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Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of molecules have recently been described that effect the correct transport and assembly of cytoplasmically synthesized proteins to cellular membranes. To identify proteins that bind or modify other proteins during the process of membrane translocation, we developed a yeast selection scheme that employs the yeast transcriptional activator GAL4. This selection facilitates the isolation of cDNAs that encode proteases and binding proteins for known target peptide sequences. We report the isolation of an Arabidopsis cDNA encoding a polypeptide that can interact with the amino terminus of a ligh-harvesting chlorophyll a/b-binding protein (LHCP), a cytoplasmically synthesized protein that is integral to the chloroplast thylakoid membrane. The cDNA was selected in yeast from an Arabidopsis expression library for its ability to inhibit a transcriptional activator GAL4-LHCP fusion protein, but not inhibit native GAL4 protein. The LHCP amino-terminal sequences included in the fusion protein are known to regulate LHCP biogenesis and function. The Arabidopsis cDNA encodes a 595-amino acid protein with at least two functional domains, one with similarity to the family of protein-serine/threonine kinases and another that contains an epidermal growth factor repeat. The identification of an EGF repeat in Arabidopsis indicates that the motif is conserved between the plant and animal kingdoms. Hybridization studies indicate that this gene is likely to be present in other genera of plants. Its mRNA is detected in green leaves but not in other plant tissues or in etiolated plants. The specificity in yeast and the expression pattern in plants together are suggestive of a role for this protein kinase in the assembly or regulation of LHCP.
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PMID:An Arabidopsis serine/threonine kinase homologue with an epidermal growth factor repeat selected in yeast for its specificity for a thylakoid membrane protein. 143 3

OmpR is a transcriptional activator for the ompF and ompC genes of Escherichia coli. Its phosphorylation is mediated by a transmembrane sensory-receptor protein, EnvZ, and is essential for transcriptional activation. In a previous study, when the aspartic acid residue at position 55, the putative phosphorylation site, was replaced with glutamine (D55Q), ompF and ompC expression were completely lost. In this study two pseudorevertants of the D55Q mutation were isolated and identified to be the replacement of threonine at position 83 with alanine (T83A) and glycine at position 94 with serine (G94S). The revertant OmpRs no longer responded to EnvZ function when ompF and ompC expression were examined. The purified D55Q-T83A OmpR was unable to be phosphorylated by EnvZ in vitro. The role of EnvZ as an osmosensor for the environmentally regulated expression of OmpF and OmpC has been indicated in previous studies. The isolation of seemingly EnvZ-independent OmpR revertants in this study, however, made it possible to examine the osmolarity-regulated expression of OmpF and OmpC in the absence of effects exerted by EnvZ. We found that the expression of OmpF and OmpC supported by these revertant OmpRs was clearly regulated in accordance with the change in osmolarity of the growth media. These results indicate that another EnvZ-independent mechanism(s) may also contribute to the regulated expression of the ompF and ompC genes.
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PMID:Intramolecular second-site revertants to the phosphorylation site mutation in OmpR, a kinase-dependent transcriptional activator in Escherichia coli. 164 88

Mutations in Vp1 and ABl3 genes of maize and Arabidopsis lead to drastic reductions in the synthesis of a subset of maturation-specific products including seed storage proteins. Gene Phaseolus vulgaris ABl3-like factor (PvAlf), whose protein product is similar to the ABl3 and Vp1 proteins, has been cloned. Here, it is shown that PvAlf positively regulates phaseolin and phytohemagglutinin (PHA-L) promoters in particle bombardment assays. PvAlf mRNA expression is embryo-specific and temporally complex. PvAlf mRNA abundance is highest during two periods (9-14 and 22-35 days after flowering) that precede the onsets of seed maturation and seed abscission, respectively. Protein fusions with the DNA-binding domain of the yeast transcriptional activator GAL4 demonstrated that the N-terminal 243 amino acids of PvAlf function as a strong transcriptional activation domain in yeast (Saccharomyces cerevisiae) and plant cells. This domain consists of a central cluster rich in serine, threonine and proline (STP cluster) flanked by two negatively charged regions containing bulky hydrophobic residues similar to acidic activation domains of Vp1, the herpes simplex virus virion protein VP16 and transcription factors GCN4 and HAP4 from yeast. Together with the Vp1 proteins of maize and rice and ABl3, PvAlf constitutes a class (Vp1/ABl3-like factors or VAlfs) of regulatory factors that are pivotal for the promotion of seed maturation and dormancy in angiosperms.
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PMID:PvAlf, an embryo-specific acidic transcriptional activator enhances gene expression from phaseolin and phytohemagglutinin promoters. 755 Mar 72

