Coactivation in vitro of the sigma54-dependent promoter Pu of the TOL plasmid of Pseudomonas putida by HU and the mammalian HMG-1 protein.
The mechanism by which the prokaryotic histone-like protein HU replaces the integration host factor (IHF) in the coactivation of the sigma54-dependent promoter Pu of Pseudomonas putida has been investigated. By using a preactivated form of the cognate activator protein XylR, we show that the functional replacement of IHF with HU previously suggested in vivo can be faithfully reproduced in vitro with purified components. Furthermore, the coactivation effect of IHF on Pu could be mimicked not only by HU but also by the mammalian nonhistone chromatin protein HMG-1 and could be bypassed by intrinsically curved DNA. These results suggest that either of two different mechanisms (generation of a site-specific static DNA bend or a general flexibilization of the promoter region) gives rise to the same structural effect of stimulating transcription from Pu through changes in promoter architecture.
Pérez-Martín
J
J
Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
De Lorenzo
V
V
D000818:Animals; D001426:Bacterial Proteins / Q000494:pharmacology*; D002352:Carrier Proteins / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000494:pharmacology*; D012321:DNA-Directed RNA Polymerases / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D024243:HMGB1 Protein; D006609:High Mobility Group Proteins / Q000494:pharmacology*; D034982:Integration Host Factors; D051379:Mice; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D016958:Pseudomonas putida / Q000235:genetics*; D051877:RNA Polymerase Sigma 54; D012808:Sigma Factor / Q000502:physiology; D014157:Transcription Factors / Q000494:pharmacology; D015533:Transcriptional Activation / Q000235:genetics*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D024243:HMGB1 Protein; D006609:High Mobility Group Proteins; D034982:Integration Host Factors; D012808:Sigma Factor; D014157:Transcription Factors; C074322:XylR protein, Pseudomonas; C040330:histone-like protein HU, bacteria; C440503:integration host factor, Pseudomonas; C497751:rpoN protein, E coli; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54