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A model for the photosystem II reaction center core including the structure of the primary donor P-680

Svensson, B; Etchebest, C; Tuffery, P; van Kan, Paul; Smith, J and Styring, Stenbjörn LU (1996) In Biochemistry 35(46). p.14486-14502
Abstract
For a detailed understanding of the function of photosystem II (PSII), a molecular structure is needed, The crystal structure has not yet been determined, but the PSII reaction center proteins D1 and D2 show homology with the L and M subunits of the photosynthetic reaction center from purple bacteria, We have modeled important parts of the D1 and D2 proteins on the basis of the crystallographic structure of The reaction center from Rhodopseudomonas viridis. The model contains the central core of the PSII reaction center, including the protein regions for the transmembrane helices B, C, D, and E and loops B-C and C-D connecting the helices, In the model, four chlorophylls, two pheophytins, and the nonheme Fe2+ ion are included. We have... (More)
For a detailed understanding of the function of photosystem II (PSII), a molecular structure is needed, The crystal structure has not yet been determined, but the PSII reaction center proteins D1 and D2 show homology with the L and M subunits of the photosynthetic reaction center from purple bacteria, We have modeled important parts of the D1 and D2 proteins on the basis of the crystallographic structure of The reaction center from Rhodopseudomonas viridis. The model contains the central core of the PSII reaction center, including the protein regions for the transmembrane helices B, C, D, and E and loops B-C and C-D connecting the helices, In the model, four chlorophylls, two pheophytins, and the nonheme Fe2+ ion are included. We have applied techniques from computational chemistry that incorporate statistical data on side-chain rotameric states from known protein structures and that describe interactions within the model using an empirical potential energy function. The conformation of chlorophyll pigments in the model was optimized by using exciton interaction calculations in combination with potential energy calculations to rind a solution that agrees with experimentally determined exciton interaction energies, The model is analyzed and compared with experimental results for the regions of Pb-680, the redox active pheophytin, the acceptor side Fe2+, and the tyrosyl radicals Tyr(D) and Tyr(Z), P-680 is proposed to be a weakly coupled chlorophyll a pair which makes three hydrogen bonds with residues on the D1 and D2 proteins. In the model the redox-active pheophytin is hydrogen bonded to D1-Glu130 and possibly also to D1-Tyr126 and D1-Tyr147. Tyr(D) is hydrogen bonded to D2-His190 and also interacts with D2-Gln165. Tyr(Z) is bound in a hydrophilic environment which is partially constituted by D1-Gln165, D1-Asp170, D1-Glu189, and D1-His190, These polar residues are most likely involved in proton transfer from oxidized Tyr(Z) or in metal binding. (Less)
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subject
keywords
PHOTOSYNTHETIC REACTION-CENTER, ELECTRON-PARAMAGNETIC-RES, SITE-DIRECTED MUTANTS, NON-HEME IRON, RHODOBACTER-SPHAEROIDES R-26, ENVELOPE MODULATION ESEEM, SYNECHOCYSTIS SP PCC-6803, HERBICIDE BINDING NICHE, REACTION-CENTER COMPLEX, AMINO-ACID SEQUENCE
in
Biochemistry
volume
35
issue
46
pages
14486 - 14502
publisher
The American Chemical Society
external identifiers
  • scopus:0030448542
ISSN
0006-2960
DOI
10.1021/bi960764k
language
English
LU publication?
yes
id
443048a0-41ab-4d20-ba07-3d0c0de78387 (old id 127070)
date added to LUP
2007-07-06 16:39:58
date last changed
2017-10-01 03:41:11
@article{443048a0-41ab-4d20-ba07-3d0c0de78387,
  abstract     = {For a detailed understanding of the function of photosystem II (PSII), a molecular structure is needed, The crystal structure has not yet been determined, but the PSII reaction center proteins D1 and D2 show homology with the L and M subunits of the photosynthetic reaction center from purple bacteria, We have modeled important parts of the D1 and D2 proteins on the basis of the crystallographic structure of The reaction center from Rhodopseudomonas viridis. The model contains the central core of the PSII reaction center, including the protein regions for the transmembrane helices B, C, D, and E and loops B-C and C-D connecting the helices, In the model, four chlorophylls, two pheophytins, and the nonheme Fe2+ ion are included. We have applied techniques from computational chemistry that incorporate statistical data on side-chain rotameric states from known protein structures and that describe interactions within the model using an empirical potential energy function. The conformation of chlorophyll pigments in the model was optimized by using exciton interaction calculations in combination with potential energy calculations to rind a solution that agrees with experimentally determined exciton interaction energies, The model is analyzed and compared with experimental results for the regions of Pb-680, the redox active pheophytin, the acceptor side Fe2+, and the tyrosyl radicals Tyr(D) and Tyr(Z), P-680 is proposed to be a weakly coupled chlorophyll a pair which makes three hydrogen bonds with residues on the D1 and D2 proteins. In the model the redox-active pheophytin is hydrogen bonded to D1-Glu130 and possibly also to D1-Tyr126 and D1-Tyr147. Tyr(D) is hydrogen bonded to D2-His190 and also interacts with D2-Gln165. Tyr(Z) is bound in a hydrophilic environment which is partially constituted by D1-Gln165, D1-Asp170, D1-Glu189, and D1-His190, These polar residues are most likely involved in proton transfer from oxidized Tyr(Z) or in metal binding.},
  author       = {Svensson, B and Etchebest, C and Tuffery, P and van Kan, Paul and Smith, J and Styring, Stenbjörn},
  issn         = {0006-2960},
  keyword      = {PHOTOSYNTHETIC REACTION-CENTER,ELECTRON-PARAMAGNETIC-RES,SITE-DIRECTED MUTANTS,NON-HEME IRON,RHODOBACTER-SPHAEROIDES R-26,ENVELOPE MODULATION ESEEM,SYNECHOCYSTIS SP PCC-6803,HERBICIDE BINDING NICHE,REACTION-CENTER COMPLEX,AMINO-ACID SEQUENCE},
  language     = {eng},
  number       = {46},
  pages        = {14486--14502},
  publisher    = {The American Chemical Society},
  series       = {Biochemistry},
  title        = {A model for the photosystem II reaction center core including the structure of the primary donor P-680},
  url          = {http://dx.doi.org/10.1021/bi960764k},
  volume       = {35},
  year         = {1996},
}