Integration host factor suppresses promiscuous activation of the sigma 54-dependent promoter Pu of Pseudomonas putida.
In the presence of m-xylene, the Pu promoter of the TOL plasmid of Pseudomonas putida is activated by the prokaryotic enhancer-binding protein XylR. The intervening DNA segment between the upstream activating sequences (UASs) and those for RNA polymerase binding contains an integration host factor (IHF) attachment site that is required for full transcriptional activity. In the absence of IHF, the Pu promoter can be cross-activated by other members of the sigma 54-dependent family of regulatory proteins. Such illegitimate activation does not require the binding of the heterologous regulators to DNA and it is suppressed by bent DNA structures, either static or protein induced, between the promoter core elements (UAS and RNA polymerase recognition sequence). The role of IHF in some sigma 54 promoters is, therefore, not only a structural aid for assembling a correct promoter geometry but also that of an active suppressor (restrictor) of promiscuous activation by heterologous regulators for increased promoter specificity.
Pérez-Martín
J
J
Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
De Lorenzo
V
V
D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D005786:Gene Expression Regulation; D034982:Integration Host Factors; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D016958:Pseudomonas putida / Q000235:genetics*; D051877:RNA Polymerase Sigma 54; D012808:Sigma Factor / Q000235:genetics*; D013489:Suppression, Genetic
D001426:Bacterial Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D034982:Integration Host Factors; D012808:Sigma Factor; C440503:integration host factor, Pseudomonas; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54