Regular articleFruR-mediated transcriptional activation at the ppsA promoter of Escherichia coli1

Add time:08/19/2019    Source:sciencedirect.com

The start site of transcription of the ppsA gene, whose expression is controlled by the regulatory protein FruR in Escherichia coli, was determined by primer extension of in vivo transcripts. The interactions of the ppsA promoter with either RNA polymerase or FruR factor were analysed by the base removal method. Our results indicate that: (i) the RNA polymerase binding site has a −10 extended module but lacks its −35 hexamer; (ii) FruR binds to a target DNA region centered around position −45.5 upstream of the ppsA gene. In addition, circular permutation analysis showed that, upon binding to its site, FruR induces a sharp bend of 120° in the DNA helix, which suggests a crucial involvement of FruR-induced bending in ppsA promoter activation. Direct contacts between the upstream activating DNA and RNA polymerase were studied in an in vitro transcription assay by using reconstituted RNA polymerase mutants containing Ala substitutions in the C-terminal domain of their α subunit. The α[L262A], α[R265A] and α[N268A] substitutions, which caused the most drastic reduction in the FruR-mediated activation of the ppsA promoter, had previously been shown to inhibit the upstream element-mediated activation at the rrnBP1 promoter.

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Prev:Sequence and evolution of the FruR protein (cas 138186-82-0) of Salmonella typhimurium: a pleiotropic transcriptional regulatory protein possessing both activator and repressor functions which is homologous to the periplasmic ribose-binding proteinSéquence et évolution de la protéine FruR de Salmonella typhimurium: une protéine pléiotrope de transcription et de régulation ayant les fonctions á la fois d'activation et de répression, homologue de la protéine périplasmique liant le ribose
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