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The role of FIS protein in the physiological control of the expression of the Escherichia coli meta-hpa operon

AuthorsGalán, Beatriz ; Manso, Isabel ; Kolb, Annie; García, José Luis ; Prieto, María Auxiliadora
KeywordsCRP, catabolite repression protein
EMSA, electromobility shift assay
FIS, factor for inversion stimulation
HPA, hydroxyphenylacetate
HPC, 3,4-dihydroxyphenylacetic acid
IHF, integration host factor
RNAP, RNA polymerase
RT-PCR, reverse transcriptase PCR
Issue Date1-Jul-2008
PublisherSociety for General Microbiology
CitationMicrobiology 154(7):2151-2160(2008)
AbstractExpression from the Escherichia coli W meta-hpa operon promoter (Pg) is under a strict catabolic repression control mediated by the cAMP-catabolite repression protein (CRP) complex in a glucose-containing medium. The Pg promoter is also activated by the integration host factor (IHF) and repressed by the specific transcriptional regulator HpaR when 4-hydroxyphenylacetate (4HPA) is not present in the medium. Expression from the hpa promoter is also repressed in undefined rich medium such as LB, but the molecular basis of this mechanism is not understood. We present in vitro and in vivo studies to demonstrate the involvement of FIS protein in this catabolic repression. DNase I footprinting experiments show that FIS binds to multiple sites within the Pg promoter. FIS-site I overlaps the CRP-binding site. By using an electromobility shift assay, we demonstrated that FIS efficiently competes with CRP for binding to the Pg promoter, suggesting an antagonist/competitive mechanism. RT-PCR showed that the Pg repression effect is relieved in a FIS deleted strain. The repression role of FIS at Pg was further demonstrated by in vitro transcription assays. These results suggest that FIS contributes to silencing the Pg promoter in the exponential phase of growth in an undefined rich medium when FIS is predominantly expressed
Description10 páginas, 6 figuras, 1 tabla -- PAGS nros. 2151-2160
Publisher version (URL)http://dx.doi.org/10.1099/mic.0.2007/015578-0
Appears in Collections:(CIB) Artículos
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