Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As part of a study of transcriptional regulation by viral proteins, we examined whether an acidic region from a regulatory protein of an RNA virus could function as a trans-activator. The NH2-terminal highly acidic domain I of the phosphoprotein (P) of vesicular stomatitis virus (VSV) was fused to the DNA-binding domain of the yeast trans-activator, GAL4. In transient transfection assays, the resulting chimeric protein failed to activate transcription of a reporter CAT gene. However, mutation of basic amino acid residues located at positions 6 and 8 or the alteration of eight amino acids within the acidic domain to eight different amino acids converted the chimeric protein into a transcriptional activator comparable to wild-type GAL4. When subjected to SDS-polyacrylamide gel electrophoresis, the P proteins containing trans-activation-positive mutations in domain I showed an altered mobility, suggesting that these mutations may have caused a conformational change that is critical for trans-activation. Since the acidity of P domain I is not sufficient to activate transcription, additional features of this region must play an important role in GAL4-mediated trans-activation. None of the trans-activation-positive mutants supported VSV RNA transcription in vitro. These results suggest that the amino acid residues within P domain I that can be made to function in the trans-activation of DNA-dependent RNA transcription are distinct from those involved in VSV RNA-dependent RNA transcription.
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PMID:Alteration of specific amino acid residues in the acidic domain I of VSV phosphoprotein (P) converts a GAL4-P(I) hybrid into a transcriptional activator. 165 11

Activating region I of GAL4 protein is a stretch of amino acids, positioned adjacent to the DNA-binding region, that activates transcription in yeast and, as we show here, in mammalian cells. Here we describe mutations located throughout a 65-amino acid region that increase the activation function of region I. Most of these mutations replace positively charged amino acids in the region with neutral ones, although we also describe substitutions at one position that do not alter the charge of the region. Mutations of region I that alter the activation function in yeast have similar effects on activation when assayed in mammalian cells. When individual mutations that raise the acidity of the activating region are recombined, the activities of the mutant proteins increase with increasing negative charge in both yeast and mammalian cells. These results extend and modify the correlation between acidity and activation and suggest that the requirements for a strong activating region are conserved in yeast and mammals.
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PMID:Mutations that increase the activity of a transcriptional activator in yeast and mammalian cells. 217 50

Activating region I of GAL4 has been defined as a region 48 amino acids long which, when attached to GAL4's DNA-binding domain, activates transcription in yeast. Here we describe mutants bearing changes in and around this highly acidic activating region. We find mutations that increase the activation function invariably increase the acidity of the region and some but not all of the mutations that decrease the activation function decrease the acidity of the region.
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PMID:Mutants of GAL4 protein altered in an activation function. 311 92

Gene activation by a DNA-binding regulatory protein in yeast requires the protein to have two components: one to recognize a specific DNA sequence and a second, the 'activating region', to interact with a general transcription factor or perhaps with RNA polymerase. The activating regions that have been characterized are acidic, and mutational analysis of one indicates that this acidity is important for activity. Here we report the design of an artificial protein bearing a novel 15-amino acid peptide linked to a DNA binding fragment of the yeast regulatory protein GAL4). The synthetic peptide is acidic and should it form an alpha-helix, that helix would be amphipathic, having one hydrophilic face bearing the acidic residues, and one hydrophobic face. When expressed in yeast, the artificial protein bearing this peptide efficiently activates the GAL1 gene which is ordinarily activated by GAL4. An otherwise identical protein with the novel 15 amino acids in a scrambled order, and which is thus unable to form an amphipathic structure, does not activate GAL1 transcription.
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PMID:Transcription in yeast activated by a putative amphipathic alpha helix linked to a DNA binding unit. 331 67

AFLR, a DNA-binding protein of 444 amino acids, transactivates the expression of aflatoxin biosynthesis genes in Aspergillus parasiticus and Aspergillus flavus, as well as the sterigmatocystin synthesis genes in Aspergillus nidulans. We show here by fusion of various aflR coding regions to the GAL4 DNA-binding coding region that the AFLR carboxyl terminus contained a region that activated GAL1::lacZ gene expression in Saccharomyces cerevisiae and that the AFLR internal region was required for the activation activity. Compared to the AFLR carboxy-terminal fusion protein (AFLRC), a mutant AFLRC retained approximately 75% of the activation activity after deletion of three acidic amino acids, Asp365, Glu366, and Glu367, in a previously identified acidic stretch. Removal of the carboxy-terminal amino acid, Glu444, did not affect the activation activity. Substitutions of acidic Glu423, Asp439, or Asp436/Asp439 with basic amino acids, Lys and His, resulted in 10- to 15-fold-lower activation activities. Strikingly, the Asp436His mutation abolished the activation activity. Substitutions of basic His428 and His442 with acidic Asp resulted in 20 and 40% decreases in the activation activities, respectively. Simultaneous substitutions of Arg427, Arg429, and Arg431 with Leu also significantly decreased the activation activity; the decrease was approximately 50-fold. Results suggest that the AFLR carboxy-terminal region is involved in transcription activation and that total acidity in this region is not a major determinant of AFLR's activation ability in S. cerevisiae.
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PMID:The carboxy-terminal portion of the aflatoxin pathway regulatory protein AFLR of Aspergillus parasiticus activates GAL1::lacZ gene expression in Saccharomyces cerevisiae. 1034 35