Isolation of an oxygen-evolving Photosystem II preparation containing only one tightly bound calcium atom from a chlorophyll b-deficient mutant of rice

Jian Ren Shen, Kazuhiko Satoh, Sakae Katoh

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Oxygen-evolving Photosystem II (PS II) particles were prepared from the thylakoid membranes of a chlorophyll b-less rice mutant, which totally lacks light-harvesting chlorophyll a/b proteins, after solubilization with β-octylglucoside. The preparation was essentially free of Photosystem I as judged from its low-temperature fluorescence spectrum and polypeptide composition. The PS II particles contained all the major subunit polypeptides of the PS II reaction center core complexes and the three extrinsic proteins related to oxygen evolution. The relative abundances of the 33, 21 and 15 kDa proteins were 100, 64 and 20%, respectively, of the corresponding proteins in the mutant thylakoids. The chlorophyll-to-QA ratio was 53 and there was only one bound Ca2+ per QA. Thus, one of the two bound Ca2+ present in the oxygen-evolving PS II membrane preparations from wild-type rice (Shen J.-R., Satoh, K. and Katoh, S. (1988) Biochim. Biophys. Acta 933, 358-364) is missing. The mutant PS II particles were highly active in oxygen evolution in the absence of exogenously added Ca2+, although addition of 5 mM Ca2+ enhanced the activity by 30%. When the 21 and 15 kDa proteins were supplemented to the particles, the Ca2+-effect disappeared and the rate of oxygen evolution increased to a level exceeding 1000 μmol O2 per mg chlorophyll per h. The results indicate that the number of Ca2+ needed to promote a high rate of oxygen evolution is one per PS II in higher plants.

Original languageEnglish
Pages (from-to)386-394
Number of pages9
JournalBBA - Bioenergetics
Volume936
Issue number3
DOIs
Publication statusPublished - Dec 7 1988
Externally publishedYes

Keywords

  • (Rice)
  • Calcium
  • Chlorophyll b less mutant
  • Oxygen evolution
  • Photosystem II

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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