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Twigg J, Vaid N, Chavda A, Seymour D, Hyde TP, Nixon PJ. A Randomised Controlled Trial of Postoperative Sensitivity after Class II Restoration with Bulk-Fill vs Conventional Composites. Eur J Prosthodont Restor Dent 2024. [PMID: 38373222 DOI: 10.1922/ejprd_2529twigg09] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 12/18/2023] [Indexed: 02/21/2024]
Abstract
INTRODUCTION Bulk-fill composites may simplify posterior restorations, saving time and reducing technical complexity. Post-operative sensitivity is a risk of posterior composites; bulk-fill composites could mitigate this. This single centre, double-blinded, parallel groups randomised controlled trial compared postoperative sensitivity following restoration of class II carious lesions with bulk-fill or conventional, layered composite. NULL HYPOTHESIS there will be no difference in post-operative sensitivity between the two materials. METHODS Participants requiring class II restoration of posterior teeth were randomised to bulk-fill (FU) (Coltene Fill-UpTM) or conventional, layered (BE) (Coltene Brilliant Everglow) composite. Allocation was concealed during cavity preparation. Only the operating dentist knew allocation. The outcome was 24 h post-operative sensitivity. RESULTS 41 patients were randomised (20/group). Two patients from FU group were excluded from analysis (factors unrelated to intervention). There was no difference in postoperative sensitivity at 24 h nor any time point. Only participant age and baseline sensitivity scores significantly impacted post-operative sensitivity. One restoration debonded in FU group at 10 days, with no other adverse effects. No difference in time taken to place restorations was seen. CONCLUSIONS Within the study's limitations, post-operative sensitivity after class II posterior restorations was no different in bulk-fill restorations compared with conventional, incrementally cured composite.
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Affiliation(s)
- J Twigg
- NIHR Academic Clinical Lecturer, School of Dentistry, University of Leeds, Leeds, UK
- StR Restorative Dentistry, Leeds Teaching Hospitals Trust, UK
| | - N Vaid
- Private Practice, Manchester, UK
| | - A Chavda
- Research Nurse / Study Coordinator, Dental & Clinical Translational Research Unit (DenTCRU), School of Dentistry, University of Leeds, UK
| | - D Seymour
- Consultant in Oral Rehabilitation / Restorative Dentistry, York and Scarborough Teaching Hospitals NHS Foundation Trust, York, UK
- Department of Restorative Dentistry, York Hospital, Wigginton Road, York, North Yorkshire, UK
| | - T P Hyde
- Associate Professor in Clinical and Translational Research, School of Dentistry, University of Leeds, UK
| | - P J Nixon
- Consultant in Restorative Dentistry, York and Scarborough Teaching Hospitals NHS Foundation Trust, York, UK
- Department of Restorative Dentistry, York Hospital, Wigginton Road, York, North Yorkshire, UK
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Zhao Z, Vercellino I, Knoppová J, Sobotka R, Murray JW, Nixon PJ, Sazanov LA, Komenda J. The Ycf48 accessory factor occupies the site of the oxygen-evolving manganese cluster during photosystem II biogenesis. Nat Commun 2023; 14:4681. [PMID: 37542031 PMCID: PMC10403576 DOI: 10.1038/s41467-023-40388-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 07/26/2023] [Indexed: 08/06/2023] Open
Abstract
Robust oxygenic photosynthesis requires a suite of accessory factors to ensure efficient assembly and repair of the oxygen-evolving photosystem two (PSII) complex. The highly conserved Ycf48 assembly factor binds to the newly synthesized D1 reaction center polypeptide and promotes the initial steps of PSII assembly, but its binding site is unclear. Here we use cryo-electron microscopy to determine the structure of a cyanobacterial PSII D1/D2 reaction center assembly complex with Ycf48 attached. Ycf48, a 7-bladed beta propeller, binds to the amino-acid residues of D1 that ultimately ligate the water-oxidising Mn4CaO5 cluster, thereby preventing the premature binding of Mn2+ and Ca2+ ions and protecting the site from damage. Interactions with D2 help explain how Ycf48 promotes assembly of the D1/D2 complex. Overall, our work provides valuable insights into the early stages of PSII assembly and the structural changes that create the binding site for the Mn4CaO5 cluster.
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Affiliation(s)
- Ziyu Zhao
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, S. Kensington Campus, London, SW7 2AZ, UK
| | - Irene Vercellino
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
- Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428, Jülich, Germany
| | - Jana Knoppová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, Třeboň, 379 81, Czech Republic
| | - Roman Sobotka
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, Třeboň, 379 81, Czech Republic
- Faculty of Science, University of South Bohemia, Branišovská 31, České Budĕjovice, 37005, Czech Republic
| | - James W Murray
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, S. Kensington Campus, London, SW7 2AZ, UK
| | - Peter J Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, S. Kensington Campus, London, SW7 2AZ, UK.
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria.
| | - Josef Komenda
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, Třeboň, 379 81, Czech Republic.
- Faculty of Science, University of South Bohemia, Branišovská 31, České Budĕjovice, 37005, Czech Republic.
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3
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Masuda T, Bečková M, Turóczy Z, Pilný J, Sobotka R, Trinugroho JP, Nixon PJ, Prášil O, Komenda J. Accumulation of Cyanobacterial Photosystem II Containing the 'Rogue' D1 Subunit Is Controlled by FtsH Protease and Synthesis of the Standard D1 Protein. Plant Cell Physiol 2023; 64:660-673. [PMID: 36976618 DOI: 10.1093/pcp/pcad027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 03/24/2023] [Accepted: 03/27/2023] [Indexed: 06/16/2023]
Abstract
Unicellular diazotrophic cyanobacteria contribute significantly to the photosynthetic productivity of the ocean and the fixation of molecular nitrogen, with photosynthesis occurring during the day and nitrogen fixation during the night. In species like Crocosphaera watsonii WH8501, the decline in photosynthetic activity in the night is accompanied by the disassembly of oxygen-evolving photosystem II (PSII) complexes. Moreover, in the second half of the night phase, a small amount of rogue D1 (rD1), which is related to the standard form of the D1 subunit found in oxygen-evolving PSII, but of unknown function, accumulates but is quickly degraded at the start of the light phase. We show here that the removal of rD1 is independent of the rD1 transcript level, thylakoid redox state and trans-thylakoid pH but requires light and active protein synthesis. We also found that the maximal level of rD1 positively correlates with the maximal level of chlorophyll (Chl) biosynthesis precursors and enzymes, which suggests a possible role for rogue PSII (rPSII) in the activation of Chl biosynthesis just before or upon the onset of light, when new photosystems are synthesized. By studying strains of Synechocystis PCC 6803 expressing Crocosphaera rD1, we found that the accumulation of rD1 is controlled by the light-dependent synthesis of the standard D1 protein, which triggers the fast FtsH2-dependent degradation of rD1. Affinity purification of FLAG-tagged rD1 unequivocally demonstrated the incorporation of rD1 into a non-oxygen-evolving PSII complex, which we term rPSII. The complex lacks the extrinsic proteins stabilizing the oxygen-evolving Mn4CaO5 cluster but contains the Psb27 and Psb28-1 assembly factors.
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Affiliation(s)
- Takako Masuda
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
| | - Martina Bečková
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
| | - Zoltán Turóczy
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
| | - Jan Pilný
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
| | - Roman Sobotka
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
- Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice 370 05, Czech Republic
| | - Joko P Trinugroho
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Peter J Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
| | - Josef Komenda
- Institute of Microbiology, The Czech Academy of Sciences, Centre Algatech, Opatovický mlýn, Třeboň 37901, Czech Republic
- Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice 370 05, Czech Republic
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Yamamoto H, Cheuk A, Shearman J, Nixon PJ, Meier T, Shikanai T. Impact of engineering the ATP synthase rotor ring on photosynthesis in tobacco chloroplasts. Plant Physiol 2023; 192:1221-1233. [PMID: 36703219 PMCID: PMC10231360 DOI: 10.1093/plphys/kiad043] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 01/05/2023] [Accepted: 01/06/2023] [Indexed: 06/01/2023]
Abstract
The chloroplast ATP synthase produces the ATP needed for photosynthesis and plant growth. The trans-membrane flow of protons through the ATP synthase rotates an oligomeric assembly of c subunits, the c-ring. The ion-to-ATP ratio in rotary F1F0-ATP synthases is defined by the number of c-subunits in the rotor c-ring. Engineering the c-ring stoichiometry is, therefore, a possible route to manipulate ATP synthesis by the ATP synthase and hence photosynthetic efficiency in plants. Here, we describe the construction of a tobacco (Nicotiana tabacum) chloroplast atpH (chloroplastic ATP synthase subunit c gene) mutant in which the c-ring stoichiometry was increased from 14 to 15 c-subunits. Although the abundance of the ATP synthase was decreased to 25% of wild-type (WT) levels, the mutant lines grew as well as WT plants and photosynthetic electron transport remained unaffected. To synthesize the necessary ATP for growth, we found that the contribution of the membrane potential to the proton motive force was enhanced to ensure a higher proton flux via the c15-ring without unwanted low pH-induced feedback inhibition of electron transport. Our work opens avenues to manipulate plant ion-to-ATP ratios with potentially beneficial consequences for photosynthesis.
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Affiliation(s)
- Hiroshi Yamamoto
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Anthony Cheuk
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - Julia Shearman
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - Peter J Nixon
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - Thomas Meier
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - Toshiharu Shikanai
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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5
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Chen T, Hojka M, Davey P, Sun Y, Dykes GF, Zhou F, Lawson T, Nixon PJ, Lin Y, Liu LN. Engineering α-carboxysomes into plant chloroplasts to support autotrophic photosynthesis. Nat Commun 2023; 14:2118. [PMID: 37185249 PMCID: PMC10130085 DOI: 10.1038/s41467-023-37490-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 03/17/2023] [Indexed: 05/17/2023] Open
Abstract
The growth in world population, climate change, and resource scarcity necessitate a sustainable increase in crop productivity. Photosynthesis in major crops is limited by the inefficiency of the key CO2-fixing enzyme Rubisco, owing to its low carboxylation rate and poor ability to discriminate between CO2 and O2. In cyanobacteria and proteobacteria, carboxysomes function as the central CO2-fixing organelles that elevate CO2 levels around encapsulated Rubisco to enhance carboxylation. There is growing interest in engineering carboxysomes into crop chloroplasts as a potential route for improving photosynthesis and crop yields. Here, we generate morphologically correct carboxysomes in tobacco chloroplasts by transforming nine carboxysome genetic components derived from a proteobacterium. The chloroplast-expressed carboxysomes display a structural and functional integrity comparable to native carboxysomes and support autotrophic growth and photosynthesis of the transplastomic plants at elevated CO2. Our study provides proof-of-concept for a route to engineering fully functional CO2-fixing modules and entire CO2-concentrating mechanisms into chloroplasts to improve crop photosynthesis and productivity.
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Affiliation(s)
- Taiyu Chen
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China
| | - Marta Hojka
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Philip Davey
- School of Life Sciences, University of Essex, Colchester, CO4 4SQ, UK
| | - Yaqi Sun
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Gregory F Dykes
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Fei Zhou
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China
| | - Tracy Lawson
- School of Life Sciences, University of Essex, Colchester, CO4 4SQ, UK
| | - Peter J Nixon
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Yongjun Lin
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, 430070, Wuhan, China.
| | - Lu-Ning Liu
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK.
- College of Marine Life Sciences, and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, 266003, Qingdao, China.
