title: Solution NMR investigation of the response of the lactose repressor core domain dimer to hydrostatic pressure.
abstract: Previous investigations of the sensitivity of the lac repressor to high-hydrostatic pressure have led to varying conclusions. Here high-pressure solution NMR spectroscopy is used to provide an atomic level view of the pressure induced structural transition of the lactose repressor regulatory domain (LacI* RD) bound to the ligand IPTG. As the pressure is raised from ambient to 3kbar the native state of the protein is converted to a partially unfolded form. Estimates of rotational correlation times using transverse optimized relaxation indicates that a monomeric state is never reached and that the predominate form of the LacI* RD is dimeric throughout this pressure change. Spectral analysis suggests that the pressure-induced transition is localized and is associated with a volume change of approximately -115mlmol-1and an average pressure dependent change in compressibility of approximately 30mlmol-1kbar-1. In addition, a subset of resonances emerge at high-pressures indicating the presence of a non-native but folded alternate state.
authors.affiliation: Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, 905 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104-6059, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Fuglestad
authors.affiliation: Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, 905 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104-6059, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Stetz
authors.affiliation: Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, 905 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104-6059, USA.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Belnavis
authors.affiliation: Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, 905 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104-6059, USA. Electronic address: wand@upenn.edu.
authors.forename: A Joshua
authors.initials: AJ
authors.lastname: Wand
mesh_terms: D019281:Dimerization; D004926:Escherichia coli / Q000378:metabolism; D006874:Hydrostatic Pressure; D007544:Isopropyl Thiogalactoside / Q000737:chemistry / Q000378:metabolism; D056968:Lac Repressors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D058767:Protein Unfolding; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D013816:Thermodynamics
chemical_list: D056968:Lac Repressors; D011994:Recombinant Proteins; D007544:Isopropyl Thiogalactoside
keywords: Conformational drift; High pressure NMR; Lac repressor; Local and subglobal unfolding