title: Transcriptional regulation of the pas gene of enterohemorrhagic Escherichia coli.
abstract: The Pas protein plays a key role in the pathogenesis of enterohemorrhagic Escherichia coli (EHEC), being required for the secretion of the Esp proteins. Here, the transcriptional regulation of the pas gene was analyzed through the construction of a pas::lacZ translational fusion. When bacteria were grown in Luria Bertani medium or tissue culture medium supplemented with HEPES, a bimodal activation curve was observed. The early phase of induction was not significantly modified by the incubation temperature (either 25 or 37 degrees C), whereas the second phase, which overlaps with the late exponential growth phase, was enhanced at 37 degrees C. The early phase was also stimulated by growth on tissue culture medium and by the addition of Ca(2+), Mn(2+)or Mg(2+) to the M9-glucose minimal medium. Primer extension analysis showed the presence of two major starts of transcription, which were located 58 and 60 bp upstream of the ATG-start codon of the Pas protein, respectively. Although these sites are very close to each other, the transcripts produced during the early induction phase mainly start on the -60 position, whereas the -58 start was activated during the second induction phase.
authors.affiliation: Department of Microbial Pathogenesis and Vaccine Research, Division of Microbiology, GBF-German Research Centre for Biotechnology, Mascheroder Weg 1, D-38124, Braunschweig, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Beltrametti
authors.forename: A U
authors.initials: AU
authors.lastname: Kresse
authors.forename: C A
authors.initials: CA
authors.lastname: Guzmán
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002122:Calcium Chloride / Q000494:pharmacology; D003470:Culture Media / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D007763:Lac Operon / Q000235:genetics; D015636:Magnesium Chloride / Q000494:pharmacology; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013696:Temperature; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000187:drug effects; D000069296:Type III Secretion Systems; D001616:beta-Galactosidase / Q000187:drug effects / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C114344:PAS protein, E coli; D011993:Recombinant Fusion Proteins; D000069296:Type III Secretion Systems; D015636:Magnesium Chloride; D001616:beta-Galactosidase; D002122:Calcium Chloride