1
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Assefa GT, Botha JL, van Heerden B, Kyeyune F, Krüger TPJ, Gwizdala M. ApcE plays an important role in light-induced excitation energy dissipation in the Synechocystis PCC6803 phycobilisomes. PHOTOSYNTHESIS RESEARCH 2024; 160:17-29. [PMID: 38407779 PMCID: PMC11006782 DOI: 10.1007/s11120-024-01078-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 01/18/2024] [Indexed: 02/27/2024]
Abstract
Phycobilisomes (PBs) play an important role in cyanobacterial photosynthesis. They capture light and transfer excitation energy to the photosynthetic reaction centres. PBs are also central to some photoprotective and photoregulatory mechanisms that help sustain photosynthesis under non-optimal conditions. Amongst the mechanisms involved in excitation energy dissipation that are activated in response to excessive illumination is a recently discovered light-induced mechanism that is intrinsic to PBs and has been the least studied. Here, we used single-molecule spectroscopy and developed robust data analysis methods to explore the role of a terminal emitter subunit, ApcE, in this intrinsic, light-induced mechanism. We isolated the PBs from WT Synechocystis PCC 6803 as well as from the ApcE-C190S mutant of this strain and compared the dynamics of their fluorescence emission. PBs isolated from the mutant (i.e., ApcE-C190S-PBs), despite not binding some of the red-shifted pigments in the complex, showed similar global emission dynamics to WT-PBs. However, a detailed analysis of dynamics in the core revealed that the ApcE-C190S-PBs are less likely than WT-PBs to enter quenched states under illumination but still fully capable of doing so. This result points to an important but not exclusive role of the ApcE pigments in the light-induced intrinsic excitation energy dissipation mechanism in PBs.
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Affiliation(s)
- Gonfa Tesfaye Assefa
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
| | - Joshua L Botha
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
| | - Bertus van Heerden
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
- National Institute for Theoretical and Computational Sciences (NITheCS), Stellenbosch, South Africa
| | - Farooq Kyeyune
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
- Department of Physics, Faculty of Science, Kyambogo University, P.O. Box 1, Kyambogo, Kampala, Uganda
| | - Tjaart P J Krüger
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa
- National Institute for Theoretical and Computational Sciences (NITheCS), Stellenbosch, South Africa
| | - Michal Gwizdala
- Department of Physics, University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa.
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Lynnwood Road, Pretoria, 0002, South Africa.
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, 08860, Spain.
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2
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Stadnichuk IN, Krasilnikov PM. Relationship between non-photochemical quenching efficiency and the energy transfer rate from phycobilisomes to photosystem II. PHOTOSYNTHESIS RESEARCH 2024; 159:177-189. [PMID: 37328680 DOI: 10.1007/s11120-023-01031-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 06/02/2023] [Indexed: 06/18/2023]
Abstract
The chromophorylated PBLcm domain of the ApcE linker protein in the cyanobacterial phycobilisome (PBS) serves as a bottleneck for Förster resonance energy transfer (FRET) from the PBS to the antennal chlorophyll of photosystem II (PS II) and as a redirection point for energy distribution to the orange protein ketocarotenoid (OCP), which is excitonically coupled to the PBLcm chromophore in the process of non-photochemical quenching (NPQ) under high light conditions. The involvement of PBLcm in the quenching process was first directly demonstrated by measuring steady-state fluorescence spectra of cyanobacterial cells at different stages of NPQ development. The time required to transfer energy from the PBLcm to the OCP is several times shorter than the time it takes to transfer energy from the PBLcm to the PS II, ensuring quenching efficiency. The data obtained provide an explanation for the different rates of PBS quenching in vivo and in vitro according to the half ratio of OCP/PBS in the cyanobacterial cell, which is tens of times lower than that realized for an effective NPQ process in solution.
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Affiliation(s)
- Igor N Stadnichuk
- K.A. Timiryazev Institute of Plant Physiology, RAS, Botanicheskaya 35, 127726, Moscow, Russia.
