title: Structural and dynamics studies of a truncated variant of CI repressor from bacteriophage TP901-1.
abstract: The CI repressor from the temperate bacteriophage TP901-1 consists of two folded domains, an N-terminal helix-turn-helix DNA-binding domain (NTD) and a C-terminal oligomerization domain (CTD), which we here suggest to be further divided into CTD1 and CTD2. Full-length CI is a hexameric protein, whereas a truncated version, CI∆58, forms dimers. We identify the dimerization region of CI∆58 as CTD1 and determine its secondary structure to be helical both within the context of CI∆58 and in isolation. To our knowledge this is the first time that a helical dimerization domain has been found in a phage repressor. We also precisely determine the length of the flexible linker connecting the NTD to the CTD. Using electrophoretic mobility shift assays and native mass spectrometry, we show that CI∆58 interacts with the OL operator site as one dimer bound to both half-sites, and with much higher affinity than the isolated NTD domain thus demonstrating cooperativity between the two DNA binding domains. Finally, using small angle X-ray scattering data and state-of-the-art ensemble selection techniques, we delineate the conformational space sampled by CI∆58 in solution, and we discuss the possible role that the dynamics play in CI-repressor function.
authors.affiliation: Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen, Denmark.
authors.forename: Kim Krighaar
authors.initials: KK
authors.lastname: Rasmussen
authors.affiliation: Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen, Denmark.
authors.forename: Kristian E H
authors.initials: KE
authors.lastname: Frandsen
authors.affiliation: Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, Grenoble, France.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Boeri Erba
authors.affiliation: Department of Biology, University of Copenhagen, Ole Maaløes vej 5, DK-2200 Copenhagen N, Denmark.
authors.forename: Margit
authors.initials: M
authors.lastname: Pedersen
authors.affiliation: Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen, Denmark.
authors.forename: Anders K
authors.initials: AK
authors.lastname: Varming
authors.affiliation: Metabolic signalling and regulation, Department of Systems Biology, Technical University of Denmark, DK-2800 Lyngby, Denmark.
authors.forename: Karin
authors.initials: K
authors.lastname: Hammer
authors.affiliation: Metabolic signalling and regulation, Department of Systems Biology, Technical University of Denmark, DK-2800 Lyngby, Denmark.
authors.forename: Mogens
authors.initials: M
authors.lastname: Kilstrup
authors.affiliation: Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen, Denmark.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Thulstrup
authors.affiliation: Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, Grenoble, France.
authors.forename: Martin
authors.initials: M
authors.lastname: Blackledge
authors.affiliation: Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, Grenoble, France.
authors.forename: Malene Ringkjøbing
authors.initials: MR
authors.lastname: Jensen
authors.affiliation: Department of Chemistry, University of Copenhagen, Universitetsparken 5, Copenhagen, Denmark.
authors.forename: Leila
authors.initials: L
authors.lastname: Lo Leggio
mesh_terms: D000595:Amino Acid Sequence; D001435:Bacteriophages / Q000737:chemistry*; D001665:Binding Sites; D004247:DNA / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000737:chemistry*; D054334:Viral Regulatory and Accessory Proteins / Q000737:chemistry*
chemical_list: D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D004247:DNA