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Cao K, Cui Y, Sun F, Zhang H, Fan J, Ge B, Cao Y, Wang X, Zhu X, Wei Z, Yao Q, Ma J, Wang Y, Meng C, Gao Z. Metabolic engineering and synthetic biology strategies for producing high-value natural pigments in Microalgae. Biotechnol Adv 2023; 68:108236. [PMID: 37586543 DOI: 10.1016/j.biotechadv.2023.108236] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 07/16/2023] [Accepted: 08/11/2023] [Indexed: 08/18/2023]
Abstract
Microalgae are microorganisms capable of producing bioactive compounds using photosynthesis. Microalgae contain a variety of high value-added natural pigments such as carotenoids, phycobilins, and chlorophylls. These pigments play an important role in many areas such as food, pharmaceuticals, and cosmetics. Natural pigments have a health value that is unmatched by synthetic pigments. However, the current commercial production of natural pigments from microalgae is not able to meet the growing market demand. The use of metabolic engineering and synthetic biological strategies to improve the production performance of microalgal cell factories is essential to promote the large-scale production of high-value pigments from microalgae. This paper reviews the health and economic values, the applications, and the synthesis pathways of microalgal pigments. Overall, this review aims to highlight the latest research progress in metabolic engineering and synthetic biology in constructing engineered strains of microalgae with high-value pigments and the application of CRISPR technology and multi-omics in this context. Finally, we conclude with a discussion on the bottlenecks and challenges of microalgal pigment production and their future development prospects.
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Affiliation(s)
- Kai Cao
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China; School of Life Sciences and medicine, Shandong University of Technology, Zibo 255049, China
| | - Yulin Cui
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Fengjie Sun
- Department of Biological Sciences, School of Science and Technology, Georgia Gwinnett College, Lawrenceville, GA 30043, USA
| | - Hao Zhang
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Jianhua Fan
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Baosheng Ge
- State Key Laboratory of Heavy Oil Processing and Center for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao 266580, China
| | - Yujiao Cao
- School of Foreign Languages, Shandong University of Technology, Zibo 255090, China
| | - Xiaodong Wang
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Xiangyu Zhu
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China; School of Life Sciences and medicine, Shandong University of Technology, Zibo 255049, China
| | - Zuoxi Wei
- School of Life Sciences and medicine, Shandong University of Technology, Zibo 255049, China
| | - Qingshou Yao
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Jinju Ma
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Yu Wang
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Chunxiao Meng
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China.
| | - Zhengquan Gao
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China.
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2
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Cao K, Wang X, Sun F, Zhang H, Cui Y, Cao Y, Yao Q, Zhu X, Yao T, Wang M, Meng C, Gao Z. Promoting Heme and Phycocyanin Biosynthesis in Synechocystis sp. PCC 6803 by Overexpression of Porphyrin Pathway Genes with Genetic Engineering. Mar Drugs 2023; 21:403. [PMID: 37504934 PMCID: PMC10382063 DOI: 10.3390/md21070403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 07/08/2023] [Accepted: 07/12/2023] [Indexed: 07/29/2023] Open
Abstract
Due to their unique biochemical and spectroscopic properties, both heme and phycocyanobilin are widely applied in the medical and food industries. Synechocystis sp. PCC 6803 contains both heme and phycocyanin, and is capable of synthesizing phycocyanin using heme as a precursor. The aim of this study was to uncover viable metabolic targets in the porphyrin pathway from Synechocystis sp. PCC 6803 to promote the accumulation of heme and phycocyanin in the recombinant strains of microalgae. A total of 10 genes related to heme synthesis pathway derived from Synechococcus elongatus PCC 7942 and 12 genes related to endogenous heme synthesis were individually overexpressed in strain PCC 6803. The growth rate and pigment content (heme, phycocyanin, chlorophyll a and carotenoids) of 22 recombinant algal strains were characterized. Quantitative real-time PCR technology was used to investigate the molecular mechanisms underlying the changes in physiological indicators in the recombinant algal strains. Among the 22 mutant strains, the mutant overexpressing the haemoglobin gene (glbN) of strain PCC 6803 had the highest heme content, which was 2.5 times higher than the wild type; the mutant overexpressing the gene of strain PCC 7942 (hemF) had the highest phycocyanin content, which was 4.57 times higher than the wild type. Overall, the results suggest that genes in the porphyrin pathway could significantly affect the heme and phycocyanin content in strain PCC 6803. Our study provides novel crucial targets for promoting the accumulation of heme and phycocyanin in cyanobacteria.
