title: Mapping conformational heterogeneity of mitochondrial nucleotide transporter in uninhibited states.
abstract: One of the less well understood aspects of membrane transporters is the dynamic coupling between conformational change and substrate transport. NMR approaches are used herein to investigate conformational heterogeneity of the GTP/GDP carrier (GGC) from yeast mitochondria. NMR residual dipolar coupling (RDC) analysis of GGC in a DNA-origami nanotube liquid crystal shows that several structured segments have different generalized degrees of order (GDO), thus indicating the presence of conformational heterogeneity. Complete GDO mapping reveals asymmetry between domains of the transporter and even within certain transmembrane helices. Nucleotide binding partially reduces local structural heterogeneity, and the substrate binds to multiple sites along the transport cavity. These observations suggest that mitochondrial carriers in the uninhibited states are intrinsically plastic and structural plasticity is asymmetrically distributed among the three homologous domains.
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115 (USA); Present address: Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 5203, Institut National de la Santé et de la Recherche Médicale (INSERM) U1191, Université de Montpellier, F-34000 Montpellier (France).
authors.forename: Remy
authors.initials: R
authors.lastname: Sounier
authors.forename: Gaetan
authors.initials: G
authors.lastname: Bellot
authors.forename: James J
authors.initials: JJ
authors.lastname: Chou
mesh_terms: D001665:Binding Sites; D008928:Mitochondria / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D009711:Nucleotides / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D009711:Nucleotides; D029701:Saccharomyces cerevisiae Proteins
keywords: DNA; NMR spectroscopy; conformation analysis; membranes; nucleotides