Upstream activating sequence

About: Upstream activating sequence is a research topic. Over the lifetime, 1633 publications have been published within this topic receiving 100112 citations.

Functional binding of the "TATA" box binding component of transcription factor TFIID to the -30 region of TATA-less promoters

Abstract: Many viral and cellular promoters transcribed in higher eukaryotes by RNA polymerase II lack obvious A+T-rich sequences, called "TATA" boxes, that bind the transcription factor TFIID. One such TATA-less promoter, the simian virus 40 major late promoter, contains a genetically important sequence element 30 base pairs upstream of its transcription initiation site that has no obvious sequence similarity to a TATA box. We show here that the cloned human TATA box-binding protein, hTFIID tau, functionally binds to this upstream sequence element, although with an affinity one-sixth of that to which it binds the TATA box of the adenovirus type 2 major late promoter. Analysis of point mutations in the -30 element of the simian virus 40 major late promoter shows that the affinity of binding correlates with the efficiency of transcription from this promoter. Furthermore, this element has genetic properties similar to those of a TATA box. (i) It directs RNA polymerase II to initiate transcription approximately 30 base pairs downstream of its location, and (ii) inactivation of this element results in increased heterogeneity in the sites of transcription initiation. All of five other TATA-less promoters tested were found to contain a sequence approximately 30 base pairs upstream of their major transcription initiation sites to which hTFIID tau binds. We conclude that many, if not all, TATA-less promoters differ from TATA box-containing promoters simply in the affinity of their -30 regions for binding of TFIID, with functional binding of TFIID supported in part by other nearby sequence elements of the promoter.

FIS-dependent trans activation of stable RNA operons of Escherichia coli under various growth conditions.

Abstract: In Escherichia coli transcription of the tRNA operon thrU (tufB) and the rRNA operon rrnB is trans-activated by the protein FIS. This protein, which stimulates the inversion of various viral DNA segments, binds specifically to a cis-acting sequence (designated UAS) upstream of the promoter of thrU (tufB) and the P1 promoter of the rrnB operon. There are indications that this type of regulation is representative for the regulation of more stable RNA operons. In the present investigation we have studied UAS-dependent transcription activation of the thrU (tufB) operon in the presence and absence of FIS during a normal bacterial growth cycle and after a nutritional shift-up. In early log phase the expression of the operon rises steeply in wild-type cells, whereafter it declines. Concomitantly, a peak of the cellular FIS concentration is observed. Cells in the stationary phase are depleted of FIS. The rather abrupt increase of transcription activation depends on the nutritional quality of the medium. It is not seen in minimal medium. After a shift from minimal to rich medium, a peak of transcription activation and of FIS concentration is measured. This peak gets higher as the medium gets more strongly enriched. We conclude that a correlation between changes of the UAS-dependent activation of the thrU (tufB) operon and changes of the cellular FIS concentration under a variety of experimental conditions exists. This correlation strongly suggests that the production of FIS responds to environmental signals, thereby trans-activating the operon. Cells unable to produce FIS (fis cells) also show an increase of operon transcription in the early log phase and after a nutritional shift-up, albeit less pronounced than that wild-type cells. Presumably it is controlled by the ribosome feedback regulatory system. cis activation of the operon by the upstream activator sequence is apparent in the absence of FIS. This activation is constant throughout the entire growth cycle and is independent of nutritional factors. The well-known growth rate-dependent control, displayed by exponentially growing cells studied under various nutritional conditions, is governed by two regulatory mechanisms: repression, presumably by ribosome feedback inhibition, and stimulation by trans activation. FIS allows very fast bacterial growth.

Regulation of a yeast HSP70 gene by a cAMP responsive transcriptional control element.

Abstract: HSP70 genes exhibit complex regulation in response to stress and a variety of cellular and developmental events. The SSA3 HSP70 gene of Saccharomyces cerevisiae is activated at the transcriptional level under conditions of nutrient limitation. Analysis of deletions revealed that cis-acting DNA sequences present immediately upstream and downstream of the previously identified heat shock elements (UASHS) mediate this regulation. A 35 bp region of SSA3, distinct from UASHS, contains sequences capable of activating a heterologous promoter following the diauxic shift and in the stationary phase of the yeast life cycle; this region has been designated an upstream activating sequence, UASPDS. Expression driven by UASPDS is regulated by the RAS/cAMP pathway. Reduced cAMP dependent protein kinase activity results in UASPDS dependent activation of the SSA3 promoter while constitutive cAMP dependent protein kinase activity prevents UASPDS mediated transcription, even under growth conditions that would normally result in full activation. Although the heat shock element alone exhibits no UAS activity under conditions in which UASPDS promotes transcription, UASHS interacts positively with UASPDS to mediate high levels of SSA3 transcription in response to nutrient limitation and lowered intracellular cAMP concentration. This interaction is independent of the precise spacing and relative orientation of the two elements.

Sequence and nuclear localization of the Saccharomyces cerevisiae HAP2 protein, a transcriptional activator.

Abstract: Activation of the CYC1 upstream activation site (UAS2) and other Saccharomyces cerevisiae genes encoding respiratory functions requires the products of the regulatory loci HAP2 and HAP3. We present here the DNA sequence of the yeast HAP2 gene and an initial investigation into the function of its product. The DNA sequence indicated that HAP2 encoded a 265-amino-acid protein whose carboxyl third was highly basic. Also found in the sequence was a polyglutamine tract spanning residues 120 to 133. Several experiments described herein suggest that HAP2 encodes a direct activator of transcription. First, a bifunctional HAP2-beta-galactosidase fusion gene was localized to the yeast nucleus. Second, a lexA-HAP2 fusion gene was capable of activating transcription when bound to a lexA operator site. The additional requirement for the HAP3 product in activation is discussed.