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

The upstream activator (UAS) of the yeast PGK gene comprises three different sequence elements. These are 1) a region of strong protein binding called the YFP, 2) three repeats of the motif CTTCC and 3) an essential activator core (AC) sequence that binds the protein RAP1. To assess the function of each of these elements in transcriptional activation we have inserted them individually and in various combinations into a PGK mini-promoter. This comprises only the transcription initiation elements from the PGK promoter and is inactive in the absence of activator sequences. None of the individual sequence elements was capable of activating the mini-promoter. However either the YFP or the CTTCC boxes in conjunction with the AC box resulted in efficient expression. Transcription levels were not however as high as when all three elements were inserted. These data suggest that the efficiency of PGK transcription depends upon the interactions between three different sequences. Furthermore while RAP1 per se is not a transcriptional activator it can associate promiscuously with other factors to create a functional transcription complex.
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PMID:Characterization of the transcriptional potency of sub-elements of the UAS of the yeast PGK gene in a PGK mini-promoter. 268 57

The UAS (upstream activator sequence) of the yeast PGK gene contains a transcriptional activator domain located between bases -479 and -402 upstream from the initiating ATG. This region of the UAS contains three direct repeats of the sequence 5'CTTCC3'. The roles in transcriptional activation of these repeats and other sequences within the activator domain were investigated. When short regions containing the repeats were removed PGK expression was considerably reduced, the magnitude of the effect depended upon which CTTCC block was absent. Sequences between -473 and -458 which did not contain a CTTCC block were also shown to be necessary for high levels of PGK expression. A DNA fragment containing activator sequences up to -473 was shown to interact specifically in vitro with a yeast nuclear protein extract. DNase I footprinting identified a protected region between -473 and -458 and single base changes in DNase I sensitivity at the CTTCC repeats.
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PMID:The UAS of the yeast PGK gene is composed of multiple functional elements. 304 80

Promoter analysis was performed on the Rhizopus niveus 3-phosphoglycerate kinase 2-encoding gene (pgk2), one of the two pgk genes (pgk1 and pgk2) from this filamentous fungus sequenced so far. Deletion mutants of the promoter region were fused to the Escherichia coli uidA gene (which codes for beta-glucuronidase; GUS), and introduced into R. niveus to measure the intracellular GUS activities of the transformants. Deletion of the sequence between nt -174 to -133 (numbers indicate the position from the putative translation start codon) caused a significant decrease in the ratio of the GUS activity of the transformant cultured in glucose medium compared to that in glycerol medium. In this region, a 21-nt sequence which is well conserved between pgk1 and pgk2 is present. When it was inserted into the promoter region of the uninducible gene encoding RNase Rh of R. niveus, ligated in front of uidA and introduced into R. niveus, the GUS activity of the transformant was greatly induced by glucose, but less by glycerol. We therefore suggest that the 21-nt sequence is a glucose-inducible transcriptional activator of R. niveus. This is the first report on a transcriptional activator in zygomycetes.
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PMID:Analysis of the 3-phosphoglycerate kinase 2 promoter in Rhizopus niveus. 782 18

During autotrophic growth of Xanthobacter flavus, energy derived from the oxidation of hydrogen methanol or formate is used to drive the assimilation of CO2 via the Calvin cycle. The genes encoding the Calvin cycle enzymes are organized in the cbb operon, which is expressed only during autotrophic growth. Although it has been established that the transcriptional activator CbbR is required for the expression of the cbb operon, it is unclear whether CbbR is the only factor contributing to the regulation of the cbb operon. This paper describes the isolation of X. flavus mutants which were affected in the regulation of the cbb operon. One of the mutant strains was subject to an enhanced repression of the cbb operon promoter by the gluconeogenic substrate succinate and in addition failed to grow autotrophically. The rate of growth of the X. flavus mutant on succinate-containing medium was lower than that of the wild-type strain, but rates of growth on medium supplemented with gluconate were identical. A genomic library of X. flavus was constructed and was used to complement the mutant strain. The nucleotide sequence of the DNA fragment required to restore autotrophic growth of the X. flavus mutant was determined. One open reading frame that displayed extensive similarities to phosphoglycerate kinase-encoding genes (pgk) was identified. The X. flavus mutant lacked phosphoglycerate kinase activity following growth on gluconate or succinate. Introduction of the pgk gene into the X. flavus mutant partially restored the activity of phosphoglycerate kinase. Induction of the cbb operon of the X. flavus wild-type strain resulted in a simultaneous and parallel increase in the activities of ribulose-1,5-biphosphate carboxylase and phosphoglycerate kinase, whereas the latter activity remained absent in the X. flavus pgk mutant. It is concluded that X. flavus employees a single phosphoglycerate kinase enzyme and this is not encoded within the cbb operon.
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PMID:The Calvin cycle enzyme phosphoglycerate kinase of Xanthobacter flavus required for autotrophic CO2 fixation is not encoded by the cbb operon. 792 74

In a previous study, a gene (pgk) encoding phosphoglycerate kinase was isolated from a genomic library of Xanthobacter flavus. Although this gene is essential for autotrophic growth, it is not located within the cbb operon encoding other Calvin cycle enzymes. An analysis of the nucleotide sequence upstream from pgk showed the presence of a gene encoding glyceraldehyde-3-phosphate dehydrogenase and the 3' end of an open reading frame encoding a protein which is 50% identical to transketolase encoded by cbbT of X. flavus. Gene fusions between pgk and lacZ demonstrated that the gap and pgk genes are organized in an operon. Induction of the Calvin cycle in heterotrophically growing cells resulted in a sixfold increase in phosphoglycerate kinase activity in parallel with the appearance of ribulosebisphosphate carboxylase activity. This superinduction of phosphoglycerate kinase did not occur in an X. flavus strain in which cbbR, encoding the transcriptional activator of the cbb operon, was disrupted. The failure to superinduce the gap-pgk operon is not caused by the absence of a functional Calvin cycle, since the expression of this operon in an X. flavus strain with a defective ribulosebisphosphate carboxylase enzyme was the same as the expression in the wild type. It is therefore concluded that the expression of both the cbb and gap-pgk operons is controlled by CbbR.
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PMID:Induction of the gap-pgk operon encoding glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase of Xanthobacter flavus requires the LysR-type transcriptional activator CbbR. 855 May 26

Constitutive promoters are used routinely to drive ectopic gene expression. Here, we carried out a systematic comparison of eight commonly used constitutive promoters (SV40, CMV, UBC, EF1A, PGK and CAGG for mammalian systems, and COPIA and ACT5C for Drosophila systems). We also included in the comparison the TRE promoter, which can be activated by the rtTA transcriptional activator in a doxycycline-inducible manner. To make our findings representative, we conducted the comparison in a variety of cell types derived from several species. We found that these promoters vary considerably from one another in their strength. Most promoters have fairly consistent strengths across different cell types, but the CMV promoter can vary considerably from cell type to cell type. At maximal induction, the TRE promoter is comparable to a strong constitutive promoter. These results should facilitate more rational choices of promoters in ectopic gene expression studies.
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PMID:Systematic comparison of constitutive promoters and the doxycycline-inducible promoter. 2048 54