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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.
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TL;DR: It is concluded that A-tracts function as UP elements, stimulating transcription by providing binding site(s) for the RNAP alphaCTD, and it is suggested that these interactions could contribute to the previously described wrapping of promoter DNA around RNAP.
Abstract: Upstream A-tracts stimulate transcription from a variety of bacterial promoters, and this has been widely attributed to direct effects of the intrinsic curvature of A-tract-containing DNA. In this work we report experiments that suggest a different mechanism for the effects of upstream A-tracts on transcription. The similarity of A-tract-containing sequences to the adenine- and thymine-rich upstream recognition elements (UP elements) found in some bacterial promoters suggested that A-tracts might increase promoter activity by interacting with the α subunit of RNA polymerase (RNAP). We found that an A-tract-containing sequence placed upstream of the Escherichia coli lac or rrnB P1 promoters stimulated transcription both in vivo and in vitro, and that this stimulation required the C-terminal (DNA-binding) domain of the RNAP α subunit. The A-tract sequence was protected by wild-type RNAP but not by α-mutant RNAPs in footprints. The effect of the A-tracts on transcription was not as great as that of the most active UP elements, consistent with the degree of similarity of the A-tract sequence to the UP element consensus. A-tracts functioned best when positioned close to the −35 hexamer rather than one helical turn farther upstream, similar to the positioning optimal for UP element function. We conclude that A-tracts function as UP elements, stimulating transcription by providing binding site(s) for the RNAP αCTD, and we suggest that these interactions could contribute to the previously described wrapping of promoter DNA around RNAP.
112 citations
TL;DR: The results reveal that the GCLM promoter includes two functional AREs, one having a variant sequence and indicates that the consensus ARE sequence should be revised to 5′-RTKAYnnnGCR-3′.
112 citations
TL;DR: Findings implicate HMG-I in the regulation of constitutive lymphotoxin gene expression in PD and PD31 cells by altering chromatin structure and/or by creating recognition sites for other activator DNA-binding proteins, some of which may be unique to or uniquely modified in these constitutive LT mRNA producers.
Abstract: Lymphotoxin (LT; also known as tumor necrosis factor-beta) is a pleiotropic cytokine whose expression is tightly regulated in most cells and is repressed prior to activation signals. In some early B cells and Abelson murine leukemia virus-transformed pre-B-cell lines, LT mRNA is constitutively expressed. To examine the molecular regulation of the LT gene in a constitutively expressing cell line, we studied the Abelson murine leukemia virus-transformed lines PD and PD31. As demonstrated by primer extension analysis, constitutively expressed pre-B-cell-derived and inducibly expressed T-cell-derived LT mRNA were initiated at the same cap sites and predominant cap site utilization was conserved. Furthermore, we delineated an upstream activating sequence that was an important functional component of lymphotoxin transcriptional activation in PD and PD31 cells. The upstream activating sequence was localized to an essentially homopolymeric A + T-rich region (LT-612/-580), which was bound specifically by recombinant human high-mobility group I protein (HMG-I) and a PD/PD31 nuclear extract HMG-I (HMG-I-like) protein. The nuclear extract-derived HMG-I-like protein was recognized by anti-HMG-I antibody and bound to LT DNA to effect an electrophoretic mobility shift identical to that of bound recombinant human HMG-I. These findings implicate HMG-I in the regulation of constitutive lymphotoxin gene expression in PD and PD31 cells. HMG-I and HMG-I-like proteins could facilitate the formation of active initiation complexes by altering chromatin structure and/or by creating recognition sites for other activator DNA-binding proteins, some of which may be unique to or uniquely modified in these constitutive LT mRNA producers.
112 citations
TL;DR: This connection between biochemical and genetic studies reveals that mediator is important for both activation and repression of transcription, and that mediators plays a role in transcriptional regulation in vivo as well as in vitro.
111 citations
TL;DR: These transgenic Drosophila melanogaster lines that express green fluorescent protein (GFP) exclusively in the nervous system provide an unprecedented view of the nervousSystem in living animals and will be valuable tools for investigating a number of developmental, physiological, and genetic neurobiological problems.
Abstract: We have constructed transgenic Drosophila melanogaster lines that express green fluorescent protein (GFP) exclusively in the nervous system. Expression is controlled with transcriptional regulatory elements present in the 5′ flanking DNA of the Drosophila Na+,K+-ATPase β-subunit gene Nervana2 (Nrv2). This regulatory DNA is fused to the yeast transcriptional activator GAL4, which binds specifically to a sequence motif termed the UAS (upstream activating sequence). Drosophila lines carrying Nrv2-GAL4 transgenes have been genetically recombined with UAS–GFP (S65T) transgenes (Nrv2-GAL4+UAS–GFP) inserted on the same chromosomes. We observe strong nervous system-specific fluorescence in embryos, larvae, pupae, and adults. The GFP fluorescence is sufficiently bright to allow dynamic imaging of the nervous system at all of these developmental stages directly through the cuticle of live Drosophila. These lines provide an unprecedented view of the nervous system in living animals and will be valuable tools for investigating a number of developmental, physiological, and genetic neurobiological problems.
111 citations