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Kim W, Park Y, Jung J, Jeon CO, Toyofuku M, Lee J, Park W. Biological and Chemical Approaches for Controlling Harmful Microcystis Blooms. J Microbiol 2024; 62:249-260. [PMID: 38587591 DOI: 10.1007/s12275-024-00115-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 04/09/2024]
Abstract
The proliferation of harmful cyanobacterial blooms dominated by Microcystis aeruginosa has become an increasingly serious problem in freshwater ecosystems due to climate change and eutrophication. Microcystis-blooms in freshwater generate compounds with unpleasant odors, reduce the levels of dissolved O2, and excrete microcystins into aquatic ecosystems, potentially harming various organisms, including humans. Various chemical and biological approaches have thus been developed to mitigate the impact of the blooms, though issues such as secondary pollution and high economic costs have not been adequately addressed. Red clays and H2O2 are conventional treatment methods that have been employed worldwide for the mitigation of the blooms, while novel approaches, such as the use of plant or microbial metabolites and antagonistic bacteria, have also recently been proposed. Many of these methods rely on the generation of reactive oxygen species, the inhibition of photosynthesis, and/or the disruption of cellular membranes as their mechanisms of action, which may also negatively impact other freshwater microbiota. Nevertheless, the underlying molecular mechanisms of anticyanobacterial chemicals and antagonistic bacteria remain unclear. This review thus discusses both conventional and innovative approaches for the management of M. aeruginosa in freshwater bodies.
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Affiliation(s)
- Wonjae Kim
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Yerim Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Jaejoon Jung
- Department of Life Science, Chung-Ang University, Seoul, 02841, Republic of Korea
| | - Che Ok Jeon
- Department of Life Science, Chung-Ang University, Seoul, 02841, Republic of Korea
| | - Masanori Toyofuku
- Department of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-0006, Japan
| | - Jiyoung Lee
- Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, OH, 43210, USA
- Department of Food Science and Technology, The Ohio State University, Columbus, OH, 43210, USA
| | - Woojun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea.
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Kukil K, Lindberg P. Metabolic engineering of Synechocystis sp. PCC 6803 for the improved production of phenylpropanoids. Microb Cell Fact 2024; 23:57. [PMID: 38369470 PMCID: PMC10875765 DOI: 10.1186/s12934-024-02330-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 02/09/2024] [Indexed: 02/20/2024] Open
Abstract
BACKGROUND Phenylpropanoids are a large group of plant secondary metabolites with various biological functions, derived from aromatic amino acids. Cyanobacteria are promising host organisms for sustainable production of plant phenylpropanoids. We have previously engineered Synechocystis sp. PCC 6803 to produce trans-cinnamic acid (tCA) and p-coumaric acid (pCou), the first intermediates of phenylpropanoid pathway, by overexpression of phenylalanine- and tyrosine ammonia lyases. In this study, we aimed to enhance the production of the target compounds tCA and pCou in Synechocystis. RESULTS We eliminated the 4-hydroxyphenylpyruvate dioxygenase (HPPD) activity, which is a competing pathway consuming tyrosine and, possibly, phenylalanine for tocopherol synthesis. Moreover, several genes of the terminal steps of the shikimate pathway were overexpressed alone or in operons, such as aromatic transaminases, feedback insensitive cyclohexadienyl dehydrogenase (TyrC) from Zymomonas mobilis and the chorismate mutase (CM) domain of the fused chorismate mutase/prephenate dehydratase enzyme from Escherichia coli. The obtained engineered strains demonstrated nearly 1.5 times enhanced tCA and pCou production when HPPD was knocked out compared to the parental production strains, accumulating 138 ± 3.5 mg L-1 of tCA and 72.3 ± 10.3 mg L-1 of pCou after seven days of photoautotrophic growth. However, there was no further improvement when any of the pathway genes were overexpressed. Finally, we used previously obtained AtPRM8 and TsPRM8 Synechocystis strains with deregulated shikimate pathway as a background for the overexpression of synthetic constructs with ppd knockout. CONCLUSIONS HPPD elimination enhances the tCA and pCou productivity to a similar extent. The use of PRM8 based strains as a background for overexpression of synthetic constructs, however, did not promote tCA and pCou titers, which indicates a tight regulation of the terminal steps of phenylalanine and tyrosine synthesis. This work contributes to establishing cyanobacteria as hosts for phenylpropanoid production.
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Affiliation(s)
- Kateryna Kukil
- Microbial Chemistry, Department of Chemistry - Ångström, Uppsala University, Box 523, SE 751 20, Uppsala, Sweden
| | - Pia Lindberg
- Microbial Chemistry, Department of Chemistry - Ångström, Uppsala University, Box 523, SE 751 20, Uppsala, Sweden.