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Affiliation(s)
- Kai Cao
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo 255049, China
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Xiaodong Wang
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo 255049, China
| | - Fengjie Sun
- Department of Biological Sciences, School of Science and Technology, Georgia Gwinnett College, Lawrenceville, GA 30043, USA
| | - Hao Zhang
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Yulin Cui
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Yujiao Cao
- School of Foreign Languages, Shandong University of Technology, Zibo 255090, China
| | - Qingshou Yao
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Xiangyu Zhu
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Ting Yao
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Meng Wang
- Yantai Hongyuan Bio-Fertilizer Co., Ltd., Yantai 264000, China
| | - Chunxiao Meng
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo 255049, China
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Zhengquan Gao
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo 255049, China
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
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3
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Puzorjov A, Dunn KE, McCormick AJ. Production of thermostable phycocyanin in a mesophilic cyanobacterium. Metab Eng Commun 2021; 13:e00175. [PMID: 34168957 PMCID: PMC8209669 DOI: 10.1016/j.mec.2021.e00175] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/12/2021] [Accepted: 05/28/2021] [Indexed: 11/01/2022] Open
Abstract
Phycocyanin (PC) is a soluble phycobiliprotein found within the light-harvesting phycobilisome complex of cyanobacteria and red algae, and is considered a high-value product due to its brilliant blue colour and fluorescent properties. However, commercially available PC has a relatively low temperature stability. Thermophilic species produce more thermostable variants of PC, but are challenging and energetically expensive to cultivate. Here, we show that the PC operon from the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 (cpcBACD) is functional in the mesophile Synechocystis sp. PCC 6803. Expression of cpcBACD in an 'Olive' mutant strain of Synechocystis lacking endogenous PC resulted in high yields of thermostable PC (112 ± 1 mg g-1 DW) comparable to that of endogenous PC in wild-type cells. Heterologous PC also improved the growth of the Olive mutant, which was further supported by evidence of a functional interaction with the endogenous allophycocyanin core of the phycobilisome complex. The thermostability properties of the heterologous PC were comparable to those of PC from T. elongatus, and could be purified from the Olive mutant using a low-cost heat treatment method. Finally, we developed a scalable model to calculate the energetic benefits of producing PC from T. elongatus in Synechocystis cultures. Our model showed that the higher yields and lower cultivation temperatures of Synechocystis resulted in a 3.5-fold increase in energy efficiency compared to T. elongatus, indicating that producing thermostable PC in non-native hosts is a cost-effective strategy for scaling to commercial production.
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Affiliation(s)
- Anton Puzorjov
- SynthSys & Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Katherine E Dunn
- Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh, EH9 3DW, UK
| | - Alistair J McCormick
- SynthSys & Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3BF, UK
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Rathbone HW, Michie KA, Landsberg MJ, Green BR, Curmi PMG. Scaffolding proteins guide the evolution of algal light harvesting antennas. Nat Commun 2021; 12:1890. [PMID: 33767155 PMCID: PMC7994580 DOI: 10.1038/s41467-021-22128-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 02/17/2021] [Indexed: 11/19/2022] Open
Abstract
Photosynthetic organisms have developed diverse antennas composed of chromophorylated proteins to increase photon capture. Cryptophyte algae acquired their photosynthetic organelles (plastids) from a red alga by secondary endosymbiosis. Cryptophytes lost the primary red algal antenna, the red algal phycobilisome, replacing it with a unique antenna composed of αβ protomers, where the β subunit originates from the red algal phycobilisome. The origin of the cryptophyte antenna, particularly the unique α subunit, is unknown. Here we show that the cryptophyte antenna evolved from a complex between a red algal scaffolding protein and phycoerythrin β. Published cryo-EM maps for two red algal phycobilisomes contain clusters of unmodelled density homologous to the cryptophyte-αβ protomer. We modelled these densities, identifying a new family of scaffolding proteins related to red algal phycobilisome linker proteins that possess multiple copies of a cryptophyte-α-like domain. These domains bind to, and stabilise, a conserved hydrophobic surface on phycoerythrin β, which is the same binding site for its primary partner in the red algal phycobilisome, phycoerythrin α. We propose that after endosymbiosis these scaffolding proteins outcompeted the primary binding partner of phycoerythrin β, resulting in the demise of the red algal phycobilisome and emergence of the cryptophyte antenna. Cryptophytes acquired plastids from red algae but replaced the light-harvesting phycobilisome with a unique cryptophyte antenna. Here via analysis of phycobilisome cryo-EM structures, Rathbone et al. propose that the α subunit of the cryptophyte antenna originated from phycobilisome linker proteins
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Affiliation(s)
- Harry W Rathbone
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Katharine A Michie
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia.,Mark Wainwright Analytical Centre, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Michael J Landsberg
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, Australia
| | - Beverley R Green
- Botany Department, University of British Columbia, Vancouver, BC, V6N 3T7, Canada
| | - Paul M G Curmi
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia.
