoters of the phosphate regulon, and that the role of PhoR is to catalyze the formation and breakdown of phosphorylated PhoB in response to phosphate concentrations in the medium.
J Mol Biol 1989 Dec 05
PMID:Signal transduction in the phosphate regulon of Escherichia coli involves phosphotransfer between PhoR and PhoB proteins. 269 38

The FNR protein of E. coli is a transcriptional activator required for the expression of genes involved in anaerobic respiratory pathways. Site-directed mutagenesis was used to alter three amino acids in the recognition helix of the putative DNA-binding domain of FNR, with the aim of changing its specificity to that of the cyclic AMP receptor protein (CRP). In the presence of the mutant protein (FNR-215) expression of the lac operon was activated during anaerobiosis and unaffected by glucose. FNR-215 did not have a uniform effect on the expression of other cAMP-CRP-dependent genes, but the results demonstrate the fundamental similarity between FNR- and CRP-mediated transcriptional activation.
Mol Microbiol 1987 Jul
PMID:Activation of the lac operon of Escherichia coli by a mutant FNR protein. 283 28

Specific cysteine residues at possible methyl acceptor sites of the Ada protein of Escherichia coli were converted to other amino acids by site-directed mutagenesis of the cloned ada gene of E. coli. Ada protein with the cysteine residue at 321 replaced by alanine was capable of accepting the methyl group from the methylphosphotriester but not from O6-methylguanine or O4-methylthymine of alkylated DNA, whereas the protein with alanine at position 69 accepted the methyl group from the methylated bases but not from the methylphosphotriester. These two mutants were used to elucidate the biological significance of repair of the two types of alkylation lesions. Introduction of the ada gene with the Ala69 mutation into an ada- cell rendered the cell more resistant to alkylating agents with respect to both killing and induction of mutations, but the gene with the Ala321 mutation exhibited no such activity. Replacement of the cysteine residue at position 69, but not at position 321, abolished the ability of Ada protein to promote transcription of both ada and alkA genes in vitro. These results are compatible with the idea that methylation of the cysteine residue at position 69 renders Ada protein active as a transcriptional regulator, whilst the cysteine residue at position 321 is responsible for repair of pre-mutagenic and lethal lesions in DNA. The actions of mutant Ada proteins on the ada and alkA promoters in vivo were investigated using an artificially composed gene expression system. When the ada gene with the Ala69 mutation was introduced into the cell, there was little induction of expression of either the ada or the alkA genes, even after treatment with an alkylating agent, in agreement with the data obtained from studies in vitro. With the Ala321 mutation, however, a considerable degree of ada gene expression occurred without adaptive treatment. The latter finding suggests that the cysteine residue at position 321, which is located near the C terminus of the Ada protein, is involved in regulating activity, as the transcriptional activator.
J Mol Biol 1988 May 20
PMID:Functional sites of the Ada regulatory protein of Escherichia coli. Analysis by amino acid substitutions. 304

The DNA sequence UAST (TCGTTTTGTACGTTTTTCA) was found to mediate transcription of yeast ribosomal protein gene TCM1. UAST was defined as a transcriptional activator on the basis of loss of transcription accompanying deletions of all or part of UAST, orientation-independent restoration of transcription promoted by a synthetic UAST oligomer inserted either into TCM1 or into the yeast CYC1 gene lacking its transcriptional activation region, and diminished transcription following nucleotide alterations in UAST. UAST bound in vitro to a protein denoted TAF (TCM1 activation factor); TAF was concluded to be a transcriptional activator protein because nucleotide alterations in UAST that diminished transcription in vivo also diminished TAF binding in vitro. The sequence of UAST bore no obvious resemblance to UASrpg, the principal cis-acting element common to most yeast ribosomal protein genes. Likewise, TAF was distinguished from the UASrpg-binding protein TUF, since (i) TAF and TUF were chromatographically separable, (ii) binding of either TAF or TUF to its corresponding UAS was unaffected by an excess of UASrpg or UAST DNA, respectively, and (iii) photochemical cross-linking experiments showed that TAF was a protein of 147 kilodaltons (kDa), while TUF was detected as an approximately 120-kDa polypeptide, consistent with its known size. Cross-linking experiments also revealed that both UAST and UASrpg bound a second heretofore unobserved 82-kDa protein; binding of this additional protein appeared to require binding of TAF or TUF. On the basis of the biochemical characterization of TAF and a lack of sequence similarity between UAST and UASrpg, we suggest that transcription of TCM1 is mediated by a cis-acting sequence and at least one trans-acting factor different from the elements which promote transcription of most other ribosomal protein genes. A second trans-acting factor may be shared by TCM1 and other ribosomal protein genes; this factor could mediate coordinate regulation of these genes.
Mol Cell Biol 1988 Oct
PMID:Constitutive transcription of yeast ribosomal protein gene TCM1 is promoted by uncommon cis- and trans-acting elements. 305 14

