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Zhang L, Ruan J, Gao F, Xin Q, Che LP, Cai L, Liu Z, Kong M, Rochaix JD, Mi H, Peng L. Thylakoid protein FPB1 synergistically cooperates with PAM68 to promote CP47 biogenesis and Photosystem II assembly. Nat Commun 2024; 15:3122. [PMID: 38600073 PMCID: PMC11006888 DOI: 10.1038/s41467-024-46863-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 03/13/2024] [Indexed: 04/12/2024] Open
Abstract
In chloroplasts, insertion of proteins with multiple transmembrane domains (TMDs) into thylakoid membranes usually occurs in a co-translational manner. Here, we have characterized a thylakoid protein designated FPB1 (Facilitator of PsbB biogenesis1) which together with a previously reported factor PAM68 (Photosynthesis Affected Mutant68) is involved in assisting the biogenesis of CP47, a subunit of the Photosystem II (PSII) core. Analysis by ribosome profiling reveals increased ribosome stalling when the last TMD segment of CP47 emerges from the ribosomal tunnel in fpb1 and pam68. FPB1 interacts with PAM68 and both proteins coimmunoprecipitate with SecY/E and Alb3 as well as with some ribosomal components. Thus, our data indicate that, in coordination with the SecY/E translocon and the Alb3 integrase, FPB1 synergistically cooperates with PAM68 to facilitate the co-translational integration of the last two CP47 TMDs and the large loop between them into thylakoids and the PSII core complex.
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Affiliation(s)
- Lin Zhang
- Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Junxiang Ruan
- Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Fudan Gao
- Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Qiang Xin
- Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Li-Ping Che
- Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Lujuan Cai
- Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Zekun Liu
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Mengmeng Kong
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences / Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, Shanghai, 200032, China
| | - Jean-David Rochaix
- Departments of Molecular Biology and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Hualing Mi
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences / Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, Shanghai, 200032, China
| | - Lianwei Peng
- Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China.
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2
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Keller JM, Frieboes MJ, Jödecke L, Kappel S, Wulff N, Rindfleisch T, Sandoval-Ibanez O, Gerlach I, Thiele W, Bock R, Eirich J, Finkemeier I, Schünemann D, Zoschke R, Schöttler MA, Armbruster U. Eukaryote-specific assembly factor DEAP2 mediates an early step of photosystem II assembly in Arabidopsis. PLANT PHYSIOLOGY 2023; 193:1970-1986. [PMID: 37555435 PMCID: PMC10602607 DOI: 10.1093/plphys/kiad446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/28/2023] [Accepted: 07/06/2023] [Indexed: 08/10/2023]
Abstract
The initial step of oxygenic photosynthesis is the thermodynamically challenging extraction of electrons from water and the release of molecular oxygen. This light-driven process, which is the basis for most life on Earth, is catalyzed by photosystem II (PSII) within the thylakoid membrane of photosynthetic organisms. The biogenesis of PSII requires a controlled step-wise assembly process of which the early steps are considered to be highly conserved between plants and their cyanobacterial progenitors. This assembly process involves auxiliary proteins, which are likewise conserved. In the present work, we used Arabidopsis (Arabidopsis thaliana) as a model to show that in plants, a eukaryote-exclusive assembly factor facilitates the early assembly step, during which the intrinsic antenna protein CP47 becomes associated with the PSII reaction center (RC) to form the RC47 intermediate. This factor, which we named DECREASED ELECTRON TRANSPORT AT PSII (DEAP2), works in concert with the conserved PHOTOSYNTHESIS AFFECTED MUTANT 68 (PAM68) assembly factor. The deap2 and pam68 mutants showed similar defects in PSII accumulation and assembly of the RC47 intermediate. The combined lack of both proteins resulted in a loss of functional PSII and the inability of plants to grow photoautotrophically on the soil. While overexpression of DEAP2 partially rescued the pam68 PSII accumulation phenotype, this effect was not reciprocal. DEAP2 accumulated at 20-fold higher levels than PAM68, together suggesting that both proteins have distinct functions. In summary, our results uncover eukaryotic adjustments to the PSII assembly process, which involve the addition of DEAP2 for the rapid progression from RC to RC47.
