PDBsum entry 1s5l

Photosynthesis

PDB id: 1s5l

Contents

Protein chains

333 a.a.

476 a.a.

421 a.a.

339 a.a.

76 a.a.

33 a.a.

53 a.a.

38 a.a.

38 a.a.

37 a.a.

37 a.a.

30 a.a.

246 a.a.

31 a.a.

105 a.a.

137 a.a.

40 a.a.

37 a.a.

58 a.a.

Ligands

BCT-OEC ×2

CLA ×72

PHO ×4

PL9 ×4

LMT ×2

BCR ×14

BCT ×2

HEC ×4

Metals

_FE ×2

References listed in PDB file

Key reference

Title

Architecture of the photosynthetic oxygen-Evolving center.

Authors

K.N.Ferreira, T.M.Iverson, K.Maghlaoui, J.Barber, S.Iwata.

Ref.

Science, 2004, 303, 1831-1838. [DOI no: 10.1126/science.1093087]

PubMed id

14764885

Abstract

Photosynthesis uses light energy to drive the oxidation of water at an oxygen-evolving catalytic site within photosystem II (PSII). We report the structure of PSII of the cyanobacterium Thermosynechococcus elongatus at 3.5 angstrom resolution. We have assigned most of the amino acid residues of this 650-kilodalton dimeric multisubunit complex and refined the structure to reveal its molecular architecture. Consequently, we are able to describe details of the binding sites for cofactors and propose a structure of the oxygen-evolving center (OEC). The data strongly suggest that the OEC contains a cubane-like Mn3CaO4 cluster linked to a fourth Mn by a mono-micro-oxo bridge. The details of the surrounding coordination sphere of the metal cluster and the implications for a possible oxygen-evolving mechanism are discussed.

Figure 1.
Fig. 1. Overall structure of PSII. (A) View of the PSII dimer perpendicular to the membrane normal. Helices are represented as cylinders with D1 in yellow; D2 in orange; CP47 in red; CP43 in green; cyt b559 in wine red; PsbL, PsbM, and PsbT in medium blue; and PsbH, PsbI, PsbJ, PsbK, PsbX, PsbZ, and the putative PsbN in gray. The extrinsic proteins are PsbO in blue, PsbU in magenta, and PsbV in cyan. Chlorophylls of the D1/D2 reaction center are light green, pheophytins are blue, chlorophylls of the antenna complexes are dark green, ß-carotenes are in orange, hemes are in red, nonheme Fe is red, Q[A] and Q[B] are purple. The oxygen-evolving center (OEC) is shown as the red (oxygen atoms), magenta (Mn ions), and cyan (Ca^2+) balls. (B) View of the PSII monomer along the membrane normal from the lumenal side. A part of the other monomer in the dimmer is shown to emphasize the region of monomer/monomer interaction along the dotted line. The pseudo-twofold axis perpendicular to the membrane plane passing through the nonheme Fe relates the transmembrane helices of the D1/D2 heterodimer, the low molecular subunits, PsbI and PsbX, and CP43 and CP47 as emphasized by the black lines encircling these subunits. Coloring is the same as in (A).

Figure 2.
Fig. 2. Cofactors involved in electron transfer. (A) Electron transfer cofactors shown perpendicular to the internal pseudo-twofold. Coloring scheme is the same as in Fig. 1. The phytol tails of the chlorophylls and pheophytins have been removed for clarity. The side chains of Tyr[Z] (D1 Tyr161) and D1 His190 are shown in yellow, and Tyr[D] (D2 Tyr160) and D2 His189 are in orange. The four chlorophylls comprising P680 are in direct van der Waals contact, and other electron transfer distances are given in Å. (B) The P680 dimer of chlorophylls (P[D1] and P[D2]) and accessory Chls (Chl[D1] and Chl[D2]). Coloring scheme is the same as in Fig. 1, except that the protein main chain is depicted in light gray, whereas the side-chain bonds and carbon atoms follow the coloring of the protein subunits (D1, yellow; D2, orange). The histidine ligands D1 His198 and D2 His197 are shown, as well as the redox-active Tyr[Z]-D1 His190 and Tyr[D]-D2 His189 pairs. The view is down the pseudo-twofold axis from the stromal side.

The above figures are reprinted by permission from the AAAs: Science (2004, 303, 1831-1838) copyright 2004.