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Yanykin D, Paskhin M, Ashikhmin AA, Bolshakov MA. Carotenoid-dependent singlet oxygen photogeneration in light-harvesting complex 2 of Ectothiorhodospira haloalkaliphila leads to the formation of organic hydroperoxides and damage to both pigments and protein matrix. PeerJ 2024; 12:e16615. [PMID: 38250719 PMCID: PMC10798160 DOI: 10.7717/peerj.16615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/15/2023] [Indexed: 01/23/2024] Open
Abstract
Earlier, it was suggested that carotenoids in light-harvesting complexes 2 (LH2) can generate singlet oxygen, further oxidizing bacteriochlorophyll to 3-acetyl-chlorophyll. In the present work, it was found that illumination of isolated LH2 preparations of purple sulfur bacterium Ectothiorhodospira haloalkaliphila with light in the carotenoid absorption region leads to the photoconsumption of molecular oxygen, which is accompanied by the formation of hydroperoxides of organic molecules in the complexes. Photoformation of two types of organic hydroperoxides were revealed: highly lipophilic (12 molecules per one LH2) and relatively hydrophobic (68 per one LH2). It has been shown that illumination leads to damage to light-harvesting complexes. On the one hand, photobleaching of bacteriochlorophyll and a decrease in its fluorescence intensity are observed. On the other hand, the photoinduced increase in the hydrodynamic radius of the complexes, the reduction in their thermal stability, and the change in fluorescence intensity indicate conformational changes occurring in the protein molecules of the LH2 preparations. Inhibition of the processes described above upon the addition of singlet oxygen quenchers (L-histidine, Trolox, sodium L-ascorbate) may support the hypothesis that carotenoids in LH2 preparations are capable of generating singlet oxygen, which, in turn, damage to protein molecules.
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Affiliation(s)
- Denis Yanykin
- Institute of Basic Biological Problems, FRC PSCBR, Pushchino, Moscow, Russia
- Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow, Moscow, Russia
| | - Mark Paskhin
- Institute of Basic Biological Problems, FRC PSCBR, Pushchino, Moscow, Russia
- Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow, Moscow, Russia
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Gates C, Ananyev G, Roy-Chowdhury S, Fromme P, Dismukes GC. Regulation of light energy conversion between linear and cyclic electron flow within photosystem II controlled by the plastoquinone/quinol redox poise. PHOTOSYNTHESIS RESEARCH 2023; 156:113-128. [PMID: 36436152 DOI: 10.1007/s11120-022-00985-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 11/09/2022] [Indexed: 06/16/2023]
Abstract
Ultrapurified Photosystem II complexes crystalize as uniform microcrystals (PSIIX) of unprecedented homogeneity that allow observation of details previously unachievable, including the longest sustained oscillations of flash-induced O2 yield over > 200 flashes and a novel period-4.7 water oxidation cycle. We provide new evidence for a molecular-based mechanism for PSII-cyclic electron flow that accounts for switching from linear to cyclic electron flow within PSII as the downstream PQ/PQH2 pool reduces in response to metabolic needs and environmental input. The model is supported by flash oximetry of PSIIX as the LEF/CEF switch occurs, Fourier analysis of O2 flash yields, and Joliot-Kok modeling. The LEF/CEF switch rebalances the ratio of reductant energy (PQH2) to proton gradient energy (H+o/H+i) created by PSII photochemistry. Central to this model is the requirement for a regulatory site (QC) with two redox states in equilibrium with the dissociable secondary electron carrier site QB. Both sites are controlled by electrons and protons. Our evidence fits historical LEF models wherein light-driven water oxidation delivers electrons (from QA-) and stromal protons through QB to generate plastoquinol, the terminal product of PSII-LEF in vivo. The new insight is the essential regulatory role of QC. This site senses both the proton gradient (H+o/H+i) and the PQ pool redox poise via e-/H+ equilibration with QB. This information directs switching to CEF upon population of the protonated semiquinone in the Qc site (Q-H+)C, while the WOC is in the reducible S2 or S3 states. Subsequent photochemical primary charge separation (P+QA-) forms no (QH2)B, but instead undergoes two-electron backward transition in which the QC protons are pumped into the lumen, while the electrons return to the WOC forming (S1/S2). PSII-CEF enables production of additional ATP needed to power cellular processes including the terminal carboxylation reaction and in some cases PSI-dependent CEF.
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Affiliation(s)
- Colin Gates
- Dept of Chemistry & Chemical Biology, Rutgers University, Piscataway, USA
- Waksman Institute of Microbiology, Rutgers University, Piscataway, USA
- Dept of Computational Biology & Molecular Biophysics, Rutgers University, Piscataway, NJ, USA
- Dept of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, USA
| | - Gennady Ananyev
- Dept of Chemistry & Chemical Biology, Rutgers University, Piscataway, USA
- Waksman Institute of Microbiology, Rutgers University, Piscataway, USA
| | - Shatabdi Roy-Chowdhury
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Petra Fromme
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - G Charles Dismukes
- Dept of Chemistry & Chemical Biology, Rutgers University, Piscataway, USA.
- Waksman Institute of Microbiology, Rutgers University, Piscataway, USA.
