Two types of fucoxanthin-chlorophyll-binding proteins i tightly bound to the photosystem i core complex in marine centric diatoms

Yohei Ikeda, Atsushi Yamagishi, Masayuki Komura, Takehiro Suzuki, Naoshi Dohmae, Yutaka Shibata, Shigeru Itoh, Hiroyuki Koike, Kazuhiko Satoh

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)

Abstract

Intact fucoxanthin (Fucox)-chlorophyll (Chl)-binding protein I-photosystem I supercomplexes (FCPI-PSIs) were prepared by a newly developed simple fast procedure from centric diatoms Chaetoceros gracilis and Thalassiosira pseudonana to study the mechanism of their efficient solar energy accumulation. FCPI-PSI purified from C. gracilis contained 252 Chl a, 23 Chl c, 56 Fucox, 34 diadinoxanthin + diatoxanthin, 1 violaxanthin, 21 ß-carotene, and 2 menaquinone-4 per P700. The complex showed a high electron transfer activity at 185,000 μmol mg Chl a- 1 · h- 1 to reduce methyl viologen from added cytochrome c6. We identified 14 and 21 FCP proteins in FCPI-PSI of C. gracilis and T. pseudonana, respectively, determined by N-terminal and internal amino acid sequences and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses. PsaO and a red lineage Chla/b-binding-like protein (RedCAP), Thaps3:270215, were also identified. Severe detergent treatment of FCPI-PSI released FCPI-1 first, leaving the FCPI-2-PSI-core complex. FCPI-1 contained more Chl c and showed Chl a fluorescence at a shorter wavelength than FCPI-2, suggesting an excitation-energy transfer from FCPI-1 to FCPI-2 and then to the PSI core. Fluorescence emission spectra at 17 K in FCPI-2 varied depending on the excitation wavelength, suggesting two independent energy transfer routes. We formulated a model of FCPI-PSI based on the biochemical assay results.

Original languageEnglish
Pages (from-to)529-539
Number of pages11
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1827
Issue number4
DOIs
Publication statusPublished - 2013 Apr

Keywords

  • Chaetoceros gracilis
  • Diatom
  • Fucoxanthin-chlorophyll-binding protein I
  • Keywords
  • Photosystem I
  • Thalassiosira pseudonana

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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