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Jin H, Zhang J, Wang Y, Ge W, Jing Y, Cao X, Huo Y, Fu Y. A codon-based live-cell biomonitoring system for assessing intracellular phenylalanine bioavailability in cyanobacteria. Biosens Bioelectron 2024; 244:115792. [PMID: 37922807 DOI: 10.1016/j.bios.2023.115792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 10/17/2023] [Accepted: 10/25/2023] [Indexed: 11/07/2023]
Abstract
Phenylalanine, as an essential aromatic amino acid, is not only needed for protein and vital molecules such as neurotransmitter and hormone synthesis but also a substrate for the biosynthesis of phenylpropanoids and various bioactive compounds. The metabolism of phenylalanine is dynamic and transitory, which would otherwise inhibit cell growth. Therefore, it is challenging and imperative to monitor intracellular phenylalanine bioavailability in real time, which has great significance for evaluating the effectiveness of introducing pathway-specific genetic modifications to enhance phenylalanine generation. In this study, we proposed a live-cell biomonitoring system to assess phenylalanine bioavailability in real time in cyanobacteria based on codon degeneracy and species-specific usage bias. The biomonitoring system was generated through genetic modification of phenylalanine codons in the chloramphenicol antibiotic resistance gene to wholly preferred and rare codons, in combination with an orthogonal constitutive promoter Trc to express these genes. Cyanobacterial cells equipped with a preferred codon-based gene showed a significant growth advantage over those with rare codons under antibiotic pressure, while the delayed growth caused by rare codon-based genes could be rescued by supplementing phenylalanine in the cultivation medium. Increasing intracellular phenylalanine bioavailability could promote rare codon-based gene containing cell growth to a similar level as wild-type strains harboring preferred codon-based gene, providing a live-cell visualized screening method to relatively define phenylalanine content from either random mutation libraries or pathway-specific engineering cyanobacterial chassis before conducting labor-intensive quantitative measurements.
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Affiliation(s)
- Haojie Jin
- The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, 100083, PR China; Ecological Observation and Research Station of Heilongjiang Sanjiang Plain Wetlands, National Forestry and Grassland Administration, Shuangyashan, 518000, PR China
| | - Jiaqi Zhang
- The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, 100083, PR China
| | - Yan Wang
- Center of Basic Medical Research, Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing, 100191, PR China
| | - Wanzhao Ge
- The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, 100083, PR China
| | - Yike Jing
- The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, 100083, PR China
| | - Xiaoyu Cao
- The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, 100083, PR China
| | - Yixin Huo
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, PR China
| | - Yujie Fu
- The Key Laboratory for Silviculture and Conservation of Ministry of Education, College of Forestry, Beijing Forestry University, Beijing, 100083, PR China; Ecological Observation and Research Station of Heilongjiang Sanjiang Plain Wetlands, National Forestry and Grassland Administration, Shuangyashan, 518000, PR China.
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Sporre E, Karlsen J, Schriever K, Asplund-Samuelsson J, Janasch M, Strandberg L, Karlsson A, Kotol D, Zeckey L, Piazza I, Syrén PO, Edfors F, Hudson EP. Metabolite interactions in the bacterial Calvin cycle and implications for flux regulation. Commun Biol 2023; 6:947. [PMID: 37723200 PMCID: PMC10507043 DOI: 10.1038/s42003-023-05318-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 09/01/2023] [Indexed: 09/20/2023] Open
Abstract
Metabolite-level regulation of enzyme activity is important for microbes to cope with environmental shifts. Knowledge of such regulations can also guide strain engineering for biotechnology. Here we apply limited proteolysis-small molecule mapping (LiP-SMap) to identify and compare metabolite-protein interactions in the proteomes of two cyanobacteria and two lithoautotrophic bacteria that fix CO2 using the Calvin cycle. Clustering analysis of the hundreds of detected interactions shows that some metabolites interact in a species-specific manner. We estimate that approximately 35% of interacting metabolites affect enzyme activity in vitro, and the effect is often minor. Using LiP-SMap data as a guide, we find that the Calvin cycle intermediate glyceraldehyde-3-phosphate enhances activity of fructose-1,6/sedoheptulose-1,7-bisphosphatase (F/SBPase) from Synechocystis sp. PCC 6803 and Cupriavidus necator in reducing conditions, suggesting a convergent feed-forward activation of the cycle. In oxidizing conditions, glyceraldehyde-3-phosphate inhibits Synechocystis F/SBPase by promoting enzyme aggregation. In contrast, the glycolytic intermediate glucose-6-phosphate activates F/SBPase from Cupriavidus necator but not F/SBPase from Synechocystis. Thus, metabolite-level regulation of the Calvin cycle is more prevalent than previously appreciated.
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Affiliation(s)
- Emil Sporre
- Department of Protein Science, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Jan Karlsen
- Department of Protein Science, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Karen Schriever
- Department of Fiber and Polymer Technology, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Johannes Asplund-Samuelsson
- Department of Protein Science, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Markus Janasch
- Department of Protein Science, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
- Department of Biotechnology and Nanomedicine, SINTEF Industry, 7465, Trondheim, Norway
| | - Linnéa Strandberg
- Department of Protein Science, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Anna Karlsson
- Department of Protein Science, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - David Kotol
- Department of Protein Science, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Luise Zeckey
- Department of Protein Science, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Ilaria Piazza
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Per-Olof Syrén
- Department of Fiber and Polymer Technology, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Fredrik Edfors
- Department of Protein Science, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Elton P Hudson
- Department of Protein Science, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden.
