TY - JOUR
T1 - Proton and Water Transfer Pathways in the S2→ S3Transition of the Water-Oxidizing Complex in Photosystem II
T2 - Time-Resolved Infrared Analysis of the Effects of D1-N298A Mutation and NO3-Substitution
AU - Okamoto, Yasutada
AU - Shimada, Yuichiro
AU - Nagao, Ryo
AU - Noguchi, Takumi
N1 - Funding Information:
This study was supported by JSPS KAKENHI grant number JP17H06435, JP17H03662, and JP17H06433 (to T.N.).
Publisher Copyright:
© 2021 American Chemical Society
PY - 2021/7/1
Y1 - 2021/7/1
N2 - Photosynthetic water oxidation is performed through a light-driven cycle of five intermediates (S0-S4states) in photosystem II (PSII). The S2→ S3transition, which involves concerted water and proton transfer, is a key process for understanding the water oxidation mechanism. Here, to identify the water and proton transfer pathways during the S2→ S3transition, we examined the effects of D1-N298A mutation and NO3-substitution for Cl-, which perturbed the O1 and Cl channels, respectively, on the S2→ S3kinetics using time-resolved infrared spectroscopy. The S2→ S3transition was retarded both upon NO3-substitution and upon D1-N298A mutation, whereas it was unaffected by further NO3-substitution in N298A PSII. The H/D kinetic isotope effect in N298A PSII was relatively small, revealing that water transfer is a rate-limiting step in this mutant. From these results, it was suggested that during the S2→ S3transition, water delivery and proton release occur through the O1 and Cl channels, respectively.
AB - Photosynthetic water oxidation is performed through a light-driven cycle of five intermediates (S0-S4states) in photosystem II (PSII). The S2→ S3transition, which involves concerted water and proton transfer, is a key process for understanding the water oxidation mechanism. Here, to identify the water and proton transfer pathways during the S2→ S3transition, we examined the effects of D1-N298A mutation and NO3-substitution for Cl-, which perturbed the O1 and Cl channels, respectively, on the S2→ S3kinetics using time-resolved infrared spectroscopy. The S2→ S3transition was retarded both upon NO3-substitution and upon D1-N298A mutation, whereas it was unaffected by further NO3-substitution in N298A PSII. The H/D kinetic isotope effect in N298A PSII was relatively small, revealing that water transfer is a rate-limiting step in this mutant. From these results, it was suggested that during the S2→ S3transition, water delivery and proton release occur through the O1 and Cl channels, respectively.
UR - http://www.scopus.com/inward/record.url?scp=85110265923&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85110265923&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcb.1c03386
DO - 10.1021/acs.jpcb.1c03386
M3 - Article
C2 - 34152151
AN - SCOPUS:85110265923
SN - 1520-6106
VL - 125
SP - 6864
EP - 6873
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 25
ER -