Iron Bound to the High-Affinity Mn-Binding Site of the Oxygen-Evolving Complex Shifts the pKof a Component Controlling Electron Transport via YZ†

Biochemistry ◽  
2004 ◽  
Vol 43 (21) ◽  
pp. 6772-6782 ◽  
Author(s):  
Boris K. Semin ◽  
Michael Seibert
Keyword(s):  
Electron Transport ◽  
Binding Site ◽  
Oxygen Evolving Complex ◽  
High Affinity ◽  
Oxygen Evolving

Iron-Blocking the High-Affinity Mn-Binding Site in Photosystem II Facilitates Identification of the Type of Hydrogen Bond Participating in Proton-Coupled Electron Transport via YZ•†

Biochemistry ◽  
2005 ◽  
Vol 44 (28) ◽  
pp. 9746-9757 ◽  
Author(s):  
Boris K. Semin ◽  
Elena R. Lovyagina ◽  
Kirill N. Timofeev ◽  
Ilya I. Ivanov ◽  
Andrei B. Rubin ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Electron Transport ◽  
Photosystem Ii ◽  
Binding Site ◽  
High Affinity

Photoinactivation of Photosynthetic Electron Transport under Anaerobic and Aerobic Conditions in Isolated Thylakoids of Spinach

1992 ◽  
Vol 47 (1-2) ◽  
pp. 63-68 ◽  
Author(s):  
Rekha Chaturvedi ◽  
M. Singh ◽  
P. V. Sane
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Oxygen Evolving Complex ◽  
Reaction Centre ◽  
Ps Ii ◽  
Ps I ◽  
S2 State ◽  
The Stability ◽  
Oxygen Evolving ◽  
Spinach Thylakoids

Abstract The effect of exposure to strong white light on photosynthetic electron transport reactions of PS I and PS II were investigated in spinach thylakoids in the absence or presence of oxygen. Irrespective of the conditions used for photoinactivation, the damage to PS II was always much more than to PS I. Photoinactivation was severe under anaerobic conditions compared to that in air for the same duration. This shows that the presence of oxygen is required for prevention of photoinactivation of thylakoids. The susceptibility of water-splitting complex in photoinactivation is indicated by our data from experiments with chloride-deficient chloroplast membranes wherein it was observed that the whole chain electron transport from DPC to MV was much less photoinhibited than that from water. The data from the photoinactivation experiments with the Tris-treated thylakoids indicate another photodam age site at or near reaction centre of PS II. DCMU-protected PS II and oxygen-evolving complex from photoinactivation. DCMU protection can also be interpreted in terms of the stability of the PS II complex when it is in S2 state.

scholarly journals Identification of a Na+-Binding Site near the Oxygen-Evolving Complex of Spinach Photosystem II

Biochemistry ◽  
2020 ◽  
Vol 59 (30) ◽  
pp. 2823-2831
Author(s):  
Jimin Wang ◽  
Joshua M. Perez-Cruet ◽  
Hao-Li Huang ◽  
Krystle Reiss ◽  
Christopher J. Gisriel ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Binding Site ◽  
Oxygen Evolving Complex ◽  
Oxygen Evolving

A Diterpene γ-Lactone Derivative from Pterodon polygalaeflorus Benth. as a Photosystem II Inhibitor and Uncoupler of Photosynthesis

2006 ◽  
Vol 61 (3-4) ◽  
pp. 227-233 ◽  
Author(s):  
Beatriz King-Díaz ◽  
Flávio J. L. dos Santos ◽  
Mayura M. M. Rubinger ◽  
Dorila Piló -Veloso ◽  
Blas Lotina-Hennsen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Transport Rate ◽  
Atp Synthesis ◽  
Transport Rate ◽  
Hill Reaction ◽  
Oxygen Evolving Complex ◽  
Photosynthesis Inhibition ◽  
Chlorophyll A Fluorescence Transient ◽  
Oxygen Evolving

6α,7β-Dihydroxyvouacapan-17β-oic acid (1) was isolated from Pterodon polygalaeflorus Benth. Modification of 1 yielded 6α-hydroxyvouacapan-7β,17β-lactone (2) and then 6-oxovouacapan- 7β,17β-lactone (3). Photosynthesis inhibition by 3 was evaluated in spinach chloroplasts. The uncoupled non-cyclic electron transport rate and ATP synthesis were inhibited by 3, which behaved as a Hill reaction inhibitor. Furthermore, 3 acted as an uncoupler because it enhanced the basal and phosphorylating electron transport rate on thylakoids. This last property of 3 was corroborated when it was observed that it enhances the Mg2+-ATPase activity. In contrast, 3 did not affect photosystem I (PSI) activity. Analysis of the partial photosystem II (PSII) reactions from water to DCPIPox and water to silicomolybdate allowed to locate the inhibition sites at the redox components of PSII. The OJIP test of the chlorophyll a fluorescence transient confirmed that the inhibition sites were 1.) the oxygen-evolving complex (OEC) and 2.) by the formation of silent centers in the non-QA reducing centers.

