title: Structure and function of the PsbP protein of photosystem II from higher plants.
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 (Delta19) 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 Delta19 to trypsin digestion. Thus, a truncated PsbP lacking 15 N-terminal residues (Delta15), which retained core PsbP structure, was produced. Whereas Delta15 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.
authors.affiliation: Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan. ifuku@kais.kyoto-u.ac.jp
authors.forename: Kentaro
authors.initials: K
authors.lastname: Ifuku
authors.forename: Toru
authors.initials: T
authors.lastname: Nakatsu
authors.forename: Ren
authors.initials: R
authors.lastname: Shimamoto
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Seiko
authors.initials: S
authors.lastname: Ishihara
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kato
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
mesh_terms: D000595:Amino Acid Sequence; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002712:Chlorides / Q000737:chemistry / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D021122:Protein Subunits; D018724:Spinacia oleracea / Q000737:chemistry* / Q000201:enzymology / Q000378:metabolism*
chemical_list: D002712:Chlorides; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D021122:Protein Subunits; D002118:Calcium