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6
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Chen T, Riaz S, Davey P, Zhao Z, Sun Y, Dykes GF, Zhou F, Hartwell J, Lawson T, Nixon PJ, Lin Y, Liu LN. Producing fast and active Rubisco in tobacco to enhance photosynthesis. Plant Cell 2023; 35:795-807. [PMID: 36471570 PMCID: PMC9940876 DOI: 10.1093/plcell/koac348] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/24/2022] [Accepted: 12/02/2022] [Indexed: 05/28/2023]
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) performs most of the carbon fixation on Earth. However, plant Rubisco is an intrinsically inefficient enzyme given its low carboxylation rate, representing a major limitation to photosynthesis. Replacing endogenous plant Rubisco with a faster Rubisco is anticipated to enhance crop photosynthesis and productivity. However, the requirement of chaperones for Rubisco expression and assembly has obstructed the efficient production of functional foreign Rubisco in chloroplasts. Here, we report the engineering of a Form 1A Rubisco from the proteobacterium Halothiobacillus neapolitanus in Escherichia coli and tobacco (Nicotiana tabacum) chloroplasts without any cognate chaperones. The native tobacco gene encoding Rubisco large subunit was genetically replaced with H. neapolitanus Rubisco (HnRubisco) large and small subunit genes. We show that HnRubisco subunits can form functional L8S8 hexadecamers in tobacco chloroplasts at high efficiency, accounting for ∼40% of the wild-type tobacco Rubisco content. The chloroplast-expressed HnRubisco displayed a ∼2-fold greater carboxylation rate and supported a similar autotrophic growth rate of transgenic plants to that of wild-type in air supplemented with 1% CO2. This study represents a step toward the engineering of a fast and highly active Rubisco in chloroplasts to improve crop photosynthesis and growth.
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Affiliation(s)
- Taiyu Chen
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, Wuhan 430070, China
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Saba Riaz
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Philip Davey
- School of Life Sciences, University of Essex, Colchester CO4 4SQ, UK
| | - Ziyu Zhao
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Yaqi Sun
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Gregory F Dykes
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Fei Zhou
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, Wuhan 430070, China
| | - James Hartwell
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Tracy Lawson
- School of Life Sciences, University of Essex, Colchester CO4 4SQ, UK
| | - Peter J Nixon
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Yongjun Lin
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, Wuhan 430070, China
| | - Lu-Ning Liu
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
- College of Marine Life Sciences, and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao 266003, China
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Krynická V, Skotnicová P, Jackson PJ, Barnett S, Yu J, Wysocka A, Kaňa R, Dickman MJ, Nixon PJ, Hunter CN, Komenda J. FtsH4 protease controls biogenesis of the PSII complex by dual regulation of high light-inducible proteins. Plant Commun 2023; 4:100502. [PMID: 36463410 PMCID: PMC9860182 DOI: 10.1016/j.xplc.2022.100502] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 11/11/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
FtsH proteases are membrane-embedded proteolytic complexes important for protein quality control and regulation of various physiological processes in bacteria, mitochondria, and chloroplasts. Like most cyanobacteria, the model species Synechocystis sp. PCC 6803 contains four FtsH homologs, FtsH1-FtsH4. FtsH1-FtsH3 form two hetero-oligomeric complexes, FtsH1/3 and FtsH2/3, which play a pivotal role in acclimation to nutrient deficiency and photosystem II quality control, respectively. FtsH4 differs from the other three homologs by the formation of a homo-oligomeric complex, and together with Arabidopsis thaliana AtFtsH7/9 orthologs, it has been assigned to another phylogenetic group of unknown function. Our results exclude the possibility that Synechocystis FtsH4 structurally or functionally substitutes for the missing or non-functional FtsH2 subunit in the FtsH2/3 complex. Instead, we demonstrate that FtsH4 is involved in the biogenesis of photosystem II by dual regulation of high light-inducible proteins (Hlips). FtsH4 positively regulates expression of Hlips shortly after high light exposure but is also responsible for Hlip removal under conditions when their elevated levels are no longer needed. We provide experimental support for Hlips as proteolytic substrates of FtsH4. Fluorescent labeling of FtsH4 enabled us to assess its localization using advanced microscopic techniques. Results show that FtsH4 complexes are concentrated in well-defined membrane regions at the inner and outer periphery of the thylakoid system. Based on the identification of proteins that co-purified with the tagged FtsH4, we speculate that FtsH4 concentrates in special compartments in which the biogenesis of photosynthetic complexes takes place.
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Affiliation(s)
- Vendula Krynická
- The Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, Novohradská 237, 379 01 Třeboň, Czech Republic.
| | - Petra Skotnicová
- The Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, Novohradská 237, 379 01 Třeboň, Czech Republic
| | - 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
| | - Samuel Barnett
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Jianfeng Yu
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, South Kensington Campus, Imperial College London, London SW7 2AZ, UK
| | - Anna Wysocka
- The Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, Novohradská 237, 379 01 Třeboň, Czech Republic; Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic
| | - Radek Kaňa
- The Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, Novohradská 237, 379 01 Třeboň, Czech Republic
| | - Mark J Dickman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, UK
| | - Peter J Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, South Kensington Campus, Imperial College London, London SW7 2AZ, UK
| | - C Neil Hunter
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Josef Komenda
- The Czech Academy of Sciences, Institute of Microbiology, Centre Algatech, Novohradská 237, 379 01 Třeboň, Czech Republic
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8
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Nixon PJ, Telfer A. Remembering James Barber (1940-2020). Photosynth Res 2022; 153:1-20. [PMID: 35534741 PMCID: PMC9522743 DOI: 10.1007/s11120-022-00919-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/31/2022] [Indexed: 06/14/2023]
Abstract
James Barber, known to colleagues and friends as Jim, passed away in January 2020 after a long battle against cancer. During his long and distinguished career in photosynthesis research, Jim made many outstanding contributions with the pinnacle achieving his dream of determining the first detailed structure of the Mn cluster involved in photosynthetic water oxidation. Here, colleagues and friends remember Jim and reflect upon his scientific career and the impact he had on their lives and the scientific community.
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Affiliation(s)
- Peter J Nixon
- Sir Ernst Chain Building - Wolfson Laboratories, Department of Life Sciences, Imperial College London, S. Kensington Campus, London, SW7 2AZ, UK.
| | - Alison Telfer
- Sir Ernst Chain Building - Wolfson Laboratories, Department of Life Sciences, Imperial College London, S. Kensington Campus, London, SW7 2AZ, UK.
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9
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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 Physiol 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] [What about the content of this article? (0)] [Affiliation(s)] [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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10
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Yi L, Liu B, Nixon PJ, Yu J, Chen F. Recent Advances in Understanding the Structural and Functional Evolution of FtsH Proteases. Front Plant Sci 2022; 13:837528. [PMID: 35463435 PMCID: PMC9020784 DOI: 10.3389/fpls.2022.837528] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/24/2022] [Indexed: 05/18/2023]
Abstract
The FtsH family of proteases are membrane-anchored, ATP-dependent, zinc metalloproteases. They are universally present in prokaryotes and the mitochondria and chloroplasts of eukaryotic cells. Most bacteria bear a single ftsH gene that produces hexameric homocomplexes with diverse house-keeping roles. However, in mitochondria, chloroplasts and cyanobacteria, multiple FtsH homologs form homo- and heterocomplexes with specialized functions in maintaining photosynthesis and respiration. The diversification of FtsH homologs combined with selective pairing of FtsH isomers is a versatile strategy to enable functional adaptation. In this article we summarize recent progress in understanding the evolution, structure and function of FtsH proteases with a focus on the role of FtsH in photosynthesis and respiration.
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Affiliation(s)
- Lanbo Yi
- Institute for Food and Bioresource Engineering, College of Engineering, Peking University, Beijing, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, China
- Institute for Innovative Development of Food Industry, Shenzhen University, Shenzhen, China
| | - Bin Liu
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, China
- Institute for Innovative Development of Food Industry, Shenzhen University, Shenzhen, China
| | - Peter J. Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, London, United Kingdom
- *Correspondence: Peter J. Nixon, ; orcid.org/0000-0003-1952-6937
| | - Jianfeng Yu
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, China
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, London, United Kingdom
- Jianfeng Yu, ; orcid.org/0000-0001-7174-3803
| | - Feng Chen
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, China
- Institute for Innovative Development of Food Industry, Shenzhen University, Shenzhen, China
- Feng Chen, ; orcid.org/0000-0002-9054-943X
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11
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Huokko T, Ni T, Dykes GF, Simpson DM, Brownridge P, Conradi FD, Beynon RJ, Nixon PJ, Mullineaux CW, Zhang P, Liu LN. Probing the biogenesis pathway and dynamics of thylakoid membranes. Nat Commun 2021; 12:3475. [PMID: 34108457 PMCID: PMC8190092 DOI: 10.1038/s41467-021-23680-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 05/11/2021] [Indexed: 01/30/2023] Open
Abstract
How thylakoid membranes are generated to form a metabolically active membrane network and how thylakoid membranes orchestrate the insertion and localization of protein complexes for efficient electron flux remain elusive. Here, we develop a method to modulate thylakoid biogenesis in the rod-shaped cyanobacterium Synechococcus elongatus PCC 7942 by modulating light intensity during cell growth, and probe the spatial-temporal stepwise biogenesis process of thylakoid membranes in cells. Our results reveal that the plasma membrane and regularly arranged concentric thylakoid layers have no physical connections. The newly synthesized thylakoid membrane fragments emerge between the plasma membrane and pre-existing thylakoids. Photosystem I monomers appear in the thylakoid membranes earlier than other mature photosystem assemblies, followed by generation of Photosystem I trimers and Photosystem II complexes. Redistribution of photosynthetic complexes during thylakoid biogenesis ensures establishment of the spatial organization of the functional thylakoid network. This study provides insights into the dynamic biogenesis process and maturation of the functional photosynthetic machinery.
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Affiliation(s)
- Tuomas Huokko
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Tao Ni
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Gregory F Dykes
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Deborah M Simpson
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Philip Brownridge
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Fabian D Conradi
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Robert J Beynon
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Peter J Nixon
- Department of Life Sciences, Imperial College London, London, UK
| | - Conrad W Mullineaux
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Lu-Ning Liu
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK.
- College of Marine Life Sciences, and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, China.
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12
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Davies K, Buczkowski H, Welch SR, Green N, Mawer D, Woodford N, Roberts ADG, Nixon PJ, Seymour DW, Killip MJ. Effective in vitro inactivation of SARS-CoV-2 by commercially available mouthwashes. J Gen Virol 2021; 102. [PMID: 33913803 PMCID: PMC8290272 DOI: 10.1099/jgv.0.001578] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Infectious SARS-CoV-2 can be recovered from the oral cavities and saliva of COVID-19 patients with potential implications for disease transmission. Reducing viral load in patient saliva using antiviral mouthwashes may therefore have a role as a control measure in limiting virus spread, particularly in dental settings. Here, the efficacy of SARS-CoV-2 inactivation by seven commercially available mouthwashes with a range of active ingredients were evaluated in vitro. We demonstrate ≥4.1 to ≥5.5 log10 reduction in SARS-CoV-2 titre following a 1 min treatment with commercially available mouthwashes containing 0.01–0.02 % stabilised hypochlorous acid or 0.58 % povidone iodine, and non-specialist mouthwashes with both alcohol-based and alcohol-free formulations designed for home use. In contrast, products containing 1.5 % hydrogen peroxide or 0.2 % chlorhexidine gluconate were ineffective against SARS-CoV-2 in these tests. This study contributes to the growing body of evidence surrounding virucidal efficacy of mouthwashes/oral rinses against SARS-CoV-2, and has important applications in reducing risk associated with aerosol generating procedures in dentistry and potentially for infection control more widely.
