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Dipolar Relaxation Dynamics at the Active Site of an ATPase Regulated by Membrane Lateral Pressure
Author(s) -
Fischermeier Elisabeth,
Pospíšil Petr,
Sayed Ahmed,
Hof Martin,
Solioz Marc,
Fahmy Karim
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201611582
Subject(s) - relaxation (psychology) , dipole , dynamics (music) , biophysics , chemistry , membrane , atpase , chemical physics , nuclear magnetic resonance , physics , biology , biochemistry , enzyme , neuroscience , organic chemistry , acoustics
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 P 1B ‐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.