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Affiliation(s)
- Jakob-Maximilian Keller
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Maureen Julia Frieboes
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Ludwig Jödecke
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Sandrine Kappel
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Natalia Wulff
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Tobias Rindfleisch
- Computational Biology Unit, Department of Chemistry, University of Bergen, 5008 Bergen, Norway
| | - Omar Sandoval-Ibanez
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Ines Gerlach
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Wolfram Thiele
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Ralph Bock
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Jürgen Eirich
- Plant Physiology, Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany
| | - Iris Finkemeier
- Plant Physiology, Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany
| | - Danja Schünemann
- Molecular Biology of Plant Organelles, Ruhr University Bochum, 44780 Bochum, Germany
| | - Reimo Zoschke
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Mark Aurel Schöttler
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
| | - Ute Armbruster
- Max Planck Institute of Molecular Plant Physiology, Potsdam Science Park, 14476 Potsdam, Germany
- Institute of Molecular Photosynthesis, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
- CEPLAS - Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
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3
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Jackson PJ, Hitchcock A, Brindley AA, Dickman MJ, Hunter CN. Absolute quantification of cellular levels of photosynthesis-related proteins in Synechocystis sp. PCC 6803. PHOTOSYNTHESIS RESEARCH 2023; 155:219-245. [PMID: 36542271 PMCID: PMC9958174 DOI: 10.1007/s11120-022-00990-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 11/24/2022] [Indexed: 06/17/2023]
Abstract
Quantifying cellular components is a basic and important step for understanding how a cell works, how it responds to environmental changes, and for re-engineering cells to produce valuable metabolites and increased biomass. We quantified proteins in the model cyanobacterium Synechocystis sp. PCC 6803 given the general importance of cyanobacteria for global photosynthesis, for synthetic biology and biotechnology research, and their ancestral relationship to the chloroplasts of plants. Four mass spectrometry methods were used to quantify cellular components involved in the biosynthesis of chlorophyll, carotenoid and bilin pigments, membrane assembly, the light reactions of photosynthesis, fixation of carbon dioxide and nitrogen, and hydrogen and sulfur metabolism. Components of biosynthetic pathways, such as those for chlorophyll or for photosystem II assembly, range between 1000 and 10,000 copies per cell, but can be tenfold higher for CO2 fixation enzymes. The most abundant subunits are those for photosystem I, with around 100,000 copies per cell, approximately 2 to fivefold higher than for photosystem II and ATP synthase, and 5-20 fold more than for the cytochrome b6f complex. Disparities between numbers of pathway enzymes, between components of electron transfer chains, and between subunits within complexes indicate possible control points for biosynthetic processes, bioenergetic reactions and for the assembly of multisubunit complexes.
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Affiliation(s)
- Philip J Jackson
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK.
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, S1 3JD, UK.
| | - Andrew Hitchcock
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Amanda A Brindley
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Mark J Dickman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, S1 3JD, UK
| | - C Neil Hunter
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
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4
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Knoppová J, Sobotka R, Yu J, Bečková M, Pilný J, Trinugroho JP, Csefalvay L, Bína D, Nixon PJ, Komenda J. Assembly of D1/D2 complexes of photosystem II: Binding of pigments and a network of auxiliary proteins. PLANT PHYSIOLOGY 2022; 189:790-804. [PMID: 35134246 PMCID: PMC9157124 DOI: 10.1093/plphys/kiac045] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
Photosystem II (PSII) is the multi-subunit light-driven oxidoreductase that drives photosynthetic electron transport using electrons extracted from water. To investigate the initial steps of PSII assembly, we used strains of the cyanobacterium Synechocystis sp. PCC 6803 arrested at early stages of PSII biogenesis and expressing affinity-tagged PSII subunits to isolate PSII reaction center assembly (RCII) complexes and their precursor D1 and D2 modules (D1mod and D2mod). RCII preparations isolated using either a His-tagged D2 or a FLAG-tagged PsbI subunit contained the previously described RCIIa and RCII* complexes that differ with respect to the presence of the Ycf39 assembly factor and high light-inducible proteins (Hlips) and a larger complex consisting of RCIIa bound to monomeric PSI. All RCII complexes contained the PSII subunits D1, D2, PsbI, PsbE, and PsbF and the assembly factors rubredoxin A and Ycf48, but we also detected PsbN, Slr1470, and the Slr0575 proteins, which all have plant homologs. The RCII preparations also contained prohibitins/stomatins (Phbs) of unknown function and FtsH protease subunits. RCII complexes were active in light-induced primary charge separation and bound chlorophylls (Chls), pheophytins, beta-carotenes, and heme. The isolated D1mod consisted of D1/PsbI/Ycf48 with some Ycf39 and Phb3, while D2mod contained D2/cytochrome b559 with co-purifying PsbY, Phb1, Phb3, FtsH2/FtsH3, CyanoP, and Slr1470. As stably bound, Chl was detected in D1mod but not D2mod, formation of RCII appears to be important for stable binding of most of the Chls and both pheophytins. We suggest that Chl can be delivered to RCII from either monomeric Photosystem I or Ycf39/Hlips complexes.