| | - Pavel M Krasilnikov
- Biological Faculty of M.V., Lomonosov State University, Lenin Hills 12, 119991, Moscow, Russia
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3
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Elanskaya IV, Bulychev AA, Lukashev EP, Muronets EM, Maksimov EG. Roles of ApcD and orange carotenoid protein in photoinduction of electron transport upon dark-light transition in the Synechocystis PCC 6803 mutant deficient in flavodiiron protein Flv1. PHOTOSYNTHESIS RESEARCH 2024; 159:97-114. [PMID: 37093504 DOI: 10.1007/s11120-023-01019-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 04/13/2023] [Indexed: 05/03/2023]
Abstract
Flavodiiron proteins Flv1/Flv3 accept electrons from photosystem (PS) I. In this work we investigated light adaptation mechanisms of Flv1-deficient mutant of Synechocystis PCC 6803, incapable to form the Flv1/Flv3 heterodimer. First seconds of dark-light transition were studied by parallel measurements of light-induced changes in chlorophyll fluorescence, P700 redox transformations, fluorescence emission at 77 K, and OCP-dependent fluorescence quenching. During the period of Calvin cycle activation upon dark-light transition, the linear electron transport (LET) in wild type is supported by the Flv1/Flv3 heterodimer, whereas in Δflv1 mutant activation of LET upon illumination is preceded by cyclic electron flow that maintains State 2. The State 2-State 1 transition and Orange Carotenoid Protein (OCP)-dependent non-photochemical quenching occur independently of each other, begin in about 10 s after the illumination of the cells and are accompanied by a short-term re-reduction of the PSI reaction center (P700+). ApcD is important for the State 2-State 1 transition in the Δflv1 mutant, but S-M rise in chlorophyll fluorescence was not completely inhibited in Δflv1/ΔapcD mutant. LET in Δflv1 mutant starts earlier than the S-M rise in chlorophyll fluorescence, and the oxidation of plastoquinol (PQH2) pool promotes the activation of PSII, transient re-reduction of P700+ and transition to State 1. An attempt to induce state transition in the wild type under high intensity light using methyl viologen, highly oxidizing P700 and PQH2, was unsuccessful, showing that oxidation of intersystem electron-transport carriers might be insufficient for the induction of State 2-State 1 transition in wild type of Synechocystis under high light.
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Affiliation(s)
- Irina V Elanskaya
- Department of Genetics, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Alexander A Bulychev
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Evgeny P Lukashev
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Elena M Muronets
- Department of Genetics, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Eugene G Maksimov
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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Wyatt L, Gichuki S, Yalcin YS, Sitther V. Impact of Ascorbic Acid on Zero-Valent Iron Nanoparticle and UV-B Mediated Stress in the Cyanobacterium, Fremyella diplosiphon. Microorganisms 2023; 11:1245. [PMID: 37317219 DOI: 10.3390/microorganisms11051245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/29/2023] [Accepted: 05/05/2023] [Indexed: 06/16/2023] Open
Abstract
Fremyella diplosiphon is an ideal third-generation biofuel source due to its ability to produce transesterified lipids. While nanofer 25s zero-valent iron nanoparticles (nZVIs) improve lipid production, an imbalance between reactive oxygen species (ROS) and cellular defense can be catastrophic to the organism. In the present study, the effect of ascorbic acid on nZVI and UV-induced stress in F. diplosiphon strain B481-SD was investigated, and lipid profiles in the combination regimen of nZVIs and ascorbic acid compared. Comparison of F. diplosiphon growth in BG11 media amended with 2, 4, 6, 8, and 10 mM ascorbic acid indicated 6 mM to be optimal for the growth of B481-SD. Further, growth in 6 mM ascorbic acid combined with 3.2 mg/L nZVIs was significantly higher when compared to the combination regimen of 12.8 and 51.2 mg/L of nZVIs and 6 mM ascorbic acid. The reversal effect of UV-B radiation for 30 min and 1 h indicated that ascorbic acid restored B481-SD growth. Transesterified lipids characterized by gas chromatography-mass spectrometry indicated C16 hexadecanoate to be the most abundant fatty acid methyl ester in the combination regimen of 6 mM ascorbic acid and 12.8 mg/L nZVI-treated F. diplosiphon. These findings were supported by microscopic observations in which cellular degradation was observed in B481-SD cells treated with 6 mM ascorbic acid and 12.8 mg/L nZVIs. Our results indicate that ascorbic acid counteracts the damaging effect of oxidative stress produced by nZVIs.
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Affiliation(s)
- LaDonna Wyatt
- Department of Biology, Morgan State University, 1700 E. Cold Spring Lane, Baltimore, MD 21251, USA
| | - Samson Gichuki
- Department of Biology, Morgan State University, 1700 E. Cold Spring Lane, Baltimore, MD 21251, USA
| | - Yavuz S Yalcin
- Department of Biology, Morgan State University, 1700 E. Cold Spring Lane, Baltimore, MD 21251, USA
| | - Viji Sitther
- Department of Biology, Morgan State University, 1700 E. Cold Spring Lane, Baltimore, MD 21251, USA
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Characterization of Molecular Diversity and Organization of Phycobilisomes in Thermophilic Cyanobacteria. Int J Mol Sci 2023; 24:ijms24065632. [PMID: 36982707 PMCID: PMC10053587 DOI: 10.3390/ijms24065632] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/07/2023] [Accepted: 03/14/2023] [Indexed: 03/18/2023] Open
Abstract
Thermophilic cyanobacteria are cosmopolitan and abundant in the thermal environment. Their light-harvesting complexes, phycobilisomes (PBS), are highly important in photosynthesis. To date, there is limited information on the PBS composition of thermophilic cyanobacteria whose habitats are challenging for survival. Herein, genome-based methods were used to investigate the molecular components of PBS in 19 well-described thermophilic cyanobacteria. These cyanobacteria are from the genera Leptolyngbya, Leptothermofonsia, Ocullathermofonsia, Thermoleptolyngbya, Trichothermofonsia, Synechococcus, Thermostichus, and Thermosynechococcus. According to the phycobiliprotein (PBP) composition of the rods, two pigment types are observed in these thermophiles. The amino acid sequence analysis of different PBP subunits suggests several highly conserved cysteine residues in these thermophiles. Certain amino acid contents in the PBP of thermophiles are significantly higher than their mesophilic counterparts, highlighting the potential roles of specific substitutions of amino acid in the adaptive thermostability of light-harvesting complexes in thermophilic cyanobacteria. Genes encoding PBS linker polypeptides vary among the thermophiles. Intriguingly, motifs in linker apcE indicate a photoacclimation of a far-red light by Leptolyngbya JSC-1, Leptothermofonsia E412, and Ocullathermofonsia A174. The composition pattern of phycobilin lyases is consistent among the thermophiles, except for Thermostichus strains that have extra homologs of cpcE, cpcF, and cpcT. In addition, phylogenetic analyses of genes coding for PBPs, linkers, and lyases suggest extensive genetic diversity among these thermophiles, which is further discussed with the domain analyses. Moreover, comparative genomic analysis suggests different genomic distributions of PBS-related genes among the thermophiles, indicating probably various regulations of expression. In summary, the comparative analysis elucidates distinct molecular components and organization of PBS in thermophilic cyanobacteria. These results provide insights into the PBS components of thermophilic cyanobacteria and fundamental knowledge for future research regarding structures, functions, and photosynthetic improvement.