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Shukshina AK, Terentyev VV. Involvement of Carbonic Anhydrase CAH3 in the Structural and Functional Stabilization of the Water-Oxidizing Complex of Photosystem II from Chlamydomonas reinhardtii. BIOCHEMISTRY (MOSCOW) 2021; 86:867-877. [PMID: 34284710 DOI: 10.1134/s0006297921070075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The involvement of carbonic anhydrases (CA) and CA activity in the functioning of photosystem II (PSII) has been studied for a long time and has been shown in many works. However, so far only for CAH3 from Chlamydomonas reinhardtii there is evidence for its association with the donor side of PSII, where the CA activity of CAH3 can influence the functioning of the water-oxidizing complex (WOC). Our results suggest that CAH3 is also involved in the organization of the native structure of WOC independently of its CA activity. It was shown that in PSII preparations from wild type (WT) the high O2-evolving activity of WOC was observed up to 100 mM NaCl in the medium and practically did not decrease with increasing incubation time with NaCl. At the same time, the WOC function in PSII preparations from CAH3-deficient mutant cia3 is significantly inhibited already at NaCl concentrations above 35 mM, reaching 50% at 100 mM NaCl and increased incubation time. It is suggested that the absence of CAH3 in PSII from cia3 causes disruption of the native structure of WOC, allowing more pronounced conformational changes of its proteins and, consequently, suppression of the WOC active center function, when the ionic strength of the medium is increased. The results of Western blot analysis indicate a more difficult removal of PsbP protein from PSII of cia3 at higher NaCl concentrations, apparently due to the changes in the intermolecular interactions between proteins of WOC in the absence of CAH3. At the same time, the values of the maximum quantum yield of PSII did not practically differ between preparations from WT and cia3, indicating no effect of CAH3 on the photoinduced electron transfer in the reaction center of PSII. The obtained results indicate the involvement of the CAH3 protein in the native organization of the WOC and, as a consequence, in the stabilization of its functional state in PSII from C. reinhardtii.
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Affiliation(s)
- Anna K Shukshina
- Institute of Basic Biological Problems, Pushchino Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Vasily V Terentyev
- Institute of Basic Biological Problems, Pushchino Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
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Khorobrykh A. Hydrogen Peroxide and Superoxide Anion Radical Photoproduction in PSII Preparations at Various Modifications of the Water-Oxidizing Complex. PLANTS 2019; 8:plants8090329. [PMID: 31491946 PMCID: PMC6784185 DOI: 10.3390/plants8090329] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 08/25/2019] [Accepted: 08/29/2019] [Indexed: 11/24/2022]
Abstract
The photoproduction of superoxide anion radical (O2−•) and hydrogen peroxide (H2O2) in photosystem II (PSII) preparations depending on the damage to the water-oxidizing complex (WOC) was investigated. The light-induced formation of O2−• and H2O2 in the PSII preparations rose with the increased destruction of the WOC. The photoproduction of superoxide both in the PSII preparations holding intact WOC and the samples with damage to the WOC was approximately two times higher than H2O2. The rise of O2−• and H2O2 photoproduction in the PSII preparations in the course of the disassembly of the WOC correlated with the increase in the fraction of the low-potential (LP) Cyt b559. The restoration of electron flow in the Mn-depleted PSII preparations by exogenous electron donors (diphenylcarbazide, Mn2+) suppressed the light-induced formation of O2−• and H2O2. The decrease of O2−• and H2O2 photoproduction upon the restoration of electron transport in the Mn-depleted PSII preparations could be due to the re-conversion of the LP Cyt b559 into higher potential forms. It is supposed that the conversion of the high potential Cyt b559 into its LP form upon damage to the WOC leads to the increase of photoproduction of O2−• and H2O2 in PSII.
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Affiliation(s)
- Andrey Khorobrykh
- Institute of Basic Biological Problems, FRC PSCBR RAS, Pushchino 142290, Moscow Region, Russia.
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Yanykin DV, Malferrari M, Rapino S, Venturoli G, Semenov AY, Mamedov MD. Hydroxyectoine protects Mn-depleted photosystem II against photoinhibition acting as a source of electrons. PHOTOSYNTHESIS RESEARCH 2019; 141:165-179. [PMID: 30701483 DOI: 10.1007/s11120-019-00617-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/17/2019] [Indexed: 06/09/2023]
Abstract
In the present study, we have investigated the effect of hydroxyectoine (Ect-OH), a heterocyclic amino acid, on oxygen evolution in photosystem II (PS II) membrane fragments and on photoinhibition of Mn-depleted PS II (apo-WOC-PS II) preparations. The degree of photoinhibition of apo-WOC-PS II preparations was estimated by the loss of the capability of exogenous electron donor (sodium ascorbate) to restore the amplitude of light-induced changes of chlorophyll fluorescence yield (∆F). It was found that Ect-OH (i) stimulates the oxygen-evolving activity of PS II, (ii) accelerates the electron transfer from exogenous electron donors (K4[Fe(CN)6], DPC, TMPD, Fe2+, and Mn2+) to the reaction center of apo-WOC-PS II, (iii) enhances the protective effect of exogenous electron donors against donor-side photoinhibition of apo-WOC-PS II preparations. It is assumed that Ect-OH can serve as an artificial electron donor for apo-WOC-PS II, which does not directly interact with either the donor or acceptor side of the reaction center. We suggest that the protein conformation in the presence of Ect-OH, which affects the extent of hydration, becomes favorable for accepting electrons from exogenous donors. To our knowledge, this is the first study dealing with redox activity of Ect-OH towards photosynthetic pigment-protein complexes.
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Affiliation(s)
- D V Yanykin
- Institute of Basic Biological Problems, FRC PSCBR RAS, Pushchino, Moscow Region, Russia, 142290.
| | - M Malferrari
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Via F. Selmi 2, 40126, Bologna, Italy
| | - S Rapino
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Via F. Selmi 2, 40126, Bologna, Italy
| | - G Venturoli
- Laboratory of Biochemistry and Molecular Biophysics, Department of Pharmacy and Biotechnology, FaBiT, University of Bologna, 40126, Bologna, Italy
| | - A Yu Semenov
- Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1-40, Moscow, Russia, 119992
| | - M D Mamedov
- Belozersky Institute of Physical-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory 1-40, Moscow, Russia, 119992
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