Antagonistic Effects of α-Tocopherol and α-Tocoquinone in the Regulation of Cyclic Electron Transport around Photosystem II

1997 ◽  
Vol 52 (11-12) ◽  
pp. 766-774 ◽  
Author(s):  
J. Kruk ◽  
K. Burda ◽  
A. Radunz ◽  
K. Strzałka ◽  
G. H. Schmid
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Oxygen Evolution ◽  
Transition Probability ◽  
Continuous Illumination ◽  
Oxygen Evolving Complex ◽  
Cyclic Electron Transport ◽  
State Distribution ◽  
Ps Ii ◽  
Oxygen Evolving

Abstract α-Tocoquinone (α-TQ ) and α-tocopherol (α-TOC) which cannot substitute for plastoquinone-9 (PQ-A) as an electron acceptor from photosystem II (PS II), influence the oxygen evolution activity of thylakoid membranes under continuous illumination. In the presence of the herbicide DCMU and the protonophore FCCP which stimulate cyclic electron transport around PS II, α-TQ decreased oxygen evolution whereas α-TOC enhanced it. The effects are attributed to a stimulation or an inhibition of cyclic electron transport around PS II by α-TQ and α-TOC, respectively. Results of flash light experiments on PS II preparations show that both α-TQ and α-TOC increased the d-parameter which describes the transition probability from the S3- to the S0-state of the oxygen-evolving complex, although to a smaller extent when PQ-A is added alone to the preparations. The initial S-state distribution in darkadapted samples was changed only upon PQ-A addition and influenced neither by α-TQ nor by α-TO C supplementation. These effects indicate different kinds of interaction of PQ-A, α-TQ and α-TOC with the PS II components. α-TQ increased and α-TOC decreased the “total miss” parameter both in the presence or absence of PQ-A. A possible site of interaction of α-TQ and α-TO C with the cyclic electron transport around PS II is suggested.

Investigation of the Calcium-Binding Site of the Oxygen Evolving Complex of Photosystem II Using87Sr ESEEM Spectroscopy

2004 ◽  
Vol 126 (23) ◽  
pp. 7228-7237 ◽  
Author(s):  
Sun Hee Kim ◽  
Wolfgang Gregor ◽  
Jeffrey M. Peloquin ◽  
Marcin Brynda ◽  
R. David Britt
Keyword(s):  
Photosystem Ii ◽  
Binding Site ◽  
Calcium Binding ◽  
Oxygen Evolving Complex ◽  
Calcium Binding Site ◽  
Oxygen Evolving

Excitation pressure as a measure of the sensitivity of photosystem II to photoinactivation

2010 ◽  
Vol 37 (10) ◽  
pp. 943 ◽  
Author(s):  
Dmytro Kornyeyev ◽  
Barry A. Logan ◽  
A. Scott Holaday
Keyword(s):  
Electron Transport ◽  
Uv Light ◽  
Thermal Dissipation ◽  
Oxygen Evolving Complex ◽  
Thermal Energy Dissipation ◽  
Cluster Mechanism ◽  
Oxygen Evolving ◽  
New Hypothesis ◽  
Excitation Pressure

The appearance of a new hypothesis implicating the oxygen-evolving complex as the dominant target of PSII photoinactivation (the ‘manganese cluster’ mechanism) suggests that the inactivation of PSII can be predicted on the basis of the total amount of incident photons, and challenges the role that electron transport and thermal dissipation of excitation energy play in mitigating PSII photoinactivation. This viewpoint article discusses evidence showing that minimising of the amount of energy reaching closed PSII reaction centres (i.e. the excitation pressure) is important for photoprotection. Examples are described where the parameters derived from excitation pressure correlate with the level of PSII photoinactivation, whereas the counting of incident photons does not. These examples confirm the role of electron transport and thermal energy dissipation as factors modulating PSII photoinactivation, and validate strategies that are aimed at understanding and improving PSII resistance to photoinactivation by analysis and manipulation of photoprotective processes. The authors conclude that an integrated model that incorporates various mechanisms of PSII photoinactivation and analysis of their contribution is needed. In addition, the role of UV light in naturally occurring PSII photoinactivation is evaluated. It is suggested that, when compared with visible light, the damaging effect of UV light may be limited under field conditions.

scholarly journals Investigation of substrate water interactions at the high-affinity Mn site in the photosystem II oxygen-evolving complex

2007 ◽  
Vol 363 (1494) ◽  
pp. 1229-1235 ◽  
Author(s):  
Sonita Singh ◽  
Richard J Debus ◽  
Tom Wydrzynski ◽  
Warwick Hillier
Keyword(s):  
Hydrogen Bonding ◽  
Photosystem Ii ◽  
Exchange Rates ◽  
Isotope Exchange ◽  
Water Molecules ◽  
Oxygen Evolving Complex ◽  
Wild Type ◽  
High Affinity ◽  
O Isotope ◽  
Oxygen Evolving

18 O isotope exchange measurements of photosystem II (PSII) in thylakoids from wild-type and mutant Synechocystis have been performed to investigate binding of substrate water to the high-affinity Mn 4 site in the oxygen-evolving complex (OEC). The mutants investigated were D1-D170H, a mutation of a direct ligand to the Mn 4 ion, and D1-D61N, a mutation in the second coordination sphere. The substrate water 18 O exchange rates for D61N were found to be 0.16±0.02 s −1 and 3.03±0.32 s −1 for the slow and fast phases of exchange, respectively, compared with 0.47±0.04 s −1 and 19.7±1.3 s −1 for the wild-type. The D1-D170H rates were found to be 0.70±0.16 s −1 and 24.4±4.6 s −1 and thus are almost within the error limits for the wild-type rates. The results from the D1-D170H mutant indicate that the high-affinity Mn 4 site does not directly bind to the substrate water molecule in slow exchange, but the binding of non-substrate water to this Mn ion cannot be excluded. The results from the D61N mutation show an interaction with both substrate water molecules, which could be an indication that D61 is involved in a hydrogen bonding network with the substrate water. Our results provide limitations as to where the two substrate water molecules bind in the OEC of PSII.

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