The PsbJ protein is required for photosystem II activity in centers lacking the PsbO and PsbV lumenal subunits

Choo, Priscilla; Forsman, Jack; Hui, Lanfeng; Khaing, Ei Phyo; Summerfield, Tina C.; Eaton‐Rye, Julian J.

doi:10.1007/s11120-021-00862-y

Cited by 9 publications

(15 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fluorescence data suggested PS II levels may be altered in different mutants; to investigate further, BN-PAGE was performed, and the separated PS II complexes detected using antibodies to the D1, D2, CP43, and CP47 proteins (Figure ). Control cells and the Y244F and Y244H mutants showed a similar pattern for the relative levels of the PS II dimer and monomer bands, whereas the Y244A mutant displayed a small upshift in the mobility of the protein complexes suggestive of stress-induced carotenoids being produced. , …”

Section: Resultsmentioning

confidence: 79%

“…Control cells and the Y244F and Y244H mutants showed a similar pattern for the relative levels of the PS II dimer and monomer bands, whereas the Y244A mutant displayed a small upshift in the mobility of the protein complexes suggestive of stress-induced carotenoids being produced. 51,52 When probed with the CP43 antibody, each of the mutants, but not the control, exhibited accumulation of a pre-assembly complex containing the CP43 subunit (Figure 8E) indicating an impairment in PS II assembly (or that the CP43-containing pre-complex was less tightly bound). Relative levels of monomeric and dimeric PS II complexes between the different mutants, however, was difficult to determine since the results were based on chemiluminescence detection, and this analysis does not linearly correlate with the amount of protein present.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Tyr244 of the D2 Protein Is Required for Correct Assembly and Operation of the Quinone-Iron-Bicarbonate Acceptor Complex of Photosystem II

et al. 2022

Self Cite

View full text Add to dashboard Cite

Two plastoquinone electron acceptors, QA and QB, are present in Photosystem II (PS II) with their binding sites formed by the D2 and D1 proteins, respectively. A hexacoordinate non-heme iron is bound between QA and QB by D2 and D1, each providing two histidine ligands, and a bicarbonate that is stabilized via hydrogen bonds with D2-Tyr244 and D1-Tyr246. Both tyrosines and bicarbonate are conserved in oxygenic photosynthetic organisms but absent from the corresponding quinone-iron electron acceptor complex of anoxygenic photosynthetic bacteria. We investigated the role of D2-Tyr244 by introducing mutations in the cyanobacterium Synechocystis sp. PCC 6803. Alanine, histidine, and phenylalanine substitutions were introduced creating the Y244A, Y244H, and Y244F mutants. Electron transfer between QA and QB was impaired, the back-reaction with the S2 state of the oxygen-evolving complex was modified, and PS II assembly was disrupted, with the Y244A strain being more affected than the Y244F and Y244H mutants. The strains were also highly susceptible to photodamage in the presence of PS II-specific electron acceptors. Thermoluminescence and chlorophyll a fluorescence decay measurements indicated that the redox potential of the QA/QA – couple became more positive in the Y244F and Y244H mutants, consistent with bicarbonate binding being impacted. The replacement of Tyr244 by alanine also led to an insertion of two amino acid repeats from Gln239 to Ala249 within the DE loop of D2, resulting in an inactive PS II complex that lacked PS II-specific variable fluorescence. The 66 bp insertion giving rise to the inserted amino acids therefore created an obligate photoheterotrophic mutant.

show abstract

Section: Resultsmentioning

confidence: 79%

mentioning

confidence: 99%

Tyr244 of the D2 Protein Is Required for Correct Assembly and Operation of the Quinone-Iron-Bicarbonate Acceptor Complex of Photosystem II

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…The phenomenon was also present in a ΔPsbM:ΔPsbY double mutant and strains carrying amino acid substitutions at D2-Tyr244. , In each of these examples, one explanation has been that the inclusion of the native quinone in the bicarbonate-supported whole chain electron transport circumvented the susceptibility that was present in the presence of the artificial quinone. Alternatively, it has been considered that in the case of bicarbonate-supported whole chain electron transport, enough centers remained active that when assayed under saturating light, the oxidation of the plastoquinone pool was the rate-limiting step in both the control and mutants (e.g., Choo et al). The result with K264E cells in Figure B offers an alternative explanation.…”

