title: Fluorescence approach to evaluating conformational changes upon binding of beta-spectrin ankyrin-binding domain mutants with the lipid bilayer.
abstract: The major component of the cell membrane skeleton, spectrin, is anchored in the cell membrane via interactions with membrane proteins. It has been previously shown that both erythroid and non-erythroid spectrin interact directly with membrane phospholipids (mainly aminophospholipids). One of the binding sites responsible for these interactions is located in the ankyrin-binding domain. In the present study, in order to better understand the character of binding, a more detailed investigation of the interactions between the beta-spectrin fragments corresponding to the truncated mutants of the ankyrin-binding domain (Frag1 and Frag3) and liposomes of different compositions were carried out. The obtained results suggest that the binding of both spectrin fragments with liposomes induces conformational changes within the protein. Analysis of the changes in intrinsic tryptophan fluorescence spectra upon binding with liposomes, together with quenching studies (from the water and membrane hydrocarbon environment), allows for qualitative description of changes in proteins conformation. Our results suggest that the largest conformational changes occur for Frag1 bound to PC : PE (2 : 3) liposomes what is consistent with previous studies on monolayers. They are also in good agreement with those obtained previously for native erythroid and nonerythroid spectrin molecules.
authors.affiliation: Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Pazdzior
authors.forename: Anna
authors.initials: A
authors.lastname: Chorzalska
authors.forename: Aleksander
authors.initials: A
authors.lastname: Czogalla
authors.forename: Tomasz
authors.initials: T
authors.lastname: Borowik
authors.forename: Aleksander F
authors.initials: AF
authors.lastname: Sikorski
authors.forename: Marek
authors.initials: M
authors.lastname: Langner
mesh_terms: D000465:Algorithms; D000818:Animals; D017487:Ankyrins / Q000737:chemistry; D001665:Binding Sites / Q000235:genetics*; D005453:Fluorescence; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D008564:Membrane Potentials; D008956:Models, Chemical; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013049:Spectrin / Q000737:chemistry* / Q000235:genetics*; D013057:Spectrum Analysis; D014364:Tryptophan / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D017487:Ankyrins; D008051:Lipid Bilayers; D008081:Liposomes; D011994:Recombinant Proteins; D014867:Water; D013049:Spectrin; D014364:Tryptophan