The monomeric photosystem I-complex of the diatom Phaeodactylum tricornutum binds specific fucoxanthin chlorophyll proteins (FCPs) as light-harvesting complexes

Veith, Thomas; Büchel, Claudia

doi:10.1016/j.bbabio.2007.09.004

Cited by 82 publications

(75 citation statements)

References 39 publications

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“…Treatment with the photosystem II inhibitor DCMU prior to FR light exposure had no effect on the expression of these genes ( Figure 3D), which further rules out any regulation of their expression by feedback from photosynthesis. Any photosystem I-mediated regulation can also be excluded given the absence of absorption of photosystem I complexes above 710 nm (Veith and Büchel, 2007;Ikeda et al, 2008). On the contrary, the Class 2 genes are maximally induced by the shorter wavelengths and their expression profiles do not match the Pt-DPH spectra of any of the two forms ( Figure 3E).…”

Section: R-fr-light-mediated Gene Expression In P Tricornutummentioning

confidence: 99%

Diatom Phytochromes Reveal the Existence of Far-Red-Light-Based Sensing in the Ocean

et al. 2016

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The absorption of visible light in aquatic environments has led to the common assumption that aquatic organisms sense and adapt to penetrative blue/green light wavelengths but show little or no response to the more attenuated red/far-red wavelengths. Here, we show that two marine diatom species, Phaeodactylum tricornutum and Thalassiosira pseudonana, possess a bona fide red/far-red light sensing phytochrome (DPH) that uses biliverdin as a chromophore and displays accentuated red-shifted absorbance peaks compared with other characterized plant and algal phytochromes. Exposure to both red and far-red light causes changes in gene expression in P. tricornutum, and the responses to far-red light disappear in DPH knockout cells, demonstrating that P. tricornutum DPH mediates far-red light signaling. The identification of DPH genes in diverse diatom species widely distributed along the water column further emphasizes the ecological significance of far-red light sensing, raising questions about the sources of far-red light. Our analyses indicate that, although far-red wavelengths from sunlight are only detectable at the ocean surface, chlorophyll fluorescence and Raman scattering can generate red/far-red photons in deeper layers. This study opens up novel perspectives on phytochrome-mediated far-red light signaling in the ocean and on the light sensing and adaptive capabilities of marine phototrophs.

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Section: R-fr-light-mediated Gene Expression In P Tricornutummentioning

confidence: 99%

Diatom Phytochromes Reveal the Existence of Far-Red-Light-Based Sensing in the Ocean

et al. 2016

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“…Although there have been reports of trimeric forms of PSI in plants (Heinemeyer et al, 2004;Kouril et al, 2005), it is now widely accepted that plant PSI forms only monomeric complexes (Kitmitto et al, 1998;Kouril et al, 2005). Furthermore, it is known that PSI is a monomer in green and red algae (Gardian et al, 2007) as well as in diatoms (Veith and Büchel, 2007).…”

Section: Introductionmentioning

confidence: 99%

Characterization and Evolution of Tetrameric Photosystem I from the Thermophilic Cyanobacterium Chroococcidiopsis sp TS-821

Semchonok

Boekema

et al. 2014

Plant Cell

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ORCID ID: 0000-0002-4045-9815 (B.D.B.)Photosystem I (PSI) is a reaction center associated with oxygenic photosynthesis. Unlike the monomeric reaction centers in green and purple bacteria, PSI forms trimeric complexes in most cyanobacteria with a 3-fold rotational symmetry that is primarily stabilized via adjacent PsaL subunits; however, in plants/algae, PSI is monomeric. In this study, we discovered a tetrameric form of PSI in the thermophilic cyanobacterium Chroococcidiopsis sp TS-821 (TS-821). In TS-821, PSI forms tetrameric and dimeric species. We investigated these species by Blue Native PAGE, Suc density gradient centrifugation, 77K fluorescence, circular dichroism, and single-particle analysis. Transmission electron microscopy analysis of native membranes confirms the presence of the tetrameric PSI structure prior to detergent solubilization. To investigate why TS-821 forms tetramers instead of trimers, we cloned and analyzed its psaL gene. Interestingly, this gene product contains a short insert between the second and third predicted transmembrane helices. Phylogenetic analysis based on PsaL protein sequences shows that TS-821 is closely related to heterocyst-forming cyanobacteria, some of which also have a tetrameric form of PSI. These results are discussed in light of chloroplast evolution, and we propose that PSI evolved stepwise from a trimeric form to tetrameric oligomer en route to becoming monomeric in plants/algae.

