An Intrinsically Disordered Photosystem II Subunit, PsbO, Provides a Structural Template and a Sensor of the Hydrogen-bonding Network in Photosynthetic Water Oxidation

Offenbacher, Adam R.; Polander, Brandon C.; Barry, Bridgette A.

doi:10.1074/jbc.m113.487561

Cited by 30 publications

(33 citation statements)

References 110 publications

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“…The possibility of such long‐range effects on the FTIR differential spectra is also in line with PsbO, PsbP and PsbQ depletion experiments (Offenbacher et al , Ifuku and Noguchi ), reporting a strong dependence of the spectra on the S state. These proteins are involved in water delivery and proton channels Shutova et al (), therefore may differ in different states.…”

Section: Introductionsupporting

confidence: 73%

On the comparison between differential vibrational spectroscopy spectra and theoretical data in the carboxyl region of photosystem II

Capone

Narzi

Tychengulova

et al. 2019

Physiologia Plantarum

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Understanding the structural modification experienced by the Mn4CaO5 oxygen‐evolving complex of photosystem II along the Kok‐Joliot's cycle has been a challenge for both theory and experiments since many decades. In particular, differential infrared spectroscopy was extensively used to probe the surroundings of the reaction center, to catch spectral changes between different S‐states along the catalytic cycle. Because of the complexity of the signals, only a limited quantity of identified peaks have been assigned so far, also because of the difficulty of a direct comparison with theoretical calculations. In the present work, we critically reconsider the comparison between differential vibrational spectroscopy and theoretical calculations performed on the structural models of the photosystem II active site and an inorganic structural mimic. Several factors are currently limiting the reliability of a quantitative comparison, such as intrinsic errors associated to theoretical methods, and most of all, the uncertainty attributed to the lack of knowledge about the localization of the underlying structural changes. Critical points in this comparison are extensively discussed. Comparing several computational data of differential S2/S1 infrared spectroscopy, we have identified weak and strong points in their interpretation when compared with experimental spectra.

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Section: Introductionsupporting

confidence: 73%

On the comparison between differential vibrational spectroscopy spectra and theoretical data in the carboxyl region of photosystem II

Capone

Narzi

Tychengulova

et al. 2019

Physiologia Plantarum

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“…[42][43][44]46 It should be noted that although it was recently reported that the removal of PsbP and PsbQ from PSII core preparations of spinach showed no significant effect on the S 2 /S 1 spectrum, 73 the control S 2 /S 1 spectrum in ref 73 exhibited a typical amide I feature of PsbP-depleted PSII, i.e., lower and higher intensities for the 1668 and 1686 cm −1 peaks, respectively (compare the spectrum of Figure 4A in ref 73 with our spectra of Figure 1b in ref 42). Hence, it is suggested that the intact PSII core complexes from spinach in ref 73 were actually depleted of the PsbP and PsbQ proteins when FTIR spectra were measured, possibly because of the presence of potassium ferricyanide in addition to 20 mM CaCl 2 . The latter work also showed that removal of PsbO significantly affected the amide I bands of the S 2 /S 1 difference spectrum, 73 whereas our previous measurements showed that PsbO depletion did not induce further changes in the amide I bands of PsbP-and PsbQ-depleted PSII membranes.…”

Section: ■ Discussionmentioning

confidence: 97%

Effects of Extrinsic Proteins on the Protein Conformation of the Oxygen-Evolving Center in Cyanobacterial Photosystem II As Revealed by Fourier Transform Infrared Spectroscopy