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Voerman SE, Ruseckas A, Turnbull GA, Samuel IDW, Burdett HL. Red algae acclimate to low light by modifying phycobilisome composition to maintain efficient light harvesting. BMC Biol 2022; 20:291. [PMID: 36575464 PMCID: PMC9794408 DOI: 10.1186/s12915-022-01480-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 11/24/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Despite a global prevalence of photosynthetic organisms in the ocean's mesophotic zone (30-200+ m depth), the mechanisms that enable photosynthesis to proceed in this low light environment are poorly defined. Red coralline algae are the deepest known marine benthic macroalgae - here we investigated the light harvesting mechanism and mesophotic acclimatory response of the red coralline alga Lithothamnion glaciale. RESULTS Following initial absorption by phycourobilin and phycoerythrobilin in phycoerythrin, energy was transferred from the phycobilisome to photosystems I and II within 120 ps. This enabled delivery of 94% of excitations to reaction centres. Low light intensity, and to a lesser extent a mesophotic spectrum, caused significant acclimatory change in chromophores and biliproteins, including a 10% increase in phycoerythrin light harvesting capacity and a 20% reduction in chlorophyll-a concentration and photon requirements for photosystems I and II. The rate of energy transfer remained consistent across experimental treatments, indicating an acclimatory response that maintains energy transfer. CONCLUSIONS Our results demonstrate that responsive light harvesting by phycobilisomes and photosystem functional acclimation are key to red algal success in the mesophotic zone.
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Affiliation(s)
- Sofie E. Voerman
- Lyell Centre for Earth and Marine Science and Technology, Edinburgh, EH14 4BA UK ,grid.9531.e0000000106567444School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh, EH14 4AS UK
| | - Arvydas Ruseckas
- grid.11914.3c0000 0001 0721 1626Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS UK
| | - Graham A. Turnbull
- grid.11914.3c0000 0001 0721 1626Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS UK
| | - Ifor D. W. Samuel
- grid.11914.3c0000 0001 0721 1626Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS UK
| | - Heidi L. Burdett
- Lyell Centre for Earth and Marine Science and Technology, Edinburgh, EH14 4BA UK ,grid.9531.e0000000106567444School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh, EH14 4AS UK ,grid.12650.300000 0001 1034 3451Present Address: Department of Ecology and Environmental Sciences, Umeå University, Umeå, Sweden ,grid.12650.300000 0001 1034 3451Umeå Marine Sciences Centre, Umeå University, Norrbyn, Sweden
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7
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Structures of a phycobilisome in light-harvesting and photoprotected states. Nature 2022; 609:835-845. [PMID: 36045294 DOI: 10.1038/s41586-022-05156-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 07/27/2022] [Indexed: 11/08/2022]
Abstract
Phycobilisome (PBS) structures are elaborate antennae in cyanobacteria and red algae1,2. These large protein complexes capture incident sunlight and transfer the energy through a network of embedded pigment molecules called bilins to the photosynthetic reaction centres. However, light harvesting must also be balanced against the risks of photodamage. A known mode of photoprotection is mediated by orange carotenoid protein (OCP), which binds to PBS when light intensities are high to mediate photoprotective, non-photochemical quenching3-6. Here we use cryogenic electron microscopy to solve four structures of the 6.2 MDa PBS, with and without OCP bound, from the model cyanobacterium Synechocystis sp. PCC 6803. The structures contain a previously undescribed linker protein that binds to the membrane-facing side of PBS. For the unquenched PBS, the structures also reveal three different conformational states of the antenna, two previously unknown. The conformational states result from positional switching of two of the rods and may constitute a new mode of regulation of light harvesting. Only one of the three PBS conformations can bind to OCP, which suggests that not every PBS is equally susceptible to non-photochemical quenching. In the OCP-PBS complex, quenching is achieved through the binding of four 34 kDa OCPs organized as two dimers. The complex reveals the structure of the active form of OCP, in which an approximately 60 Å displacement of its regulatory carboxy terminal domain occurs. Finally, by combining our structure with spectroscopic properties7, we elucidate energy transfer pathways within PBS in both the quenched and light-harvesting states. Collectively, our results provide detailed insights into the biophysical underpinnings of the control of cyanobacterial light harvesting. The data also have implications for bioengineering PBS regulation in natural and artificial light-harvesting systems.
