TY - JOUR
T1 - Rate-limiting steps in the dark-tolight transition of photosystem ii-revealed by chlorophyll-a fluorescence induction
AU - Magyar, Melinda
AU - Sipka, Gábor
AU - Kovács, László
AU - Ughy, Bettina
AU - Zhu, Qingjun
AU - Han, Guangye
AU - Špunda, Vladimír
AU - Lambrev, Petar H.
AU - Shen, Jian Ren
AU - Garab, Győző
N1 - Funding Information:
This work was supported by a Strategic Priority Research Program (XDB17030100), a Key Research Project for Frontier Science (QYZDY-SSW-SMC003) from CAS, China, and a National Natural Science Foundation of China grant 31470339 (to JRS), grants from the National Research Development and Innovation Office of Hungary (OTKA K 112688, KH 124985 and TÉT_15-1-2016-0144 to GG, GINOP-2.3.2-15-2016-00058 to UB and OTKA PD 121225 to MM) and from the Moravian-Silesian Region (Project title: Strengthening international cooperation in science, research and education; ID: 01211/2016/RRC to VŠ). We are indebted to Prof. Govindjee for critical reading of the manuscript and helpful comments, Prof. William A. Cramer and Dr. László Nagy for stimulating discussions and Dr. Ghada Ajlani for the PAL mutant.
Publisher Copyright:
© The Author(s) 2018.
PY - 2018
Y1 - 2018
N2 - Photosystem II (PSII) catalyses the photoinduced oxygen evolution and, by producing reducing equivalents drives, in concert with PSI, the conversion of carbon dioxide to sugars. Our knowledge about the architecture of the reaction centre (RC) complex and the mechanisms of charge separation and stabilisation is well advanced. However, our understanding of the processes associated with the functioning of RC is incomplete: the photochemical activity of PSII is routinely monitored by chlorophyll-a fluorescence induction but the presently available data are not free of controversy. In this work, we examined the nature of gradual fluorescence rise of PSII elicited by trains of singleturnover saturating flashes (STSFs) in the presence of a PSII inhibitor, permitting only one stable charge separation. We show that a substantial part of the fluorescence rise originates from lightinduced processes that occur after the stabilisation of charge separation, induced by the first STSF; the temperature-dependent relaxation characteristics suggest the involvement of conformational changes in the additional rise. In experiments using double flashes with variable waiting times (∆τ) between them, we found that no rise could be induced with zero or short ∆τ, the value of which depended on the temperature-revealing a previously unknown rate-limiting step in PSII.
AB - Photosystem II (PSII) catalyses the photoinduced oxygen evolution and, by producing reducing equivalents drives, in concert with PSI, the conversion of carbon dioxide to sugars. Our knowledge about the architecture of the reaction centre (RC) complex and the mechanisms of charge separation and stabilisation is well advanced. However, our understanding of the processes associated with the functioning of RC is incomplete: the photochemical activity of PSII is routinely monitored by chlorophyll-a fluorescence induction but the presently available data are not free of controversy. In this work, we examined the nature of gradual fluorescence rise of PSII elicited by trains of singleturnover saturating flashes (STSFs) in the presence of a PSII inhibitor, permitting only one stable charge separation. We show that a substantial part of the fluorescence rise originates from lightinduced processes that occur after the stabilisation of charge separation, induced by the first STSF; the temperature-dependent relaxation characteristics suggest the involvement of conformational changes in the additional rise. In experiments using double flashes with variable waiting times (∆τ) between them, we found that no rise could be induced with zero or short ∆τ, the value of which depended on the temperature-revealing a previously unknown rate-limiting step in PSII.
UR - http://www.scopus.com/inward/record.url?scp=85049552779&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85049552779&partnerID=8YFLogxK
U2 - 10.1038/s41598-018-21195-2
DO - 10.1038/s41598-018-21195-2
M3 - Article
C2 - 29426901
AN - SCOPUS:85049552779
VL - 8
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
IS - 1
M1 - 2755
ER -