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Affiliation(s)
- Katherine Davies
- High Containment Microbiology, NIS Laboratories, National Infection Service, Public Health England, 61 Colindale Avenue, Colindale, London, NW9 5EQ, UK
| | - Hubert Buczkowski
- High Containment Microbiology, NIS Laboratories, National Infection Service, Public Health England, 61 Colindale Avenue, Colindale, London, NW9 5EQ, UK
| | - Stephen R Welch
- High Containment Microbiology, NIS Laboratories, National Infection Service, Public Health England, 61 Colindale Avenue, Colindale, London, NW9 5EQ, UK
| | - Nicole Green
- High Containment Microbiology, NIS Laboratories, National Infection Service, Public Health England, 61 Colindale Avenue, Colindale, London, NW9 5EQ, UK
| | - Damian Mawer
- York Hospitals NHS Foundation Trust, Wigginton Road, York, YO31 8HE, UK
| | - Neil Woodford
- National Laboratories, National Infection Service, Public Health England, 61 Colindale Avenue, Colindale, NW9 5EQ, London, UK
| | - Allen D G Roberts
- High Containment Microbiology, NIS Laboratories, National Infection Service, Public Health England, 61 Colindale Avenue, Colindale, London, NW9 5EQ, UK
| | - Peter J Nixon
- York Hospitals NHS Foundation Trust, Wigginton Road, York, YO31 8HE, UK
| | - David W Seymour
- York Hospitals NHS Foundation Trust, Wigginton Road, York, YO31 8HE, UK
| | - Marian J Killip
- High Containment Microbiology, NIS Laboratories, National Infection Service, Public Health England, 61 Colindale Avenue, Colindale, London, NW9 5EQ, UK
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13
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Feng Y, Morgan RML, Fraser PD, Hellgardt K, Nixon PJ. Crystal Structure of Geranylgeranyl Pyrophosphate Synthase (CrtE) Involved in Cyanobacterial Terpenoid Biosynthesis. Front Plant Sci 2020; 11:589. [PMID: 32523588 PMCID: PMC7261888 DOI: 10.3389/fpls.2020.00589] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 04/20/2020] [Indexed: 06/11/2023]
Abstract
Cyanobacteria are photosynthetic prokaryotes that perform oxygenic photosynthesis. Due to their ability to use the photon energy of sunlight to fix carbon dioxide into biomass, cyanobacteria are promising hosts for the sustainable production of terpenoids, also known as isoprenoids, a diverse class of natural products with potential as advanced biofuels and high-value chemicals. However, the cyanobacterial enzymes involved in the biosynthesis of the terpene precursors needed to make more complicated terpenoids are poorly characterized. Here we show that the predicted type II prenyltransferase CrtE encoded by the model cyanobacterium Synechococcus sp. PCC 7002 is homodimeric and able to synthesize C20-geranylgeranyl pyrophosphate (GGPP) from C5-isopentenyl pyrophosphate (IPP) and C5-dimethylallyl pyrophosphate (DMAPP). The crystal structure of CrtE solved to a resolution of 2.7 Å revealed a strong structural similarity to the large subunit of the heterodimeric geranylgeranyl pyrophosphate synthase 1 from Arabidopsis thaliana with each subunit containing 14 helices. Using mutagenesis, we confirmed that the fourth and fifth amino acids (Met-87 and Ser-88) before the first conserved aspartate-rich motif (FARM) play important roles in controlling chain elongation. While the WT enzyme specifically produced GGPP, variants M87F and S88Y could only generate C15-farnesyl pyrophosphate (FPP), indicating that residues with large side chains obstruct product elongation. In contrast, replacement of M87 with the smaller Ala residue allowed the formation of the longer C25-geranylfarnesyl pyrophosphate (GFPP) product. Overall, our results provide new structural and functional information on the cyanobacterial CrtE enzyme that could lead to the development of improved cyanobacterial platforms for terpenoid production.
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Affiliation(s)
- Yuchi Feng
- Department of Chemical Engineering, Imperial College London, London, United Kingdom
| | - R. Marc L. Morgan
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Paul D. Fraser
- School of Biological Sciences, Royal Holloway, University of London, Egham, United Kingdom
| | - Klaus Hellgardt
- Department of Chemical Engineering, Imperial College London, London, United Kingdom
| | - Peter J. Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, London, United Kingdom
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14
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Pope MA, Hodge JA, Nixon PJ. An Improved Natural Transformation Protocol for the Cyanobacterium Synechocystis sp. PCC 6803. Front Plant Sci 2020; 11:372. [PMID: 32351517 PMCID: PMC7174562 DOI: 10.3389/fpls.2020.00372] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 03/16/2020] [Indexed: 06/11/2023]
Abstract
The naturally transformable cyanobacterium Synechocystis sp. PCC 6803 is a widely used chassis strain for the photosynthetic production of chemicals. However, Synechocystis possesses multiple genome copies per cell which means that segregating mutations across all genome copies can be time-consuming. Here we use flow cytometry in combination with DNA staining to investigate the effect of phosphate deprivation on the genome copy number of the glucose-tolerant GT-P sub-strain of Synechocystis 6803. Like the PCC 6803 wild type strain, the ploidy of GT-P cells grown in BG-11 medium is growth phase dependent with an average genome copy number of 6.05 ± 0.27 in early growth (OD740 = 0.1) decreasing to 2.49 ± 0.11 in late stationary phase (OD740 = 7). We show that a 10-fold reduction in the initial phosphate concentration of the BG-11 growth medium reduces the average genome copy number of GT-P cells from 4.51 ± 0.20 to 2.94 ± 0.13 and increases the proportion of monoploid cells from 0 to 6% after 7 days of growth. In addition, we also show that the DnaA protein, which unusually for bacteria is not required for DNA replication in Synechocystis, plays a role in restoring polyploidy upon subsequent phosphate supplementation. Based on these observations, we have developed an alternative natural transformation protocol involving phosphate depletion that decreases the time required to obtain fully segregated mutants.
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15
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Trinugroho JP, Bečková M, Shao S, Yu J, Zhao Z, Murray JW, Sobotka R, Komenda J, Nixon PJ. Publisher Correction: Chlorophyll f synthesis by a super-rogue photosystem II complex. Nat Plants 2020; 6:427. [PMID: 32246096 DOI: 10.1038/s41477-020-0649-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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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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16
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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. Nat 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] [What about the content of this article? (0)] [Affiliation(s)] [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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17
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Ahmad N, Khan MO, Islam E, Wei ZY, McAusland L, Lawson T, Johnson GN, Nixon PJ. Contrasting Responses to Stress Displayed by Tobacco Overexpressing an Algal Plastid Terminal Oxidase in the Chloroplast. Front Plant Sci 2020; 11:501. [PMID: 32411169 PMCID: PMC7199157 DOI: 10.3389/fpls.2020.00501] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 04/03/2020] [Indexed: 05/10/2023]
Abstract
The plastid terminal oxidase (PTOX) - an interfacial diiron carboxylate protein found in the thylakoid membranes of chloroplasts - oxidizes plastoquinol and reduces molecular oxygen to water. It is believed to play a physiologically important role in the response of some plant species to light and salt (NaCl) stress by diverting excess electrons to oxygen thereby protecting photosystem II (PSII) from photodamage. PTOX is therefore a candidate for engineering stress tolerance in crop plants. Previously, we used chloroplast transformation technology to over express PTOX1 from the green alga Chlamydomonas reinhardtii in tobacco (generating line Nt-PTOX-OE). Contrary to expectation, growth of Nt-PTOX-OE plants was more sensitive to light stress. Here we have examined in detail the effects of PTOX1 on photosynthesis in Nt-PTOX-OE tobacco plants grown at two different light intensities. Under 'low light' (50 μmol photons m-2 s-1) conditions, Nt-PTOX-OE and WT plants showed similar photosynthetic activities. In contrast, under 'high light' (125 μmol photons m-2 s-1) conditions, Nt-PTOX-OE showed less PSII activity than WT while photosystem I (PSI) activity was unaffected. Nt-PTOX-OE grown under high light also failed to increase the chlorophyll a/b ratio and the maximum rate of CO2 assimilation compared to low-light grown plants, suggesting a defect in acclimation. In contrast, Nt-PTOX-OE plants showed much better germination, root length, and shoot biomass accumulation than WT when exposed to high levels of NaCl and showed better recovery and less chlorophyll bleaching after NaCl stress when grown hydroponically. Overall, our results strengthen the link between PTOX and the resistance of plants to salt stress.
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Affiliation(s)
- Niaz Ahmad
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan
- Department of Life Sciences, Sir Ernst Chain Building–Wolfson Laboratories, Imperial College London, London, United Kingdom
- *Correspondence: Niaz Ahmad, ;
| | - Muhammad Omar Khan
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan
| | - Ejazul Islam
- Soil and Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan
| | - Zheng-Yi Wei
- Department of Life Sciences, Sir Ernst Chain Building–Wolfson Laboratories, Imperial College London, London, United Kingdom
- Institute of Agricultural Biotechnology, Jilin Academy of Agricultural Science, Changchun, China
| | - Lorna McAusland
- School of Life Sciences, University of Essex, Essex, United Kingdom
| | - Tracy Lawson
- School of Life Sciences, University of Essex, Essex, United Kingdom
| | - Giles N. Johnson
- School of Natural Sciences, The University of Manchester, Manchester, United Kingdom
| | - Peter J. Nixon
- Department of Life Sciences, Sir Ernst Chain Building–Wolfson Laboratories, Imperial College London, London, United Kingdom
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18
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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. 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] [What about the content of this article? (0)] [Affiliation(s)] [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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19
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Selão TT, Włodarczyk A, Nixon PJ, Norling B. Growth and selection of the cyanobacterium Synechococcus sp. PCC 7002 using alternative nitrogen and phosphorus sources. Metab Eng 2019; 54:255-263. [PMID: 31063791 DOI: 10.1016/j.ymben.2019.04.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 04/08/2019] [Accepted: 04/29/2019] [Indexed: 12/14/2022]
Abstract
Cyanobacteria, such as Synechococcus sp. PCC 7002 (Syn7002), are promising chassis strains for "green" biotechnological applications as they can be grown in seawater using oxygenic photosynthesis to fix carbon dioxide into biomass. Their other major nutritional requirements for efficient growth are sources of nitrogen (N) and phosphorus (P). As these organisms are more economically cultivated in outdoor open systems, there is a need to develop cost-effective approaches to prevent the growth of contaminating organisms, especially as the use of antibiotic selection markers is neither economically feasible nor ecologically desirable due to the risk of horizontal gene transfer. Here we have introduced a synthetic melamine degradation pathway into Syn7002 and evolved the resulting strain to efficiently use the nitrogen-rich xenobiotic compound melamine as the sole N source. We also show that expression of phosphite dehydrogenase in the absence of its cognate phosphite transporter permits growth of Syn7002 on phosphite and can be used as a selectable marker in Syn7002. We combined these two strategies to generate a strain that can grow on melamine and phosphite as sole N and P sources, respectively. This strain is able to resist deliberate contamination in large excess and should be a useful chassis for metabolic engineering and biotechnological applications using cyanobacteria.
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Affiliation(s)
| | - Artur Włodarczyk
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Peter J Nixon
- School of Biological Sciences, Nanyang Technological University, Singapore; Sir Ernst Chain Building- Wolfson Laboratories, Department of Life Sciences, Imperial College London, S. Kensington Campus, London, SW7 2AZ, UK
| | - Birgitta Norling
- School of Biological Sciences, Nanyang Technological University, Singapore.
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20
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Abstract
In this review, we highlight recent research and current ideas on how to improve the efficiency of the light reactions of photosynthesis in crops. We note that the efficiency of photosynthesis is a balance between how much energy is used for growth and the energy wasted or spent protecting the photosynthetic machinery from photodamage. There are reasons to be optimistic about enhancing photosynthetic efficiency, but many appealing ideas are still on the drawing board. It is envisioned that the crops of the future will be extensively genetically modified to tailor them to specific natural or artificial environmental conditions.
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Affiliation(s)
- Tanai Cardona
- Department of Life Sciences, Sir Ernst Chain Building - Wolfson Laboratories, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K
| | - Shengxi Shao
- Department of Life Sciences, Sir Ernst Chain Building - Wolfson Laboratories, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K
| | - Peter J Nixon
- Department of Life Sciences, Sir Ernst Chain Building - Wolfson Laboratories, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K.