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Affiliation(s)
- Jana Knoppová
- Institute of Microbiology of the Czech Academy of Sciences, Centre Algatech, Laboratory of Photosynthesis, Třeboň 37901, Czech Republic
| | - Roman Sobotka
- Institute of Microbiology of the Czech Academy of Sciences, Centre Algatech, Laboratory of Photosynthesis, Třeboň 37901, Czech Republic
| | - Jianfeng Yu
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Martina Bečková
- Institute of Microbiology of the Czech Academy of Sciences, Centre Algatech, Laboratory of Photosynthesis, Třeboň 37901, Czech Republic
| | - Jan Pilný
- Institute of Microbiology of the Czech Academy of Sciences, Centre Algatech, Laboratory of Photosynthesis, Třeboň 37901, Czech Republic
| | - Joko P Trinugroho
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Ladislav Csefalvay
- Institute of Microbiology of the Czech Academy of Sciences, Centre Algatech, Laboratory of Photosynthesis, Třeboň 37901, Czech Republic
| | - David Bína
- Faculty of Science, University of South Bohemia in České Budějovice, České Budějovice 370 05, Czech Republic
- Institute of Plant Molecular Biology, Biology Centre of the Czech Academy of Sciences, České Budějovice 370 05, Czech Republic
| | - Peter J Nixon
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Josef Komenda
- Institute of Microbiology of the Czech Academy of Sciences, Centre Algatech, Laboratory of Photosynthesis, Třeboň 37901, Czech Republic
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5
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Advances in the Understanding of the Lifecycle of Photosystem II. Microorganisms 2022; 10:microorganisms10050836. [PMID: 35630282 PMCID: PMC9145668 DOI: 10.3390/microorganisms10050836] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/14/2022] [Accepted: 04/16/2022] [Indexed: 02/04/2023] Open
Abstract
Photosystem II is a light-driven water-plastoquinone oxidoreductase present in cyanobacteria, algae and plants. It produces molecular oxygen and protons to drive ATP synthesis, fueling life on Earth. As a multi-subunit membrane-protein-pigment complex, Photosystem II undergoes a dynamic cycle of synthesis, damage, and repair known as the Photosystem II lifecycle, to maintain a high level of photosynthetic activity at the cellular level. Cyanobacteria, oxygenic photosynthetic bacteria, are frequently used as model organisms to study oxygenic photosynthetic processes due to their ease of growth and genetic manipulation. The cyanobacterial PSII structure and function have been well-characterized, but its lifecycle is under active investigation. In this review, advances in studying the lifecycle of Photosystem II in cyanobacteria will be discussed, with a particular emphasis on new structural findings enabled by cryo-electron microscopy. These structural findings complement a rich and growing body of biochemical and molecular biology research into Photosystem II assembly and repair.
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6
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Linhartová M, Skotnicová P, Hakkila K, Tichý M, Komenda J, Knoppová J, Gilabert JF, Guallar V, Tyystjärvi T, Sobotka R. Mutations Suppressing the Lack of Prepilin Peptidase Provide Insights Into the Maturation of the Major Pilin Protein in Cyanobacteria. Front Microbiol 2021; 12:756912. [PMID: 34712217 PMCID: PMC8546353 DOI: 10.3389/fmicb.2021.756912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/14/2021] [Indexed: 11/24/2022] Open
Abstract
Type IV pili are bacterial surface-exposed filaments that are built up by small monomers called pilin proteins. Pilins are synthesized as longer precursors (prepilins), the N-terminal signal peptide of which must be removed by the processing protease PilD. A mutant of the cyanobacterium Synechocystis sp. PCC 6803 lacking the PilD protease is not capable of photoautotrophic growth because of the impaired function of Sec translocons. Here, we isolated phototrophic suppressor strains of the original ΔpilD mutant and, by sequencing their genomes, identified secondary mutations in the SigF sigma factor, the γ subunit of RNA polymerase, the signal peptide of major pilin PilA1, and in the pilA1-pilA2 intergenic region. Characterization of suppressor strains suggests that, rather than the total prepilin level in the cell, the presence of non-glycosylated PilA1 prepilin is specifically harmful. We propose that the restricted lateral mobility of the non-glycosylated PilA1 prepilin causes its accumulation in the translocon-rich membrane domains, which attenuates the synthesis of membrane proteins.
