TY - JOUR
T1 - The regulatory mechanism of ion permeation through a channelrhodopsin derived from Mesostigma viride (MvChR1)
AU - Watanabe, Shota
AU - Ishizuka, Toru
AU - Hososhima, Shoko
AU - Zamani, Alemeh
AU - Hoque, Mohammad Razuanul
AU - Yawo, Hiromu
N1 - Funding Information:
We thank Dr J. L. Spudich and E. G. Govorunova (the University of Texas Medical School, Houston, Texas 77030, U. S. A.) for comments on the manuscript as well as for MvChR1 cDNA, and B. Bell for language assistance. This work was supported by Grant-in-Aid for Japan Society for the Promotion of Science (JSPS) Fellows (Number, 13J06372), scientific research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan (Numbers, 25290002, 25670103, 25250001, 25115701), the Global COE Program (Basic & Translational Research Center for Global Brain Science), MEXT and the Program for Promotion of Fundamental Studies in Health Sciences of the National Institute of Biomedical Innovation (NIBIO).
Publisher Copyright:
© The Royal Society of Chemistry and Owner Societies 2016.
PY - 2016/3/1
Y1 - 2016/3/1
N2 - The five glutamate (E) residues of transmembrane (TM)-2 of channelrhodopsin (CrChR)-2 are conserved among several members of the ChR family. A point mutation of one of them, E97, to a nonpolar alanine (E97A) reduced the photocurrent amplitude without influencing other photocurrent properties. The charge at this position is also the determinant of the Gd3+-dependent block of the channel. It has thus been suggested that E97 interacts with hydrated cations to facilitate their permeation and that these residues are the primary binding sites of Gd3+. However, the counterpart of this position is alanine for MvChR1 from Mesostigma viride. Here we investigated the ion permeation and the Gd3+-dependent channel block of MvChR1. We found that the high-affinity binding site of Gd3+ was absent in MvChR1, but was dependent on the negativity at this position. However, the ion permeation through the channel was markedly interfered with a negative charge at this position. Based on these findings, it is proposed that the ions can pass through the pore with minimal interaction with this position.
AB - The five glutamate (E) residues of transmembrane (TM)-2 of channelrhodopsin (CrChR)-2 are conserved among several members of the ChR family. A point mutation of one of them, E97, to a nonpolar alanine (E97A) reduced the photocurrent amplitude without influencing other photocurrent properties. The charge at this position is also the determinant of the Gd3+-dependent block of the channel. It has thus been suggested that E97 interacts with hydrated cations to facilitate their permeation and that these residues are the primary binding sites of Gd3+. However, the counterpart of this position is alanine for MvChR1 from Mesostigma viride. Here we investigated the ion permeation and the Gd3+-dependent channel block of MvChR1. We found that the high-affinity binding site of Gd3+ was absent in MvChR1, but was dependent on the negativity at this position. However, the ion permeation through the channel was markedly interfered with a negative charge at this position. Based on these findings, it is proposed that the ions can pass through the pore with minimal interaction with this position.
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U2 - 10.1039/c5pp00290g
DO - 10.1039/c5pp00290g
M3 - Article
C2 - 26853505
AN - SCOPUS:84960840755
VL - 15
SP - 365
EP - 374
JO - Photochemical and Photobiological Sciences
JF - Photochemical and Photobiological Sciences
SN - 1474-905X
IS - 3
ER -