Two functional sites of phosphatidylglycerol for regulation of reaction of plastoquinone Q B in photosystem II

Shigeru Itoh, Takashi Kozuki, Koji Nishida, Yoshimasa Fukushima, Hisanori Yamakawa, Ildikó Domonkos, Hajnalka Laczkó-Dobos, Mihály Kis, Bettina Ughy, Zoltán Gombos

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19 Citations (Scopus)

Abstract

Functional roles of an anionic lipid phosphatidylglycerol (PG) were studied in pgsA-gene-inactivated and cdsA-gene-inactivated/phycobilisome-less mutant cells of a cyanobacterium Synechocystis sp. PCC 6803, which can grow only in PG-supplemented media. 1) A few days of PG depletion suppressed oxygen evolution of mutant cells supported by p-benzoquinone (BQ). The suppression was recovered slowly in a week after PG re-addition. Measurements of fluorescence yield indicated the enhanced sensitivity of Q B to the inactivation by BQ. It is assumed that the loss of low-affinity PG (PG L) enhances the affinity for BQ that inactivates Q B. 2) Oxygen evolution without BQ, supported by the endogenous electron acceptors, was slowly suppressed due to the direct inactivation of Q B during 10 days of PG depletion, and was recovered rapidly within 10 h upon the PG re-addition. It is concluded that the loss of high-affinity PG (PG H) displaces Q B directly. 3) Electron microscopy images of PG-depleted cells showed the specific suppression of division of mutant cells, which had developed thylakoid membranes attaching phycobilisomes (PBS). 4) Although the PG-depletion for 14 days decreased the chlorophyll/PBS ratio to about 1/4, florescence spectra/lifetimes were not modified indicating the flexible energy transfer from PBS to different numbers of PSII. Longer PG-depletion enhanced allophycocyanin fluorescence at 683 nm with a long 1.2 ns lifetime indicating the suppression of energy transfer from PBS to PSII. 5) Action sites of PG H, PG L and other PG molecules on PSII structure are discussed.

Original languageEnglish
Pages (from-to)287-297
Number of pages11
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1817
Issue number2
DOIs
Publication statusPublished - Feb 1 2012

Keywords

  • Chlorophyll fluorescence
  • Lipid
  • Oxygen evolution
  • Phosphatidylglycerol
  • Photosystem II assembly
  • Q plastoquinone

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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    Itoh, S., Kozuki, T., Nishida, K., Fukushima, Y., Yamakawa, H., Domonkos, I., Laczkó-Dobos, H., Kis, M., Ughy, B., & Gombos, Z. (2012). Two functional sites of phosphatidylglycerol for regulation of reaction of plastoquinone Q B in photosystem II. Biochimica et Biophysica Acta - Bioenergetics, 1817(2), 287-297. https://doi.org/10.1016/j.bbabio.2011.10.002