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Kukil K, Englund E, Crang N, Hudson EP, Lindberg P. Laboratory evolution of Synechocystis sp. PCC 6803 for phenylpropanoid production. Metab Eng 2023; 79:27-37. [PMID: 37392984 DOI: 10.1016/j.ymben.2023.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/14/2023] [Accepted: 06/29/2023] [Indexed: 07/03/2023]
Abstract
Cyanobacteria are promising as a biotechnological platform for production of various industrially relevant compounds, including aromatic amino acids and their derivatives, phenylpropanoids. In this study, we have generated phenylalanine resistant mutant strains (PRMs) of the unicellular cyanobacterium Synechocystis sp. PCC 6803, by laboratory evolution under the selective pressure of phenylalanine, which inhibits the growth of wild type Synechocystis. The new strains of Synechocystis were tested for their ability to secrete phenylalanine in the growth medium during cultivation in shake flasks as well as in a high-density cultivation (HDC) system. All PRM strains secreted phenylalanine into the culture medium, with one of the mutants, PRM8, demonstrating the highest specific production of 24.9 ± 7 mg L-1·OD750-1 or 610 ± 196 mg L-1 phenylalanine after four days of growth in HDC. We further overexpressed phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) in the mutant strains in order to determine the potential of PRMs for production of trans-cinnamic acid (tCA) and para-coumaric acid (pCou), the first intermediates of the plant phenylpropanoid pathway. Productivities of these compounds were found to be lower in the PRMs compared to respective control strains, except for PRM8 under HDC conditions. The PRM8 background strain in combination with PAL or TAL expression demonstrated a specific production of 52.7 ± 15 mg L-1·OD750-1tCA and 47.1 ± 7 mg L-1·OD750-1pCou, respectively, with a volumetric titer reaching above 1 g L-1 for both products after four days of HDC cultivation. The genomes of PRMs were sequenced in order to identify which mutations caused the phenotype. Interestingly, all of the PRMs contained at least one mutation in their ccmA gene, which encodes DAHP synthase, the first enzyme of the pathway for aromatic amino acids biosynthesis. Altogether, we demonstrate that the combination of laboratory-evolved mutants and targeted metabolic engineering can be a powerful tool in cyanobacterial strain development.
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Affiliation(s)
- Kateryna Kukil
- Microbial Chemistry, Department of Chemistry - Ångström, Uppsala University, Box 523, SE 751 20, Uppsala, Sweden
| | - Elias Englund
- School of Engineering Sciences in Chemistry, Biotechnology and Health, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Nick Crang
- School of Engineering Sciences in Chemistry, Biotechnology and Health, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Elton P Hudson
- School of Engineering Sciences in Chemistry, Biotechnology and Health, Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Pia Lindberg
- Microbial Chemistry, Department of Chemistry - Ångström, Uppsala University, Box 523, SE 751 20, Uppsala, Sweden.
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Kukil K, Lindberg P. Expression of phenylalanine ammonia lyases in Synechocystis sp. PCC 6803 and subsequent improvements of sustainable production of phenylpropanoids. Microb Cell Fact 2022; 21:8. [PMID: 35012528 PMCID: PMC8750797 DOI: 10.1186/s12934-021-01735-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 12/29/2021] [Indexed: 11/18/2022] Open
Abstract
Background Phenylpropanoids represent a diverse class of industrially important secondary metabolites, synthesized in plants from phenylalanine and tyrosine. Cyanobacteria have a great potential for sustainable production of phenylpropanoids directly from CO2, due to their photosynthetic lifestyle with a fast growth compared to plants and the ease of generating genetically engineered strains. This study focuses on photosynthetic production of the starting compounds of the phenylpropanoid pathway, trans-cinnamic acid and p-coumaric acid, in the unicellular cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis). Results A selected set of phenylalanine ammonia lyase (PAL) enzymes from different organisms was overexpressed in Synechocystis, and the productivities of the resulting strains compared. To further improve the titer of target compounds, we evaluated the use of stronger expression cassettes for increasing PAL protein levels, as well as knock-out of the laccase gene slr1573, as this was previously reported to prevent degradation of the target compounds in the cell. Finally, to investigate the effect of growth conditions on the production of trans-cinnamic and p-coumaric acids from Synechocystis, cultivation conditions promoting rapid, high density growth were tested. Comparing the different PALs, the highest specific titer was achieved for the strain AtC, expressing PAL from Arabidopsis thaliana. A subsequent increase of protein level did not improve the productivity. Production of target compounds in strains where the slr1573 laccase had been knocked out was found to be lower compared to strains with wild type background, and the Δslr1573 strains exhibited a strong phenotype of slower growth rate and lower pigment content. Application of a high-density cultivation system for the growth of production strains allowed reaching the highest total titers of trans-cinnamic and p-coumaric acids reported so far, at around 0.8 and 0.4 g L−1, respectively, after 4 days. Conclusions Production of trans-cinnamic acid, unlike that of p-coumaric acid, is not limited by the protein level of heterologously expressed PAL in Synechocystis. High density cultivation led to higher titres of both products, while knocking out slr1573 did not have a positive effect on production. This work contributes to capability of exploiting the primary metabolism of cyanobacteria for sustainable production of plant phenylpropanoids. Supplementary Information The online version contains supplementary material available at 10.1186/s12934-021-01735-8.
