Kinetics of proton release and uptake by channelrhodopsin-2.

Autor: Nack M; Freie Universität Berlin, Institute for Experimental Physics, Berlin, Germany., Radu I, Schultz BJ, Resler T, Schlesinger R, Bondar AN, del Val C, Abbruzzetti S, Viappiani C, Bamann C, Bamberg E, Heberle J
Jazyk: angličtina
Zdroj: FEBS letters [FEBS Lett] 2012 May 07; Vol. 586 (9), pp. 1344-8. Date of Electronic Publication: 2012 Apr 06.
DOI: 10.1016/j.febslet.2012.03.047
Abstrakt: 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 P(3)(520) intermediate. As the P(3)(520) 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.
(Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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