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Affiliation(s)
- Markéta Linhartová
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia.,Faculty of Science, University of South Bohemia, České Budějovice, Czechia
| | - Petra Skotnicová
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Kaisa Hakkila
- Biotechnology/Molecular Plant Biology, University of Turku, Turku, Finland
| | - Martin Tichý
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Josef Komenda
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Jana Knoppová
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | | | - Victor Guallar
- Barcelona Supercomputing Center, Barcelona, Spain.,ICREA: Institucio Catalana de Recerca i Estudis Avançats Passeig Lluis Companys, Barcelona, Spain
| | - Taina Tyystjärvi
- Biotechnology/Molecular Plant Biology, University of Turku, Turku, Finland
| | - Roman Sobotka
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
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7
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The Photosystem II Assembly Factor Ycf48 from the Cyanobacterium Synechocystis sp. PCC 6803 Is Lipidated Using an Atypical Lipobox Sequence. Int J Mol Sci 2021; 22:ijms22073733. [PMID: 33918522 PMCID: PMC8038367 DOI: 10.3390/ijms22073733] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/25/2021] [Accepted: 03/29/2021] [Indexed: 01/24/2023] Open
Abstract
Photochemical energy conversion during oxygenic photosynthesis is performed by membrane-embedded chlorophyll-binding protein complexes. The biogenesis and maintenance of these complexes requires auxiliary protein factors that optimize the assembly process and protect nascent complexes from photodamage. In cyanobacteria, several lipoproteins contribute to the biogenesis and function of the photosystem II (PSII) complex. They include CyanoP, CyanoQ, and Psb27, which are all attached to the lumenal side of PSII complexes. Here, we show that the lumenal Ycf48 assembly factor found in the cyanobacterium Synechocystis sp. PCC 6803 is also a lipoprotein. Detailed mass spectrometric analysis of the isolated protein supported by site-directed mutagenesis experiments indicates lipidation of the N-terminal C29 residue of Ycf48 and removal of three amino acids from the C-terminus. The lipobox sequence in Ycf48 contains a cysteine residue at the -3 position compared to Leu/Val/Ile residues found in the canonical lipobox sequence. The atypical Ycf48 lipobox sequence is present in most cyanobacteria but is absent in eukaryotes. A possible role for lipoproteins in the coordinated assembly of cyanobacterial PSII is discussed.
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8
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Fu HY, Ghandour R, Ruf S, Zoschke R, Bock R, Schöttler MA. The availability of neither D2 nor CP43 limits the biogenesis of photosystem II in tobacco. PLANT PHYSIOLOGY 2021; 185:1111-1130. [PMID: 33793892 PMCID: PMC8133689 DOI: 10.1093/plphys/kiaa052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 11/17/2020] [Indexed: 06/12/2023]
Abstract
The pathway of photosystem II (PSII) assembly is well understood, and multiple auxiliary proteins supporting it have been identified, but little is known about rate-limiting steps controlling PSII biogenesis. In the cyanobacterium Synechocystis PCC6803 and the green alga Chlamydomonas reinhardtii, indications exist that the biosynthesis of the chloroplast-encoded D2 reaction center subunit (PsbD) limits PSII accumulation. To determine the importance of D2 synthesis for PSII accumulation in vascular plants and elucidate the contributions of transcriptional and translational regulation, we modified the 5'-untranslated region of psbD via chloroplast transformation in tobacco (Nicotiana tabacum). A drastic reduction in psbD mRNA abundance resulted in a strong decrease in PSII content, impaired photosynthetic electron transport, and retarded growth under autotrophic conditions. Overexpression of the psbD mRNA also increased transcript abundance of psbC (the CP43 inner antenna protein), which is co-transcribed with psbD. Because translation efficiency remained unaltered, translation output of pbsD and psbC increased with mRNA abundance. However, this did not result in increased PSII accumulation. The introduction of point mutations into the Shine-Dalgarno-like sequence or start codon of psbD decreased translation efficiency without causing pronounced effects on PSII accumulation and function. These data show that neither transcription nor translation of psbD and psbC are rate-limiting for PSII biogenesis in vascular plants and that PSII assembly and accumulation in tobacco are controlled by different mechanisms than in cyanobacteria or in C. reinhardtii.
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Affiliation(s)
- Han-Yi Fu
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany
| | - Rabea Ghandour
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany
| | - Stephanie Ruf
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany
| | - Reimo Zoschke
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany
| | - Mark Aurel Schöttler
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany
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9
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Breinlinger S, Phillips TJ, Haram BN, Mareš J, Martínez Yerena JA, Hrouzek P, Sobotka R, Henderson WM, Schmieder P, Williams SM, Lauderdale JD, Wilde HD, Gerrin W, Kust A, Washington JW, Wagner C, Geier B, Liebeke M, Enke H, Niedermeyer THJ, Wilde SB. Hunting the eagle killer: A cyanobacterial neurotoxin causes vacuolar myelinopathy. Science 2021; 371:eaax9050. [PMID: 33766860 PMCID: PMC8318203 DOI: 10.1126/science.aax9050] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 10/30/2020] [Accepted: 01/26/2021] [Indexed: 12/30/2022]
Abstract
Vacuolar myelinopathy is a fatal neurological disease that was initially discovered during a mysterious mass mortality of bald eagles in Arkansas in the United States. The cause of this wildlife disease has eluded scientists for decades while its occurrence has continued to spread throughout freshwater reservoirs in the southeastern United States. Recent studies have demonstrated that vacuolar myelinopathy is induced by consumption of the epiphytic cyanobacterial species Aetokthonos hydrillicola growing on aquatic vegetation, primarily the invasive Hydrilla verticillata Here, we describe the identification, biosynthetic gene cluster, and biological activity of aetokthonotoxin, a pentabrominated biindole alkaloid that is produced by the cyanobacterium A. hydrillicola We identify this cyanobacterial neurotoxin as the causal agent of vacuolar myelinopathy and discuss environmental factors-especially bromide availability-that promote toxin production.
