title: The trigger enzyme PepA (aminopeptidase A) of Escherichia coli, a transcriptional repressor that generates positive supercoiling.
abstract: Escherichia coli aminopeptidase A (PepA) is a trigger enzyme endowed with catalytic activity and DNA-binding properties prominent in transcriptional regulation and site-specific DNA recombination. The current work demonstrates that PepA is a repressor in its own right, capable of specifically inhibiting transcription initiation at promoter P1 of the carAB operon, encoding carbamoylphosphate synthase. Furthermore, in vitro topology studies performed with DNA minicircles demonstrate that PepA binding constrains a single positive supercoil in the carP1 control region. Such a topological event is understood to constitute an impediment to transcription initiation and may serve as a mechanism to regulate gene expression.
authors.affiliation: Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Belgium.
authors.forename: Phu
authors.initials: P
authors.lastname: Nguyen Le Minh
authors.affiliation: Institut Jacques Monod, CNRS-Université Paris Diderot, Paris Cedex 13, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Nadal
authors.affiliation: Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Belgium.
authors.forename: Daniel
authors.initials: D
authors.lastname: Charlier
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D004278:DNA, Superhelical / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D043384:Glutamyl Aminopeptidase / Q000235:genetics / Q000378:metabolism*; D009876:Operon / Q000502:physiology; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology
chemical_list: D004269:DNA, Bacterial; D004278:DNA, Superhelical; D029968:Escherichia coli Proteins; C496211:PepA protein, E coli; D012097:Repressor Proteins; D043384:Glutamyl Aminopeptidase
keywords: DNA topology; Protein-DNA interactions; arginine biosynthesis; carbamoylphosphate synthase; pyrimidine biosynthesis; transcription regulation