title: Dipolar Relaxation Dynamics at the Active Site of an ATPase Regulated by Membrane Lateral Pressure.
abstract: The active transport of ions across biological membranes requires their hydration shell to interact with the interior of membrane proteins. However, the influence of the external lipid phase on internal dielectric dynamics is hard to access by experiment. Using the octahelical transmembrane architecture of the copper-transporting P1B-type ATPase from Legionella pneumophila as a model structure, we have established the site-specific labeling of internal cysteines with a polarity-sensitive fluorophore. This enabled dipolar relaxation studies in a solubilized form of the protein and in its lipid-embedded state in nanodiscs. Time-dependent fluorescence shifts revealed the site-specific hydration and dipole mobility around the conserved ion-binding motif. The spatial distribution of both features is shaped significantly and independently of each other by membrane lateral pressure.
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstrasse 400, 01328, Dresden, Germany.|Technische Universität Dresden, Biotechnology Center, Tatzberg 47-49, 01307, Dresden, Germany.|Nationales Zentrum für Tumorerkrankungen Heidelberg, Im Neuenheimer Feld 460, 69120, Heidelberg, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Fischermeier
authors.affiliation: J. Heyrovský Inst. Physical Chemistry of the A.S.C.R. v.v.i., Prague, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Pospíšil
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstrasse 400, 01328, Dresden, Germany.|Technische Universität Dresden, Biotechnology Center, Tatzberg 47-49, 01307, Dresden, Germany.|Institute for Experimental Physics I, Universität Leipzig, Linnéstrasse 5, 04103, Leipzig, Germany.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Sayed
authors.affiliation: J. Heyrovský Inst. Physical Chemistry of the A.S.C.R. v.v.i., Prague, Czech Republic.
authors.forename: Martin
authors.identifier: 0000-0003-2884-3037
authors.initials: M
authors.lastname: Hof
authors.affiliation: University of Bern, Dept. of Clinical Pharmacology, Murtenstrasse 35, 3008, Bern, Switzerland.
authors.forename: Marc
authors.identifier: 0000-0002-7989-6721
authors.initials: M
authors.lastname: Solioz
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstrasse 400, 01328, Dresden, Germany.|Technische Universität Dresden, Biotechnology Center, Tatzberg 47-49, 01307, Dresden, Germany.
authors.forename: Karim
authors.identifier: 0000-0002-8752-5824
authors.initials: K
authors.lastname: Fahmy
mesh_terms: D015081:2-Naphthylamine / Q000031:analogs & derivatives / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D020134:Catalytic Domain; D002942:Circular Dichroism; D003545:Cysteine / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D016952:Legionella pneumophila / Q000201:enzymology; D049329:Nanostructures / Q000737:chemistry; D017433:Protein Structure, Secondary
chemical_list: C122155:6-bromoacetyl-2-dimethylaminonaphthalene; D001426:Bacterial Proteins; C071263:CopA protein, Bacteria; D005456:Fluorescent Dyes; D015081:2-Naphthylamine; D003545:Cysteine
keywords: fluorescence; ion pump; membrane proteins; nanodiscs; time-resolved emission