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Affiliation(s)
- Kateryna Kukil
- Microbial Chemistry, Department of Chemistry - Ångström, Uppsala University, Box 523, SE 751 20, Uppsala, Sweden
| | - Pia Lindberg
- Microbial Chemistry, Department of Chemistry - Ångström, Uppsala University, Box 523, SE 751 20, Uppsala, Sweden.
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Jin H, Wang Y, Zhao P, Wang L, Zhang S, Meng D, Yang Q, Cheong LZ, Bi Y, Fu Y. Potential of Producing Flavonoids Using Cyanobacteria As a Sustainable Chassis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:12385-12401. [PMID: 34649432 DOI: 10.1021/acs.jafc.1c04632] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Numerous plant secondary metabolites have remarkable impacts on both food supplements and pharmaceuticals for human health improvement. However, higher plants can only generate small amounts of these chemicals with specific temporal and spatial arrangements, which are unable to satisfy the expanding market demands. Cyanobacteria can directly utilize CO2, light energy, and inorganic nutrients to synthesize versatile plant-specific photosynthetic intermediates and organic compounds in large-scale photobioreactors with outstanding economic merit. Thus, they have been rapidly developed as a "green" chassis for the synthesis of bioproducts. Flavonoids, chemical compounds based on aromatic amino acids, are considered to be indispensable components in a variety of nutraceutical, pharmaceutical, and cosmetic applications. In contrast to heterotrophic metabolic engineering pioneers, such as yeast and Escherichia coli, information about the biosynthesis flavonoids and their derivatives is less comprehensive than that of their photosynthetic counterparts. Here, we review both benefits and challenges to promote cyanobacterial cell factories for flavonoid biosynthesis. With increasing concerns about global environmental issues and food security, we are confident that energy self-supporting cyanobacteria will attract increasing attention for the generation of different kinds of bioproducts. We hope that the work presented here will serve as an index and encourage more scientists to join in the relevant research area.
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Affiliation(s)
- Haojie Jin
- College of Forestry, Beijing Forestry University, Beijing 100083, P.R. China
| | - Yan Wang
- Center of Basic Medical Research, Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing 100191, P.R. China
| | - Pengquan Zhao
- College of Forestry, Beijing Forestry University, Beijing 100083, P.R. China
| | - Litao Wang
- College of Forestry, Beijing Forestry University, Beijing 100083, P.R. China
| | - Su Zhang
- College of Forestry, Beijing Forestry University, Beijing 100083, P.R. China
| | - Dong Meng
- College of Forestry, Beijing Forestry University, Beijing 100083, P.R. China
| | - Qing Yang
- College of Forestry, Beijing Forestry University, Beijing 100083, P.R. China
| | - Ling-Zhi Cheong
- Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, College of Food and Pharmaceutical Science, Ningbo University, Ningbo 315211, China
| | - Yonghong Bi
- State Key Laboratory of Fresh Water Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430070, P.R. China
| | - Yujie Fu
- College of Forestry, Beijing Forestry University, Beijing 100083, P.R. China
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Liu H, Cao Y, Guo J, Xu X, Long Q, Song L, Xian M. Study on the isoprene-producing co-culture system of Synechococcus elongates-Escherichia coli through omics analysis. Microb Cell Fact 2021; 20:6. [PMID: 33413404 PMCID: PMC7791884 DOI: 10.1186/s12934-020-01498-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 12/15/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The majority of microbial fermentations are currently performed in the batch or fed-batch manner with the high process complexity and huge water consumption. The continuous microbial production can contribute to the green sustainable development of the fermentation industry. The co-culture systems of photo-autotrophic and heterotrophic species can play important roles in establishing the continuous fermentation mode for the bio-based chemicals production. RESULTS In the present paper, the co-culture system of Synechococcus elongates-Escherichia coli was established and put into operation stably for isoprene production. Compared with the axenic culture, the fermentation period of time was extended from 100 to 400 h in the co-culture and the isoprene production was increased to eightfold. For in depth understanding this novel system, the differential omics profiles were analyzed. The responses of BL21(DE3) to S. elongatus PCC 7942 were triggered by the oxidative pressure through the Fenton reaction and all these changes were linked with one another at different spatial and temporal scales. The oxidative stress mitigation pathways might contribute to the long-lasting fermentation process. The performance of this co-culture system can be further improved according to the fundamental rules discovered by the omics analysis. CONCLUSIONS The isoprene-producing co-culture system of S. elongates-E. coli was established and then analyzed by the omics methods. This study on the co-culture system of the model S. elongates-E. coli is of significance to reveal the common interactions between photo-autotrophic and heterotrophic species without natural symbiotic relation, which could provide the scientific basis for rational design of microbial community.