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21
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Abstract
The concept that photosynthesis is a highly inefficient process in terms of conversion of light energy into biomass is embedded in the literature. It is only in the past decade that the processes limiting photosynthetic efficiency have been understood to an extent that allows a step change in our ability to manipulate light energy assimilation into carbon gain. We can therefore envisage that future increases in the grain yield potential of our major crops may depend largely on increasing the efficiency of photosynthesis. The papers in this issue provide new insights into the nature of current limitations on photosynthesis and identify new targets that can be used for crop improvement, together with information on the impacts of a changing environment on the productivity of photosynthesis on land and in our oceans.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'.
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Affiliation(s)
- Christine H Foyer
- Centre of Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Alexander V Ruban
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Peter J Nixon
- Faculty of Natural Sciences, Department of Life Sciences, Imperial College, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK
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22
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Bec Ková M, Yu J, Krynická V, Kozlo A, Shao S, Koník P, Komenda J, Murray JW, Nixon PJ. Structure of Psb29/Thf1 and its association with the FtsH protease complex involved in photosystem II repair in cyanobacteria. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0394. [PMID: 28808107 PMCID: PMC5566888 DOI: 10.1098/rstb.2016.0394] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2017] [Indexed: 12/15/2022] Open
Abstract
One strategy for enhancing photosynthesis in crop plants is to improve their ability to repair photosystem II (PSII) in response to irreversible damage by light. Despite the pivotal role of thylakoid-embedded FtsH protease complexes in the selective degradation of PSII subunits during repair, little is known about the factors involved in regulating FtsH expression. Here we show using the cyanobacterium Synechocystis sp. PCC 6803 that the Psb29 subunit, originally identified as a minor component of His-tagged PSII preparations, physically interacts with FtsH complexes in vivo and is required for normal accumulation of the FtsH2/FtsH3 hetero-oligomeric complex involved in PSII repair. We show using X-ray crystallography that Psb29 from Thermosynechococcus elongatus has a unique fold consisting of a helical bundle and an extended C-terminal helix and contains a highly conserved region that might be involved in binding to FtsH. A similar interaction is likely to occur in Arabidopsis chloroplasts between the Psb29 homologue, termed THF1, and the FTSH2/FTSH5 complex. The direct involvement of Psb29/THF1 in FtsH accumulation helps explain why THF1 is a target during the hypersensitive response in plants induced by pathogen infection. Downregulating FtsH function and the PSII repair cycle via THF1 would contribute to the production of reactive oxygen species, the loss of chloroplast function and cell death. This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.
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Affiliation(s)
- Martina Bec Ková
- Institute of Microbiology, Center Algatech, Opatovický mlýn, 37981 Třeboň, Czech Republic.,Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic
| | - Jianfeng Yu
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Vendula Krynická
- Institute of Microbiology, Center Algatech, Opatovický mlýn, 37981 Třeboň, Czech Republic
| | - Amanda Kozlo
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Shengxi Shao
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Peter Koník
- Institute of Microbiology, Center Algatech, Opatovický mlýn, 37981 Třeboň, Czech Republic.,Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic
| | - Josef Komenda
- Institute of Microbiology, Center Algatech, Opatovický mlýn, 37981 Třeboň, Czech Republic .,Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic
| | - James W Murray
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Peter J Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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23
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Sawa M, Fantuzzi A, Bombelli P, Howe CJ, Hellgardt K, Nixon PJ. Electricity generation from digitally printed cyanobacteria. Nat Commun 2017; 8:1327. [PMID: 29109396 PMCID: PMC5673893 DOI: 10.1038/s41467-017-01084-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 08/15/2017] [Indexed: 11/10/2022] Open
Abstract
Microbial biophotovoltaic cells exploit the ability of cyanobacteria and microalgae to convert light energy into electrical current using water as the source of electrons. Such bioelectrochemical systems have a clear advantage over more conventional microbial fuel cells which require the input of organic carbon for microbial growth. However, innovative approaches are needed to address scale-up issues associated with the fabrication of the inorganic (electrodes) and biological (microbe) parts of the biophotovoltaic device. Here we demonstrate the feasibility of using a simple commercial inkjet printer to fabricate a thin-film paper-based biophotovoltaic cell consisting of a layer of cyanobacterial cells on top of a carbon nanotube conducting surface. We show that these printed cyanobacteria are capable of generating a sustained electrical current both in the dark (as a ‘solar bio-battery’) and in response to light (as a ‘bio-solar-panel’) with potential applications in low-power devices. Cyanobacteria can be exploited to convert light energy into electrical current, however utilising them efficiently for power generation is a challenge. Here, the authors use a simple commercial inkjet printer to fabricate a thin-film paper-based biophotovoltaic cell capable of driving low-power devices.
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Affiliation(s)
- Marin Sawa
- Central Saint Martins College of Arts and Design, University of Arts London, Granary Building, London, N1C 4AA, UK.,Department of Life Sciences, Imperial College London, Sir Ernst Chain Building - Wolfson Laboratories, South Kensington Campus, London, SW7 2AZ, UK
| | - Andrea Fantuzzi
- Department of Life Sciences, Imperial College London, Sir Ernst Chain Building - Wolfson Laboratories, South Kensington Campus, London, SW7 2AZ, UK
| | - Paolo Bombelli
- Department of Biochemistry, University of Cambridge, Hopkins Building, Downing Site, Cambridge, CB2 1QW, UK
| | - Christopher J Howe
- Department of Biochemistry, University of Cambridge, Hopkins Building, Downing Site, Cambridge, CB2 1QW, UK
| | - Klaus Hellgardt
- Department of Chemical Engineering, Imperial College London, Bone Building, South Kensington Campus, London, SW7 2AZ, UK
| | - Peter J Nixon
- Department of Life Sciences, Imperial College London, Sir Ernst Chain Building - Wolfson Laboratories, South Kensington Campus, London, SW7 2AZ, UK.
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Barretto SS, Michoux F, Hellgardt K, Nixon PJ. Pneumatic hydrodynamics influence transplastomic protein yields and biological responses during in vitro shoot regeneration of Nicotiana tabacum callus: Implications for bioprocess routes to plant-made biopharmaceuticals. Biochem Eng J 2017; 117:73-81. [PMID: 28111521 PMCID: PMC5221668 DOI: 10.1016/j.bej.2016.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Transplastomic plants are capable of high-yield production of recombinant biopharmaceutical proteins. Plant tissue culture combines advantages of agricultural cultivation with the bioprocess consistency associated with suspension culture. Overexpression of recombinant proteins through regeneration of transplastomic Nicotiana tabacum shoots from callus tissue in RITA® temporary immersion bioreactors has been previously demonstrated. In this study we investigated the hydrodynamics of periodic pneumatic suspension of liquid medium during temporary immersion culture (4 min aeration every 8 h), and the impact on biological responses and transplastomic expression of fragment C of tetanus toxin (TetC). Biomass was grown under a range of aeration rates for 3, 20 and 40-day durations. Growth, mitochondrial activity (a viability indicator) and TetC protein yields were correlated against the hydrodynamic parameters, shear rate and energy dissipation rate (per kg of medium). A critical aeration rate of 440 ml min-1 was identified, corresponding to a shear rate of 96.7 s-1, pneumatic power input of 8.8 mW kg-1 and initial 20-day pneumatic energy dissipation of 127 J kg-1, at which significant reductions in biomass accumulation and mitochondrial activity were observed. There was an exponential decline in TetC yields with increasing aeration rates at 40 days, across the entire range of conditions tested. These observations have important implications for the optimisation and scale-up of transplastomic plant tissue culture bioprocesses for biopharmaceutical production.
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Key Words
- Biopharmaceutical
- CIM, callus induction medium
- Hydrodynamics
- MS medium, Murashige & Skoog medium
- Pneumatic energy dissipation
- RITA®, recipient for automated temporary immersion (translated from French)
- SDS-PAGE, sodium dodecyl sulphate polyacrylamide gel electrophoresis
- TF, triphenylformazan
- TIB, temporary immersion bioreactor
- TSP, total soluble protein
- TTC, 2,3,5-triphenyltetrazolium chloride
- Temporary immersion culture
- TetC, fragment C of tetanus toxin
- Transplastomic protein
- in vitro organogenesis
- kDa, kiloDalton
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Affiliation(s)
- Sherwin S Barretto
- Department of Life Sciences, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom
| | - Franck Michoux
- Alkion Biopharma SAS, Pépinière Entreprise Genopole, 4 rue Pierre Fontaine, 91058, Evry, France
| | - Klaus Hellgardt
- Department of Chemical Engineering, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom
| | - Peter J Nixon
- Department of Life Sciences, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom
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Bečková M, Gardian Z, Yu J, Konik P, Nixon PJ, Komenda J. Association of Psb28 and Psb27 Proteins with PSII-PSI Supercomplexes upon Exposure of Synechocystis sp. PCC 6803 to High Light. Mol Plant 2017; 10:62-72. [PMID: 27530366 DOI: 10.1016/j.molp.2016.08.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 06/29/2016] [Accepted: 08/04/2016] [Indexed: 05/23/2023]
Abstract
Formation of the multi-subunit oxygen-evolving photosystem II (PSII) complex involves a number of auxiliary protein factors. In this study we compared the localization and possible function of two homologous PSII assembly factors, Psb28-1 and Psb28-2, from the cyanobacterium Synechocystis sp. PCC 6803. We demonstrate that FLAG-tagged Psb28-2 is present in both the monomeric PSII core complex and a PSII core complex lacking the inner antenna CP43 (RC47), whereas Psb28-1 preferentially binds to RC47. When cells are exposed to increased irradiance, both tagged Psb28 proteins additionally associate with oligomeric forms of PSII and with PSII-PSI supercomplexes composed of trimeric photosystem I (PSI) and two PSII monomers as deduced from electron microscopy. The presence of the Psb27 accessory protein in these complexes suggests the involvement of PSI in PSII biogenesis, possibly by photoprotecting PSII through energy spillover. Under standard culture conditions, the distribution of PSII complexes is similar in the wild type and in each of the single psb28 null mutants except for loss of RC47 in the absence of Psb28-1. In comparison with the wild type, growth of mutants lacking Psb28-1 and Psb27, but not Psb28-2, was retarded under high-light conditions and, especially, intermittent high-light/dark conditions, emphasizing the physiological importance of PSII assembly factors for light acclimation.
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Affiliation(s)
- Martina Bečková
- Institute of Microbiology, Center Algatech, Opatovický mlýn, 37981 Třeboň, Czech Republic; Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic
| | - Zdenko Gardian
- Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic; Institute of Plant Molecular Biology, Biology Centre Academy of Sciences, Branišovská 31, 37005 České Budějovice, Czech Republic
| | - Jianfeng Yu
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Peter Konik
- Institute of Microbiology, Center Algatech, Opatovický mlýn, 37981 Třeboň, Czech Republic; Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic
| | - Peter J Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Josef Komenda
- Institute of Microbiology, Center Algatech, Opatovický mlýn, 37981 Třeboň, Czech Republic; Faculty of Science, University of South Bohemia, Branišovská 1760, 37005 České Budějovice, Czech Republic.
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26
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Abstract
Plastid transformation has emerged as an alternative platform to generate transgenic plants. Attractive features of this technology include specific integration of transgenes-either individually or as operons-into the plastid genome through homologous recombination, the potential for high-level protein expression, and transgene containment because of the maternal inheritance of plastids. Several issues associated with nuclear transformation such as gene silencing, variable gene expression due to the Mendelian laws of inheritance, and epigenetic regulation have not been observed in the plastid genome. Plastid transformation has been successfully used for the production of therapeutics, vaccines, antigens, and commercial enzymes, and for engineering various agronomic traits including resistance to biotic and abiotic stresses. However, these demonstrations have usually focused on model systems such as tobacco, and the technology per se has not yet reached the market. Technical factors limiting this technology include the lack of efficient protocols for the transformation of cereals, poor transgene expression in non-green plastids, a limited number of selection markers, and the lengthy procedures required to recover fully segregated plants. This article discusses the technology of transforming the plastid genome, the positive and negative features compared with nuclear transformation, and the current challenges that need to be addressed for successful commercialization.
