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

详细信息    查看全文

• 作者：Yohei Ikeda^a ; ^b ; ^{yohei_ikeda@spring8.or.jp} ; Atsushi Yamagishi^c ; Masayuki Komura^c ; Takehiro Suzuki^d ; Naoshi Dohmae^d ; Yutaka Shibata^c ; ¹ ; Shigeru Itoh^c ; ² ; Hiroyuki Koike^a ; ³ ; Kazuhiko Satoh^a
• 关键词：Chl ; chlorophyll ; PSI and PSII ; photosystems I and II ; LHC ; light-harvesting chlorophyll-binding protein ; FCPI ; fucoxanthin-chlorophyll-binding protein I ; LIL protein ; light-harvesting-like protein ; RedCAP ; red lineage Chla/b-binding-like protein ; P700 ; p
• 刊名：Biochimica et Biophysica Acta (BBA)/Bioenergetics
• 出版年：2013
• 出版时间：April, 2013
• 年：2013
• 卷：1827
• 期：4
• 页码：529-539
• 全文大小：1252 K

文摘

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 ?-carotene, and 2 menaquinone-4 per P700. The complex showed a high electron transfer activity at 185,000 ¦Ìmol 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.