GCN4 encodes a transcriptional activator of amino acid biosynthetic genes in Saccharomyces cerevisiae. The GCN3 product is a positive regulator required for increased synthesis of GCN4 protein in amino acid-starved cells. GCN3 appears to act indirectly by antagonizing GCD-encoded negative regulators of GCN4 expression under starvation conditions; however, GCN3 can also suppress the effects of gcd12 mutations under nonstarvation conditions. These results imply that the GCN3 product can promote either repression or activation of GCN4 expression depending on amino acid availability. We present a complete physical description of the GCN3 gene and its transcript, plus measurements of GCN3 expression at the transcriptional and translational levels under different growth conditions. GCN3 encodes a 305-amino-acid polypeptide with no significant homology to any other known protein sequence. GCN3 mRNA contains no leader AUG codons, and no potential GCN4 binding sites were found in GCN3 5' noncoding DNA. In accord with the absence of these regulatory sequences found at other genes in the general control system, GCN3 mRNA and a GCN3-lacZ fusion enzyme are present at similar levels under both starvation and nonstarvation conditions. These data suggest that modulation of GCN3 regulatory function in response to amino acid availability occurs posttranslationally. A gcn3 deletion leads to unconditional lethality in a gcd1-101 mutant, supporting the idea that GCN3 is expressed under normal growth conditions and cooperates with the GCD1 product under these circumstances to carry out an essential cellular function. We describe a point mutation that adds three amino acids to the carboxyl terminus of GCN3, which inactivates its positive regulatory function required under starvation conditions without impairing its ability to promote functions carried out by GCD12 under nonstarvation conditions.
Mol Cell Biol 1988 Nov
PMID:Molecular analysis of GCN3, a translational activator of GCN4: evidence for posttranslational control of GCN3 regulatory function. 306 70

We previously reported the isolation of yeast mutants that seem to affect the function of certain autonomously replicating sequences (ARSs). These mutants are known as mcm for their defect in the maintenance of minichromosomes. We have now characterized in more detail one ARS-specific mutation, mcm1-1. This Mcm1 mutant has a second phenotype; MAT alpha mcm1-1 strains are sterile. MCM1 is non-allelic to other known alpha-specific sterile mutations and, unlike most genes required for mating, it is essential for growth. The alpha-specific sterile phenotype of the mcm1-1 mutant is manifested by its failure to produce a normal amount of the mating pheromone, alpha-factor. In addition, transcripts of the MF alpha 1 and STE3 genes, which encode the alpha-factor precursor and the alpha-factor receptor, respectively, are greatly reduced in this mutant. These and other properties of the mcm1-1 mutant suggest that the MCM1 protein may act as a transcriptional activator of alpha-specific genes. We have cloned, mapped and sequenced the wild-type and mutant alleles of MCM1, which is located on the right arm of chromosome XIII near LYS7. The MCM1 gene product is a protein of 286 amino acid residues and contains an unusual region in which 19 out of 20 residues are either aspartic or glutamic acid, followed by a series of glutamine tracts. MCM1 has striking homology to ARG80, a regulatory gene of the arginine metabolic pathway located about 700 base-pairs upstream from MCM1. A substitution of leucine for proline at amino acid position 97, immediately preceding the polyanionic region, was shown to be responsible for both the alpha-specific sterile and minichromosome-maintenance defective phenotypes of the mcm1-1 mutant.
J Mol Biol 1988 Dec 05
PMID:Saccharomyces cerevisiae protein involved in plasmid maintenance is necessary for mating of MAT alpha cells. 306 8

