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          Institute: MPI für Biophysik     Collection: Abt. Biophysikalische Chemie     Display Documents

ID: 631431.0, MPI für Biophysik / Abt. Biophysikalische Chemie
Kinetics of proton release and uptake by channelrhodopsin-2
Authors:Nack, Melanie; Radu, Ionela; Schultz, Bernd-Joachim; Resler, Tom; Schlesinger, Ramona; Bondar, Ana-Nicoleta; del Val, Coral; Abbruzzetti, Stefania; Viappiani, Cristiano; Bamann, Christian; Bamberg, Ernst; Heberle, Joachim
Date of Publication (YYYY-MM-DD):2012-05-07
Title of Journal:FEBS Letters
Journal Abbrev.:FEBS L.
Issue / Number:9
Start Page:1344
End Page:1348
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Electrophysiological experiments showed that the light-activated cation channel channelrhodopsin-2 (ChR2) pumps protons in the absence of a membrane potential. We determined here the kinetics of transient pH change using a water-soluble pH-indicator. It is shown that ChR2 released protons prior to uptake with a stoichiometry of 0.3 protons per ChR2. Comparison to the photocycle kinetics revealed that proton release and uptake match rise and decay of the P3520 intermediate. As the P3520 state also represents the conductive state of cation channeling, the concurrence of proton pumping and channel gating implies an intimate mechanistic link of the two functional modes. Studies on the E123T and S245E mutants show that these residues are not critically involved in proton translocation.
Free Keywords:Bacteriorhodopsin; Proton transfer; Optogenetics; Rhodopsin; Ion channel
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Biophysik/Abteilung Biophysikalische Chemie
External Affiliations:Freie Universität Berlin, Institute for Experimental Physics, Arnimallee 14, 14195 Berlin, Germany;
University of Granada, Department of Computer Science and Artificial Intelligence, E-18071, Spain;
Università degli Studi di Parma, Dipartimento di Fisica, 43100 Parma, Italy
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