Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The E. coli rrnB P1 promoter owes its strength, in part, to the transcriptional activator protein FIS. FIS binds to three sites upstream of the RNA polymerase (RNAP) binding site and increases transcription in vivo four to ten-fold. In this report, hydroxyl radical and DMS footprinting analyses show that FIS binds to its three sites along one side of the DNA helix, and that FIS bound at the promoter-proximal site (site I) and RNAP bound at the promoter are in close proximity. The binding of FIS at site I and RNAP at the promoter are mutually cooperative. These observations support a model for direct interaction between the FIS protein bound at site I and RNAP in transcription activation at rrnB P1. We also find that FIS does not bind cooperatively to its three sites upstream of rrnB P1, and that the relatively small activation associated with FIS bound at sites II and III does not result indirectly by facilitation of binding of FIS to site I.
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PMID:The transcriptional activator protein FIS: DNA interactions and cooperative interactions with RNA polymerase at the Escherichia coli rrnB P1 promoter. 784 12

FIS (factor for inversion stimulation) is a small dimeric DNA-bending protein which both stimulates DNA inversion and activates transcription at stable RNA promoters in Escherichia coli. Both these processes involve the initial formation of a complex nucleoprotein assembly followed by local DNA untwisting at a specific site. We have demonstrated previously that at the tyrT promoter three FIS dimers are required to form a nucleoprotein complex with RNA polymerase. We now show that this complex is structurally dynamic and that FIS, uniquely for a prokaryotic transcriptional activator, facilitates sequential steps in the initiation process, enabling efficient polymerase recruitment, untwisting of DNA at the transcription startpoint and finally the escape of polymerase from the promoter. Activation of all these steps requires that the three FIS dimers bind in helical register. We suggest that FIS acts by stabilizing a DNA microloop whose topology is coupled to the local topological transitions generated during the initiation of transcription.
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PMID:FIS activates sequential steps during transcription initiation at a stable RNA promoter. 921 6

In the human enteropathogen Shigella transcription of virF, the primary regulator of the invasion functions, is strictly temperature-dependent and is antagonistically mediated by H-NS and FIS, which bind to specific sites on the virF promoter. Here we report on the relevance of DNA geometry to the thermoregulation of virF and demonstrate that the virF promoter hosts a major DNA bend halfway between two H-NS sites. The bent region has been mutagenized in vitro to mimic temperature-induced changes of DNA curvature. Functional analysis of curvature mutants and of promoter constructs in which the two H-NS sites are phased-out by a half-helix turn reveals that modifying the spatial relationships between these sites severely affects the interaction of H-NS with the virF promoter, as well as its in vivo and in vitro temperature-dependent activity. The role of promoter curvature as thermosensor is also compatible with the present observation that, with increasing temperature, the virF bending centre moves downstream at a rate having its maximum around the transition temperature, abruptly unmasking a binding site for the transcriptional activator FIS.
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PMID:The virF promoter in Shigella: more than just a curved DNA stretch. 1475 91