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 P5203 intermediate. As the P520 3 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.

Kinetics of Proton Release and Uptake by Channelrhodopsin-2 / M., Nack; L., Radu; B. J., Schultz; T., Resler; R., Schlesinger; A. N., Bondar; C., del Val; Abbruzzetti, Stefania; Viappiani, Cristiano; C., Bamann; E., Bamberg; J., Heberle. - In: FEBS LETTERS. - ISSN 0014-5793. - 586:(2012), pp. 1344-1348. [10.1016/j.febslet.2012.03.047]

Kinetics of Proton Release and Uptake by Channelrhodopsin-2

ABBRUZZETTI, Stefania;VIAPPIANI, Cristiano;
2012-01-01

Abstract

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 P5203 intermediate. As the P520 3 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.
2012
Kinetics of Proton Release and Uptake by Channelrhodopsin-2 / M., Nack; L., Radu; B. J., Schultz; T., Resler; R., Schlesinger; A. N., Bondar; C., del Val; Abbruzzetti, Stefania; Viappiani, Cristiano; C., Bamann; E., Bamberg; J., Heberle. - In: FEBS LETTERS. - ISSN 0014-5793. - 586:(2012), pp. 1344-1348. [10.1016/j.febslet.2012.03.047]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2423598
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