PsaK2 SUBUNIT IN PHOTOSYSTEM I IS INVOLVED IN STATE TRANSITION UNDER HIGH-LIGHT CONDITION IN THE CYANOBACTERIUM Synechocystis SP. PCC 6803

• 日原, 由香子

抄録

type:text

In order to avoid the photodamage, cyanobacteria regulate the distribution of light energy absorbed by phycobilisome antenna either to photosystem II (PSII) or to photosystem I (PSI) upon high-light acclimation by the process so called state transition. We found that an alternative PSI subunit, PsaK2 (sll0629 gene product), is involved in this process in the cyanobacterium Synechocystis sp. PCC 6803. Examination of the subunit composition of the purified PSI reaction center complexes revealed that PsaK2 subunit was absent in the PSI complexes under low-light condition, but was incorporated into the complexes during acclimation to high light. The growth of the psaK2 mutant on solid medium was inhibited under high-light condition. We determined the photosynthetic characteristics of the wild type strain and the two mutants, the psaK1 (ssr0390) mutant and the psaK2 mutant, using pulse amplitude modulation (PAM) fluorometer. Non-photochemical quenching (qN), which reflects the energy transfer from phycobilisome to PSI in cyanobacteria, was higher in high-light grown cells than in low-light grown cells, both in the wild type and the psaK1 mutant. However, this change of qN during acclimation to high light was not observed in the psaK2 mutant. Thus, PsaK2 subunit is involved in the energy transfer from phycobilisome to PSI under high-light condition. The role of PsaK2 in state transition under high-light condition was also confirmed by chlorophyll fluorescence emission spectra determined at 77 K. The results suggest that PsaK2-dependent state transition is essential for the growth of this cyanobacterium under high-light condition.

Copyright notice. c2002 Journal of Biological Chemistry. All rights reserved. Source published by American Physical Society.

収録刊行物

• Journal of biological chemistry

  Journal of biological chemistry 280 (23), 22191-22197, 2005

  American Society for Biochemistry and Molecular Biology

詳細情報

• CRID: 1050564287771217536
• NII論文ID: 120006385001
• ISSN: 00219258
• Web Site: http://id.nii.ac.jp/1586/00012509/
• 本文言語コード: en
• 資料種別: journal article
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