Structure and function of the PsbP protein of Photosystem II from higher plants |
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Authors: | Kentaro Ifuku Toru Nakatsu Ren Shimamoto Yumiko Yamamoto Seiko Ishihara Hiroaki Kato Fumihiko Sato |
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Affiliation: | (1) Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan;(2) RIKEN Harima Institute at SPring-8, Sayo-gun, Hyogo 679-5148, Japan;(3) Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan |
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Abstract: | PsbP is a membrane extrinsic subunit of Photosystem II (PS II), which is involved in retaining Ca2+ and Cl−, two inorganic cofactors for the water-splitting reaction. In this study, we re-investigated the role of N-terminal region of PsbP on the basis of its three-dimensional structure. In previous paper [Ifuku and Sato (2002) Plant Cell Physiol 43: 1244–1249], a truncated PsbP lacking 19 N-terminal residues (Δ19) was found to bind to NaCl-washed PS II lacking PsbP and PsbQ without activation of oxygen evolution at all. Three-dimensional (3D) structure of PsbP suggests that deletion of 19 N-terminal residues would destabilize its protein structure, as indicated by the high sensitivity of Δ19 to trypsin digestion. Thus, a truncated PsbP lacking 15 N-terminal residues (Δ15), which retained core PsbP structure, was produced. Whereas Δ15 was resistant to trypsin digestion and bound to NaCl-washed PS II membranes, it did not show the activation of oxygen evolution. This result indicated that the interaction of 15-residue N-terminal flexible region of PsbP with PS II was important for Ca2+ and Cl− retention in PS II, although the 15 N-terminal residues were not essential for the binding of PsbP to PS II. The possible N-terminal residues of PsbP that would be involved in this interaction are discussed. |
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Keywords: | Calcium ion chloride ion crystal structure extrinsic protein higher plants Photosystem II PsbP |
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