Characterization of the transcriptional stimulatory properties of the Pseudomonas putida RapA protein

Autor: Agnieszka Szalewska-Pałasz, Victoria Shingler, Eleonore Skärfstad, Robert Lyzen, Ewa Stec-Dziedzic
Rok vydání: 2013
Předmět:
Zdroj: Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms. 1829:219-230
ISSN: 1874-9399
DOI: 10.1016/j.bbagrm.2012.11.008
Popis: RNA polymerase-associated factors can significantly affect its performance at specific promoters. Here we identified a Pseudomonas putida RNA polymerases-associated protein as a homolog of Escherichia coli RapA. We found that P. putida RapA stimulates the transcription from promoters dependent on a variety of σ-factors (σ(70), σ(S), σ(54), σ(32), σ(E)) in vitro. The level of stimulation varied from 2- to 10-fold, with the maximal effect observed with the σ(E)-dependent PhtrA promoter. Stimulation by RapA was apparent in the multi-round reactions and was modulated by salt concentration in vitro. However, in contrast to findings with E. coli RapA, P. putida RapA-mediated stimulation of transcription was also evident using linear templates. These properties of P. putida RapA were apparent using either E. coli- or P. putida-derived RNA polymerases. Analysis of individual steps of transcription revealed that P. putida RapA enhances the stability of competitor-resistant open-complexes formed by RNA polymerase at promoters. In vivo, P. putida RapA can complement the inhibitory effect of high salt on growth of an E. coli RapA null strain. However, a P. putida RapA null mutant was not sensitive to high salt. The in vivo effects of lack of RapA were only detectable for the σ(E)-PhtrA promoter where the RapA-deficiency resulted in lower activity. The presented characteristics of P. putida RapA indicate that its functions may extend beyond a role in facilitating RNA polymerase recycling to include a role in transcription initiation efficiency.
Databáze: OpenAIRE