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  Tuning the Primary Reaction of Channelrhodopsin-2 by Imidazole, pH, and Site-Specific Mutations

Scholz, F., Bamberg, E., Bamann, C., & Wachtveitl, J. (2012). Tuning the Primary Reaction of Channelrhodopsin-2 by Imidazole, pH, and Site-Specific Mutations. Biophysical Journal, 102(11), 2649-2657.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0024-D562-C Version Permalink: http://hdl.handle.net/11858/00-001M-0000-0024-D563-A
Genre: Journal Article

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Scholz, Frank, Author
Bamberg, Ernst1, Author              
Bamann, Christian1, Author              
Wachtveitl, Josef, Author
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1Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max Planck Society, ou_2068289              

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 Abstract: Femtosecond time-resolved absorption measurements were performed to investigate the influence of the pH, imidazole concentration, and point mutations on the isomerization process of Channelrhodopsin-2. Apart from the typical spectral characteristics of retinal isomerization, an additional absorption feature rises for the wild-type (wt) on a timescale from tens of ps to 1 ns within the spectral range of the photoproduct and is attributed to an equilibration between different K-intermediates. Remarkably, this absorption feature vanishes upon addition of imidazole or lowering the pH. In the latter case, the isomerization is dramatically slowed down, due to protonation of negatively charged amino acids within the retinal binding pocket, e.g., E123 and D253. Moreover, we investigated the influence of several point mutations within the retinal binding pocket E123T, E123D, C128T, and D156C. For E123T, the isomerization is retarded compared to wt and E123D, indicating that a negatively charged residue at this position functions as an effective catalyst in the isomerization process. In the case of the C128T mutant, all primary processes are slightly accelerated compared to the wt, whereas the isomerization dynamics for the D156C mutant is similar to wt after addition of imidazole.

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Language(s): eng - English
 Dates: 2012-06-06
 Publication Status: Published in print
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 Rev. Method: Peer
 Identifiers: eDoc: 631421
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Title: Biophysical Journal
  Alternative Title : Biophys. J.
Source Genre: Journal
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Pages: - Volume / Issue: 102 (11) Sequence Number: - Start / End Page: 2649 - 2657 Identifier: -