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Affiliation(s)
- Hui Liu
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
| | - Yujin Cao
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
| | - Jing Guo
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
| | - Xin Xu
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
| | - Qi Long
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
| | - Lili Song
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
| | - Mo Xian
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
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Combining Random Mutagenesis and Metabolic Engineering for Enhanced Tryptophan Production in Synechocystis sp. Strain PCC 6803. Appl Environ Microbiol 2020; 86:AEM.02816-19. [PMID: 32144109 DOI: 10.1128/aem.02816-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 02/27/2020] [Indexed: 01/08/2023] Open
Abstract
Tryptophan (Trp) is an essential aromatic amino acid that has value as an animal feed supplement, as the amount found in plant-based sources is insufficient. An alternative to production by engineered microbial fermentation is to have tryptophan biosynthesized by a photosynthetic microorganism that could replace or supplement both the plant and industrially used microbes. We selected Synechocystis sp. strain PCC 6803, a model cyanobacterium, as the host and studied metabolic engineering and random mutagenesis approaches. Previous work on engineering heterotrophic microbes for improved Trp titers has targeted allosteric feedback regulation in enzymes 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase (DAHPS) and anthranilate synthase (AS) as major bottlenecks in the shikimate pathway. In this work, the genes encoding feedback-resistant enzymes from Escherichia coli, aroGfbr and trpEfbr , were overexpressed in the host wild-type (WT) strain. Separately, the WT strain was subjected to random mutagenesis and selection using an amino acid analog to isolate tryptophan-overproducing strains. The randomly mutagenized strains were sequenced in order to identify the mutations that resulted in the desirable phenotypes. Interestingly, the tryptophan overproducers had mutations in the gene encoding chorismate mutase (CM), which catalyzes the conversion of chorismate to prephenate. The best tryptophan overproducer from random mutagenesis was selected as a host for metabolic engineering where aroGfbr and trpEfbr were overexpressed. The best strain developed produced 212 ± 23 mg/liter of tryptophan after 10 days of photoautotrophic growth under 3% (vol/vol) CO2 We demonstrated that a combination of random mutagenesis and metabolic engineering was superior to either individual approach.IMPORTANCE Aromatic amino acids such as tryptophan are primarily used as additives in the animal feed industry and are typically produced using genetically engineered heterotrophic organisms such as Escherichia coli This involves a two-step process, where the substrate such as molasses is first obtained from plants followed by fermentation by heterotrophic organisms. We have engineered photoautotrophic cyanobacterial strains by a combination of random mutagenesis and metabolic engineering. These strains grow on CO2 as the sole carbon source and utilize light as the sole energy source to produce tryptophan, thus converting the two-step process into a single step. Our results show that combining random mutagenesis and metabolic engineering was superior to either approach alone. This study also builds a foundation for further engineering of cyanobacteria for industrial tryptophan production.
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Stebegg R, Schmetterer G, Rompel A. Transport of organic substances through the cytoplasmic membrane of cyanobacteria. PHYTOCHEMISTRY 2019; 157:206-218. [PMID: 30447471 DOI: 10.1016/j.phytochem.2018.08.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 07/25/2018] [Accepted: 08/17/2018] [Indexed: 06/09/2023]
Abstract
Cyanobacteria are mainly known to incorporate inorganic molecules like carbon dioxide and ammonia from the environment into organic material within the cell. Nevertheless cyanobacteria do import and export organic substances through the cytoplasmic membrane and these processes are essential for all cyanobacteria. In addition understanding the mechanisms of transport of organic molecules through the cytoplasmic membrane might become very important. Genetically modified strains of cyanobacteria could serve as producers and exporters of commercially important substances. In this review we attempt to present all data of transport of organic molecules through the cytoplasmic membrane of cyanobacteria that are currently available with the transported molecules ordered according to their chemical classes.
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Affiliation(s)
- Ronald Stebegg
- Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie, Althanstraße 14, 1090 Wien, Austria(1).
| | - Georg Schmetterer
- Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie, Althanstraße 14, 1090 Wien, Austria(1).
| | - Annette Rompel
- Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie, Althanstraße 14, 1090 Wien, Austria(1).