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Affiliation(s)
- Niaz Ahmad
- Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad, Pakistan
| | - Franck Michoux
- Alkion Biopharma SAS, 4 rue Pierre Fontaine, 91058 Evry, France
| | - Andreas G Lössl
- Department of Applied Plant Sciences and Plant Biotechnology, University of Natural Resources and Applied Life Sciences (BOKU), Vienna, Austria
| | - Peter J Nixon
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College, South Kensington Campus, London SW7 2AZ, UK
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Knoppová J, Yu J, Konik P, Nixon PJ, Komenda J. CyanoP is Involved in the Early Steps of Photosystem II Assembly in the Cyanobacterium Synechocystis sp. PCC 6803. Plant Cell Physiol 2016; 57:1921-31. [PMID: 27388341 DOI: 10.1093/pcp/pcw115] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/08/2016] [Indexed: 05/07/2023]
Abstract
Although the PSII complex is highly conserved in cyanobacteria and chloroplasts, the PsbU and PsbV subunits stabilizing the oxygen-evolving Mn4CaO5 cluster in cyanobacteria are absent in chloroplasts and have been replaced by the PsbP and PsbQ subunits. There is, however, a distant cyanobacterial homolog of PsbP, termed CyanoP, of unknown function. Here we show that CyanoP plays a role in the early stages of PSII biogenesis in Synechocystis sp. PCC 6803. CyanoP is present in the PSII reaction center assembly complex (RCII) lacking both the CP47 and CP43 modules and binds to the smaller D2 module. A small amount of larger PSII core complexes co-purifying with FLAG-tagged CyanoP indicates that CyanoP can accompany PSII on most of its assembly pathway. A role in biogenesis is supported by the accumulation of unassembled D1 precursor and impaired formation of RCII in a mutant lacking CyanoP. Interestingly, the pull-down preparations of CyanoP-FLAG from a strain lacking CP47 also contained PsbO, indicating engagement of this protein with PSII at a much earlier stage in assembly than previously assumed.
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Affiliation(s)
- Jana Knoppová
- Institute of Microbiology, Center Algatech, Opatovický mlýn, 37981 Třeboň, Czech Republic Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic
| | - Jianfeng Yu
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Peter Konik
- Institute of Microbiology, Center Algatech, Opatovický mlýn, 37981 Třeboň, Czech Republic Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, 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, Center Algatech, Opatovický mlýn, 37981 Třeboň, Czech Republic
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Michoux F, Ahmad N, Wei ZY, Belgio E, Ruban AV, Nixon PJ. Testing the Role of the N-Terminal Tail of D1 in the Maintenance of Photosystem II in Tobacco Chloroplasts. Front Plant Sci 2016; 7:844. [PMID: 27446098 PMCID: PMC4914591 DOI: 10.3389/fpls.2016.00844] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 05/30/2016] [Indexed: 05/29/2023]
Abstract
A key step in the repair of photoinactivated oxygen-evolving photosystem II (PSII) complexes is the selective recognition and degradation of the damaged PSII subunit, usually the D1 reaction center subunit. FtsH proteases play a major role in D1 degradation in both cyanobacteria and chloroplasts. In the case of the cyanobacterium Synechocystis sp. PCC 6803, analysis of an N-terminal truncation mutant of D1 lacking 20 amino-acid residues has provided evidence that FtsH complexes can remove damaged D1 in a processive reaction initiated at the exposed N-terminal tail. To test the importance of the N-terminal D1 tail in higher plants, we have constructed the equivalent truncation mutant in tobacco using chloroplast transformation techniques. The resulting mutant grew poorly and only accumulated about 25% of wild-type levels of PSII in young leaves which declined as the leaves grew so that there was little PSII activity in mature leaves. Truncating D1 led to the loss of PSII supercomplexes and dimeric complexes in the membrane. Extensive and rapid non-photochemical quenching (NPQ) was still induced in the mutant, supporting the conclusion that PSII complexes are not required for NPQ. Analysis of leaves exposed to high light indicated that PSII repair in the truncation mutant was impaired at the level of synthesis and/or assembly of PSII but that D1 could still be degraded. These data support the idea that tobacco plants possess a number of back-up and compensatory pathways for removal of damaged D1 upon severe light stress.
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Affiliation(s)
- Franck Michoux
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College LondonLondon, UK
| | - Niaz Ahmad
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College LondonLondon, UK
| | - Zheng-Yi Wei
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College LondonLondon, UK
| | - Erica Belgio
- School of Biological and Chemical Sciences, Queen Mary University of LondonLondon, UK
| | - Alexander V. Ruban
- School of Biological and Chemical Sciences, Queen Mary University of LondonLondon, UK
| | - Peter J. Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College LondonLondon, UK
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29
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Abstract
Despite the largely maternal inheritance of plastid genomes, the risk of transgene dissemination from transplastomic plants can limit the scope for field cultivation. There is a need for a cost-effective, scalable process to grow large quantities of transplastomic plant biomass for biosynthesis of biopharmaceuticals and other high-value heterologous proteins. Temporary immersion culture is a means of achieving this under fully contained conditions. This method describes the organogenesis of transplastomic Nicotiana tabacum callus in RITA(®) temporary immersion bioreactors to produce rootless leafy biomass, and subsequent total soluble protein extraction, SDS-PAGE, and Western immunoblot analysis of heterologous protein expression. This method can be used for propagation of plastid or nuclear transformants, though is especially suitable for transplastomic biomass, as organogenesis leads to greater expression and accumulation of transplastomic proteins due to increases in chloroplast number and size.
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Affiliation(s)
- Sherwin Barretto
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life, Imperial College London, S. Kensington Campus, SW2 AZ, London, UK
| | - Franck Michoux
- Alkion Biopharma, 4 rue Pierre Fontaine, 91058, Evry, France.
| | - Peter J Nixon
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life, Imperial College London, S. Kensington Campus, SW2 AZ, London, UK
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30
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Burgess SJ, Taha H, Yeoman JA, Iamshanova O, Chan KX, Boehm M, Behrends V, Bundy JG, Bialek W, Murray JW, Nixon PJ. Identification of the Elusive Pyruvate Reductase of Chlamydomonas reinhardtii Chloroplasts. Plant Cell Physiol 2016; 57:82-94. [PMID: 26574578 PMCID: PMC4722173 DOI: 10.1093/pcp/pcv167] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 10/27/2015] [Indexed: 05/19/2023]
Abstract
Under anoxic conditions the green alga Chlamydomonas reinhardtii activates various fermentation pathways leading to the creation of formate, acetate, ethanol and small amounts of other metabolites including d-lactate and hydrogen. Progress has been made in identifying the enzymes involved in these pathways and their subcellular locations; however, the identity of the enzyme involved in reducing pyruvate to d-lactate has remained unclear. Based on sequence comparisons, enzyme activity measurements, X-ray crystallography, biochemical fractionation and analysis of knock-down mutants, we conclude that pyruvate reduction in the chloroplast is catalyzed by a tetrameric NAD(+)-dependent d-lactate dehydrogenase encoded by Cre07.g324550. Its expression during aerobic growth supports a possible function as a 'lactate valve' for the export of lactate to the mitochondrion for oxidation by cytochrome-dependent d-lactate dehydrogenases and by glycolate dehydrogenase. We also present a revised spatial model of fermentation based on our immunochemical detection of the likely pyruvate decarboxylase, PDC3, in the cytoplasm.
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Affiliation(s)
- Steven J Burgess
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK These authors contributed equally to this work
| | - Hussein Taha
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK These authors contributed equally to this work Present address: Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Brunei Darussalam
| | - Justin A Yeoman
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - Oksana Iamshanova
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - Kher Xing Chan
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Marko Boehm
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - Volker Behrends
- Department of Biomolecular Medicine, Sir Alexander Fleming Building, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - Jacob G Bundy
- Department of Biomolecular Medicine, Sir Alexander Fleming Building, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - Wojciech Bialek
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - James W Murray
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
| | - Peter J Nixon
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington Campus, London SW7 2AZ, UK
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31
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Krynická V, Shao S, Nixon PJ, Komenda J. Accessibility controls selective degradation of photosystem II subunits by FtsH protease. Nat Plants 2015; 1:15168. [PMID: 27251713 DOI: 10.1038/nplants.2015.168] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/07/2015] [Indexed: 05/21/2023]
Abstract
The oxygen-evolving photosystem II (PSII) complex located in chloroplasts and cyanobacteria is sensitive to light-induced damage(1) that unless repaired causes reduction in photosynthetic capacity and growth. Although a potential target for crop improvement, the mechanism of PSII repair remains unclear. The D1 reaction center protein is the main target for photodamage(2), with repair involving the selective degradation of the damaged protein by FtsH protease(3). How a single damaged PSII subunit is recognized for replacement is unknown. Here, we have tested the dark stability of PSII subunits in strains of the cyanobacterium Synechocystis PCC 6803 blocked at specific stages of assembly. We have found that when D1, which is normally shielded by the CP43 subunit, becomes exposed in a photochemically active PSII complex lacking CP43, it is selectively degraded by FtsH even in the dark. Removal of the CP47 subunit, which increases accessibility of FtsH to the D2 subunit, induced dark degradation of D2 at a faster rate than that of D1. In contrast, CP47 and CP43 are resistant to degradation in the dark. Our results indicate that protease accessibility induced by PSII disassembly is an important determinant in the selection of the D1 and D2 subunits to be degraded by FtsH.
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Affiliation(s)
- Vendula Krynická
- Faculty of Science, University of South Bohemia, Branišovská 31, České Budějovice 37005, Czech Republic
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Center Algatech, Opatovický mlýn, Třeboň 379 81, Czech Republic
| | - Shengxi Shao
- Sir Ernst Chain Building, Wolfson Laboratories, Department of Life Sciences, Imperial College London, S. Kensington campus, London SW7 2AZ, UK
| | - Peter J Nixon
- Sir Ernst Chain Building, Wolfson Laboratories, Department of Life Sciences, Imperial College London, S. Kensington campus, London SW7 2AZ, UK
| | - Josef Komenda
- Faculty of Science, University of South Bohemia, Branišovská 31, České Budějovice 37005, Czech Republic
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Center Algatech, Opatovický mlýn, Třeboň 379 81, Czech Republic
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Sacharz J, Bryan SJ, Yu J, Burroughs NJ, Spence EM, Nixon PJ, Mullineaux CW. Sub-cellular location of FtsH proteases in the cyanobacterium Synechocystis sp. PCC 6803 suggests localised PSII repair zones in the thylakoid membranes. Mol Microbiol 2015; 96:448-62. [PMID: 25601560 PMCID: PMC4949578 DOI: 10.1111/mmi.12940] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2015] [Indexed: 12/21/2022]
Abstract
In cyanobacteria and chloroplasts, exposure to HL damages the photosynthetic apparatus, especially the D1 subunit of Photosystem II. To avoid chronic photoinhibition, a PSII repair cycle operates to replace damaged PSII subunits with newly synthesised versions. To determine the sub-cellular location of this process, we examined the localisation of FtsH metalloproteases, some of which are directly involved in degrading damaged D1. We generated transformants of the cyanobacterium Synechocystis sp. PCC6803 expressing GFP-tagged versions of its four FtsH proteases. The ftsH2-gfp strain was functional for PSII repair under our conditions. Confocal microscopy shows that FtsH1 is mainly in the cytoplasmic membrane, while the remaining FtsH proteins are in patches either in the thylakoid or at the interface between the thylakoid and cytoplasmic membranes. HL exposure which increases the activity of the Photosystem II repair cycle led to no detectable changes in FtsH distribution, with the FtsH2 protease involved in D1 degradation retaining its patchy distribution in the thylakoid membrane. We discuss the possibility that the FtsH2-GFP patches represent Photosystem II 'repair zones' within the thylakoid membranes, and the possible advantages of such functionally specialised membrane zones. Anti-GFP affinity pull-downs provide the first indication of the composition of the putative repair zones.
