Coordination of proton and electron transfer from the redox-active tyrosine, YZ, of Photosystem II and examination of the electrostatic influence of oxidized tyrosine, YD˙(H+)

2004 ◽  
Vol 6 (20) ◽  
pp. 4844-4850 ◽  
Author(s):  
Bruce A. Diner ◽  
James A. Bautista ◽  
Peter J. Nixon ◽  
Catherine Berthomieu ◽  
Rainer Hienerwadel ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Redox Active

scholarly journals Modeling of variant copies of subunit D1 in the structure of photosystem II from Thermosynechococcus elongatus

2008 ◽  
Vol 389 (5) ◽  
Author(s):  
Bernhard Loll ◽  
Matthias Broser ◽  
Peter B. Kós ◽  
Jan Kern ◽  
Jacek Biesiadka ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Hot Springs ◽  
High Light Intensity ◽  
Culture Conditions ◽  
Partial Replacement ◽  
Expression Of Genes ◽  
Redox Active ◽  
Pigment Complex ◽  
Protection Mechanisms

Abstract In the cyanobacterium Thermosynechococcus elongatus BP-1, living in hot springs, the light environment directly regulates expression of genes that encode key components of the photosynthetic multi-subunit protein-pigment complex photosystem II (PSII). Light is not only essential as an energy source to power photosynthesis, but leads to formation of aggressive radicals which induce severe damage of protein subunits and organic cofactors. Photosynthetic organisms develop several protection mechanisms against this photo-damage, such as the differential expression of genes coding for the reaction center subunit D1 in PSII. Testing the expression of the three different genes (psbAI, psbAII, psbAIII) coding for D1 in T. elongatus under culture conditions used for preparing the material used in crystallization of PSII showed that under these conditions only subunit PsbA1 is present. However, exposure to high-light intensity induced partial replacement of PsbA1 with PsbA3. Modeling of the variant amino acids of the three different D1 copies in the 3.0 Å resolution crystal structure of PSII revealed that most of them are in the direct vicinity to redox-active cofactors of the electron transfer chain. Possible structural and mechanistic consequences for electron transfer are discussed.

Proton-Coupled Electron-Transfer Processes in Photosystem II Probed by Highly Resolvedg-Anisotropy of Redox-Active Tyrosine YZ

2011 ◽  
Vol 133 (12) ◽  
pp. 4655-4660 ◽  
Author(s):  
Hideto Matsuoka ◽  
Jian-Ren Shen ◽  
Asako Kawamori ◽  
Kei Nishiyama ◽  
Yasunori Ohba ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Transfer Processes ◽  
Proton Coupled Electron Transfer ◽  
Redox Active ◽  
Electron Transfer Processes

scholarly journals High-resolution cryo-EM structure of photosystem II reveals damage from high-dose electron beams

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Koji Kato ◽  
Naoyuki Miyazaki ◽  
Tasuku Hamaguchi ◽  
Yoshiki Nakajima ◽  
Fusamichi Akita ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Physiological State ◽  
High Dose ◽  
Final State ◽  
X Ray ◽  
Redox States ◽  
X Ray Crystallography ◽  
Cryo Electron Microscopy ◽  
Redox Active ◽  
Beam Damage

AbstractPhotosystem II (PSII) plays a key role in water-splitting and oxygen evolution. X-ray crystallography has revealed its atomic structure and some intermediate structures. However, these structures are in the crystalline state and its final state structure has not been solved. Here we analyzed the structure of PSII in solution at 1.95 Å resolution by single-particle cryo-electron microscopy (cryo-EM). The structure obtained is similar to the crystal structure, but a PsbY subunit was visible in the cryo-EM structure, indicating that it represents its physiological state more closely. Electron beam damage was observed at a high-dose in the regions that were easily affected by redox states, and reducing the beam dosage by reducing frames from 50 to 2 yielded a similar resolution but reduced the damage remarkably. This study will serve as a good indicator for determining damage-free cryo-EM structures of not only PSII but also all biological samples, especially redox-active metalloproteins.

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