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Affiliation(s)
- Steffen Breinlinger
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Tabitha J Phillips
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA
| | - Brigette N Haram
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA
| | - Jan Mareš
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, České Budějovice, Czech Republic
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - José A Martínez Yerena
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Pavel Hrouzek
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Roman Sobotka
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - W Matthew Henderson
- Office of Research and Development, Center for Environmental Measurement and Modeling, U.S. Environmental Protection Agency, Athens, GA, USA
| | - Peter Schmieder
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Susan M Williams
- Department of Population Health, Poultry Diagnostic and Research Center, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
| | | | - H Dayton Wilde
- Horticulture Department, University of Georgia, Athens, GA, USA
| | - Wesley Gerrin
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA
| | - Andreja Kust
- Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, České Budějovice, Czech Republic
| | - John W Washington
- Office of Research and Development, Center for Environmental Measurement and Modeling, U.S. Environmental Protection Agency, Athens, GA, USA
| | - Christoph Wagner
- Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Benedikt Geier
- Max Planck Institute for Marine Microbiology (MPIMM), Bremen, Germany
| | - Manuel Liebeke
- Max Planck Institute for Marine Microbiology (MPIMM), Bremen, Germany
| | | | - Timo H J Niedermeyer
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany.
| | - Susan B Wilde
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA.
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10
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Koskela MM, Skotnicová P, Kiss É, Sobotka R. Purification of Protein-complexes from the Cyanobacterium Synechocystis sp. PCC 6803 Using FLAG-affinity Chromatography. Bio Protoc 2020; 10:e3616. [PMID: 33659289 DOI: 10.21769/bioprotoc.3616] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/24/2020] [Accepted: 03/26/2020] [Indexed: 01/19/2023] Open
Abstract
Exploring the structure and function of protein complexes requires their isolation in the native state-a task that is made challenging when studying labile and/or low abundant complexes. The difficulties in preparing membrane-protein complexes are especially notorious. The cyanobacterium Synechocystis sp. PCC 6803 is a widely used model organism for the physiology of oxygenic phototrophs, and the biogenesis of membrane-bound photosynthetic complexes has traditionally been studied using this cyanobacterium. In a typical approach, the protein complexes are purified with a combination of His-affinity chromatography and a size-based fractionation method such as gradient ultracentrifugation and/or native electrophoresis. However, His-affinity purification harbors prominent contaminants and the levels of many proteins are too low for a feasible multi-step purification. Here, we have developed a purification method for the isolation of 3x FLAG-tagged proteins from the membrane and soluble fractions of Synechocystis. Soluble proteins or solubilized thylakoids are subjected to a single affinity purification step that utilizes the highly specific binding of FLAG-affinity resin. After an intensive wash, the captured proteins are released from the resin under native conditions using an excess of synthetic 3x FLAG peptide. The protocol allows fast isolation of low abundant protein complexes with a superb purity.
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Affiliation(s)
- Minna M Koskela
- Centre Algatech, Institute of Microbiology, Czech Academy of Sciences, Třeboň, Czech Republic
| | - Petra Skotnicová
- Centre Algatech, Institute of Microbiology, Czech Academy of Sciences, Třeboň, Czech Republic
| | - Éva Kiss
- Centre Algatech, Institute of Microbiology, Czech Academy of Sciences, Třeboň, Czech Republic
| | - Roman Sobotka
- Centre Algatech, Institute of Microbiology, Czech Academy of Sciences, Třeboň, Czech Republic.,Faculty of Science, University of South Bohemia, České Budějovice, 370 05, Czech Republic
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11
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Reiter B, Vamvaka E, Marino G, Kleine T, Jahns P, Bolle C, Leister D, Rühle T. The Arabidopsis Protein CGL20 Is Required for Plastid 50S Ribosome Biogenesis. PLANT PHYSIOLOGY 2020; 182:1222-1238. [PMID: 31937683 PMCID: PMC7054867 DOI: 10.1104/pp.19.01502] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 12/22/2019] [Indexed: 05/29/2023]
Abstract
Biogenesis of plastid ribosomes is facilitated by auxiliary factors that process and modify ribosomal RNAs (rRNAs) or are involved in ribosome assembly. In comparison with their bacterial and mitochondrial counterparts, the biogenesis of plastid ribosomes is less well understood, and few auxiliary factors have been described so far. In this study, we report the functional characterization of CONSERVED ONLY IN THE GREEN LINEAGE20 (CGL20) in Arabidopsis (Arabidopsis thaliana; AtCGL20), which is a Pro-rich, ∼10-kD protein that is targeted to mitochondria and chloroplasts. In Arabidopsis, CGL20 is encoded by segmentally duplicated genes of high sequence similarity (AtCGL20A and AtCGL20B). Inactivation of these genes in the atcgl20ab mutant led to a visible virescent phenotype and growth arrest at low temperature. The chloroplast proteome, pigment composition, and photosynthetic performance were significantly affected in atcgl20ab mutants. Loss of AtCGL20 impaired plastid translation, perturbing the formation of a hidden break in the 23S rRNA and causing abnormal accumulation of 50S ribosomal subunits in the high-molecular-mass fraction of chloroplast stromal extracts. Moreover, AtCGL20A-eGFP fusion proteins comigrated with 50S ribosomal subunits in Suc density gradients, even after RNase treatment of stromal extracts. Therefore, we propose that AtCGL20 participates in the late stages of the biogenesis of 50S ribosomal subunits in plastids, a role that presumably evolved in the green lineage as a consequence of structural divergence of plastid ribosomes.
