The activity of the σ54-promoter Pu of Pseudomonas putida was examined in vitro with a DNA template lacking upstream activating sequences, such that RNA polymerase can be activated by the enhancer-binding protein XylR only from solution. Although the transcription activation pathway in this system lacked the step of integration host factor (IHF)-mediated looping of the XylR·DNA complex toward the prebound RNA polymerase, IHF still stimulated promoter activity. The positive effect of IHF became evident not only with XylR from solution, but also with other σ54-dependent activators such as NtrC and NifA. Furthermore, an equivalent outcome was shown for the nonspecific DNA-binding protein HU. This stimulation of transcription in the absence of the enhancer was traced to the recruitment of RNA polymerase (i.e. increased efficiency of formation of closed complexes) brought about by IHF or HU binding. Thus, under limiting concentrations of the polymerase, the factor-mediated binding of the enzyme to Pu seems to enter a kinetic checkpoint in the system that prevents the XylR-mediated formation of an open complex.
Recruitment of RNA polymerase is a rate-limiting step for the activation of the σ54 promoter Pu of Pseudomonas putida / M. Carmona, V. De Lorenzo, G. Bertoni. - In: THE JOURNAL OF BIOLOGICAL CHEMISTRY. - ISSN 0021-9258. - 274:47(1999), pp. 33790-33794.
|Titolo:||Recruitment of RNA polymerase is a rate-limiting step for the activation of the σ54 promoter Pu of Pseudomonas putida|
|Parole Chiave:||Bacterial Proteins; DNA-Directed RNA Polymerases; Enhancer Elements, Genetic; Integration Host Factors; Kinetics; Pseudomonas putida; RNA Polymerase Sigma 54; Sigma Factor; Transcription, Genetic; DNA-Binding Proteins; Promoter Regions, Genetic|
|Settore Scientifico Disciplinare:||Settore BIO/19 - Microbiologia Generale|
|Data di pubblicazione:||1999|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1074/jbc.274.47.33790|
|Appare nelle tipologie:||01 - Articolo su periodico|