Alveolar rhabdomyosarcoma (ARMS) is characterized cytogenetically by a t(2;13)(q35;q14) chromosomal translocation involving two transcription factor genes: PAX3 and FKHR. ARMS cells express a PAX3-FKHR fusion protein containing the complete N-terminal, DNA-binding domain of PAX3 and the C-terminus of FKHR. Recently we demonstrated that PAX3-FKHR is a more potent transcriptional activator than PAX3 despite impaired binding to canonical PAX3 binding sites. Therefore, we propose that the gene fusion results in switching of PAX3 and FKHR transactivation domains with distinct structure, potency or function. To compare the PAX3 and putative PAX3-FKHR transactivation domains, we fused C-terminal test fragments to the heterologous GAL4 DNA-binding domain and tested activation of a reporter gene co-transfected into four cell types. GAL4-PAX3 and GAL4-PAX3-FKHR were found to be potent activators exhibiting different concentration-dependent transactivation profiles and distinct structural motifs. Deletion mapping demonstrated essential acidic and/or serine/threonine-rich domains in the extreme 3' ends of their respective coding regions and positive modifying elements in adjacent 5' sequences. These data demonstrate that PAX3 and PAX3-FKHR contain structurally distinct transcriptional activation domains and suggest that a consequent difference in function is important for oncogenesis.
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PMID:Wild type PAX3 protein and the PAX3-FKHR fusion protein of alveolar rhabdomyosarcoma contain potent, structurally distinct transcriptional activation domains. 762 19

In both Salmonella typhimurium and Escherichia coli, CysB is a LysR family transcriptional activator, which regulates genes of the cysteine regulon. Transcription activation of cys genes also requires an inducer, N-acetyl-L-serine, and cysB mutants that do not require inducer are termed constitutive, i.e. cysBc. After finding that two independently isolated cysBc mutants are substituted at amino acid residue threonine-149 (T149), we isolated the other 17 single-amino-acid substitutions by site-directed mutagenesis. Of the 19 mutant alleles, 11 supported normal growth on sulphate, and nine of these were cysBc. Four other mutants were 'leaky' cysB+, and four were cysB-. Insertions of up to 14 amino acids were also tolerated at T149, and two of three such mutants were cysBc. An allele containing a TAG translation terminator at codon 149 had no detectable function in a delta cysB strain, but gave a constitutive phenotype when introduced into either wild-type S. typhimurium or the E. coli strain NK1, which contains a cysB- mutation in a predicted helix-turn-helix region that interferes with specific binding of CysB to DNA and with autoregulation of cysB. The peptide encoded by the T149ter allele is proposed to interact with the wild-type CysB peptide or with the NK1 mutant peptide to form hetero-oligomers that do not require N-acetyl-L-serine for cys gene activation.
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PMID:Residue threonine-149 of the Salmonella typhimurium CysB transcription activator: mutations causing constitutive expression of positively regulated genes of the cysteine regulon. 781 39

The single-minded gene functions as a master developmental regulator within the midline cell lineage of the embryonic central nervous system of Drosophila melanogaster. Genetic experiments suggest that Single-minded can function as a transcriptional activator. Regions of the Single-minded protein were fused to the DNA binding domain of the mammalian transcription factor Sp1 and shown to activate transcription from a reporter gene linked to Sp1 binding sites. Three independent activation domains were identified in the carboxy terminal region of Single-minded that include areas rich in serine, threonine, glutamine and proline residues. Germ line transformation experiments indicate that the carboxy terminal activation domains, the PAS dimerization domain, and the putative DNA binding basic domain of Single-minded are required for expression of CNS midline genes in vivo. These results define in vivo a functional activation domain within Single-minded and suggest a model in which Single-minded activates transcription through a direct interaction with promoter elements of CNS midline genes.
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PMID:Transcriptional activation domains of the single-minded bHLH protein are required for CNS midline cell development. 801 58

Resistance to multiple antibiotics and certain oxidative stress compounds was conferred by three independently selected mutations (marR1, soxQ1, and cfxB1) that mapped to 34 min on the Escherichia coli chromosome. Mutations at this locus can activate the marRAB operon, in which marR encodes a putative repressor of mar transcription and marA encodes a putative transcriptional activator of defense genes against antibiotics and oxidants. Overexpression of the wild-type MarR protein reversed the phenotypes (antibiotic resistance and increased antioxidant enzyme synthesis) of all three mutants. DNA sequence analysis showed that, like marR1, the other two mutations were alterations of marR: a 285-bp deletion in cfxB1 and a GC-->AT transition at codon 70 (Ala-->Thr) in soxQ1. All three mutations cause increased amounts of mar-specific RNA, which supports the hypothesis that MarR has a repressor function in the expression of the marRAB operon. The level of mar RNA was further induced by tetracycline in both the marR1 and soxQ1 strains but not in the cfxB1 deletion mutant. In the cfxB1 strain, the level of expression of a truncated RNA, with or without tetracycline exposure, was the same as the fully induced level in the other two mutants. Overproduction of MarR in the cfxB1 strain repressed the transcription of the truncated RNA and restored transcriptional inducibility by tetracycline. Thus, induction of the marRAB operon results from the relief of the repression exerted by MarR. The marRAB operon evidently activates both antibiotic resistance and oxidative stress genes.
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PMID:Repressor mutations in the marRAB operon that activate oxidative stress genes and multiple antibiotic resistance in Escherichia coli. 828 90