Section: Discussionmentioning

confidence: 99%

Lys264 of the D2 Protein Performs a Dual Role in Photosystem II Modifying Assembly and Electron Transfer through the Quinone–Iron Acceptor Complex

Khaing,

Eaton-Rye

2023

Biochemistry

Self Cite

View full text Add to dashboard Cite

Bicarbonate (HCO3 –) binding regulates electron flow between the primary (QA) and secondary (QB) plastoquinone electron acceptors of Photosystem II (PS II). Lys264 of the D2 subunit of PS II contributes to a hydrogen-bond network that stabilizes HCO3 – ligation to the non-heme iron in the QA-Fe-QB complex. Using the cyanobacterium Synechocystis sp. PCC 6803, alanine and glutamate were introduced to create the K264A and K264E mutants. Photoautotrophic growth was slowed in K264E cells but not in the K264A strain. Both mutants accumulated an unassembled CP43 precomplex as well as the CP43-lacking RC47 assembly intermediate, indicating weakened binding of the CP43 precomplex to RC47. Assembly was impeded more in K264E cells than in the K264A strain, but K264A cells were more susceptible to high-light-induced photodamage when assayed using PS II-specific electron acceptors. Furthermore, an impaired repair mechanism was observed in the K264A mutant in protein labeling experiments. Unexpectedly, unlike the K264A strain, the K264E mutant displayed inhibited oxygen evolution following high-light exposure when HCO3 – was added to support whole chain electron transport. In both mutants, the decay of chlorophyll fluorescence was slowed, indicating impaired electron transfer between QA and QB. Furthermore, the fluorescence decay kinetics in the K264E strain were insensitive to addition of either formate or HCO3 –, whereas HCO3 –-reversible formate-induced inhibition in the K264A mutant was observed. Exchange of plastoquinol with the membrane plastoquinone pool at the QB-binding site was also retarded in both mutants. Hence, D2-Lys264 possesses key roles in both assembly and activity of PS II.

show abstract

“…Antioxidant have a critical roles for balancing of oxidative stress particularly during biological illness, For many years, lots of evidence have indicated that phytochemicals in plants exhibit a significant role to protect the living cells from free radical-induced oxidative stress with different mechanisms. [7] It has been known that plant-derived antioxidants display their biological capabilities through various mechanisms including inhibition of some critical enzymes. [8] Since long years, traditional plants have been used to treat numerous health problems such as type 2 diabetes (T2D) and obesity-related metabolic disorders.…”

Section: Introductionmentioning

confidence: 99%

Phytochemical Analysis and Biological Evaluation of Hypericum linarioides Bosse: in Vitro and in Silico Studies

et al. 2022

View full text Add to dashboard Cite

The aim of this study is to determine the phenolic composition of Hypericum linarioides Bosse, to assess its various biological properties, and finally to confirm the experimental data of enzyme inhibitions via docking studies. LC-MS/MS analysis performed over methanol extract (ME) revealed the presence of 27 phytochemicals. Antioxidant activity results indicated that ME had the strongest DPPH radical scavenging and ferric ion reducing capacity than water and hexane extracts. XTT assays revealed the strongest anti-proliferative activity of ME against MCF-7 and HT-29 cancer cells. Flow cytometry results also confirmed the notable apoptotic effect of ME on MCF-7 cells through mitochondria-dependent pathway. Enzyme activity results exhibited the most promising acetylcholinesterase and α-glycosidase inhibitory activities of the ME. Molecular docking calculations of α-glycosidase with the major compounds (1, 15, 17 and 19) indicated that 17 (isoquercitrin) had the best docking binding energy (À 10.92 kcal/mol) with appropriate binding interactions.

show abstract

The PsbJ protein is required for photosystem II activity in centers lacking the PsbO and PsbV lumenal subunits

Cited by 9 publications

References 57 publications

Tyr244 of the D2 Protein Is Required for Correct Assembly and Operation of the Quinone-Iron-Bicarbonate Acceptor Complex of Photosystem II

Tyr244 of the D2 Protein Is Required for Correct Assembly and Operation of the Quinone-Iron-Bicarbonate Acceptor Complex of Photosystem II

Lys264 of the D2 Protein Performs a Dual Role in Photosystem II Modifying Assembly and Electron Transfer through the Quinone–Iron Acceptor Complex

Phytochemical Analysis and Biological Evaluation of Hypericum linarioides Bosse: in Vitro and in Silico Studies

Contact Info

Product

Resources

About