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8
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Akhtar P, Biswas A, Balog-Vig F, Domonkos I, Kovács L, Lambrev PH. Trimeric photosystem I facilitates energy transfer from phycobilisomes in Synechocystis sp. PCC 6803. PLANT PHYSIOLOGY 2022; 189:827-838. [PMID: 35302607 PMCID: PMC9157137 DOI: 10.1093/plphys/kiac130] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 02/27/2022] [Indexed: 05/31/2023]
Abstract
In cyanobacteria, phycobilisomes (PBS) serve as peripheral light-harvesting complexes of the two photosystems, extending their antenna size and the wavelength range of photons available for photosynthesis. The abundance of PBS, the number of phycobiliproteins they contain, and their light-harvesting function are dynamically adjusted in response to the physiological conditions. PBS are also thought to be involved in state transitions that maintain the excitation balance between the two photosystems. Unlike its eukaryotic counterpart, PSI is trimeric in many cyanobacterial species and the physiological significance of this is not well understood. Here, we compared the composition and light-harvesting function of PBS in cells of Synechocystis sp. PCC 6803, which has primarily trimeric PSI, and the ΔpsaL mutant, which lacks the PsaL subunit of PSI and is unable to form trimers. We also investigated a mutant additionally lacking the PsaJ and PsaF subunits of PSI. Both strains with monomeric PSI accumulated significantly more allophycocyanin per chlorophyll, indicating higher abundance of PBS. On the other hand, a higher phycocyanin:allophycocyanin ratio in the wild type suggests larger PBS or the presence of APC-less PBS (CpcL-type) that are not assembled in cells with monomeric PSI. Steady-state and time-resolved fluorescence spectroscopy at room temperature and 77 K revealed that PSII receives more energy from the PBS at the expense of PSI in cells with monomeric PSI, regardless of the presence of PsaF. Taken together, these results show that the oligomeric state of PSI impacts the excitation energy flow in Synechocystis.
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Affiliation(s)
- Parveen Akhtar
- Szeged Biological Research Centre, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
| | - Avratanu Biswas
- Szeged Biological Research Centre, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
- Doctoral School of Biology, University of Szeged, Közép fasor 52, Szeged 6726, Hungary
| | - Fanny Balog-Vig
- Szeged Biological Research Centre, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
| | - Ildikó Domonkos
- Szeged Biological Research Centre, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
| | - László Kovács
- Szeged Biological Research Centre, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
| | - Petar H Lambrev
- Szeged Biological Research Centre, Institute of Plant Biology, Temesvári krt. 62, Szeged 6726, Hungary
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Dagnino-Leone J, Figueroa CP, Castañeda ML, Youlton AD, Vallejos-Almirall A, Agurto-Muñoz A, Pavón Pérez J, Agurto-Muñoz C. Phycobiliproteins: Structural aspects, functional characteristics, and biotechnological perspectives. Comput Struct Biotechnol J 2022; 20:1506-1527. [PMID: 35422968 PMCID: PMC8983314 DOI: 10.1016/j.csbj.2022.02.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 02/18/2022] [Accepted: 02/19/2022] [Indexed: 12/13/2022] Open
Abstract
Phycobiliproteins (PBPs) are fluorescent proteins of various colors, including fuchsia, purple-blue and cyan, that allow the capture of light energy in auxiliary photosynthetic complexes called phycobilisomes (PBS). PBPs have several highly preserved structural and physicochemical characteristics. In the PBS context, PBPs function is capture luminous energy in the 450–650 nm range and delivers it to photosystems allowing photosynthesis take place. Besides the energy harvesting function, PBPs also have shown to have multiple biological activities, including antioxidant, antibacterial and antitumours, making them an interesting focus for different biotechnological applications in areas like biomedicine, bioenergy and scientific research. Nowadays, the main sources of PBPs are cyanobacteria and micro and macro algae from the phylum Rhodophyta. Due to the diverse biological activities of PBPs, they have attracted the attention of different industries, such as food, biomedical and cosmetics. This is why a large number of patents related to the production, extraction, purification of PBPs and their application as cosmetics, biopharmaceuticals or diagnostic applications have been generated, looking less ecological impact in the natural prairies of macroalgae and less culture time or higher productivity in cyanobacteria to satisfy the markets and applications that require high amounts of these molecules. In this review, we summarize the main structural characteristics of PBPs, their biosynthesys and biotechnological applications. We also address current trends and future perspectives of the PBPs market.