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Affiliation(s)
- Joanna Sacharz
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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Burroughs NJ, Boehm M, Eckert C, Mastroianni G, Spence EM, Yu J, Nixon PJ, Appel J, Mullineaux CW, Bryan SJ. Solar powered biohydrogen production requires specific localization of the hydrogenase. Energy Environ Sci 2014; 7:3791-3800. [PMID: 26339289 PMCID: PMC4535174 DOI: 10.1039/c4ee02502d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 09/04/2014] [Indexed: 05/15/2023]
Abstract
Cyanobacteria contain a bidirectional [NiFe] hydrogenase which transiently produces hydrogen upon exposure of anoxic cells to light, potentially acting as a "valve" releasing excess electrons from the electron transport chain. However, its interaction with the photosynthetic electron transport chain remains unclear. By GFP-tagging the HoxF diaphorase subunit we show that the hydrogenase is thylakoid associated, comprising a population dispersed uniformly through the thylakoids and a subpopulation localized to discrete puncta in the distal thylakoid. Thylakoid localisation of both the HoxH and HoxY hydrogenase subunits is confirmed by immunogold electron microscopy. The diaphorase HoxE subunit is essential for recruitment to the dispersed thylakoid population, potentially anchoring the hydrogenase to the membrane, but aggregation to puncta occurs through a distinct HoxE-independent mechanism. Membrane association does not require NDH-1. Localization is dynamic on a scale of minutes, with anoxia and high light inducing a significant redistribution between these populations in favour of puncta. Since HoxE is essential for access to its electron donor, electron supply to the hydrogenase depends on a physiologically controlled localization, potentially offering a new avenue to enhance photosynthetic hydrogen production by exploiting localization/aggregation signals.
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Affiliation(s)
- Nigel J Burroughs
- Systems Biology Centre , Coventry House , University of Warwick , Coventry , CV4 7AL , UK
| | - Marko Boehm
- Imperial College London , South Kensington Campus , London , SW7 2AZ , UK
| | - Carrie Eckert
- Biosciences Centre , National Renewable Energy Laboratory , Golden , Colorado 80401 , USA ; Renewable and Sustainable Energy Institute, University of Colorado Boulder , Boulder , CO 80309 , USA
| | - Giulia Mastroianni
- School of Biological and Chemical Sciences , Queen Mary University of London , Mile End Road , London , E1 4NS , UK .
| | - Edward M Spence
- Pharmaceutical Science Division , King's College London , Franklin-Wilkins Building, 150 Stamford Street , London , SE1 9NH , UK
| | - Jianfeng Yu
- Imperial College London , South Kensington Campus , London , SW7 2AZ , UK
| | - Peter J Nixon
- Imperial College London , South Kensington Campus , London , SW7 2AZ , UK
| | - Jens Appel
- Botanical Institute , University of Kiel , Am Botanischen Garten 1-9 , 24118 Kiel , Germany
| | - Conrad W Mullineaux
- School of Biological and Chemical Sciences , Queen Mary University of London , Mile End Road , London , E1 4NS , UK .
| | - Samantha J Bryan
- School of Biological and Chemical Sciences , Queen Mary University of London , Mile End Road , London , E1 4NS , UK .
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Bryan SJ, Burroughs NJ, Shevela D, Yu J, Rupprecht E, Liu LN, Mastroianni G, Xue Q, Llorente-Garcia I, Leake MC, Eichacker LA, Schneider D, Nixon PJ, Mullineaux CW. Localisation and interactions of the Vipp1 protein in cyanobacteria. Mol Microbiol 2014; 94:1179-1195. [PMID: 25308470 PMCID: PMC4297356 DOI: 10.1111/mmi.12826] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2014] [Indexed: 12/22/2022]
Abstract
The Vipp1 protein is essential in cyanobacteria and chloroplasts for the maintenance of photosynthetic function and thylakoid membrane architecture. To investigate its mode of action we generated strains of the cyanobacteria Synechocystis sp. PCC6803 and Synechococcus sp. PCC7942 in which Vipp1 was tagged with green fluorescent protein at the C-terminus and expressed from the native chromosomal locus. There was little perturbation of function. Live-cell fluorescence imaging shows dramatic relocalisation of Vipp1 under high light. Under low light, Vipp1 is predominantly dispersed in the cytoplasm with occasional concentrations at the outer periphery of the thylakoid membranes. High light induces Vipp1 coalescence into localised puncta within minutes, with net relocation of Vipp1 to the vicinity of the cytoplasmic membrane and the thylakoid membranes. Pull-downs and mass spectrometry identify an extensive collection of proteins that are directly or indirectly associated with Vipp1 only after high-light exposure. These include not only photosynthetic and stress-related proteins but also RNA-processing, translation and protein assembly factors. This suggests that the Vipp1 puncta could be involved in protein assembly. One possibility is that Vipp1 is involved in the formation of stress-induced localised protein assembly centres, enabling enhanced protein synthesis and delivery to membranes under stress conditions.
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Affiliation(s)
- Samantha J Bryan
- School of Biological and Chemical Sciences, Queen Mary University of LondonMile End Road, London, E1 4NS, UK
| | - Nigel J Burroughs
- Mathematics Institute and Warwick Systems Biology Centre, University of WarwickCoventry, CV4 7AL, UK
| | - Dmitriy Shevela
- Department of Mathematics and Natural Science, University of Stavanger4036, Stavanger, Norway
| | - Jianfeng Yu
- Department of Life Sciences, Imperial College LondonLondon, SW7 2AZ, UK
| | - Eva Rupprecht
- Institut für Biochemie und Molekularbiologie, ZBMZ, Albert-Ludwigs-UniversitätStefan-Meier-Strasse 17, 79104, Freiburg, Germany
| | - Lu-Ning Liu
- School of Biological and Chemical Sciences, Queen Mary University of LondonMile End Road, London, E1 4NS, UK
| | - Giulia Mastroianni
- School of Biological and Chemical Sciences, Queen Mary University of LondonMile End Road, London, E1 4NS, UK
| | - Quan Xue
- Clarendon Laboratory, Department of Physics, University of OxfordParks Road, Oxford, OX1 3PU, UK
| | - Isabel Llorente-Garcia
- Clarendon Laboratory, Department of Physics, University of OxfordParks Road, Oxford, OX1 3PU, UK
- Department of Physics and Astronomy, University College LondonGower St., London, WC1E 6BT, UK
| | - Mark C Leake
- Biological Physical Sciences Institute (BPSI), Departments of Physics and Biology, University of YorkYork, YO105DD, UK
| | - Lutz A Eichacker
- Department of Mathematics and Natural Science, University of Stavanger4036, Stavanger, Norway
| | - Dirk Schneider
- Institut für Biochemie und Molekularbiologie, ZBMZ, Albert-Ludwigs-UniversitätStefan-Meier-Strasse 17, 79104, Freiburg, Germany
- Institut für Pharmazie und Biochemie, Johannes Gutenberg-Universität Mainz55128, Mainz, Germany
| | - Peter J Nixon
- Department of Life Sciences, Imperial College LondonLondon, SW7 2AZ, UK
| | - Conrad W Mullineaux
- School of Biological and Chemical Sciences, Queen Mary University of LondonMile End Road, London, E1 4NS, UK
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Michoux F, Boehm M, Bialek W, Takasaka K, Maghlaoui K, Barber J, Murray JW, Nixon PJ. Crystal structure of CyanoQ from the thermophilic cyanobacterium Thermosynechococcus elongatus and detection in isolated photosystem II complexes. Photosynth Res 2014; 122:57-67. [PMID: 24838684 PMCID: PMC4180030 DOI: 10.1007/s11120-014-0010-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 04/28/2014] [Indexed: 05/23/2023]
Abstract
The PsbQ-like protein, termed CyanoQ, found in the cyanobacterium Synechocystis sp. PCC 6803 is thought to bind to the lumenal surface of photosystem II (PSII), helping to shield the Mn4CaO5 oxygen-evolving cluster. CyanoQ is, however, absent from the crystal structures of PSII isolated from thermophilic cyanobacteria raising the possibility that the association of CyanoQ with PSII might not be a conserved feature. Here, we show that CyanoQ (encoded by tll2057) is indeed expressed in the thermophilic cyanobacterium Thermosynechococcus elongatus and provide evidence in support of its assignment as a lipoprotein. Using an immunochemical approach, we show that CyanoQ co-purifies with PSII and is actually present in highly pure PSII samples used to generate PSII crystals. The absence of CyanoQ in the final crystal structure is possibly due to detachment of CyanoQ during crystallisation or its presence in sub-stoichiometric amounts. In contrast, the PsbP homologue, CyanoP, is severely depleted in isolated PSII complexes. We have also determined the crystal structure of CyanoQ from T. elongatus to a resolution of 1.6 Å. It lacks bound metal ions and contains a four-helix up-down bundle similar to the ones found in Synechocystis CyanoQ and spinach PsbQ. However, the N-terminal region and extensive lysine patch that are thought to be important for binding of PsbQ to PSII are not conserved in T. elongatus CyanoQ.
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Affiliation(s)
- Franck Michoux
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories Imperial College London, South Kensington Campus, London, SW7 2AZ UK
- Present Address: Alkion Biopharma, 4 rue Pierre Fontaine, 91000 Evry, France
| | - Marko Boehm
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories Imperial College London, South Kensington Campus, London, SW7 2AZ UK
| | - Wojciech Bialek
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories Imperial College London, South Kensington Campus, London, SW7 2AZ UK
| | - Kenji Takasaka
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories Imperial College London, South Kensington Campus, London, SW7 2AZ UK
| | - Karim Maghlaoui
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories Imperial College London, South Kensington Campus, London, SW7 2AZ UK
| | - James Barber
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories Imperial College London, South Kensington Campus, London, SW7 2AZ UK
| | - James W. Murray
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories Imperial College London, South Kensington Campus, London, SW7 2AZ UK
| | - Peter J. Nixon
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories Imperial College London, South Kensington Campus, London, SW7 2AZ UK
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Krynická V, Tichý M, Krafl J, Yu J, Kaňa R, Boehm M, Nixon PJ, Komenda J. Two essential FtsH proteases control the level of the Fur repressor during iron deficiency in the cyanobacterium Synechocystis sp. PCC 6803. Mol Microbiol 2014; 94:609-24. [PMID: 25238320 DOI: 10.1111/mmi.12782] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/30/2014] [Indexed: 12/18/2022]
Abstract
The cyanobacterium Synechocystis sp. PCC 6803 expresses four different FtsH protease subunits (FtsH1-4) that assemble into specific homo- and heterocomplexes. The FtsH2/FtsH3 complex is involved in photoprotection but the physiological roles of the other complexes, notably the essential FtsH1/FtsH3 complex, remain unclear. Here we show that the FtsH1 and FtsH3 proteases are involved in the acclimation of cells to iron deficiency. A mutant conditionally depleted in FtsH3 was unable to induce normal expression of the IsiA chlorophyll-protein and FutA1 iron transporter upon iron deficiency due to a block in transcription, which is regulated by the Fur transcriptional repressor. Levels of Fur declined in the WT and the FtsH2 null mutant upon iron depletion but not in the FtsH3 downregulated strain. A similar stabilizing effect on Fur was also observed in a mutant conditionally depleted in the FtsH1 subunit. Moreover, a mutant overexpressing FtsH1 showed reduced levels of Fur and enhanced accumulation of both IsiA and FutA1 even under iron sufficiency. Analysis of GFP-tagged derivatives and biochemical fractionation supported a common location for FtsH1 and FtsH3 in the cytoplasmic membrane. Overall we propose that degradation of the Fur repressor mediated by the FtsH1/FtsH3 heterocomplex is critical for acclimation to iron depletion.
