Deutsch
 
Benutzerhandbuch Datenschutzhinweis Impressum Kontakt
  DetailsucheBrowse

Datensatz

DATENSATZ AKTIONENEXPORT

Freigegeben

Zeitschriftenartikel

Structural Guidance of the Photocycle of Channelrhodopsin-2 by an Interhelical Hydrogen Bond

MPG-Autoren
/persons/resource/persons137591

Bamann,  Christian
Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max Planck Society;

/persons/resource/persons137743

Kleinlogel,  Sonja
Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max Planck Society;

/persons/resource/persons137819

Nagel,  Georg
Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max Planck Society;

/persons/resource/persons137592

Bamberg,  Ernst
Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max Planck Society;

Externe Ressourcen
Es sind keine Externen Ressourcen verfügbar
Volltexte (frei zugänglich)
Es sind keine frei zugänglichen Volltexte verfügbar
Ergänzendes Material (frei zugänglich)
Es sind keine frei zugänglichen Ergänzenden Materialien verfügbar
Zitation

Bamann, C., Gueta, R., Kleinlogel, S., Nagel, G., & Bamberg, E. (2010). Structural Guidance of the Photocycle of Channelrhodopsin-2 by an Interhelical Hydrogen Bond. Biochemistry, 49(2), 267-278.


Zitierlink: http://hdl.handle.net/11858/00-001M-0000-0024-D6B6-6
Zusammenfassung
Channelrhodopsin-2 (ChR2) is a light-gated cation channel and a member of the family of retinylidene photoreceptors. Since the demonstration of light-induced depolarization of ChR2-expressing animal cell membranes, it was increasingly exploited for light triggering of action potentials. ChR2 conducts cations upon light absorption that embodies retinal isomerization as the primary reaction and a structurally unknown opening mechanism. It is evident from spectroscopic data that protonation reactions at the Schiff base are part of the photocycle, comparable to other microbial-type rhodopsins. However, the connection between the processes at the chromophore site and the channel’s pore remained enigmatic. Here, we use slow mutants of ChR2 that we generated by disturbing a postulated hydrogen bond when mutating C128 in the transmembrane (TM) helix 3 and D156 in TM helix 4. The lifetime of the mutants’ open state is increased more than 100 times. We investigated the spectral properties of the slow mutants. Whereas the deprotonation of the Schiff base (yielding P390) occurs on the same time scale as that of the wild type, reprotonation to P520 is retarded in the slow mutants and their photocycle is split, leading to the presence of two photointermediates, P390 and P520, in the open state. The photoreactions of P390 and P520 lead to a quenching of the current in electrophysiological measurements. We conclude that the putative hydrogen bond between C128 and D156 is an important structural determinant of the channel’s closing reaction. Furthermore, we show that the D156A mutant is even more suitable for light control of excitable cells than C128A.