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Affiliation(s)
- Jorge Dagnino-Leone
- Grupo Interdisciplinario de Biotecnología Marina (GIBMAR), Centro de Biotecnología, Universidad de Concepción, Concepción 4030000, Chile
| | - Cristina Pinto Figueroa
- Grupo Interdisciplinario de Biotecnología Marina (GIBMAR), Centro de Biotecnología, Universidad de Concepción, Concepción 4030000, Chile
| | - Mónica Latorre Castañeda
- Grupo Interdisciplinario de Biotecnología Marina (GIBMAR), Centro de Biotecnología, Universidad de Concepción, Concepción 4030000, Chile
| | - Andrea Donoso Youlton
- Grupo Interdisciplinario de Biotecnología Marina (GIBMAR), Centro de Biotecnología, Universidad de Concepción, Concepción 4030000, Chile
| | - Alejandro Vallejos-Almirall
- Grupo Interdisciplinario de Biotecnología Marina (GIBMAR), Centro de Biotecnología, Universidad de Concepción, Concepción 4030000, Chile
| | - Andrés Agurto-Muñoz
- Grupo Interdisciplinario de Biotecnología Marina (GIBMAR), Centro de Biotecnología, Universidad de Concepción, Concepción 4030000, Chile
| | - Jessy Pavón Pérez
- Grupo Interdisciplinario de Biotecnología Marina (GIBMAR), Centro de Biotecnología, Universidad de Concepción, Concepción 4030000, Chile
- Departamento de Ciencia y Tecnología de los Alimentos (CyTA), Facultad de Farmacia, Universidad de Concepción, Concepción 4030000 Chile
| | - Cristian Agurto-Muñoz
- Grupo Interdisciplinario de Biotecnología Marina (GIBMAR), Centro de Biotecnología, Universidad de Concepción, Concepción 4030000, Chile
- Departamento de Ciencia y Tecnología de los Alimentos (CyTA), Facultad de Farmacia, Universidad de Concepción, Concepción 4030000 Chile
- Corresponding author at: Grupo Interdisciplinario de Biotecnología Marina (GIBMAR), Centro de Biotecnología, Universidad de Concepción, Concepción 4030000, Chile.
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10
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Navotnaya P, Sohoni S, Lloyd LT, Abdulhadi SM, Ting PC, Higgins JS, Engel GS. Annihilation of Excess Excitations along Phycocyanin Rods Precedes Downhill Flow to Allophycocyanin Cores in the Phycobilisome of Synechococcus elongatus PCC 7942. J Phys Chem B 2022; 126:23-29. [PMID: 34982932 PMCID: PMC8762654 DOI: 10.1021/acs.jpcb.1c06509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Cyanobacterial phycobilisome
complexes absorb visible sunlight
and funnel photogenerated excitons to the photosystems where charge
separation occurs. In the phycobilisome complex of Synechococcus
elongatus PCC 7942, phycocyanin protein rods that absorb
bluer wavelengths are assembled on allophycocyanin cores that absorb
redder wavelengths. This arrangement creates a natural energy gradient
toward the reaction centers of the photosystems. Here, we employ broadband
pump–probe spectroscopy to observe the fate of excess excitations
in the phycobilisome complex of this organism. We show that excess
excitons are quenched through exciton–exciton annihilation
along the phycocyanin rods prior to transfer to the allophycocyanin
cores. Our observations are especially relevant in comparison to other
antenna proteins, where exciton annihilation primarily occurs in the
lowest-energy chlorophylls. The observed effect could play a limited
photoprotective role in physiological light fluences. The exciton
decay dynamics is faster in the intact phycobilisome than in isolated
C-phycocyanin trimers studied in earlier work, confirming that this
effect is an emergent property of the complex assembly. Using the
obtained annihilation data, we calculate exciton hopping times of
2.2–6.4 ps in the phycocyanin rods. This value agrees with
earlier FRET calculations of exciton hopping times along phycocyanin
hexamers by Sauer and Scheer.
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Affiliation(s)
- Polina Navotnaya
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Siddhartha Sohoni
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Lawson T Lloyd
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Sami M Abdulhadi
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Po-Chieh Ting
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Jacob S Higgins
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Gregory S Engel
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
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11
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Li M, Ma J, Li X, Sui SF. In situ cryo-ET structure of phycobilisome-photosystem II supercomplex from red alga. eLife 2021; 10:e69635. [PMID: 34515634 PMCID: PMC8437437 DOI: 10.7554/elife.69635] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 08/19/2021] [Indexed: 11/13/2022] Open
Abstract
Phycobilisome (PBS) is the main light-harvesting antenna in cyanobacteria and red algae. How PBS transfers the light energy to photosystem II (PSII) remains to be elucidated. Here we report the in situ structure of the PBS-PSII supercomplex from Porphyridium purpureum UTEX 2757 using cryo-electron tomography and subtomogram averaging. Our work reveals the organized network of hemiellipsoidal PBS with PSII on the thylakoid membrane in the native cellular environment. In the PBS-PSII supercomplex, each PBS interacts with six PSII monomers, of which four directly bind to the PBS, and two bind indirectly. Additional three 'connector' proteins also contribute to the connections between PBS and PSIIs. Two PsbO subunits from adjacent PSII dimers bind with each other, which may promote stabilization of the PBS-PSII supercomplex. By analyzing the interaction interface between PBS and PSII, we reveal that αLCM and ApcD connect with CP43 of PSII monomer and that αLCM also interacts with CP47' of the neighboring PSII monomer, suggesting the multiple light energy delivery pathways. The in situ structures illustrate the coupling pattern of PBS and PSII and the arrangement of the PBS-PSII supercomplex on the thylakoid, providing the near-native 3D structural information of the various energy transfer from PBS to PSII.
