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Kaihong Zhao – One of the best experts on this subject based on the ideXlab platform.

  • chromophorylation in escherichia coli of Allophycocyanin b subunits from far red light acclimated chroococcidiopsis thermalis sp pcc7203
    Photochemical and Photobiological Sciences, 2017
    Co-Authors: Qianzhao Xu, Qiying Tang, Wenlong Ding, Baoqing Zhao, Ming Zhou, Wolfgang Gartner, Hugo Scheer, Kaihong Zhao

    Abstract:

    Cyanobacterial phycobilisomes funnel the harvested light energy to the reaction centers via two terminal emitters, Allophycocyanin B and the core–membrane linker. ApcD is the α-subunit of Allophycocyanin B responsible for its red-shifted absorbance (λmax 665 nm). Far-red photo-acclimated cyanobacteria contain certain Allophycocyanins that show even further red-shifted absorbances (λmax > 700 nm). We studied the chromophorylation of the three far-red induced ApcD subunits ApcD2, ApcD3 and ApcD4 from Chroococcidiopsis thermalis sp. PCC7203 during the expression in E. coli. The complex behavior emphasizes that a variety of factors contribute to the spectral red-shift. Only ApcD2 bound phycocyanobilin covalently at the canonical position C81, while ApcD3 and ApcD4 gave only traces of stable products. The product of ApcD2 was, however, heterogeneous. The major fraction had a broad absorption around 560 nm and double-peaked fluorescence at 615 and 670 nm. A minor fraction was similar to the product of conventional ApcD, with maximal absorbance around 610 nm and fluorescence around 640 nm. The heterogeneity was lost in C65 and C132 variants; in these variants only the conventional product was formed. With ApcD4, a red-shifted product carrying non-covalently bound phycocyanobilin could be detected in the supernatant after cell lysis. While this chromophore was lost during purification, it could be stabilized by co-assembly with a far-red light-induced β-subunit, ApcB3.

  • chromophorylation in escherichia coli of Allophycocyanin b subunits from far red light acclimated chroococcidiopsis thermalis sp pcc7203
    Photochemical and Photobiological Sciences, 2017
    Co-Authors: Qiying Tang, Wenlong Ding, Baoqing Zhao, Ming Zhou, Wolfgang Gartner, Hugo Scheer, Jiaxin Han, Kaihong Zhao

    Abstract:

    Cyanobacterial phycobilisomes funnel the harvested light energy to the reaction centers via two terminal emitters, Allophycocyanin B and the core-membrane linker. ApcD is the α-subunit of Allophycocyanin B responsible for its red-shifted absorbance (λmax 665 nm). Far-red photo-acclimated cyanobacteria contain certain Allophycocyanins that show even further red-shifted absorbances (λmax > 700 nm). We studied the chromophorylation of the three far-red induced ApcD subunits ApcD2, ApcD3 and ApcD4 from Chroococcidiopsis thermalis sp. PCC7203 during the expression in E. coli. The complex behavior emphasizes that a variety of factors contribute to the spectral red-shift. Only ApcD2 bound phycocyanobilin covalently at the canonical position C81, while ApcD3 and ApcD4 gave only traces of stable products. The product of ApcD2 was, however, heterogeneous. The major fraction had a broad absorption around 560 nm and double-peaked fluorescence at 615 and 670 nm. A minor fraction was similar to the product of conventional ApcD, with maximal absorbance around 610 nm and fluorescence around 640 nm. The heterogeneity was lost in C65 and C132 variants; in these variants only the conventional product was formed. With ApcD4, a red-shifted product carrying non-covalently bound phycocyanobilin could be detected in the supernatant after cell lysis. While this chromophore was lost during purification, it could be stabilized by co-assembly with a far-red light-induced β-subunit, ApcB3.

