title: The dual role of DksA protein in the regulation of Escherichia coli pArgX promoter.
abstract: Gene expression regulation by the stringent response effector, ppGpp, is facilitated by DksA protein; however DksA and ppGpp can play independent roles in transcription. In Escherichia coli, the pArgX promoter which initiates the transcription of four tRNA genes was shown to be inhibited by ppGpp. Our studies on the role of DksA in pArgX regulation revealed that it can stimulate transcription by increasing the binding of RNA polymerase to the promoter and the productive transcription complex formation. However, when DksA is present together with ppGpp a severe down-regulation of promoter activity is observed. Our results indicate that DksA facilitates the effects of ppGpp to drive formation of inactive dead-end complexes formed by RNA polymerase at the ArgX promoter. In vivo, ppGpp-mediated regulation of pArgX transcription is dependent on DksA activity. The potential mechanisms of opposing pArgX regulation by ppGpp and DksA are discussed. pArgX is the first reported example of the promoter stimulated by DksA and inhibited by ppGpp in vitro when an overall inhibition occurs in the presence of both regulators. A dual role is thus proposed for DksA in the regulation of the pArgX promoter activity.
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Łyżeń
authors.affiliation: State University of New York at Buffalo, Buffalo, NY 14214, USA.
authors.forename: Amarnath
authors.initials: A
authors.lastname: Maitra
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Klaudia
authors.initials: K
authors.lastname: Milewska
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Maja
authors.initials: M
authors.lastname: Kochanowska-Łyżeń
authors.affiliation: Department of Cell Biology, University of Texas Southwestern Medical Center, 5335 Harry Hines Blvd. Dallas, TX 75390, USA.
authors.forename: V James
authors.initials: VJ
authors.lastname: Hernandez
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland Agnieszka.Szalewska@biol.ug.edu.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Szalewska-Pałasz
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D061785:Transcription Initiation, Genetic; D014158:Transcription, Genetic
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C090751:dksA protein, E coli; D012321:DNA-Directed RNA Polymerases