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5
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Xu C, Sun T, Li S, Chen L, Zhang W. Adaptive laboratory evolution of cadmium tolerance in Synechocystis sp. PCC 6803. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:205. [PMID: 30061927 PMCID: PMC6058365 DOI: 10.1186/s13068-018-1205-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 07/16/2018] [Indexed: 05/08/2023]
Abstract
BACKGROUND Cadmium has been a significant threat to environment and human health due to its high toxicity and wide application in fossil-fuel burning and battery industry. Cyanobacteria are one of the most dominant prokaryotes, and the previous studies suggested that they could be valuable in removing Cd2+ from waste water. However, currently, the tolerance to cadmium is very low in cyanobacteria. To further engineer cyanobacteria for the environmental application, it is thus necessary to determine the mechanism that they respond to high concentration of cadmium. RESULTS In this study, a robust strain of Synechocystis PCC 6803 (named ALE-9.0) tolerant to CdSO4 with a concentration up to 9.0 µM was successfully isolated via adaptive laboratory evolution over 802-day continuous passages under cadmium stress. Whole-genome re-sequencing was then performed and nine mutations were identified for the evolved strain compared to the wild-type strain. Among these mutations, a large fragment deletion in slr0454 encoding a cation or drug efflux system protein was found to contribute directly to the resistance to Cd2+ stress. In addition, five other mutations were also demonstrated related to the improved Cd2+ tolerance in ALE-9.0. Moreover, the evolved ALE-9.0 strain was found to obtain cross tolerance to some other heavy metals like zinc and cobalt as well as higher resistance to high light. CONCLUSIONS The work here identified six genes and their mutations related to Cd2+ tolerance in Synechocystis PCC 6803, and demonstrated the feasibility of adaptive laboratory evolution in tolerance modifications. This work also provided valuable information regarding the cadmium tolerance mechanism in Synechocystis PCC 6803, and useful insights for cyanobacterial robustness and tolerance engineering.
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Affiliation(s)
- Chunxiao Xu
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
- Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin, 300072 People’s Republic of China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, People’s Republic of China
| | - Tao Sun
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
- Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin, 300072 People’s Republic of China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, People’s Republic of China
| | - Shubin Li
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
- Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin, 300072 People’s Republic of China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, People’s Republic of China
| | - Lei Chen
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
- Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin, 300072 People’s Republic of China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, People’s Republic of China
| | - Weiwen Zhang
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
- Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin, 300072 People’s Republic of China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, People’s Republic of China
- Center for Biosafety Research and Strategy, Tianjin University, Tianjin, People’s Republic of China
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6
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Zhang P, Frankel LK, Bricker TM. Integration of apo-α-phycocyanin into phycobilisomes and its association with FNRL in the absence of the phycocyanin α-subunit lyase (CpcF) in Synechocystis sp. PCC 6803. PLoS One 2014; 9:e105952. [PMID: 25153076 PMCID: PMC4143364 DOI: 10.1371/journal.pone.0105952] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 07/29/2014] [Indexed: 12/27/2022] Open
Abstract