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Affiliation(s)
- Vendula Krynická
- Institute of Microbiology, Academy of Sciences, Opatovický mlýn, 37981, Třeboň, Czech Republic; Faculty of Science, University of South Bohemia, Branišovská 31, 370 05, České Budějovice, Czech Republic
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Hamilton ML, Franco E, Deák Z, Schlodder E, Vass I, Nixon PJ. Investigating the photoprotective role of cytochrome b-559 in photosystem II in a mutant with altered ligation of the haem. Plant Cell Physiol 2014; 55:1276-85. [PMID: 24850839 DOI: 10.1093/pcp/pcu070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Despite many years of study, the physiological role of cytochrome b-559 (Cyt b-559) within the photosystem II (PSII) complex still remains unclear. Here we describe the analysis of a mutant of the green alga Chlamydomonas reinhardtii in which the His ligand to the haem, provided by the alpha subunit, has been replaced by a Cys residue. The mutant is unable to grow photoautotrophically but can assemble oxygen-evolving PSII supercomplexes to 15-20% of the levels found in the wild-type control. Haem is still detected in the isolated PSII supercomplexes but at sub-stoichiometric levels consistent with weaker binding to the mutated cytochrome. Analysis of PSII activity in cells indicates slowed electron transfer in the mutant between plastoquinones QA and QB. We show that PSII activity in the mutant is more sensitive to chronic photoinhibition than the WT control because of two effects: a faster rate of damage and an impaired PSII repair cycle at the level of synthesis and/or incorporation of D1 into PSII. We also demonstrate that Cyt b-559 plays a role during the critical stage of assembling the Mn4CaO5 cluster. Overall we conclude that Cyt b-559 optimises electron transfer on the acceptor side of PSII and plays physiologically important roles in the assembly, repair and maintenance of the complex.
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Affiliation(s)
- Mary L Hamilton
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington campus, London, SW7 2AZ, UKPresent address: Rothamsted Research, West Common, Harpenden, Hertfordshire, AL5 2JQ, UK
| | - Emanuel Franco
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington campus, London, SW7 2AZ, UK
| | - Zsuzsanna Deák
- Institute of Plant Biology, Biological Research Center of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Eberhard Schlodder
- Max-Volmer-Institut für Biophysikalische Chemie und Biochemie, Technische Universität Berlin, D-10623 Berlin, Germany
| | - Imre Vass
- Institute of Plant Biology, Biological Research Center of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Peter J Nixon
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, S. Kensington campus, London, SW7 2AZ, UK
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Shinopoulos KE, Yu J, Nixon PJ, Brudvig GW. Using site-directed mutagenesis to probe the role of the D2 carotenoid in the secondary electron-transfer pathway of photosystem II. Photosynth Res 2014; 120:141-52. [PMID: 23334888 PMCID: PMC3961632 DOI: 10.1007/s11120-013-9793-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 01/02/2013] [Indexed: 05/07/2023]
Abstract
Secondary electron transfer in photosystem II (PSII), which occurs when water oxidation is inhibited, involves redox-active carotenoids (Car), as well as chlorophylls (Chl), and cytochrome b 559 (Cyt b 559), and is believed to play a role in photoprotection. CarD2 may be the initial point of secondary electron transfer because it is the closest cofactor to both P680, the initial oxidant, and to Cyt b 559, the terminal secondary electron donor within PSII. In order to characterize the role of CarD2 and to determine the effects of perturbing CarD2 on both the electron-transfer events and on the identity of the redox-active cofactors, it is necessary to vary the properties of CarD2 selectively without affecting the ten other Car per PSII. To this end, site-directed mutations around the binding pocket of CarD2 (D2-G47W, D2-G47F, and D2-T50F) have been generated in Synechocystis sp. PCC 6803. Characterization by near-IR and EPR spectroscopy provides the first experimental evidence that CarD2 is one of the redox-active carotenoids in PSII. There is a specific perturbation of the Car(∙+) near-IR spectrum in all three mutated PSII samples, allowing the assignment of the spectral signature of Car D2 (∙+) ; Car D2 (∙+) exhibits a near-IR peak at 980 nm and is the predominant secondary donor oxidized in a charge separation at low temperature in ferricyanide-treated wild-type PSII. The yield of secondary donor radicals is substantially decreased in PSII complexes isolated from each mutant. In addition, the kinetics of radical formation are altered in the mutated PSII samples. These results are consistent with oxidation of CarD2 being the initial step in secondary electron transfer. Furthermore, normal light levels during mutant cell growth perturb the shape of the Chl(∙+) near-IR absorption peak and generate a dark-stable radical observable in the EPR spectra, indicating a higher susceptibility to photodamage further linking the secondary electron-transfer pathway to photoprotection.
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Affiliation(s)
| | - Jianfeng Yu
- Division of Molecular Biosciences, Sir Ernst Chain Building – Wolfson Laboratories, Imperial College London, S. Kensington campus, London, SW7 2AY UK
| | - Peter J. Nixon
- Division of Molecular Biosciences, Sir Ernst Chain Building – Wolfson Laboratories, Imperial College London, S. Kensington campus, London, SW7 2AY UK
| | - Gary W. Brudvig
- Department of Chemistry, Yale University, New Haven, CT 06520-8107 USA
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Knoppová J, Sobotka R, Tichý M, Yu J, Konik P, Halada P, Nixon PJ, Komenda J. Discovery of a chlorophyll binding protein complex involved in the early steps of photosystem II assembly in Synechocystis. Plant Cell 2014; 26:1200-12. [PMID: 24681620 PMCID: PMC4001378 DOI: 10.1105/tpc.114.123919] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Efficient assembly and repair of the oxygen-evolving photosystem II (PSII) complex is vital for maintaining photosynthetic activity in plants, algae, and cyanobacteria. How chlorophyll is delivered to PSII during assembly and how vulnerable assembly complexes are protected from photodamage are unknown. Here, we identify a chlorophyll and β-carotene binding protein complex in the cyanobacterium Synechocystis PCC 6803 important for formation of the D1/D2 reaction center assembly complex. It is composed of putative short-chain dehydrogenase/reductase Ycf39, encoded by the slr0399 gene, and two members of the high-light-inducible protein (Hlip) family, HliC and HliD, which are small membrane proteins related to the light-harvesting chlorophyll binding complexes found in plants. Perturbed chlorophyll recycling in a Ycf39-null mutant and copurification of chlorophyll synthase and unassembled D1 with the Ycf39-Hlip complex indicate a role in the delivery of chlorophyll to newly synthesized D1. Sequence similarities suggest the presence of a related complex in chloroplasts.
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Affiliation(s)
- Jana Knoppová
- Institute of Microbiology, Academy of Sciences, 37981 Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic
| | - Roman Sobotka
- Institute of Microbiology, Academy of Sciences, 37981 Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic
| | - Martin Tichý
- Institute of Microbiology, Academy of Sciences, 37981 Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic
| | - Jianfeng Yu
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, London SW7 2AZ, United Kingdom
| | - Peter Konik
- Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic
| | - Petr Halada
- Laboratory of Molecular Structure Characterization, Institute of Microbiology, Academy of Sciences, 14220 Praha 4-Krč, Czech Republic
| | - Peter J. Nixon
- Department of Life Sciences, Sir Ernst Chain Building-Wolfson Laboratories, Imperial College London, London SW7 2AZ, United Kingdom
| | - Josef Komenda
- Institute of Microbiology, Academy of Sciences, 37981 Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic
- Address correspondence to
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Bialek W, Wen S, Michoux F, Beckova M, Komenda J, Murray JW, Nixon PJ. Crystal structure of the Psb28 accessory factor of Thermosynechococcus elongatus photosystem II at 2.3 Å. Photosynth Res 2013; 117:375-83. [PMID: 24126792 DOI: 10.1007/s11120-013-9939-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 10/02/2013] [Indexed: 05/03/2023]
Abstract
Members of the Psb28 family of proteins are accessory factors implicated in the assembly and repair of the photosystem II complex. We present here the crystal structure of the Psb28 protein (Tlr0493) found in the thermophilic cyanobacterium Thermosynechococcus elongatus at a resolution of 2.3 Å. Overall the crystal structure of the Psb28 monomer is similar to the solution structures of C-terminally His-tagged Psb28-1 from Synechocystis sp. PCC 6803 obtained previously by nuclear magnetic resonance spectroscopy. One new aspect is that Escherichia coli-expressed T. elongatus Psb28 is able to form dimers in solution and packs as a dimer of dimers in the crystal. Analysis of wild type and mutant strains of Synechocystis 6803 by blue native-polyacrylamide gel electrophoresis suggests that Psb28-1, the closest homologue to T. elongatus Psb28 in this organism, also exists as an oligomer in vivo, most likely a dimer. In line with the prediction based on the crystal structure of T. elongatus Psb28, the addition of a 3× Flag-tag to the C-terminus of Synechocystis 6803 Psb28-1 interferes with the accumulation of the Psb28-1 oligomer in vivo. In contrast, the more distantly related Psb28-2 protein found in Synechocystis 6803 lacks the residues that stabilize dimer formation in the T. elongatus Psb28 crystal and is detected as a monomer in vivo. Overall our data suggest that the dimer interface in the Psb28 crystal might be physiologically relevant.
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Affiliation(s)
- Wojciech Bialek
- Sir Ernst Chain Building-Wolfson Laboratories, Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
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Suzuki H, Yu J, Kobayashi T, Nakanishi H, Nixon PJ, Noguchi T. Functional roles of D2-Lys317 and the interacting chloride ion in the water oxidation reaction of photosystem II as revealed by fourier transform infrared analysis. Biochemistry 2013; 52:4748-57. [PMID: 23786399 PMCID: PMC3777104 DOI: 10.1021/bi301699h] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photosynthetic water oxidation in plants and cyanobacteria is catalyzed by a Mn4CaO5 cluster within the photosystem II (PSII) protein complex. Two Cl(-) ions bound near the Mn4CaO5 cluster act as indispensable cofactors, but their functional roles remain to be clarified. We have investigated the role of the Cl(-) ion interacting with D2-K317 (designated Cl-1) by Fourier transform infrared spectroscopy (FTIR) analysis of the D2-K317R mutant of Synechocystis sp. PCC 6803 in combination with Cl(-)/NO3(-) replacement. The D2-K317R mutation perturbed the bands in the regions of the COO(-) stretching and backbone amide vibrations in the FTIR difference spectrum upon the S1 → S2 transition. In addition, this mutation altered the (15)N isotope-edited NO3(-) bands in the spectrum of NO3(-)-treated PSII. These results provide the first experimental evidence that the Cl-1 site is coupled with the Mn4CaO5 cluster and its interaction is affected by the S1 → S2 transition. It was also shown that a negative band at 1748 cm(-1) arising from COOH group(s) was altered to a positive intensity by the D2-K317R mutation as well as by NO3(-) treatment, suggesting that the Cl-1 site affects the pKa of COOH/COO(-) group(s) near the Mn4CaO5 cluster in a common hydrogen bond network. Together with the observation that the efficiency of the S3 → S0 transition significantly decreased in the core complexes of D2-K317R upon moderate dehydration, it is suggested that D2-K317 and Cl-1 are involved in a proton transfer pathway from the Mn4CaO5 cluster to the lumen, which functions in the S3 → S0 transition.