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Barón-Sola Á, Fernández Del Campo F, Sanz-Alférez S. Influence of Glycine and Arginine on Cylindrospermopsin Production and aoa Gene Expression in Aphanizomenon ovalisporum. Toxins (Basel) 2017; 9:toxins9110355. [PMID: 29104251 PMCID: PMC5705970 DOI: 10.3390/toxins9110355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 10/24/2017] [Accepted: 10/26/2017] [Indexed: 11/16/2022] Open
Abstract
Arginine (Arg) and glycine (Gly) seem to be the only substrates accepted by the amidinotransferase that catalyze the first step of the synthesis pathway of the cyanotoxin cylindrospermopsin (CYN), leading to guanidinoacetate (GAA). Here, the effect of these amino acids on the production of CYN in cultures of the cylindrospermopsin-producing strain, Aphanizomenon ovalisporum UAM-MAO, has been studied. Arg clearly increased CYN content, the increment appearing triphasic along the culture. On the contrary, Gly caused a decrease of CYN, observable from the first day on. Interestingly, the transcript of the gene ntcA, key in nitrogen metabolism control, was also enhanced in the presence of Arg and/or Gly, the trend of the transcript oscillations being like that of aoa/cyr. The inhibitory effect of Gly in CYN production seems not to result from diminishing the activity of genes considered involved in CYN synthesis, since Gly, as Arg, enhance the transcription of genes aoaA-C and cyrJ. On the other hand, culture growth is affected by Arg and Gly in a similar way to CYN production, with Arg stimulating and Gly impairing it. Taken together, our data show that the influence of both Arg and Gly on CYN changes seems not to be due to a specific effect on the first step of CYN synthesis; it rather appears to be the result of changes in the physiological cell status.
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Affiliation(s)
- Ángel Barón-Sola
- Departament of Biology, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain.
| | | | - Soledad Sanz-Alférez
- Departament of Biology, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid, Spain.
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12
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Li T, Li CT, Butler K, Hays SG, Guarnieri MT, Oyler GA, Betenbaugh MJ. Mimicking lichens: incorporation of yeast strains together with sucrose-secreting cyanobacteria improves survival, growth, ROS removal, and lipid production in a stable mutualistic co-culture production platform. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:55. [PMID: 28344645 PMCID: PMC5360037 DOI: 10.1186/s13068-017-0736-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 02/17/2017] [Indexed: 05/04/2023]
Abstract
BACKGROUND The feasibility of heterotrophic-phototrophic symbioses was tested via pairing of yeast strains Cryptococcus curvatus, Rhodotorula glutinis, or Saccharomyces cerevisiae with a sucrose-secreting cyanobacterium Synechococcus elongatus. RESULTS The phototroph S. elongatus showed no growth in standard BG-11 medium with yeast extract, but grew well in BG-11 medium alone or supplemented with yeast nitrogen base without amino acids (YNB w/o aa). Among three yeast species, C. curvatus and R. glutinis adapted well to the BG-11 medium supplemented with YNB w/o aa, sucrose, and various concentrations of NaCl needed to maintain sucrose secretion from S. elongatus, while growth of S. cerevisiae was highly dependent on sucrose levels. R. glutinis and C. curvatus grew efficiently and utilized sucrose produced by the partner in co-culture. Co-cultures of S. elongatus and R. glutinis were sustained over 1 month in both batch and in semi-continuous culture, with the final biomass and overall lipid yields in the batch co-culture 40 to 60% higher compared to batch mono-cultures of S. elongatus. The co-cultures showed enhanced levels of palmitoleic and linoleic acids. Furthermore, cyanobacterial growth in co-culture with R. glutinis was significantly superior to axenic growth, as S. elongatus was unable to grow in the absence of the yeast partner when cultivated at lower densities in liquid medium. Accumulated reactive oxygen species was observed to severely inhibit axenic growth of cyanobacteria, which was efficiently alleviated through catalase supply and even more effectively with co-cultures of R. glutinis. CONCLUSIONS The pairing of a cyanobacterium and eukaryotic heterotroph in the artificial lichen of this study demonstrates the importance of mutual interactions between phototrophs and heterotrophs, e.g., phototrophs provide a carbon source to heterotrophs, and heterotrophs assist phototrophic growth and survival by removing/eliminating oxidative stress. Our results establish a potential stable production platform that combines the metabolic capability of photoautotrophs to capture inorganic carbon with the channeling of the resulting organic carbon directly to a robust heterotroph partner for producing biofuel and other chemical precursors.
