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Title: Nonadiabatic Photodynamics of Retinal Protonated Schiff Base in Channelrhodopsin 2

Abstract

Channelrhodopsin 2 (ChR2) is a light-gated ion channel and an important tool in optogenetics. Photoisomerization of retinal protonated Schiff base (RPSB) in ChR2 triggers channel activation. Despite the importance of ChR2 in optogenetics, the detailed mechanism for photoisomerization and channel activation is still not fully understood. Here, we report on computer simulations to investigate the photoisomerization mechanism and its effect on the activation of ChR2. Nonadiabatic dynamics simulation of ChR2 was carried out using the ab initio multiple spawning (AIMS) method and quantum mechanics/molecular mechanics (QM/MM) with a restricted ensemble Kohn–Sham (REKS) treatment of the QM region. Our results agree well with spectroscopic measurements and reveal that the RPSB isomerization is highly specific around the C 13=C 14 bond and follows the “aborted bicycle-pedal” mechanism. In addition, RPSB photoisomerization facilitates its deprotonation and partially increases the hydration level in the channel, which could trigger subsequent channel opening and ion conduction.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States). Photon Ultrafast Laser Science and Engineering Inst. (PULSE), and Dept. of Chemistry; Stanford Univ., CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE; National Science Foundation (NSF)
OSTI Identifier:
1532466
Grant/Contract Number:  
AC02-76SF00515; CHE-1740645
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry Letters
Additional Journal Information:
Journal Volume: 10; Journal Issue: 11; Journal ID: ISSN 1948-7185
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English

Citation Formats

Liang, Ruibin, Liu, Fang, and Martínez, Todd J. Nonadiabatic Photodynamics of Retinal Protonated Schiff Base in Channelrhodopsin 2. United States: N. p., 2019. Web. doi:10.1021/acs.jpclett.9b00701.
Liang, Ruibin, Liu, Fang, & Martínez, Todd J. Nonadiabatic Photodynamics of Retinal Protonated Schiff Base in Channelrhodopsin 2. United States. doi:10.1021/acs.jpclett.9b00701.
Liang, Ruibin, Liu, Fang, and Martínez, Todd J. Mon . "Nonadiabatic Photodynamics of Retinal Protonated Schiff Base in Channelrhodopsin 2". United States. doi:10.1021/acs.jpclett.9b00701.
@article{osti_1532466,
title = {Nonadiabatic Photodynamics of Retinal Protonated Schiff Base in Channelrhodopsin 2},
author = {Liang, Ruibin and Liu, Fang and Martínez, Todd J.},
abstractNote = {Channelrhodopsin 2 (ChR2) is a light-gated ion channel and an important tool in optogenetics. Photoisomerization of retinal protonated Schiff base (RPSB) in ChR2 triggers channel activation. Despite the importance of ChR2 in optogenetics, the detailed mechanism for photoisomerization and channel activation is still not fully understood. Here, we report on computer simulations to investigate the photoisomerization mechanism and its effect on the activation of ChR2. Nonadiabatic dynamics simulation of ChR2 was carried out using the ab initio multiple spawning (AIMS) method and quantum mechanics/molecular mechanics (QM/MM) with a restricted ensemble Kohn–Sham (REKS) treatment of the QM region. Our results agree well with spectroscopic measurements and reveal that the RPSB isomerization is highly specific around the C13=C14 bond and follows the “aborted bicycle-pedal” mechanism. In addition, RPSB photoisomerization facilitates its deprotonation and partially increases the hydration level in the channel, which could trigger subsequent channel opening and ion conduction.},
doi = {10.1021/acs.jpclett.9b00701},
journal = {Journal of Physical Chemistry Letters},
number = 11,
volume = 10,
place = {United States},
year = {2019},
month = {5}
}

Journal Article:
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This content will become publicly available on May 13, 2020
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