The mechanism of the degradation of psaB gene product, one of the photosynthetic reaction center subunits of photosystem I, upon photoinhibition

Kintake Sonoike*, Masaharu Kamo, Yukako Hihara, Tetsuo Hiyama, Isao Enami

*この研究の対応する著者

研究成果: Article査読

84 被引用数 (Scopus)

抄録

The psaB gene product (PsaB protein), one of the reaction center subunits of Photosystem I (PS I), was specifically degraded by light illumination of spinach thylakoid membranes. The degradation of the protein yielded N-terminal fragments of molecular mass 51 kDa and 45 kDa. The formation of the 51 kDa fragment was i) partially suppressed by the addition of phenylmethylsulfonyl fluoride or 3,4-dichloroisocoumarin, which are inhibitors of serine proteases, and ii) enhanced in the presence of hydrogen peroxide during photoinhibitory treatment, but iii) not detected following hydrogen peroxide treatment in the dark. These results suggest that the hydroxyl radical produced at the reduced iron-sulfur centers in PS I triggers the conformation change of the PS I complex, which allows access of a serine-type protease to PsaB. This results in the formation of the 51 kDa N-terminal fragment, presumably by cleavage on the loop exposed to the stromal side, between putative helices 8 and 9. On the other hand, the formation of the 45 kDa fragment, which was enhanced in the presence of methyl viologen but did not accompany the photoinhibition of PS I, was not affected by the addition of hydrogen peroxide or protease inhibitors. Another fragment of 18 kDa was identified as a C-terminal counterpart of the 45 kDa fragment. N-terminal sequence analysis of the 18 kDa fragment revealed that the cleavage occurred between Ala500 and Val501 on the loop exposed to the lumenal side, between putative helices 7 and 8 o the PsaB protein.

本文言語English
ページ(範囲)55-63
ページ数9
ジャーナルPhotosynthesis Research
53
1
DOI
出版ステータスPublished - 1997
外部発表はい

ASJC Scopus subject areas

  • 生化学
  • 植物科学
  • 細胞生物学

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