Phycocyanin is an important component of the phycobilisome, which is the principal light-harvesting complex in cyanobacteria. The covalent attachment of the phycocyanobilin chromophore to phycocyanin is catalyzed by the enzyme phycocyanin lyase. The photosynthetic properties and phycobilisome assembly state were characterized in wild type and two mutants which lack holo-α-phycocyanin. Insertional inactivation of the phycocyanin α-subunit lyase (ΔcpcF mutant) prevents the ligation of phycocyanobilin to α-phycocyanin (CpcA), while disruption of the cpcB/A/C2/C1 operon in the CK mutant prevents synthesis of both apo-α-phycocyanin (apo-CpcA) and apo-β-phycocyanin (apo-CpcB). Both mutants exhibited similar light saturation curves under white actinic light illumination conditions, indicating the phycobilisomes in the ΔcpcF mutant are not fully functional in excitation energy transfer. Under red actinic light illumination, wild type and both phycocyanin mutant strains exhibited similar light saturation characteristics. This indicates that all three strains contain functional allophycocyanin cores associated with their phycobilisomes. Analysis of the phycobilisome content of these strains indicated that, as expected, wild type exhibited normal phycobilisome assembly and the CK mutant assembled only the allophycocyanin core. However, the ΔcpcF mutant assembled phycobilisomes which, while much larger than the allophycocyanin core observed in the CK mutant, were significantly smaller than phycobilisomes observed in wild type. Interestingly, the phycobilisomes from the ΔcpcF mutant contained holo-CpcB and apo-CpcA. Additionally, we found that the large form of FNR (FNRL) accumulated to normal levels in wild type and the ΔcpcF mutant. In the CK mutant, however, significantly less FNRL accumulated. FNRL has been reported to associate with the phycocyanin rods in phycobilisomes via its N-terminal domain, which shares sequence homology with a phycocyanin linker polypeptide. We suggest that the assembly of apo-CpcA in the phycobilisomes of ΔcpcF can stabilize FNRL and modulate its function. These phycobilisomes, however, inefficiently transfer excitation energy to Photosystem II.
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Affiliation(s)
- Pengpeng Zhang
- Department of Biological Sciences, Biochemistry and Molecular Biology Division, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Laurie K. Frankel
- Department of Biological Sciences, Biochemistry and Molecular Biology Division, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Terry M. Bricker
- Department of Biological Sciences, Biochemistry and Molecular Biology Division, Louisiana State University, Baton Rouge, Louisiana, United States of America
- * E-mail:
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Leganés F, Martínez-Granero F, Muñoz-Martín MÁ, Marco E, Jorge A, Carvajal L, Vida T, González-Pleiter M, Fernández-Piñas F. Characterization and responses to environmental cues of a photosynthetic antenna-deficient mutant of the filamentous cyanobacterium Anabaena sp. PCC 7120. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:915-926. [PMID: 24913049 DOI: 10.1016/j.jplph.2014.03.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 03/19/2014] [Accepted: 03/19/2014] [Indexed: 06/03/2023]
Abstract
The cyanobacterial phycobilisome (PBS) is a giant pigment-protein complex which harvests light energy for photosynthesis and comprises two structures: a core and peripheral rods. Most studies on PBS structure and function are based on mutants of unicellular strains. In this report, we describe the phenotypic and genetic characterization of a transposon mutant of the filamentous Anabaena sp. strain PCC 7120, denoted LC1, which cannot synthesize the phycobiliprotein phycocyanin (PC), the main component of the rods; in this mutant, the transposon had inserted into the cpcB gene (orf alr0528) which putatively encodes PC-β chain. Mutant LC1 was able to synthesize phycoerythrocyanin (PEC), a phycobiliprotein (PBP) located at the terminal region of the rods; but in the absence of PC, PEC did not attach to the PBSs that only retained the allophycocyanin (APC) core; ferredoxin: NADP+-oxidoreductase (FNR) that is associated with the PBS in the wild type, was not found in isolated PBSs from LC1. The performance of the mutant exposed to different environmental conditions was evaluated. The mutant phenotype was successfully complemented by cloning and transfer of the wild type complete cpc operon to mutant LC1. Interestingly, LC1 compensated its mutation by significantly increasing the number of its core-PBS and the effective quantum yield of photosystem II (PSII) photochemistry; this feature suggests a more efficient energy conversion in the mutant which may be useful for biotechnological applications.
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Affiliation(s)
- Francisco Leganés
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | | | - M Ángeles Muñoz-Martín
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Eduardo Marco
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Alberto Jorge
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Laura Carvajal
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Teresa Vida
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Miguel González-Pleiter
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Francisca Fernández-Piñas
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049, Spain.