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Affiliation(s)
- Hiroyuki Suzuki
- Division of Material Science, Graduate School of Science, Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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Abstract
UNLABELLED Root resorption is a pathological process that may occur after surgical, mechanical, chemical or thermal insult. Generally, it can be classified as internal and external root resorption. Depending on the diagnosis, an orthograde, surgical or a combined approach is used in management of these cases. CLINICAL RELEVANCE General dental practitioners can face difficulties in diagnosis and treatment planning for cases with root resorption. An understanding of the aetiology and pathogenesis of root resorption is critical for diagnosis, effective management and improves outcome.
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Affiliation(s)
- Zaid Al-Momani
- Restorative Department, Level 5, Leeds Dental Institute, Clarendon Way, Leeds
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Krupnik T, Kotabová E, van Bezouwen LS, Mazur R, Garstka M, Nixon PJ, Barber J, Kaňa R, Boekema EJ, Kargul J. A reaction center-dependent photoprotection mechanism in a highly robust photosystem II from an extremophilic red alga, Cyanidioschyzon merolae. J Biol Chem 2013; 288:23529-42. [PMID: 23775073 DOI: 10.1074/jbc.m113.484659] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Members of the rhodophytan order Cyanidiales are unique among phototrophs in their ability to live in extremely low pH levels and moderately high temperatures. The photosynthetic apparatus of the red alga Cyanidioschyzon merolae represents an intermediate type between cyanobacteria and higher plants, suggesting that this alga may provide the evolutionary link between prokaryotic and eukaryotic phototrophs. Although we now have a detailed structural model of photosystem II (PSII) from cyanobacteria at an atomic resolution, no corresponding structure of the eukaryotic PSII complex has been published to date. Here we report the isolation and characterization of a highly active and robust dimeric PSII complex from C. merolae. We show that this complex is highly stable across a range of extreme light, temperature, and pH conditions. By measuring fluorescence quenching properties of the isolated C. merolae PSII complex, we provide the first direct evidence of pH-dependent non-photochemical quenching in the red algal PSII reaction center. This type of quenching, together with high zeaxanthin content, appears to underlie photoprotection mechanisms that are efficiently employed by this robust natural water-splitting complex under excess irradiance. In order to provide structural details of this eukaryotic form of PSII, we have employed electron microscopy and single particle analyses to obtain a 17 Å map of the C. merolae PSII dimer in which we locate the position of the protein mass corresponding to the additional extrinsic protein stabilizing the oxygen-evolving complex, PsbQ'. We conclude that this lumenal subunit is present in the vicinity of the CP43 protein, close to the membrane plane.
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Affiliation(s)
- Tomasz Krupnik
- Department of Plant Molecular Physiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
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Wobbe L, Nixon PJ. The mTERF protein MOC1 terminates mitochondrial DNA transcription in the unicellular green alga Chlamydomonas reinhardtii. Nucleic Acids Res 2013; 41:6553-67. [PMID: 23649833 PMCID: PMC3711419 DOI: 10.1093/nar/gkt313] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The molecular function of mTERFs (mitochondrial transcription termination factors) has so far only been described for metazoan members of the protein family and in animals they control mitochondrial replication, transcription and translation. Cells of photosynthetic eukaryotes harbour chloroplasts and mitochondria, which are in an intense cross-talk that is vital for photosynthesis. Chlamydomonas reinhardtii is a unicellular green alga widely used as a model organism for photosynthesis research and green biotechnology. Among the six nuclear C. reinhardtii mTERF genes is mTERF-like gene of Chlamydomonas (MOC1), whose inactivation alters mitorespiration and interestingly also light-acclimation processes in the chloroplast that favour the enhanced production of biohydrogen. We show here from in vitro studies that MOC1 binds specifically to a sequence within the mitochondrial rRNA-coding module S3, and that a knockout of MOC1 in the mutant stm6 increases read-through transcription at this site, indicating that MOC1 acts as a transcription terminator in vivo. Whereas the level of certain antisense RNA species is higher in stm6, the amount of unprocessed mitochondrial sense transcripts is strongly reduced, demonstrating that a loss of MOC1 causes perturbed mitochondrial DNA (mtDNA) expression. Overall, we provide evidence for the existence of mitochondrial antisense RNAs in C. reinhardtii and show that mTERF-mediated transcription termination is an evolutionary-conserved mechanism occurring in phototrophic protists and metazoans.
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Affiliation(s)
- Lutz Wobbe
- Department of Biology, Algae Biotechnology and Bioenergy-Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany.
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Boehm M, Yu J, Reisinger V, Beckova M, Eichacker LA, Schlodder E, Komenda J, Nixon PJ. Subunit composition of CP43-less photosystem II complexes of Synechocystis sp. PCC 6803: implications for the assembly and repair of photosystem II. Philos Trans R Soc Lond B Biol Sci 2013; 367:3444-54. [PMID: 23148271 PMCID: PMC3497071 DOI: 10.1098/rstb.2012.0066] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Photosystem II (PSII) mutants are useful experimental tools to trap potential intermediates involved in the assembly of the oxygen-evolving PSII complex. Here, we focus on the subunit composition of the RC47 assembly complex that accumulates in a psbC null mutant of the cyanobacterium Synechocystis sp. PCC 6803 unable to make the CP43 apopolypeptide. By using native gel electrophoresis, we showed that RC47 is heterogeneous and mainly found as a monomer of 220 kDa. RC47 complexes co-purify with small Cab-like proteins (ScpC and/or ScpD) and with Psb28 and its homologue Psb28-2. Analysis of isolated His-tagged RC47 indicated the presence of D1, D2, the CP47 apopolypeptide, plus nine of the 13 low-molecular-mass (LMM) subunits found in the PSII holoenzyme, including PsbL, PsbM and PsbT, which lie at the interface between the two momomers in the dimeric holoenzyme. Not detected were the LMM subunits (PsbK, PsbZ, Psb30 and PsbJ) located in the vicinity of CP43 in the holoenzyme. The photochemical activity of isolated RC47-His complexes, including the rate of reduction of P680+, was similar to that of PSII complexes lacking the Mn4CaO5 cluster. The implications of our results for the assembly and repair of PSII in vivo are discussed.
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Affiliation(s)
- M Boehm
- Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London, UK
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Michoux F, Ahmad N, Hennig A, Nixon PJ, Warzecha H. Production of leafy biomass using temporary immersion bioreactors: an alternative platform to express proteins in transplastomic plants with drastic phenotypes. Planta 2013; 237:903-8. [PMID: 23262582 PMCID: PMC3579415 DOI: 10.1007/s00425-012-1829-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 12/03/2012] [Indexed: 05/30/2023]
Abstract
Chloroplast transformation technology is a promising approach for the production of foreign proteins in plants with expression levels of up to 70 % of total soluble protein (TSP) achieved in tobacco. However, expression of foreign protein in the chloroplast can lead to drastic or even lethal effects in transplastomic plants grown in soil, thereby potentially limiting the applicability of this technology. For instance, previous attempts to express the outer surface protein A (OspA) from Borrelia burgdorferi in tobacco chloroplasts led to plant death when expressed at 10 % TSP. We show here that this earlier transplastomic line, as well as a new plant line, OspA:YFP, expressing OspA fused to the yellow fluorescent protein, can be propagated in temporary immersion bioreactors (TIBs) using AlkaBurst™ technology to produce leafy biomass that expressed OspA at levels of up to 7.6 % TSP, to give a maximum yield of OspA of about 108 mg/L. Our results show that TIBs provide an alternative method for the production of transplastomic biomass expressing proteins toxic for plants and is a particularly useful approach when 'absolute' containment is required.
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Affiliation(s)
- Franck Michoux
- Alkion Biopharma SAS, 4 rue Pierre Fontaine, 91058, Evry, France.
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Eckert C, Boehm M, Carrieri D, Yu J, Dubini A, Nixon PJ, Maness PC. Genetic analysis of the Hox hydrogenase in the cyanobacterium Synechocystis sp. PCC 6803 reveals subunit roles in association, assembly, maturation, and function. J Biol Chem 2012; 287:43502-15. [PMID: 23139416 DOI: 10.1074/jbc.m112.392407] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Hydrogenases are metalloenzymes that catalyze 2H(+) + 2e(-) ↔ H(2). A multisubunit, bidirectional [NiFe]-hydrogenase has been identified and characterized in a number of bacteria, including cyanobacteria, where it is hypothesized to function as an electron valve, balancing reductant in the cell. In cyanobacteria, this Hox hydrogenase consists of five proteins in two functional moieties: a hydrogenase moiety (HoxYH) with homology to heterodimeric [NiFe]-hydrogenases and a diaphorase moiety (HoxEFU) with homology to NuoEFG of respiratory Complex I, linking NAD(P)H ↔ NAD(P)(+) as a source/sink for electrons. Here, we present an extensive study of Hox hydrogenase in the cyanobacterium Synechocystis sp. PCC 6803. We identify the presence of HoxEFUYH, HoxFUYH, HoxEFU, HoxFU, and HoxYH subcomplexes as well as association of the immature, unprocessed large subunit (HoxH) with other Hox subunits and unidentified factors, providing a basis for understanding Hox maturation and assembly. The analysis of mutants containing individual and combined hox gene deletions in a common parental strain reveals apparent alterations in subunit abundance and highlights an essential role for HoxF and HoxU in complex/subcomplex association. In addition, analysis of individual and combined hox mutant phenotypes in a single strain background provides a clear view of the function of each subunit in hydrogenase activity and presents evidence that its physiological function is more complicated than previously reported, with no outward defects apparent in growth or photosynthesis under various growth conditions.
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Affiliation(s)
- Carrie Eckert
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA.
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Beddis HP, Nixon PJ. Layering composites for ultimate aesthetics in direct restorations. Dent Update 2012; 39:630-636. [PMID: 23479852 DOI: 10.12968/denu.2012.39.9.630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
UNLABELLED A number of modern materials are available which allow placement of highly aesthetic anterior restorations. However, some systems are complex and technique sensitive. The authors describe a layering technique for the provision of direct aesthetic anterior composite restorations suitable for a general practice setting. CLINICAL RELEVANCE Aesthetic restorations can be provided directly and in a conservative manner using composite resin, often avoiding the need for more destructive indirect techniques.
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Affiliation(s)
- Hannah P Beddis
- Restorative Department, Level 5, Leeds Dental Institute, Clarendon Way, Leeds, LS2 9JT
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Burgess SJ, Tredwell G, Molnàr A, Bundy JG, Nixon PJ. Artificial microRNA-mediated knockdown of pyruvate formate lyase (PFL1) provides evidence for an active 3-hydroxybutyrate production pathway in the green alga Chlamydomonas reinhardtii. J Biotechnol 2012; 162:57-66. [DOI: 10.1016/j.jbiotec.2012.05.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2011] [Revised: 04/02/2012] [Accepted: 05/30/2012] [Indexed: 12/17/2022]
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Seymour DW, Chan MFWY, Nixon PJ. Dentinogenesis imperfecta: full-mouth rehabilitation using implants and sinus grafts--a case report. ACTA ACUST UNITED AC 2012; 39:498-500, 503-4. [PMID: 23094570 DOI: 10.12968/denu.2012.39.7.498] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
UNLABELLED This case report outlines one possible treatment modality to manage the developmental abnormality dentinogenesis imperfecta (DI). In this case, the patient's dentition is restored using a combination of full-coverage crowns for the remaining teeth and implant-supported crowns to replace missing teeth in a re-organized occlusal scheme. The case also demonstrates the effective use of the sinus graft procedure with simultaneous placement of dental implants. This paper also aims to make the reader aware of the current thinking behind treatment delivered to this group of patients, focusing on full-mouth rehabilitation using a combination of implant-supported and conventional metal ceramic crowns. CLINICAL RELEVANCE For the general dental practitioner this case outlines the prevalence and cause of DI. It demonstrates how early diagnosis and appropriate referral has an impact on future treatment.
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