title: A Ser residue influences the structure and stability of a Pro-kinked transmembrane helix dimer.
abstract: When localized adjacent to a Pro-kink, Thr and Ser residues can form hydrogen bonds between their polar hydroxyl group and a backbone carbonyl oxygen and thereby modulate the actual bending angle of a distorted transmembrane α-helix. We have used the homo-dimeric transmembrane cytochrome b(559)' to analyze the potential role of a highly conserved Ser residue for assembly and stabilization of transmembrane proteins. Mutation of the conserved Ser residue to Ala resulted in altered heme binding properties and in increased stability of the holo-protein, most likely by tolerating subtle structural rearrangements upon heme binding. The results suggest a crucial impact of an intrahelical Ser hydrogen bond in defining the structure of a Pro-kinked transmembrane helix dimer.
authors.affiliation: Institut für Pharmazie und Biochemie, Johannes Gutenberg-Universität, Johann-Joachim-Becher-Weg 30, Mainz, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Weber
authors.forename: Lydia
authors.initials: L
authors.lastname: Tome
authors.forename: Daniel
authors.initials: D
authors.lastname: Otzen
authors.forename: Dirk
authors.initials: D
authors.lastname: Schneider
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D003573:Cytochrome b Group / Q000737:chemistry; D019281:Dimerization; D006418:Heme / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D009154:Mutation; D010100:Oxygen / Q000737:chemistry; D045332:Photosystem II Protein Complex / Q000737:chemistry; D011392:Proline / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012694:Serine / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods
chemical_list: D003573:Cytochrome b Group; D045332:Photosystem II Protein Complex; D006418:Heme; D012694:Serine; C019313:cytochrome b559; D011392:Proline; D010100:Oxygen