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Affiliation(s)
- Bennet Reiter
- Plant Molecular Biology Faculty of Biology I, Ludwig-Maximilians-Universität, D-82152 Planegg-Martinsried, Germany
| | - Evgenia Vamvaka
- Plant Molecular Biology Faculty of Biology I, Ludwig-Maximilians-Universität, D-82152 Planegg-Martinsried, Germany
| | - Giada Marino
- Plant Molecular Biology Faculty of Biology I, Ludwig-Maximilians-Universität, D-82152 Planegg-Martinsried, Germany
| | - Tatjana Kleine
- Plant Molecular Biology Faculty of Biology I, Ludwig-Maximilians-Universität, D-82152 Planegg-Martinsried, Germany
| | - Peter Jahns
- Institute of Plant Biochemistry, Heinrich-Heine University, 40225 Duesseldorf, Germany
| | - Cordelia Bolle
- Plant Molecular Biology Faculty of Biology I, Ludwig-Maximilians-Universität, D-82152 Planegg-Martinsried, Germany
| | - Dario Leister
- Plant Molecular Biology Faculty of Biology I, Ludwig-Maximilians-Universität, D-82152 Planegg-Martinsried, Germany
| | - Thilo Rühle
- Plant Molecular Biology Faculty of Biology I, Ludwig-Maximilians-Universität, D-82152 Planegg-Martinsried, Germany
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12
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Trinugroho JP, Bečková M, Shao S, Yu J, Zhao Z, Murray JW, Sobotka R, Komenda J, Nixon PJ. Chlorophyll f synthesis by a super-rogue photosystem II complex. NATURE PLANTS 2020; 6:238-244. [PMID: 32170286 DOI: 10.1038/s41477-020-0616-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 02/06/2020] [Indexed: 05/21/2023]
Abstract
Certain cyanobacteria synthesize chlorophyll molecules (Chl d and Chl f) that absorb in the far-red region of the solar spectrum, thereby extending the spectral range of photosynthetically active radiation1,2. The synthesis and introduction of these far-red chlorophylls into the photosynthetic apparatus of plants might improve the efficiency of oxygenic photosynthesis, especially in far-red enriched environments, such as in the lower regions of the canopy3. Production of Chl f requires the ChlF subunit, also known as PsbA4 (ref. 4) or super-rogue D1 (ref. 5), a paralogue of the D1 subunit of photosystem II (PSII) which, together with D2, bind cofactors involved in the light-driven oxidation of water. Current ideas suggest that ChlF oxidizes Chl a to Chl f in a homodimeric ChlF reaction centre (RC) complex and represents a missing link in the evolution of the heterodimeric D1/D2 RC of PSII (refs. 4,6). However, unambiguous biochemical support for this proposal is lacking. Here, we show that ChlF can substitute for D1 to form modified PSII complexes capable of producing Chl f. Remarkably, mutation of just two residues in D1 converts oxygen-evolving PSII into a Chl f synthase. Overall, we have identified a new class of PSII complex, which we term 'super-rogue' PSII, with an unexpected role in pigment biosynthesis rather than water oxidation.
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Affiliation(s)
- Joko P Trinugroho
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London, UK
| | - Martina Bečková
- Laboratory of Photosynthesis, Centre Algatech, Institute of Microbiology, Czech Academy of Sciences, Třeboň, Czech Republic
| | - Shengxi Shao
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London, UK
| | - Jianfeng Yu
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London, UK
| | - Ziyu Zhao
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London, UK
| | - James W Murray
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London, UK
| | - Roman Sobotka
- Laboratory of Photosynthesis, Centre Algatech, Institute of Microbiology, Czech Academy of Sciences, Třeboň, Czech Republic
| | - Josef Komenda
- Laboratory of Photosynthesis, Centre Algatech, Institute of Microbiology, Czech Academy of Sciences, Třeboň, Czech Republic
| | - Peter J Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London, UK.