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8
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Lea-Smith DJ, Bombelli P, Dennis JS, Scott SA, Smith AG, Howe CJ. Phycobilisome-Deficient Strains of Synechocystis sp. PCC 6803 Have Reduced Size and Require Carbon-Limiting Conditions to Exhibit Enhanced Productivity. PLANT PHYSIOLOGY 2014; 165:705-714. [PMID: 24760817 PMCID: PMC4044857 DOI: 10.1104/pp.114.237206] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 04/17/2014] [Indexed: 05/21/2023]
Abstract
Reducing excessive light harvesting in photosynthetic organisms may increase biomass yields by limiting photoinhibition and increasing light penetration in dense cultures. The cyanobacterium Synechocystis sp. PCC 6803 harvests light via the phycobilisome, which consists of an allophycocyanin core and six radiating rods, each with three phycocyanin (PC) discs. Via targeted gene disruption and alterations to the promoter region, three mutants with two (pcpcT→C) and one (ΔCpcC1C2:pcpcT→C) PC discs per rod or lacking PC (olive) were generated. Photoinhibition and chlorophyll levels decreased upon phycobilisome reduction, although greater penetration of white light was observed only in the PC-deficient mutant. In all strains cultured at high cell densities, most light was absorbed by the first 2 cm of the culture. Photosynthesis and respiration rates were also reduced in the ΔCpcC1C2:pcpcT→C and olive mutants. Cell size was smaller in the pcpcT→C and olive strains. Growth and biomass accumulation were similar between the wild-type and pcpcT→C under a variety of conditions. Growth and biomass accumulation of the olive mutant were poorer in carbon-saturated cultures but improved in carbon-limited cultures at higher light intensities, as they did in the ΔCpcC1C2:pcpcT→C mutant. This study shows that one PC disc per rod is sufficient for maximal light harvesting and biomass accumulation, except under conditions of high light and carbon limitation, and two or more are sufficient for maximal oxygen evolution. To our knowledge, this study is the first to measure light penetration in bulk cultures of cyanobacteria and offers important insights into photobioreactor design.
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Affiliation(s)
- David J Lea-Smith
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
| | - Paolo Bombelli
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
| | - John S Dennis
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
| | - Stuart A Scott
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
| | - Alison G Smith
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
| | - Christopher J Howe
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (D.J.L.-S., P.B., C.J.H.);Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, United Kingdom (J.S.D.);Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom (S.A.S.); andDepartment of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom (A.G.S.)
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9
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Shen G, Schluchter WM, Bryant DA. Biogenesis of phycobiliproteins: I. cpcS-I and cpcU mutants of the cyanobacterium Synechococcus sp. PCC 7002 define a heterodimeric phyococyanobilin lyase specific for beta-phycocyanin and allophycocyanin subunits. J Biol Chem 2008; 283:7503-12. [PMID: 18199754 DOI: 10.1074/jbc.m708164200] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phycobilin lyases covalently attach phycobilin chromophores to apo-phycobiliproteins (PBPs). Genome analyses of the unicellular, marine cyanobacterium Synechococcus sp. PCC 7002 identified three genes, denoted cpcS-I, cpcU, and cpcV, that were possible candidates to encode phycocyanobilin (PCB) lyases. Single and double mutant strains for cpcS-I and cpcU exhibited slower growth rates, reduced PBP levels, and impaired assembly of phycobilisomes, but a cpcV mutant had no discernable phenotype. A cpcS-I cpcU cpcT triple mutant was nearly devoid of PBP. SDS-PAGE and mass spectrometry demonstrated that the cpcS-I and cpcU mutants produced an altered form of the phycocyanin (PC) beta subunit, which had a mass approximately 588 Da smaller than the wild-type protein. Some free PCB (mass = 588 Da) was tentatively detected in the phycobilisome fraction purified from the mutants. The modified PC from the cpcS-I, cpcU, and cpcS-I cpcU mutant strains was purified, and biochemical analyses showed that Cys-153 of CpcB carried a PCB chromophore but Cys-82 did not. These results show that both CpcS-I and CpcU are required for covalent attachment of PCB to Cys-82 of the PC beta subunit in this cyanobacterium. Suggesting that CpcS-I and CpcU are also required for attachment of PCB to allophycocyanin subunits in vivo, allophycocyanin levels were significantly reduced in all but the CpcV-less strain. These conclusions have been validated by in vitro experiments described in the accompanying report (Saunée, N. A., Williams, S. R., Bryant, D. A., and Schluchter, W. M. (2008) J. Biol. Chem. 283, 7513-7522). We conclude that the maturation of PBP in vivo depends on three PCB lyases: CpcE-CpcF, CpcS-I-CpcU, and CpcT.