  • RESONANCE‐ENHANCED CARS SPECTROSCOPY OF BILIPROTEINS. INFLUENCE OF AGGREGATION and LINKER PROTEINS ON CHROMOPHORE STRUCTURE IN Allophycocyanin (Mastigocladus laminosus)
    Photochemistry and Photobiology, 2008
    Co-Authors: Siegfried Schneider, Kaihong Zhao, C. J. Prenzel, G. Brehm, Lothar Gottschalk, Hugo Scheer

    Abstract:

    — Resonance-enhanced coherent anti-Stokes Raman spectra (CARS) are reported for monomers and for trimers with and without linker proteins of Allophycocyanin isolated from Mastigocladus laminosus. The CARS spectrum of the monomer is independent of the presence of linker proteins and is very similar to that of phycocyanin monomers indicating that the equivalent chromophores exhibit like structures in both biliproteins. Large differences are, however, observed between the spectra of phycocyanin trimers and those of Allophycocyanin trimers with or without linker proteins (Lc8,9). The observed differences between monomer and trimer spectra are consistent with a change of the α-chromophore-protein arrangement upon aggregation without linker. If linker proteins are present in the trimer, then additional geometry changes of the β-chromophores are induced; these could relate to a transition from the 15Z-anti to 15Z-syn conformation.

Hugo Scheer – One of the best experts on this subject based on the ideXlab platform.

  • chromophorylation in escherichia coli of Allophycocyanin b subunits from far red light acclimated chroococcidiopsis thermalis sp pcc7203
    Photochemical and Photobiological Sciences, 2017
    Co-Authors: Qianzhao Xu, Qiying Tang, Wenlong Ding, Baoqing Zhao, Ming Zhou, Wolfgang Gartner, Hugo Scheer, Kaihong Zhao

    Abstract:

    Cyanobacterial phycobilisomes funnel the harvested light energy to the reaction centers via two terminal emitters, Allophycocyanin B and the core–membrane linker. ApcD is the α-subunit of Allophycocyanin B responsible for its red-shifted absorbance (λmax 665 nm). Far-red photo-acclimated cyanobacteria contain certain Allophycocyanins that show even further red-shifted absorbances (λmax > 700 nm). We studied the chromophorylation of the three far-red induced ApcD subunits ApcD2, ApcD3 and ApcD4 from Chroococcidiopsis thermalis sp. PCC7203 during the expression in E. coli. The complex behavior emphasizes that a variety of factors contribute to the spectral red-shift. Only ApcD2 bound phycocyanobilin covalently at the canonical position C81, while ApcD3 and ApcD4 gave only traces of stable products. The product of ApcD2 was, however, heterogeneous. The major fraction had a broad absorption around 560 nm and double-peaked fluorescence at 615 and 670 nm. A minor fraction was similar to the product of conventional ApcD, with maximal absorbance around 610 nm and fluorescence around 640 nm. The heterogeneity was lost in C65 and C132 variants; in these variants only the conventional product was formed. With ApcD4, a red-shifted product carrying non-covalently bound phycocyanobilin could be detected in the supernatant after cell lysis. While this chromophore was lost during purification, it could be stabilized by co-assembly with a far-red light-induced β-subunit, ApcB3.

  • chromophorylation in escherichia coli of Allophycocyanin b subunits from far red light acclimated chroococcidiopsis thermalis sp pcc7203
    Photochemical and Photobiological Sciences, 2017
    Co-Authors: Qiying Tang, Wenlong Ding, Baoqing Zhao, Ming Zhou, Wolfgang Gartner, Hugo Scheer, Jiaxin Han, Kaihong Zhao

    Abstract:

