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- Title
Functional dissection of twoArabidopsisPsbO proteins.
- Authors
Murakami, Reiko; Ifuku, Kentaro; Takabayashi, Atsushi; Shikanai, Toshiharu; Endo, Tsuyoshi; Sato, Fumihiko
- Abstract
PsbO protein is an extrinsic subunit of photosystem II (PSII) and has been proposed to play a central role in stabilization of the catalytic manganese cluster.Arabidopsis thalianahas twopsbO genes that express two PsbO proteins; PsbO1 and PsbO2. We reported previously that a mutant plant that lacked PsbO1 (psbo1) showed considerable growth retardation despite the presence of PsbO2[Murakami, R., Ifuku, K., Takabayashi, A., Shikanai, T., Endo, T., and Sato, F. (2002)FEBS Lett523,138–142]. In the present study, we characterized the functional differences between PsbO1 and PsbO2. We found that PsbO1 is the major isoform in the wild-type, and the amount of PsbO2 inpsbo1was significantly less than the total amount of PsbO in the wild-type. The amount of PsbO as well as the efficiency of PSII inpsbo1increased as the plants grew; howeVER, it neVER reached the total PsbO level observed in the wild-type, suggesting that the poor activity of PSII inpsbo1was caused by a shortage of PsbO. In addition, anin vitroreconstitution experiment using recombinant PsbOs and urea-washed PSII particles showed that oxygen evolution was better recoVERed by PsbO1 than by PsbO2. Further analysis using chimeric and mutated PsbOs suggested that the amino acid changes Val186→Ser, Leu246→Ile, and Val204→Ile could explain the functional difference between the two PsbOs. Therefore we concluded that both the lower expression level and the inferior functionality of PsbO2 are responsible for the phenotype observed inpsbo1.
- Subjects
ARABIDOPSIS; BRASSICACEAE; PROTEINS; AMINO acids; PHENOTYPES; GENETICS; GENES
- Publication
FEBS Journal, 2005, Vol 272, Issue 9, p2165
- ISSN
1742-464X
- Publication type
Article
- DOI
10.1111/j.1742-4658.2005.04636.x