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Affiliation(s)
- Gaozhong Shen
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Shen G, Saunée NA, Williams SR, Gallo EF, Schluchter WM, Bryant DA. Identification and characterization of a new class of bilin lyase: the cpcT gene encodes a bilin lyase responsible for attachment of phycocyanobilin to Cys-153 on the beta-subunit of phycocyanin in Synechococcus sp. PCC 7002. J Biol Chem 2006; 281:17768-78. [PMID: 16644722 DOI: 10.1074/jbc.m602563200] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Synechococcus sp. PCC 7002 and all other cyanobacteria that synthesize phycocyanin have a gene, cpcT, that is paralogous to cpeT, a gene of unknown function affecting phycoerythrin synthesis in Fremyella diplosiphon. A cpcT null mutant contains 40% less phycocyanin than wild type and produces smaller phycobilisomes with red-shifted absorbance and fluorescence emission maxima. Phycocyanin from the cpcT mutant has an absorbance maximum at 634 nm compared with 626 nm for the wild type. The phycocyanin beta-subunit from the cpcT mutant has slightly smaller apparent molecular weight on SDS-PAGE. Purified phycocyanins from the cpcT mutant and wild type were cleaved with formic acid, and the products were analyzed by SDS-PAGE. No phycocyanobilin chromophore was bound to the peptide containing Cys-153 derived from the phycocyanin beta-subunit of the cpcT mutant. Recombinant CpcT was used to perform in vitro bilin addition assays with apophycocyanin (CpcA/CpcB) and phycocyanobilin. Depending on the source of phycocyanobilin, reaction products with CpcT had absorbance maxima between 597 and 603 nm as compared with 638 nm for the control reactions, in which mesobiliverdin becomes covalently bound. After trypsin digestion and reverse phase high performance liquid chromatography, the CpcT reaction product produced one major phycocyanobilin-containing peptide. This peptide had a retention time identical to that of the tryptic peptide that includes phycocyanobilin-bound, cysteine 153 of wild-type phycocyanin. The results from characterization of the cpcT mutant as well as the in vitro biochemical assays demonstrate that CpcT is a new phycocyanobilin lyase that specifically attaches phycocyanobilin to Cys-153 of the phycocyanin beta-subunit.
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Affiliation(s)
- Gaozhong Shen
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
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Gill RT, Katsoulakis E, Schmitt W, Taroncher-Oldenburg G, Misra J, Stephanopoulos G. Genome-wide dynamic transcriptional profiling of the light-to-dark transition in Synechocystis sp. strain PCC 6803. J Bacteriol 2002; 184:3671-81. [PMID: 12057963 PMCID: PMC135141 DOI: 10.1128/jb.184.13.3671-3681.2002] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the results of whole-genome transcriptional profiling of the light-to-dark transition with the model photosynthetic prokaryote Synechocystis sp. strain PCC 6803 (Synechocystis). Experiments were conducted by growing Synechocystis cultures to mid-exponential phase and then exposing them to two cycles of light/dark conditions, during which RNA samples were obtained. These samples were probed with a full-genome DNA microarray (3,169 genes, 20 samples) as well as a partial-genome microarray (88 genes, 29 samples). We concluded that (i) 30-min sampling intervals accurately captured transcriptional dynamics throughout the light/dark transition, (ii) 25% of the Synechocystis genes (783 genes) responded positively to the presence of light, and (iii) the response dynamics varied greatly for individual genes, with a delay of up to 120 to 150 min for some genes. Four classes of genes were identified on the basis of their dynamic gene expression profiles: class I (108 genes, 30-min response time), class II (279 genes, 60 to 90 min), class III (258 genes, 120 to 150 min), and class IV (138 genes, 180 min). The dynamics of several transcripts from genes involved in photosynthesis and primary energy generation are discussed. Finally, we applied Fisher discriminant analysis to better visualize the progression of the overall transcriptional program throughout the light/dark transition and to determine those genes most indicative of the lighting conditions during growth.