    Cyanobacterial phycobilisomes funnel the harvested light energy to the reaction centers via two terminal emitters, Allophycocyanin B and the core-membrane linker. ApcD is the α-subunit of Allophycocyanin B responsible for its red-shifted absorbance (λmax 665 nm). Far-red photo-acclimated cyanobacteria contain certain Allophycocyanins that show even further red-shifted absorbances (λmax > 700 nm). We studied the chromophorylation of the three far-red induced ApcD subunits ApcD2, ApcD3 and ApcD4 from Chroococcidiopsis thermalis sp. PCC7203 during the expression in E. coli. The complex behavior emphasizes that a variety of factors contribute to the spectral red-shift. Only ApcD2 bound phycocyanobilin covalently at the canonical position C81, while ApcD3 and ApcD4 gave only traces of stable products. The product of ApcD2 was, however, heterogeneous. The major fraction had a broad absorption around 560 nm and double-peaked fluorescence at 615 and 670 nm. A minor fraction was similar to the product of conventional ApcD, with maximal absorbance around 610 nm and fluorescence around 640 nm. The heterogeneity was lost in C65 and C132 variants; in these variants only the conventional product was formed. With ApcD4, a red-shifted product carrying non-covalently bound phycocyanobilin could be detected in the supernatant after cell lysis. While this chromophore was lost during purification, it could be stabilized by co-assembly with a far-red light-induced β-subunit, ApcB3.

  • RESONANCE‐ENHANCED CARS SPECTROSCOPY OF BILIPROTEINS. INFLUENCE OF AGGREGATION and LINKER PROTEINS ON CHROMOPHORE STRUCTURE IN Allophycocyanin (Mastigocladus laminosus)
    Photochemistry and Photobiology, 2008
    Co-Authors: Siegfried Schneider, Kaihong Zhao, C. J. Prenzel, G. Brehm, Lothar Gottschalk, Hugo Scheer

    Abstract:

    — Resonance-enhanced coherent anti-Stokes Raman spectra (CARS) are reported for monomers and for trimers with and without linker proteins of Allophycocyanin isolated from Mastigocladus laminosus. The CARS spectrum of the monomer is independent of the presence of linker proteins and is very similar to that of phycocyanin monomers indicating that the equivalent chromophores exhibit like structures in both biliproteins. Large differences are, however, observed between the spectra of phycocyanin trimers and those of Allophycocyanin trimers with or without linker proteins (Lc8,9). The observed differences between monomer and trimer spectra are consistent with a change of the α-chromophore-protein arrangement upon aggregation without linker. If linker proteins are present in the trimer, then additional geometry changes of the β-chromophores are induced; these could relate to a transition from the 15Z-anti to 15Z-syn conformation.

Sashka Krumova – One of the best experts on this subject based on the ideXlab platform.

  • Structural integrity of Synechocystis sp. PCC 6803 phycobilisomes evaluated by means of differential scanning calorimetry
    Photosynthesis Research, 2018
    Co-Authors: Nia Petrova, Svetla Todinova, Hajnalka Laczko-dobos, Tomas Zakar, Sindhujaa Vajravel, Stefka Taneva, Zoltán Gombos, Sashka Krumova

    Abstract:

    Phycobilisomes (PBSs) are supramolecular pigment–protein complexes that serve as light-harvesting antennae in cyanobacteria. They are built up by phycobiliproteins assembled into Allophycocyanin core cylinders (ensuring the physical interaction with the photosystems) and phycocyanin rods (protruding from the cores and having light-harvesting function), the whole PBSs structure being maintained by linker proteins. PBSs play major role in light-harvesting optimization in cyanobacteria; therefore, the characterization of their structural integrity in intact cells is of great importance. The present study utilizes differential scanning calorimetry and spectroscopy techniques to explore for the first time, the thermodynamic stability of PBSs in intact Synechocystis sp. PCC 6803 cells and to probe its alteration as a result of mutations or under different growth conditions. As a first step, we characterize the thermodynamic behavior of intact and dismantled PBSs isolated from wild-type cells (having fully assembled PBSs) and from CK mutant cells (that lack phycocyanin rods and contain only Allophycocyanin cores), and identified the thermal transitions of phycocyanin and Allophycocyanin units in vitro. Next, we demonstrate that in intact cells PBSs exhibit sharp, high amplitude thermal transition at about 63 °C that strongly depends on the structural integrity of the PBSs supercomplex. Our findings implicate that calorimetry could offer a valuable approach for the assessment of the influence of variety of factors affecting the stability and structural organization of phycobilisomes in intact cyanobacterial cells.