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Affiliation(s)
- Meijing Li
- Key Laboratory for Protein Sciences of Ministry of Education, Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua UniversityBeijingChina
| | - Jianfei Ma
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua UniversityBeijingChina
| | - Xueming Li
- Key Laboratory for Protein Sciences of Ministry of Education, Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua UniversityBeijingChina
| | - Sen-Fang Sui
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua UniversityBeijingChina
- Department of Biology, Southern University of Science and TechnologyGuangdongChina
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12
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Bhatti AF, Kirilovsky D, van Amerongen H, Wientjes E. State transitions and photosystems spatially resolved in individual cells of the cyanobacterium Synechococcus elongatus. PLANT PHYSIOLOGY 2021; 186:569-580. [PMID: 33576804 PMCID: PMC8154081 DOI: 10.1093/plphys/kiab063] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 01/21/2021] [Indexed: 05/28/2023]
Abstract
State transitions are a low-light acclimation response through which the excitation of Photosystem I (PSI) and Photosystem II (PSII) is balanced; however, our understanding of this process in cyanobacteria remains poor. Here, picosecond fluorescence kinetics was recorded for the cyanobacterium Synechococcus elongatus using fluorescence lifetime imaging microscopy (FLIM), both upon chlorophyll a and phycobilisome (PBS) excitation. Fluorescence kinetics of single cells obtained using FLIM were compared with those of ensembles of cells obtained with time-resolved fluorescence spectroscopy. The global distribution of PSI and PSII and PBSs was mapped making use of their fluorescence kinetics. Both radial and lateral heterogeneity were found in the distribution of the photosystems. State transitions were studied at the level of single cells. FLIM results show that PSII quenching occurs in all cells, irrespective of their state (I or II). In S. elongatus cells, this quenching is enhanced in State II. Furthermore, the decrease of PSII fluorescence in State II was homogeneous throughout the cells, despite the inhomogeneous PSI/PSII ratio. Finally, some disconnected PBSs were resolved in most State II cells. Taken together our data show that PSI is enriched in the inner thylakoid, while state transitions occur homogeneously throughout the cell.
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Affiliation(s)
- Ahmad Farhan Bhatti
- Laboratory of Biophysics, Wageningen University, Wageningen, The Netherlands
| | - Diana Kirilovsky
- Institute for Integrative Biology of the Cell (12BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Herbert van Amerongen
- Laboratory of Biophysics, Wageningen University, Wageningen, The Netherlands
- MicroSpectroscopy Research Facility, Wageningen University, Wageningen, The Netherlands
| | - Emilie Wientjes
- Laboratory of Biophysics, Wageningen University, Wageningen, The Netherlands
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13
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Zhan J, Steglich C, Scholz I, Hess WR, Kirilovsky D. Inverse regulation of light harvesting and photoprotection is mediated by a 3'-end-derived sRNA in cyanobacteria. THE PLANT CELL 2021; 33:358-380. [PMID: 33793852 PMCID: PMC8136909 DOI: 10.1093/plcell/koaa030] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 12/01/2020] [Indexed: 06/12/2023]
Abstract
Phycobilisomes (PBSs), the principal cyanobacterial antenna, are among the most efficient macromolecular structures in nature, and are used for both light harvesting and directed energy transfer to the photosynthetic reaction center. However, under unfavorable conditions, excess excitation energy needs to be rapidly dissipated to avoid photodamage. The orange carotenoid protein (OCP) senses light intensity and induces thermal energy dissipation under stress conditions. Hence, its expression must be tightly controlled; however, the molecular mechanism of this regulation remains to be elucidated. Here, we describe the discovery of a posttranscriptional regulatory mechanism in Synechocystis sp. PCC 6803 in which the expression of the operon encoding the allophycocyanin subunits of the PBS is directly and in an inverse fashion linked to the expression of OCP. This regulation is mediated by ApcZ, a small regulatory RNA that is derived from the 3'-end of the tetracistronic apcABC-apcZ operon. ApcZ inhibits ocp translation under stress-free conditions. Under most stress conditions, apc operon transcription decreases and ocp translation increases. Thus, a key operon involved in the collection of light energy is functionally connected to the expression of a protein involved in energy dissipation. Our findings support the view that regulatory RNA networks in bacteria evolve through the functionalization of mRNA 3'-UTRs.