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Affiliation(s)
- Tingting Li
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Chien-Ting Li
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Kirk Butler
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Stephanie G. Hays
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115 USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115 USA
| | - Michael T. Guarnieri
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - George A. Oyler
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Michael J. Betenbaugh
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218 USA
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13
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Yang F, Li X, Li Y, Wei H, Yu G, Yin L, Liang G, Pu Y. Lysing activity of an indigenous algicidal bacterium Aeromonas sp. against Microcystis spp. isolated from Lake Taihu. ENVIRONMENTAL TECHNOLOGY 2013; 34:1421-1427. [PMID: 24191475 DOI: 10.1080/09593330.2012.752872] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This study aimed to isolate and characterize an indigenous algicidal bacterium named LTH-1 and its algae-lysing compounds active against three Microcystis aeruginosa strains (toxic TH1, nontoxic TH2 and standard FACHB 905). The LTH-1 isolated from Lake Taihu, near Wuxi City in China, was identified as Aeromonas sp. based on its morphological characteristic features and phylogenetic analysis by sequencing of 16S rDNA. Extracellular compounds produced by LTH-1 showed strong algaelysing activity, and they were water-soluble and heat-tolerant, with a molecular mass lower than 2 kDa. Two algae-lysing compounds were isolated and purified from extracellular filtrate using silica gel column chromatography. One of these was identified as phenylalanine (C9H11NO2, m/z 166.0862) and the other (C8H16N2O3, m/z 189.1232) was unidentified by hybrid ion trap/time-of-flight mass spectrometry coupled with a high-performance liquid chromatography (LC/MS-IT-TOF) system. The half maximal effective concentration (EC50) of phenylalanine produced by LTH-1 against FACHB 905 was 68.2 +/- 8.2 microg mL(-1) in 48h. These results suggest that the algicidal Aeromonas sp. LTH-1 could play a role in controlling Microcystis blooms, and its extracellular compounds are also potentially useful for regulating blooms of the harmful M. aeruginosa.
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Affiliation(s)
- Fei Yang
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University Nanjing, China
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14
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Takamura Y, Yamada T, Kimoto A, Kanehama N, Tanaka T, Nakadaira S, Yagi O. Growth Inhibition of Microcystis Cyanobacteria by L-Lysine and Disappearance of Natural Microcystis Blooms with Spraying. Microbes Environ 2004. [DOI: 10.1264/jsme2.19.31] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Yoshichika Takamura
- Department of Bioresources Sciences, School of Agriculture, Ibaraki University
| | - Takashi Yamada
- Department of Bioresources Sciences, School of Agriculture, Ibaraki University
| | - Akiko Kimoto
- Department of Bioresources Sciences, School of Agriculture, Ibaraki University
| | - Naomi Kanehama
- Department of Bioresources Sciences, School of Agriculture, Ibaraki University
| | - Tetsuya Tanaka
- Mechanical Engineering Research Laboratory and Power & Industrial Systems, Hitachi Ltd., Tsuchiura Division
| | - Shiro Nakadaira
- Mechanical Engineering Research Laboratory and Power & Industrial Systems, Hitachi Ltd., Tsuchiura Division
| | - Osami Yagi
- Research Center for Water Environment Technology, Graduate School of Engineering, The University of Tokyo
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15
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Clues from a halophilic methanogen about aromatic amino acid biosynthesis in archaebacteria. Arch Microbiol 1993. [DOI: 10.1007/bf00245304] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Amino acid overproduction by analog resistant mutants of the nitrogen fixing cyanobacteriumAnabaena sp 287. Appl Biochem Biotechnol 1992. [DOI: 10.1007/bf02921664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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17
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The effect of shikimate onNostoc linckia. World J Microbiol Biotechnol 1990; 6:343-5. [DOI: 10.1007/bf01201310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/1990] [Accepted: 03/25/1990] [Indexed: 11/25/2022]
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18
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Xia TH, Chiao JS. Regulation of the biosynthetic pathway of aromatic amino acids in Nocardia mediterranei. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 991:6-11. [PMID: 2713423 DOI: 10.1016/0304-4165(89)90020-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The regulation of enzymes in the biosynthetic pathway of aromatic amino acids in Norcardia mediterranei was studied. Anthranilate synthase was sensitive to feedback inhibition by very low concentrations of LTrp, and kinetic analysis showed that LTrp was competitive with respect to chorismate; the five enzymes in LTrp biosynthesis pathway, anthranilate synthase (AS), anthranilate-phosphoribosylpyrophosphate phosphoribosyltransferase (PRT), N-5'-phosphoribosylanthranilate isomerase (PRAI), indole-3-glycerol phosphate synthetase (InGPS) and tryptophan synthase (TS), were all repressed by LTrp; LTyr and LPhe inhibited chorismate mutase. Prephenate dehydratase activity was greatly inhibited by LPhe and activated by LTyr, nearly 60% of its activity was inhibited by 5 microM of LPhe, and 20 microM of LTyr increased the activity approx. 3-fold. In addition, the effects of LPhe and LTyr on prephenate dehydratase were highly specific. The regulatory circuit of the biosynthetic pathway of aromatic amino acids in N. mediterranei is presented.
