Abstract
The chloride ion, Cl-, is an essential cofactor for oxygen evolution of photosystem II (PSII) and is closely associated with the Mn 4Ca cluster. Its detailed location and function have not been identified, however. We substituted Cl- with a bromide ion (Br -) or an iodide ion (I-) in PSII and analyzed the crystal structures of PSII with Br- and I- substitutions. Substitution of Cl- with Br- did not inhibit oxygen evolution, whereas substitution of Cl- with I- completely inhibited oxygen evolution, indicating the efficient replacement of Cl - by I-. PSII with Br- and I- substitutions were crystallized, and their structures were analyzed. The results showed that there are 2 anion-binding sites in each PSII monomer; they are located on 2 sides of the Mn4Ca cluster at equal distances from the metal cluster. Anion-binding site 1 is close to the main chain of D1-Glu-333, and site 2 is close to the main chain of CP43-Glu-354; these 2 residues are coordinated directly with the Mn4Ca cluster. In addition, site 1 is located in the entrance of a proton exit channel. These results indicate that these 2 Cl- anions are required to maintain the coordination structure of the Mn4Ca cluster as well as the proposed proton channel, thereby keeping the oxygen-evolving complex fully active.
| Original language | English |
|---|---|
| Pages (from-to) | 8567-8572 |
| Number of pages | 6 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 106 |
| Issue number | 21 |
| DOIs | |
| Publication status | Published - May 26 2009 |
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Keywords
- Manganese enzyme
- Membrane proteins
- Oxygen evolution
- Photosynthesis
ASJC Scopus subject areas
- General
Cite this
Location of chloride and its possible functions in oxygen-evolving photosystem II revealed by X-ray crystallography. / Kawakami, Keisuke; Umena, Yasufumi; Kamiya, Nobuo; Shen, Jian-Ren.
In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 106, No. 21, 26.05.2009, p. 8567-8572.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Location of chloride and its possible functions in oxygen-evolving photosystem II revealed by X-ray crystallography
AU - Kawakami, Keisuke
AU - Umena, Yasufumi
AU - Kamiya, Nobuo
AU - Shen, Jian-Ren
PY - 2009/5/26
Y1 - 2009/5/26
N2 - The chloride ion, Cl-, is an essential cofactor for oxygen evolution of photosystem II (PSII) and is closely associated with the Mn 4Ca cluster. Its detailed location and function have not been identified, however. We substituted Cl- with a bromide ion (Br -) or an iodide ion (I-) in PSII and analyzed the crystal structures of PSII with Br- and I- substitutions. Substitution of Cl- with Br- did not inhibit oxygen evolution, whereas substitution of Cl- with I- completely inhibited oxygen evolution, indicating the efficient replacement of Cl - by I-. PSII with Br- and I- substitutions were crystallized, and their structures were analyzed. The results showed that there are 2 anion-binding sites in each PSII monomer; they are located on 2 sides of the Mn4Ca cluster at equal distances from the metal cluster. Anion-binding site 1 is close to the main chain of D1-Glu-333, and site 2 is close to the main chain of CP43-Glu-354; these 2 residues are coordinated directly with the Mn4Ca cluster. In addition, site 1 is located in the entrance of a proton exit channel. These results indicate that these 2 Cl- anions are required to maintain the coordination structure of the Mn4Ca cluster as well as the proposed proton channel, thereby keeping the oxygen-evolving complex fully active.
AB - The chloride ion, Cl-, is an essential cofactor for oxygen evolution of photosystem II (PSII) and is closely associated with the Mn 4Ca cluster. Its detailed location and function have not been identified, however. We substituted Cl- with a bromide ion (Br -) or an iodide ion (I-) in PSII and analyzed the crystal structures of PSII with Br- and I- substitutions. Substitution of Cl- with Br- did not inhibit oxygen evolution, whereas substitution of Cl- with I- completely inhibited oxygen evolution, indicating the efficient replacement of Cl - by I-. PSII with Br- and I- substitutions were crystallized, and their structures were analyzed. The results showed that there are 2 anion-binding sites in each PSII monomer; they are located on 2 sides of the Mn4Ca cluster at equal distances from the metal cluster. Anion-binding site 1 is close to the main chain of D1-Glu-333, and site 2 is close to the main chain of CP43-Glu-354; these 2 residues are coordinated directly with the Mn4Ca cluster. In addition, site 1 is located in the entrance of a proton exit channel. These results indicate that these 2 Cl- anions are required to maintain the coordination structure of the Mn4Ca cluster as well as the proposed proton channel, thereby keeping the oxygen-evolving complex fully active.
KW - Manganese enzyme
KW - Membrane proteins
KW - Oxygen evolution
KW - Photosynthesis
UR - http://www.scopus.com/inward/record.url?scp=66649106614&partnerID=8YFLogxK
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U2 - 10.1073/pnas.0812797106
DO - 10.1073/pnas.0812797106
M3 - Article
VL - 106
SP - 8567
EP - 8572
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 21
ER -