title: Identification of the basic amino acid residues on the PsbP protein involved in the electrostatic interaction with photosystem II.
abstract: The PsbP protein is an extrinsic subunit of photosystem II (PSII) that is essential for photoautotrophic growth in higher plants. Several crystal structures of PsbP have been reported, but the binding topology of PsbP in PSII has not yet been clarified. In this study, we report that the basic pocket of PsbP, which consists of conserved Arg48, Lys143, and Lys160, is important for the electrostatic interaction with the PSII complex. Our release-reconstitution experiment showed that the binding affinities of PsbP-R48A, -K143A, and -K160A mutated proteins to PSII were lower than that of PsbP-WT, and triple mutations of these residues greatly diminished the binding affinity to PSII. Even when maximum possible binding had occurred, the R48A, K143A, and K160A proteins showed a reduced ability to restore the rate of oxygen evolution at low chloride concentrations. Fourier transform infrared resonance (FTIR) difference spectroscopy results were consistent with the above finding, and suggested that these mutated proteins were not able to induce the normal conformational change around the Mn cluster during S1 to S2 transition. Finally, chemical cross-linking experiments suggested that the interaction between the N-terminus of PsbP with PsbE was inhibited by these mutations. These data suggest that the basic pocket of PsbP is important for proper association and interaction with PSII. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy.
authors.affiliation: Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Taishi
authors.initials: T
authors.lastname: Nishimura
authors.affiliation: Graduate School of Science, Nagoya University, Aichi 464-8602, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Uno
authors.affiliation: Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Kunio
authors.initials: K
authors.lastname: Ido
authors.affiliation: Graduate School of Science, Nagoya University, Aichi 464-8602, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Nagao
authors.affiliation: Graduate School of Science, Nagoya University, Aichi 464-8602, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Noguchi
authors.affiliation: Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
authors.affiliation: Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan. Electronic address: ifuku@kais.kyoto-u.ac.jp.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Ifuku
mesh_terms: D002712:Chlorides / Q000737:chemistry; D008958:Models, Molecular; D009154:Mutation; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity
chemical_list: D002712:Chlorides; D045332:Photosystem II Protein Complex
keywords: Extrinsic protein; Higher plants; Oxygen-evolving complex; Photosystem II; PsbP