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Affiliation(s)
- Jiao Zhan
- Université Paris-Saclay, Commissariat à l’Énergie Atomiques et aux Énergies Alternatives, Centre National de la Recherche Scientifique (CEA, CNRS), Institute for Integrative Biology of the Cell (I2BC), 91198 Gif sur Yvette, France
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Claudia Steglich
- Faculty of Biology, Institute of Biology III, University of Freiburg, D-79104 Freiburg im Breisgau, Germany
| | - Ingeborg Scholz
- Faculty of Biology, Institute of Biology III, University of Freiburg, D-79104 Freiburg im Breisgau, Germany
| | - Wolfgang R Hess
- Faculty of Biology, Institute of Biology III, University of Freiburg, D-79104 Freiburg im Breisgau, Germany
| | - Diana Kirilovsky
- Université Paris-Saclay, Commissariat à l’Énergie Atomiques et aux Énergies Alternatives, Centre National de la Recherche Scientifique (CEA, CNRS), Institute for Integrative Biology of the Cell (I2BC), 91198 Gif sur Yvette, France
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14
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Xie Y, Chen L, Sun T, Zhang W. Deciphering and engineering high-light tolerant cyanobacteria for efficient photosynthetic cell factories. Chin J Chem Eng 2021. [DOI: 10.1016/j.cjche.2020.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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15
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Liu H, Zhang MM, Weisz DA, Cheng M, Pakrasi HB, Blankenship RE. Structure of cyanobacterial phycobilisome core revealed by structural modeling and chemical cross-linking. SCIENCE ADVANCES 2021; 7:7/2/eaba5743. [PMID: 33523959 PMCID: PMC7787483 DOI: 10.1126/sciadv.aba5743] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 11/16/2020] [Indexed: 05/28/2023]
Abstract
In cyanobacteria and red algae, the structural basis dictating efficient excitation energy transfer from the phycobilisome (PBS) antenna complex to the reaction centers remains unclear. The PBS has several peripheral rods and a central core that binds to the thylakoid membrane, allowing energy coupling with photosystem II (PSII) and PSI. Here, we have combined chemical cross-linking mass spectrometry with homology modeling to propose a tricylindrical cyanobacterial PBS core structure. Our model reveals a side-view crossover configuration of the two basal cylinders, consolidating the essential roles of the anchoring domains composed of the ApcE PB loop and ApcD, which facilitate the energy transfer to PSII and PSI, respectively. The uneven bottom surface of the PBS core contrasts with the flat reducing side of PSII. The extra space between two basal cylinders and PSII provides increased accessibility for regulatory elements, e.g., orange carotenoid protein, which are required for modulating photochemical activity.
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Affiliation(s)
- Haijun Liu
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA.
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
- Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Mengru M Zhang
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Daniel A Weisz
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
- Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Ming Cheng
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Himadri B Pakrasi
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
- Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Robert E Blankenship
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
- Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, St. Louis, MO 63130, USA
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16
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Bhatti AF, Choubeh RR, Kirilovsky D, Wientjes E, van Amerongen H. State transitions in cyanobacteria studied with picosecond fluorescence at room temperature. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148255. [PMID: 32619427 DOI: 10.1016/j.bbabio.2020.148255] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 06/19/2020] [Accepted: 06/21/2020] [Indexed: 11/30/2022]
Abstract
Cyanobacteria can rapidly regulate the relative activity of their photosynthetic complexes photosystem I and II (PSI and PSII) in response to changes in the illumination conditions. This process is known as state transitions. If PSI is preferentially excited, they go to state I whereas state II is induced either after preferential excitation of PSII or after dark adaptation. Different underlying mechanisms have been proposed in literature, in particular i) reversible shuttling of the external antenna complexes, the phycobilisomes, between PSI and PSII, ii) reversible spillover of excitation energy from PSII to PSI, iii) a combination of both and, iv) increased excited-state quenching of the PSII core in state II. Here we investigated wild-type and mutant strains of Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803 using time-resolved fluorescence spectroscopy at room temperature. Our observations support model iv, meaning that increased excited-state quenching of the PSII core occurs in state II thereby balancing the photochemistry of photosystems I and II.
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Affiliation(s)
- Ahmad Farhan Bhatti
- Laboratory of Biophysics, Wageningen University, Wageningen, the Netherlands
| | | | - Diana Kirilovsky
- Institute for Integrative Biology of the Cell (12BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Emilie Wientjes
- Laboratory of Biophysics, Wageningen University, Wageningen, the Netherlands
| | - Herbert van Amerongen
- Laboratory of Biophysics, Wageningen University, Wageningen, the Netherlands; MicroSpectroscopy Research Facility, Wageningen University, Wageningen, the Netherlands.
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17
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Calzadilla PI, Kirilovsky D. Revisiting cyanobacterial state transitions. Photochem Photobiol Sci 2020; 19:585-603. [DOI: 10.1039/c9pp00451c] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Critical evaluation of “new” and “old” models of cyanobacterial state transitions. Phycobilisome and membrane contributions to this mechanism are addressed. The signaling transduction pathway is discussed.