In Saccharomyces cerevisiae, 3-amino-1,2,4-triazole (aminotriazole) competitively inhibits the activity of imidazoleglycerolphosphate dehydratase, the product of the HIS3 gene. Wild-type strains are able to grow in the presence of 10 mM aminotriazole because they induce the level of imidazoleglycerolphosphate dehydratase. However, strains containing gcn4 mutations are unable to grow in medium containing aminotriazole because they lack the GCN4 transcriptional activator protein necessary for the coordinate induction of HIS3 and other amino acid biosynthetic genes. Here, we isolated a new gene, designated ATR1, which when present in multiple copies per cell allowed gcn4 mutant strains to grow in the presence of aminotriazole. In wild-type strains, multiple copies of ATR1 permitted growth at extremely high concentrations of aminotriazole (80 mM), whereas a chromosomal deletion of ATR1 caused growth inhibition at very low concentrations (5 mM). When radioactive aminotriazole was added exogenously, cells with multiple copies of ATR1 accumulated less aminotriazole than wild-type cells, whereas cells with the atr1 deletion mutation retained more aminotriazole. Unlike the mammalian mdr or yeast PDR genes that confer resistance to many drugs, ATR1 appears to confer resistance only to aminotriazole. Genetic analysis, mRNA mapping, and DNA sequencing revealed that (i) the primary translation product of ATR1 contains 547 amino acids, (ii) ATR1 transcription is induced by aminotriazole, and (iii) the ATR1 promoter region contains a binding site for the GCN4 activator protein. The deduced amino acid sequence suggests that ATR1 protein is very hydrophobic with many membrane-spanning regions, has several potential glycosylation sites, and may contain an ATP-binding site. We suggest that ATR1 encodes a membrane-associated component of the machinery responsible for pumping aminotriazole (and possibly other toxic compounds) out of the cell.
Mol Cell Biol 1988 Feb
PMID:ATR1, a Saccharomyces cerevisiae gene encoding a transmembrane protein required for aminotriazole resistance. 328 Sep 70

The transcriptional activator ADR1 from Saccharomyces cerevisiae is a postulated DNA-binding protein that controls the expression of the glucose-repressible alcohol dehydrogenase (ADH2). Carboxy-terminal deletions of the ADR1 protein (1,323 amino acids in length) were used to localize its functional regions. The transcriptional activation region was localized to the N-terminal 220 amino acids of ADR1 containing two DNA-binding zinc finger motifs. In addition to the N terminus, a large part of the ADR1 sequence was shown to be essential for complete activation of ADH2. Deletion of the putative phosphorylation region, defined by ADR1c mutations that overcome glucose repression, did not render ADH2 expression insensitive to glucose repression. Instead, this region (amino acids 220 through 253) was found to be required by ADR1 to bypass glucose repression. These results suggest that ADR1c mutations enhance ADR1 function, rather than block an interaction of the putative phosphorylation region with a repressor molecule. Furthermore, the protein kinase CCR1 was shown to affect ADH2 expression when the putative phosphorylation region was removed, indicating that CCR1 does not act solely through this region. A functional ADR1 gene was also found to be necessary for growth on glycerol-containing medium. The N-terminal 506 amino acids of ADR1 were required for this newly identified function, indicating that ADH2 activation and glycerol growth are controlled by separate regions of ADR1.
Mol Cell Biol 1988 May
PMID:Identification of functional regions in the yeast transcriptional activator ADR1. 329 Jun 50

The dosage of the transcriptional activator ADR1 was varied in order to study the regulation of the glucose-repressible alcohol dehydrogenase (ADH II) from Saccharomyces cerevisiae. ADH II activity during glucose growth conditions was shown to increase linearly with increasing ADR1 gene dosage. In contrast, under derepressed growth conditions a 100-fold increase in ADR1 copy number resulted in only a 4-fold increase in ADH II expression. Saturation of ADH II gene expression by ADR1 under derepressed conditions was shown not to result from decreased ADR1 transcription. Increases in ADH2 gene dosage in conjunction with high ADR1 gene dosages resulted in increased ADH II activity, indicating that ADH2 was the limiting factor during derepression. Under glucose-repressed conditions the activator CCR1 was not required for ADR1 activity. During derepression increasing ADR1 dosage could partially compensate for a CCR1 defect. Increasing CCR1 gene dosage, however, had no effect on ADH2 expression regardless of the ADR1 allele present. These results suggest that CCR1 acts through ADR1 in controlling ADH2 expression. It was also observed that high numbers of ADR1, or a few copies of ADR1-5c, substantially increased the cell doubling time under ethanol growth conditions, indicating that increased ADR1 activity is toxic.
Mol Gen Genet 1987 Jun
PMID:The effects of ADR1 and CCR1 gene dosage on the regulation of the glucose-repressible alcohol dehydrogenase from Saccharomyces cerevisiae. 330 3


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