Document Detail

The branched photocycle of the slow-cycling channelrhodopsin-2 mutant C128T.
MedLine Citation:
PMID:  20346954     Owner:  NLM     Status:  MEDLINE    
Channelrhodopsins (ChRs) of green algae such as Chlamydomonas are used as neuroscience tools to specifically depolarize cells with light. A crude model of the ChR2 photocycle has been recently established, but details of the photoreactions are widely unknown. Here, we present the photoreactions of a slow-cycling ChR2 mutant (step function rhodopsin), with C128 replaced by threonine and 200-fold extended lifetime of the conducting-state P520. At a late state of the photocycle, a fraction of the proteins branches off into an inactive species, P380, which accumulates during prolonged illumination. At neutral pH, P380 is converted into P353, a species with a characteristic fine-structured spectrum that is interpreted as retroretinyl chromophore. The described branching reactions should be considered, when ChR is used as a neuroscience tool, especially in the case of fluorescence imaging at high light intensities.
Katja Stehfest; Eglof Ritter; Andr? Berndt; Franz Bartl; Peter Hegemann
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-03-25
Journal Detail:
Title:  Journal of molecular biology     Volume:  398     ISSN:  1089-8638     ISO Abbreviation:  J. Mol. Biol.     Publication Date:  2010 May 
Date Detail:
Created Date:  2010-05-07     Completed Date:  2010-05-18     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985088R     Medline TA:  J Mol Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  690-702     Citation Subset:  IM    
Copyright Information:
(c) 2010 Elsevier Ltd. All rights reserved.
Institut f?r Biologie, Experimentelle Biophysik, Humboldt-Universit?t zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany.
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MeSH Terms
Amino Acid Substitution / genetics*
Carrier Proteins / chemistry,  genetics*,  metabolism*
Chlamydomonas / enzymology*
Models, Biological
Mutation, Missense*
Spectroscopy, Fourier Transform Infrared
Spectrum Analysis
Time Factors
Reg. No./Substance:
0/Carrier Proteins; 0/channelopsin-2, Chlamydomonas reinhardtii

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