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“…Photosynthetic organisms have diverse antenna protein-pigment complexes, which are specifically associated with photosystems I or II (PSI or PSII, respectively) (1). Light-harvesting chlorophyll a/b-binding proteins form the peripheral antenna of PSI or PSII in green plants (2) and light-harvesting chlorophyll a/c-binding proteins are present in brown algae and related organisms (3,4). In cyanobacteria the phycobilisome (PBS) serves as a major antenna for PSII.…”

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Attachment of phycobilisomes in an antenna–photosystem I supercomplex of cyanobacteria

Watanabe

Semchonok

Webber-Birungi

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

160

153

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Oxygenic photosynthesis is driven by photosystems I and II (PSI and PSII, respectively). Both have specific antenna complexes and the phycobilisome (PBS) is the major antenna protein complex in cyanobacteria, typically consisting of a core from which several rod-like subcomplexes protrude. PBS preferentially transfers light energy to PSII, whereas a PSI-specific antenna has not been identified. The cyanobacterium Anabaena sp. PCC 7120 has rodcore linker genes (cpcG1-cpcG2-cpcG3-cpcG4). Their products, except CpcG3, have been detected in the conventional PBS. Here we report the isolation of a supercomplex that comprises a PSI tetramer and a second, unique type of a PBS, specific to PSI. This rodshaped PBS includes phycocyanin (PC) and CpcG3 (hereafter renamed "CpcL"), but no allophycocyanin or CpcGs. Fluorescence excitation showed efficient energy transfer from PBS to PSI. The supercomplex was analyzed by electron microscopy and singleparticle averaging. In the supercomplex, one to three rod-shaped CpcL-PBSs associate to a tetrameric PSI complex. They are mostly composed of two hexameric PC units and bind at the periphery of PSI, at the interfaces of two monomers. Structural modeling indicates, based on 2D projection maps, how the PsaI, PsaL, and PsaM subunits link PSI monomers into dimers and into a rhombically shaped tetramer or "pseudotetramer." The 3D model further shows where PBSs associate with the large subunits PsaA and PsaB of PSI. It is proposed that the alternative form of CpcL-PBS is functional in harvesting energy in a wide number of cyanobacteria, partially to facilitate the involvement of PSI in nitrogen fixation. I n photosynthesis, light-harvesting antennas are essential to efficiently collect solar energy. Photosynthetic organisms have diverse antenna protein-pigment complexes, which are specifically associated with photosystems I or II (PSI or PSII, respectively) (1). Light-harvesting chlorophyll a/b-binding proteins form the peripheral antenna of PSI or PSII in green plants (2) and light-harvesting chlorophyll a/c-binding proteins are present in brown algae and related organisms (3, 4). In cyanobacteria the phycobilisome (PBS) serves as a major antenna for PSII. No specific antenna has been isolated for PSI in cyanobacteria, although PBS transfers light energy to PSI under conditions of state transition (5), a temporal energy redistribution mechanism between PSII and PSI (6, 7).Generally, the PBS is a supercomplex of rod and core subcomplexes, which consist of various phycobilin-binding proteins connected by several classes of colorless linker proteins (8). Whereas phycocyanin (PC) is the major phycobiliprotein of the rod, allophycocyanin (APC) is the major phycobiliprotein of the core cylinders. The rod-core linker cyanobacterial phycocyanin protein G (CpcG), which connects the rod to the core, plays a key role in the assembly of the PBS (9). The chromosome of the filamentous, N 2 -fixing cyanobacterium Anabaena sp. PCC 7120 (hereafter "Anabaena") bears tandem repeats of rod-core linker gene...

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The monomeric photosystem I-complex of the diatom Phaeodactylum tricornutum binds specific fucoxanthin chlorophyll proteins (FCPs) as light-harvesting complexes

Cited by 82 publications

References 39 publications

Diatom Phytochromes Reveal the Existence of Far-Red-Light-Based Sensing in the Ocean

Diatom Phytochromes Reveal the Existence of Far-Red-Light-Based Sensing in the Ocean

Characterization and Evolution of Tetrameric Photosystem I from the Thermophilic Cyanobacterium Chroococcidiopsis sp TS-821

Attachment of phycobilisomes in an antenna–photosystem I supercomplex of cyanobacteria

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