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13
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Kiss É, Knoppová J, Aznar GP, Pilný J, Yu J, Halada P, Nixon PJ, Sobotka R, Komenda J. A Photosynthesis-Specific Rubredoxin-Like Protein Is Required for Efficient Association of the D1 and D2 Proteins during the Initial Steps of Photosystem II Assembly. THE PLANT CELL 2019; 31:2241-2258. [PMID: 31320483 PMCID: PMC6751121 DOI: 10.1105/tpc.19.00155] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 06/04/2019] [Accepted: 07/18/2019] [Indexed: 05/20/2023]
Abstract
Oxygenic photosynthesis relies on accessory factors to promote the assembly and maintenance of the photosynthetic apparatus in the thylakoid membranes. The highly conserved membrane-bound rubredoxin-like protein RubA has previously been implicated in the accumulation of both PSI and PSII, but its mode of action remains unclear. Here, we show that RubA in the cyanobacterium Synechocystis sp PCC 6803 is required for photoautotrophic growth in fluctuating light and acts early in PSII biogenesis by promoting the formation of the heterodimeric D1/D2 reaction center complex, the site of primary photochemistry. We find that RubA, like the accessory factor Ycf48, is a component of the initial D1 assembly module as well as larger PSII assembly intermediates and that the redox-responsive rubredoxin-like domain is located on the cytoplasmic surface of PSII complexes. Fusion of RubA to Ycf48 still permits normal PSII assembly, suggesting a spatiotemporal proximity of both proteins during their action. RubA is also important for the accumulation of PSI, but this is an indirect effect stemming from the downregulation of light-dependent chlorophyll biosynthesis induced by PSII deficiency. Overall, our data support the involvement of RubA in the redox control of PSII biogenesis.
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Affiliation(s)
- Éva Kiss
- Laboratory of Photosynthesis, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 379 01 Třeboň, Czech Republic
| | - Jana Knoppová
- Laboratory of Photosynthesis, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 379 01 Třeboň, Czech Republic
| | - Guillem Pascual Aznar
- Laboratory of Photosynthesis, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 379 01 Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic
| | - Jan Pilný
- Laboratory of Photosynthesis, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 379 01 Třeboň, Czech Republic
| | - Jianfeng Yu
- Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Petr Halada
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, 14220 Praha 4-Krc, Czech Republic
| | - Peter J Nixon
- Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Roman Sobotka
- Laboratory of Photosynthesis, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 379 01 Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic
| | - Josef Komenda
- Laboratory of Photosynthesis, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 379 01 Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic
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14
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Knoppová J, Komenda J. Sequential deletions of photosystem II assembly factors Ycf48, Ycf39 and Pam68 result in progressive loss of autotrophy in the cyanobacterium Synechocystis PCC 6803. Folia Microbiol (Praha) 2019; 64:683-689. [PMID: 31359262 DOI: 10.1007/s12223-019-00736-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 07/15/2019] [Indexed: 01/28/2023]
Abstract
The biogenesis of the cyanobacterial photosystem II (PSII) complex requires a number of auxiliary assembly factors that improve efficiency of the process but their precise function is not well understood. To assess a possible synergic action of the Ycf48 and Ycf39 factors acting in early steps of the biogenesis via interaction with the nascent D1 subunit of PSII, we constructed and characterised a double mutant of the cyanobacterium Synechocystis PCC 6803 lacking both these proteins. In addition, we also deleted the ycf39 gene in the double mutant lacking Ycf48 and Pam68, the latter being a ribosomal factor promoting insertion of chlorophyll (Chl) into the CP47 subunit of PSII. The resulting double ΔYcf48/ΔYcf39 and triple ΔYcf48/ΔPam68/ΔYcf39 mutants were deficient in PSII and total Chl, and in contrast to the source mutants, they lost the capacity for autotrophy. Interestingly, autotrophic growth was restored in both of the new multiple mutants by enhancing Chl biosynthesis using a specific ferrochelatase inhibitor. Taking together with the weak radioactive labelling of the D1 protein, these findings can be explained by inhibition of the D1 synthesis caused by the lack and/or incorrect binding of Chl molecules. The results emphasise the key importance of the sufficient Chl supply for the PSII biogenesis and also support the existence of a so far enigmatic regulatory mechanism leading to the reduced overall Chl biosynthesis/accumulation when the PSII assembly is impaired.
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Affiliation(s)
- Jana Knoppová
- Centre Algatech, Institute of Microbiology, Czech Academy of Sciences, 379 81, Třeboň, Czech Republic.