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Affiliation(s)
- Ryan T Gill
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Anderson LK, Toole CM. A model for early events in the assembly pathway of cyanobacterial phycobilisomes. Mol Microbiol 1998; 30:467-74. [PMID: 9822813 DOI: 10.1046/j.1365-2958.1998.01081.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Biological self-assembly is remarkable in its fidelity and in the efficient production of intricate molecular machines and functional materials from a heterogeneous mixture of macromolecules. The phycobilisome, a light-harvesting structure of cyanobacteria, presents the opportunity to study an in vivo assembly process in detail. The phycobilisome molecular architecture is defined, and crystal structures are available for all major proteins, as are a large sequence database (including a genome sequence) and effective genetic systems exist for some cyanobacteria. Recent studies on subunit interaction, covalent modification, and protein stability suggest a model for the earliest events in the phycobilisome assembly pathway. Partitioning of phycobilisome proteins between degradation and assembly is proposed to be controlled by the interaction equilibria between phycobilisome assembly partners, processing enzymes and chaperones. The model provides plausible explanations for existing observations and makes predictions that are amenable to direct experimental investigation.
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Affiliation(s)
- L K Anderson
- Department of Biological Science, University of Tulsa, 600 S. College Ave, Tulsa, OK 74104, USA.
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Toole CM, Plank TL, Grossman AR, Anderson LK. Bilin deletions and subunit stability in cyanobacterial light-harvesting proteins. Mol Microbiol 1998; 30:475-86. [PMID: 9822814 DOI: 10.1046/j.1365-2958.1998.01082.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Light-harvesting in cyanobacteria and red algae is a function of the biliproteins, which have covalently bound bilin chromophores. The biliproteins are assembled with linker proteins into the phycobilisome, a large complex that resides on the surface of the photosynthetic membranes. Early steps in the phycobilisome assembly pathway include the folding of biliprotein alpha- and beta-subunits, covalent modification of subunits by bilin attachment and formation of the primary assembly unit, the alphabeta heterodimer. The potential role of bilins in subunit structure and assembly is examined in this study by site mutagenesis of biliprotein genes. Phycocyanin subunits from Synechocystis sp. 6701 that were unable to bind chromophores at specific sites were generated by changing the codons for bilin-binding cysteines to alanine residues. The altered genes were then expressed in a phycocyanin-minus mutant of the transformable Synechocystis sp. strain 6803. Single and multiple chromophore deletions cause specific and reproducible variations in phycobilisome-associated phycocyanin that do not correlate with transcript levels. Sedimentation equilibrium studies with purified proteins showed that bilin absence reduces the strength of alphabeta interaction in the heterodimer. These results suggest that phycocyanin instability in bilin-deletion mutants is a consequence of diversion of unassembled alpha- and beta-subunits to a degradation pathway. Attachment of the central bilin, which is common to all biliprotein subunits, may facilitate alphabeta interaction by completing the final stage of subunit folding and stabilizing the contact domains of binding partners in the heterodimer.
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Affiliation(s)
- C M Toole
- Department of Biological Science, University of Tulsa, 600 S. College Ave, Tulsa, OK 74104, USA
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Plank T, Toole C, Anderson LK. Subunit interactions and protein stability in the cyanobacterial light-harvesting proteins. J Bacteriol 1995; 177:6798-803. [PMID: 7592470 PMCID: PMC177545 DOI: 10.1128/jb.177.23.6798-6803.1995] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Strain 4R is a phycocyanin-minus mutant of the unicellular cyanobacterium Synechocystis sp. strain 6803. Although it lacks the light-harvesting protein phycocyanin, 4R has normal levels of phycocyanin (cpc) transcripts. Sequence analysis of the cpcB gene encoding the phycocyanin beta subunit shows an insertion mutation in 4R that causes early termination of translation. Other work has shown that the phycocyanin alpha subunit and the linker proteins encoded on the cpc transcripts are all functional in 4R, yet the defective phycocyanin beta subunit results in the complete absence of the alpha subunit and the linkers. Phycocyanin-minus mutants were constructed in a wild-type background by interruption of cpcB and cpcA with an antibiotic resistance gene and were compared with the 4R strain. Immunoblot analysis of the mutants demonstrated that interruption of one subunit was accompanied by a complete absence of the unassembled partner subunit. Phycocyanin assembly begins with the formation of the alpha beta heterodimer (the monomer) and continues through higher-order trimeric and hexameric aggregates that associate with linker proteins to form the phycobilisome rods. The results in this paper indicate that monomer formation is a critical stage in the biliprotein assembly pathway and that unassembled subunits are subject to stringent controls that prevent their appearance in vivo.
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Affiliation(s)
- T Plank
- Department of Biological Science, University of Tulsa, Oklahoma 74104, USA
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