2015

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Extrinsic proteins of photosystem II (PSII) play an important role in optimizing oxygen-evolving reactions in all oxyphototrophs. The currently available crystal structures of cyanobacterial PSII core complexes show the binding structures of the extrinsic proteins, PsbO, PsbV, and PsbU; however, how the individual extrinsic proteins affect the structure and the function of the oxygen-evolving center (OEC) in cyanobacterial PSII remains unknown. In this study, we have investigated the effects of the binding of the extrinsic proteins on the protein conformation of the OEC in PSII core complexes from the thermophilic cyanobacterium Thermosynechococcus elongatus, using light-induced Fourier transform infrared (FTIR) difference spectroscopy. Upon removal of the three extrinsic proteins, an S₂-minus-S₁ FTIR difference spectrum measured in the presence of a high CaCl₂ concentration showed a drastic change in amide I bands, reflecting perturbation of the secondary structures of polypeptides, whereas the overall spectral intensity was lost at a low CaCl₂ concentration, indicative of inactivation of the Mn₄CaO₅ cluster. The amide I features as well as the overall intensity were recovered mainly by binding of PsbO, while complete amide I recovery was achieved by further binding of PsbV and PsbU. We thus concluded that PsbO, together with smaller contributions of PsbV and PsbU, plays a role in the maintenance of the proper protein conformation of the OEC in cyanobacterial PSII, which provides the stability of the Mn₄CaO₅ cluster via the enhanced retention capability of Ca²⁺ and Cl⁻ ions.

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“…This allows PsbO to respond dynamically to changes in the abundance of redox‐active thioredoxin (Roberts et al ), pH (Shutova et al , , , Bommer et al ), GTP (Lundin et al ) and the calcium ions (Heredia and De Las Rivas , Shutova et al , Murray and Barber ). The structural dynamics of PsbO have been analyzed and related to its functional role in photosynthetic water oxidation based on experiments using intra‐molecular cross‐linking (Enami et al ) and FTIR spectroscopy (Hutchison et al , Sachs et al , Offenbacher et al ). The substrate water exchange in PSII depends on the presence of the extrinsic proteins and the removal of PsbO has slightly different effect in prokaryotic and eukaryotic organisms (Hillier et al ).…”

Section: Introductionmentioning

confidence: 99%

Dynamic pH‐induced conformational changes of the PsbO protein in the fluctuating acidity of the thylakoid lumen

Carius

Rogne

Duchoslav

et al. 2019

Physiologia Plantarum

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The PsbO protein is an essential extrinsic subunit of photosystem II, the pigment–protein complex responsible for light‐driven water splitting. Water oxidation in photosystem II supplies electrons to the photosynthetic electron transfer chain and is accompanied by proton release and oxygen evolution. While the electron transfer steps in this process are well defined and characterized, the driving forces acting on the liberated protons, their dynamics and their destiny are all largely unknown. It was suggested that PsbO undergoes proton‐induced conformational changes and forms hydrogen bond networks that ensure prompt proton removal from the catalytic site of water oxidation, i.e. the Mn4CaO5 cluster. This work reports the purification and characterization of heterologously expressed PsbO from green algae Chlamydomonas reinhardtii and two isoforms from the higher plant Solanum tuberosum (PsbO1 and PsbO2). A comparison to the spinach PsbO reveals striking similarities in intrinsic protein fluorescence and CD spectra, reflecting the near‐identical secondary structure of the proteins from algae and higher plants. Titration experiments using the hydrophobic fluorescence probe ANS revealed that eukaryotic PsbO proteins exhibit acid–base hysteresis. This hysteresis is a dynamic effect accompanied by changes in the accessibility of the protein's hydrophobic core and is not due to reversible oligomerization or unfolding of the PsbO protein. These results confirm the hypothesis that pH‐dependent dynamic behavior at physiological pH ranges is a common feature of PsbO proteins and causes reversible opening and closing of their β‐barrel domain in response to the fluctuating acidity of the thylakoid lumen.

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An Intrinsically Disordered Photosystem II Subunit, PsbO, Provides a Structural Template and a Sensor of the Hydrogen-bonding Network in Photosynthetic Water Oxidation

Cited by 30 publications

References 110 publications

On the comparison between differential vibrational spectroscopy spectra and theoretical data in the carboxyl region of photosystem II

On the comparison between differential vibrational spectroscopy spectra and theoretical data in the carboxyl region of photosystem II

Effects of Extrinsic Proteins on the Protein Conformation of the Oxygen-Evolving Center in Cyanobacterial Photosystem II As Revealed by Fourier Transform Infrared Spectroscopy

Dynamic pH‐induced conformational changes of the PsbO protein in the fluctuating acidity of the thylakoid lumen

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