| | - Josef Komenda
- Centre Algatech, Institute of Microbiology, Czech Academy of Sciences, 379 81, Třeboň, Czech Republic
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15
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Pazderník M, Mareš J, Pilný J, Sobotka R. The antenna-like domain of the cyanobacterial ferrochelatase can bind chlorophyll and carotenoids in an energy-dissipative configuration. J Biol Chem 2019; 294:11131-11143. [PMID: 31167780 DOI: 10.1074/jbc.ra119.008434] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/29/2019] [Indexed: 01/19/2023] Open
Abstract
Ferrochelatase (FeCh) is an essential enzyme catalyzing the synthesis of heme. Interestingly, in cyanobacteria, algae, and plants, FeCh possesses a conserved transmembrane chlorophyll a/b binding (CAB) domain that resembles the first and the third helix of light-harvesting complexes, including a chlorophyll-binding motif. Whether the FeCh CAB domain also binds chlorophyll is unknown. Here, using biochemical and radiolabeled precursor experiments, we found that partially inhibited activity of FeCh in the cyanobacterium Synechocystis PCC 6803 leads to overproduction of chlorophyll molecules that accumulate in the thylakoid membrane and, together with carotenoids, bind to FeCh. We observed that pigments bound to purified FeCh are organized in an energy-dissipative conformation and further show that FeCh can exist in vivo as a monomer or a dimer depending on its own activity. However, pigmented FeCh was purified exclusively as a dimer. Separately expressed and purified FeCH CAB domain contained a pigment composition similar to that of full-length FeCh and retained its quenching properties. Phylogenetic analysis suggested that the CAB domain was acquired by a fusion between FeCh and a single-helix, high light-inducible protein early in the evolution of cyanobacteria. Following this fusion, the FeCh CAB domain with a functional chlorophyll-binding motif was retained in all currently known cyanobacterial genomes except for a single lineage of endosymbiotic cyanobacteria. Our findings indicate that FeCh from Synechocystis exists mostly as a pigment-free monomer in cells but can dimerize, in which case its CAB domain creates a functional pigment-binding segment organized in an energy-dissipating configuration.
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Affiliation(s)
- Marek Pazderník
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Třeboň, 379 81, Czech Republic.,Faculty of Science, University of South Bohemia, České Budějovice 370 05, Czech Republic
| | - Jan Mareš
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Třeboň, 379 81, Czech Republic.,Faculty of Science, University of South Bohemia, České Budějovice 370 05, Czech Republic.,Institute of Hydrobiology, Biology Centre of the Czech Academy of Sciences, České Budějovice 370 05, Czech Republic
| | - Jan Pilný
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Třeboň, 379 81, Czech Republic
| | - Roman Sobotka
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Třeboň, 379 81, Czech Republic .,Faculty of Science, University of South Bohemia, České Budějovice 370 05, Czech Republic
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16
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Skotnicová P, Sobotka R, Shepherd M, Hájek J, Hrouzek P, Tichý M. The cyanobacterial protoporphyrinogen oxidase HemJ is a new b-type heme protein functionally coupled with coproporphyrinogen III oxidase. J Biol Chem 2018; 293:12394-12404. [PMID: 29925590 DOI: 10.1074/jbc.ra118.003441] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 06/14/2018] [Indexed: 12/27/2022] Open
Abstract
Protoporphyrinogen IX oxidase (PPO), the last enzyme that is common to both chlorophyll and heme biosynthesis pathways, catalyzes the oxidation of protoporphyrinogen IX to protoporphyrin IX. PPO has several isoforms, including the oxygen-dependent HemY and an oxygen-independent enzyme, HemG. However, most cyanobacteria encode HemJ, the least characterized PPO form. We have characterized HemJ from the cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis 6803) as a bona fide PPO; HemJ down-regulation resulted in accumulation of tetrapyrrole precursors and in the depletion of chlorophyll precursors. The expression of FLAG-tagged Synechocystis 6803 HemJ protein (HemJ.f) and affinity isolation of HemJ.f under native conditions revealed that it binds heme b The most stable HemJ.f form was a dimer, and higher oligomeric forms were also observed. Using both oxygen and artificial electron acceptors, we detected no enzymatic activity with the purified HemJ.f, consistent with the hypothesis that the enzymatic mechanism for HemJ is distinct from those of other PPO isoforms. The heme absorption spectra and distant HemJ homology to several membrane oxidases indicated that the heme in HemJ is redox-active and involved in electron transfer. HemJ was conditionally complemented by another PPO, HemG from Escherichia coli. If grown photoautotrophically, the complemented strain accumulated tripropionic tetrapyrrole harderoporphyrin, suggesting a defect in enzymatic conversion of coproporphyrinogen III to protoporphyrinogen IX, catalyzed by coproporphyrinogen III oxidase (CPO). This observation supports the hypothesis that HemJ is functionally coupled with CPO and that this coupling is disrupted after replacement of HemJ by HemG.
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Affiliation(s)
- Petra Skotnicová
- From the Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, 379 81 Třeboň, Czech Republic.,the Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic, and
| | - Roman Sobotka
- From the Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, 379 81 Třeboň, Czech Republic.,the Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic, and
| | - Mark Shepherd
- the School of Biosciences, RAPID Group, University of Kent, Canterbury CT2 7NZ,United Kingdom
| | - Jan Hájek
- From the Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, 379 81 Třeboň, Czech Republic.,the Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic, and
| | - Pavel Hrouzek
- From the Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, 379 81 Třeboň, Czech Republic.,the Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic, and
| | - Martin Tichý
- From the Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, 379 81 Třeboň, Czech Republic, .,the Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic, and
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