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Affiliation(s)
- Pablo I. Calzadilla
- Université Paris-Saclay
- CNRS
- CEA
- Institute for Integrative Biology of the Cell (I2BC)
- 91198 Gif sur Yvette
| | - Diana Kirilovsky
- Université Paris-Saclay
- CNRS
- CEA
- Institute for Integrative Biology of the Cell (I2BC)
- 91198 Gif sur Yvette
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18
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Bryant DA, Shen G, Turner GM, Soulier N, Laremore TN, Ho MY. Far-red light allophycocyanin subunits play a role in chlorophyll d accumulation in far-red light. PHOTOSYNTHESIS RESEARCH 2020; 143:81-95. [PMID: 31760552 DOI: 10.1007/s11120-019-00689-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/31/2019] [Indexed: 06/10/2023]
Abstract
Some terrestrial cyanobacteria acclimate to and utilize far-red light (FRL; λ = 700-800 nm) for oxygenic photosynthesis, a process known as far-red light photoacclimation (FaRLiP). A conserved, 20-gene FaRLiP cluster encodes core subunits of Photosystem I (PSI) and Photosystem II (PSII), five phycobiliprotein subunits of FRL-bicylindrical cores, and enzymes for synthesis of chlorophyll (Chl) f and possibly Chl d. Deletion mutants for each of the five apc genes of the FaRLiP cluster were constructed in Synechococcus sp. PCC 7335, and all had similar phenotypes. When the mutants were grown in white (WL) or red (RL) light, the cells closely resembled the wild-type (WT) strain grown under the same conditions. However, the WT and mutant strains were very different when grown under FRL. Mutants grown in FRL were unable to assemble FRL-bicylindrical cores, were essentially devoid of FRL-specific phycobiliproteins, but retained RL-type phycobilisomes and WL-PSII. The transcript levels for genes of the FaRLiP cluster in the mutants were similar to those in WT. Surprisingly, the Chl d contents of the mutant strains were greatly reduced (~ 60-99%) compared to WT and so were the levels of FRL-PSII. We infer that Chl d may be essential for the assembly of FRL-PSII, which does not accumulate to normal levels in the mutants. We further infer that the cysteine-rich subunits of FRL allophycocyanin may either directly participate in the synthesis of Chl d or that FRL bicylindrical cores stabilize FRL-PSII to prevent loss of Chl d.
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Affiliation(s)
- Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA.
| | - Gaozhong Shen
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Gavin M Turner
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Nathan Soulier
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Tatiana N Laremore
- Proteomics and Mass Spectrometry Core Facility, Huck Institute for the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Ming-Yang Ho
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Life Science, National Taiwan University, Taipei, 10617, Taiwan
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19
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Nagarajan A, Zhou M, Nguyen AY, Liberton M, Kedia K, Shi T, Piehowski P, Shukla A, Fillmore TL, Nicora C, Smith RD, Koppenaal DW, Jacobs JM, Pakrasi HB. Proteomic Insights into Phycobilisome Degradation, A Selective and Tightly Controlled Process in The Fast-Growing Cyanobacterium Synechococcus elongatus UTEX 2973. Biomolecules 2019; 9:biom9080374. [PMID: 31426316 PMCID: PMC6722726 DOI: 10.3390/biom9080374] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 08/12/2019] [Accepted: 08/13/2019] [Indexed: 11/16/2022] Open
Abstract
Phycobilisomes (PBSs) are large (3-5 megadalton) pigment-protein complexes in cyanobacteria that associate with thylakoid membranes and harvest light primarily for photosystem II. PBSs consist of highly ordered assemblies of pigmented phycobiliproteins (PBPs) and linker proteins that can account for up to half of the soluble protein in cells. Cyanobacteria adjust to changing environmental conditions by modulating PBS size and number. In response to nutrient depletion such as nitrogen (N) deprivation, PBSs are degraded in an extensive, tightly controlled, and reversible process. In Synechococcus elongatus UTEX 2973, a fast-growing cyanobacterium with a doubling time of two hours, the process of PBS degradation is very rapid, with 80% of PBSs per cell degraded in six hours under optimal light and CO2 conditions. Proteomic analysis during PBS degradation and re-synthesis revealed multiple proteoforms of PBPs with partially degraded phycocyanobilin (PCB) pigments. NblA, a small proteolysis adaptor essential for PBS degradation, was characterized and validated with targeted mass spectrometry. NblA levels rose from essentially 0 to 25,000 copies per cell within 30 min of N depletion, and correlated with the rate of decrease in phycocyanin (PC). Implications of this correlation on the overall mechanism of PBS degradation during N deprivation are discussed.
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Affiliation(s)
- Aparna Nagarajan
- Department of Biology, Washington University, St. Louis, MO 63130, USA
| | - Mowei Zhou
- Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Amelia Y Nguyen
- Department of Biology, Washington University, St. Louis, MO 63130, USA
| | - Michelle Liberton
- Department of Biology, Washington University, St. Louis, MO 63130, USA
| | - Komal Kedia
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Tujin Shi
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Paul Piehowski
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Anil Shukla
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Thomas L Fillmore
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Carrie Nicora
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Richard D Smith
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - David W Koppenaal
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Jon M Jacobs
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Himadri B Pakrasi
- Department of Biology, Washington University, St. Louis, MO 63130, USA.
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