title: Lipid binding protein response to a bile acid library: a combined NMR and statistical approach.
abstract: Primary bile acids, differing in hydroxylation pattern, are synthesized from cholesterol in the liver and, once formed, can undergo extensive enzyme-catalysed glycine/taurine conjugation, giving rise to a complex mixture, the bile acid pool. Composition and concentration of the bile acid pool may be altered in diseases, posing a general question on the response of the carrier (bile acid binding protein) to the binding of ligands with different hydrophobic and steric profiles. A collection of NMR experiments (H/D exchange, HET-SOFAST, ePHOGSY NOESY/ROESY and (15) N relaxation measurements) was thus performed on apo and five different holo proteins, to monitor the binding pocket accessibility and dynamics. The ensemble of obtained data could be rationalized by a statistical approach, based on chemical shift covariance analysis, in terms of residue-specific correlations and collective protein response to ligand binding. The results indicate that the same residues are influenced by diverse chemical stresses: ligand binding always induces silencing of motions at the protein portal with a concomitant conformational rearrangement of a network of residues, located at the protein anti-portal region. This network of amino acids, which do not belong to the binding site, forms a contiguous surface, sensing the presence of the bound lipids, with a signalling role in switching protein-membrane interactions on and off.
authors.affiliation: NMR Laboratory, Istituto per lo Studio delle Macromolecole (ISMAC), Milano, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Tomaselli
authors.affiliation: NMR Laboratory, Istituto per lo Studio delle Macromolecole (ISMAC), Milano, Italy.
authors.forename: Katiuscia
authors.initials: K
authors.lastname: Pagano
authors.affiliation: Departments of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Boulton
authors.affiliation: Biotechnology Department, University of Verona, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Zanzoni
authors.affiliation: Departments of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada.|Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Canada.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Melacini
authors.affiliation: NMR Laboratory, Istituto per lo Studio delle Macromolecole (ISMAC), Milano, Italy.
authors.forename: Henriette
authors.initials: H
authors.lastname: Molinari
authors.affiliation: NMR Laboratory, Istituto per lo Studio delle Macromolecole (ISMAC), Milano, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Ragona
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000737:chemistry / Q000378:metabolism; D001647:Bile Acids and Salts / Q000737:chemistry* / Q000378:metabolism*; D056808:Biostatistics; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D002645:Chickens; D006639:Histidine / Q000737:chemistry; D066298:In Vitro Techniques; D008024:Ligands; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D030161:Avian Proteins; D001647:Bile Acids and Salts; D002352:Carrier Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; C037643:bile acid binding proteins; D006639:Histidine
keywords: NMR; chemical shift covariance analysis; dynamics; ligand interaction analysis; lipid binding proteins; redox potential