Heat shock proteins of the 82-90 kDa class (hsp82 and hsp90) are abundant, conserved, and ubiquitous from prokaryotes to eukaryotes. Although proposed to be chaperones, they had not been reported to possess enzymatic activity until our recent observation that pure trypanosomatid hsp83 had potent ATPase activity (Nadeau, K., Sullivan, M., Engman, D., and Walsh, C. T. (1992) Protein Sci. 1, 970-979). We have now purified the hsp90 homolog from Escherichia coli (HtpG) and from Saccharomyces cerevisiae (hsp82) to homogeneity and observe ATPase activity with kcat values of 3 min-1 and 140 min-1. In addition, examinations of purified rat hsp90 and human hsp90 detect ATPase activity with a kcat of 0.6 min-1 and 10 min-1. Each of these hsp90s undergoes autophosphorylation on serine or threonine residues. In prokaryotes and eukaryotes, the induction of hsps during heat shock is controlled, respectively, by the binding of an alternate sigma 32 or a transcriptional activator (heat shock factor or HSF) at heat shock promoter elements. Here we show that E. coli HtpG immobilized to Affi-Gel beads selectively retains sigma 32 while the yeast hsp90 and rat hsp90 retain HSF. The peptidyl prolyl isomerase hsp59 of the FK506 binding class is known to bind to hsp90. We also detect binding of the other family of PPIases, the cyclophilins, to immobilized hsp90, consistent with a functional convergence of protein foldases.
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PMID:Hsp90 chaperonins possess ATPase activity and bind heat shock transcription factors and peptidyl prolyl isomerases. 841 47

Pseudohyphal differentiation in Saccharomyces cerevisiae was first described as a response of diploid cells to nitrogen limitation. Here we report that haploid and diploid starch-degrading S. cerevisiae strains were able to switch from a yeast form to a filamentous pseudohyphal form in response to carbon limitation in the presence of an ample supply of nitrogen. Two genes, MSS10 and MUC1, were cloned and shown to be involved in pseudohyphal differentiation and invasive growth. The deletion of MSS10 resulted in extremely reduced amounts of pseudohyphal differentiation and invasive growth, whereas the deletion of MUC1 abolished pseudohyphal differentiation and invasive growth completely. Mss10 appears to be a transcriptional activator that responds to nutrient limitation and coregulates the expression of MUC1 and the STA1-3 glucoamylase genes, which are involved in starch degradation. MUC1 encodes a 1367-amino acid protein, containing several serine/threonine-rich repeats. Muc1 is a putative integral membrane-bound protein, similar to mammalian mucin-like membrane proteins that have been implicated to play a role in the ability of cancer cells to invade other tissues.
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PMID:Muc1, a mucin-like protein that is regulated by Mss10, is critical for pseudohyphal differentiation in yeast. 871 Aug 86

We isolated a cDNA clone, Elk-3, that encodes a novel Ets transcription factor from 16-day mouse embryos. The deduced amino acid sequence of the protein was homologous to human ELK-1 and SAP-1. This protein, ELK-1, and SAP-1 shared some unique structural properties such as an Ets DNA-binding site in the amino-terminal region, a serum response factor interacting domain and phosphorylation sites of serine or threonine residues in the carboxy-terminal region. Northern blotting weakly revealed that two transcripts of 4 and 2.1 kb are expressed in the adult ovary and lung and a 2.1-kb transcript predominated in 8- to 14-day embryos. We assayed the transcriptional activities of Elk-3 protein on the cytokeratin EndoA enhancer containing Ets binding sites in endodermal cells. Elk-3 protein strongly repressed enhancer activity but did not affect the activity of the basal promoter in the absence of the enhancer. Furthermore, Elk-3 can suppress the activity of Ets-2 as the transcriptional activator on the EndoA enhancer. These data suggested that the Elk-3 gene product plays a role in transcriptional regulation during embryogenesis.
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PMID:Molecular cloning of Elk-3, a new member of the Ets family expressed during mouse embryogenesis and analysis of its transcriptional repression activity. 889 57


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