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Affiliation(s)
- T H Xia
- Shanghai Institute of Plant Physiology, Academia Sinica, (Peoples Republic of China)
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19
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Bhatnagar RK, Berry A, Hendry AT, Jensen RA. The biochemical basis for growth inhibition by L-phenylalanine in Neisseria gonorrhoeae. Mol Microbiol 1989; 3:429-35. [PMID: 2568576 DOI: 10.1111/j.1365-2958.1989.tb00188.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Clinical isolates of Neisseria gonorrhoeae are commonly subject to growth inhibition by phenylpyruvate or by L-phenylalanine. A blockade of tyrosine biosynthesis is indicated since inhibition is reversed by either L-tyrosine or 4-hydroxyphenylpyruvate. Phenylalanine-resistant (PheR) and phenylalanine-sensitive (PheS) isolates both have a single 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase that is partially inhibited by L-phenylalanine (80%). However, PheS and PheR isolates differ in that the ratio of phenylpyruvate aminotransferase to 4-hydroxyphenylpyruvate aminotransferase is distinctly greater in PheS isolates than in PheR isolates. A mechanism for growth inhibition is proposed in which phenylalanine exerts two interactive effects. (i) Phenylalanine decreases precursor flow to 4-hydroxyphenylpyruvate through its controlling effect upon DAHP synthase; and (ii) phenylalanine is largely transaminated to phenylpyruvate, which saturates both aminotransferases, preventing transamination of an already limited supply of 4-hydroxyphenylpyruvate to L-tyrosine.
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Affiliation(s)
- R K Bhatnagar
- Department of Microbiology and Cell Science, University of Florida, Gainesville 32611
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20
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The regulation of aromatic amino acid biosynthesis in amino acid liberating mutant strains of Anabaena variabilis. Arch Microbiol 1988. [DOI: 10.1007/bf00407791] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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21
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Berry A, Jensen RA, Hendry AT. Enzymic arrangement and allosteric regulation of the aromatic amino acid pathway in Neisseria gonorrhoeae. Arch Microbiol 1987; 149:87-94. [PMID: 2894820 DOI: 10.1007/bf00425071] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The pathway construction and allosteric regulation of phenylalanine and tyrosine biosynthesis was examined in Neisseria gonorrhoeae. A single 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase enzyme sensitive to feedback inhibition by L-phenylalanine was found. Chorismate mutase and prephenate dehydratase appear to co-exist as catalytic components of a bifunctional enzyme, known to be present in related genera. The latter enzyme activities were both feedback inhibited by L-phenylalanine. Prephenate dehydratase was strongly activated by L-tyrosine. NAD+-linked prephenate dehydrogenase and arogenate dehydrogenase activities coeluted following ion-exchange chromatography, suggesting their identity as catalytic properties of a single broad-specificity cyclohexadienyl dehydrogenase. Each dehydrogenase activity was inhibited by 4-hydroxyphenylpyruvate, but not by L-tyrosine. Two aromatic aminotransferases were resolved, one preferring the L-phenylalanine:2-ketoglutarate substrate combination and the other preferring the L-tyrosine: 2-ketoglutarate substrate combination. Each aminotransferase was also able to transaminate prephenate. The overall picture of regulation is one in which L-tyrosine modulates L-phenylalanine synthesis via activation of prephenate dehydratase. L-Phenylalanine in turn regulates early-pathway flow through inhibition of DAHP synthase. The recent phylogenetic positioning of N. gonorrhoeae makes it a key reference organism for emerging interpretations about aromatic-pathway evolution.
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Affiliation(s)
- A Berry
- Department of Biological Sciences, State University of New York, Binghamton 13901
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22
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Labarre J, Thuriaux P, Chauvat F. Genetic analysis of amino acid transport in the facultatively heterotrophic cyanobacterium Synechocystis sp. strain 6803. J Bacteriol 1987; 169:4668-73. [PMID: 3115962 PMCID: PMC213837 DOI: 10.1128/jb.169.10.4668-4673.1987] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The existence of active transport systems (permeases) operating on amino acids in the photoautotrophic cyanobacterium Synechocystis sp. strain 6803 was demonstrated by following the initial rates of uptake with 14C-labeled amino acids, measuring the intracellular pools of amino acids, and isolating mutants resistant to toxic amino acids. One class of mutants (Pfa1) corresponds to a regulatory defect in the biosynthesis of the aromatic amino acids, but two other classes (Can1 and Aza1) are defective in amino acid transport. The Can1 mutants are defective in the active transport of three basic amino acids (arginine, histidine, and lysine) and in one of two transport systems operating on glutamine. The Aza1 mutants are not affected in the transport of the basic amino acids but have lost the capacity to transport all other amino acids except glutamate. The latter amino acid is probably transported by a third permease which could be identical to the Can1-independent transport operating on glutamine. Thus, genetic evidence suggests that strain 6803 has only a small number of amino acid transport systems with fairly broad specificity and that, with the exception of glutamine, each amino acid is accumulated by only one major transport system. Compared with heterotrophic bacteria such as Escherichia coli, these permeases are rather inefficient in terms of affinity (apparent Km ranging from 6 to 60 microM) and of Vmax.
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Affiliation(s)
- J Labarre
- Département de Biologie, Centre d'Etudes Nucléaires de Saclay, Gif-sur-Yvette, France
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23
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Barry BA, Babcock GT. Tyrosine radicals are involved in the photosynthetic oxygen-evolving system. Proc Natl Acad Sci U S A 1987; 84:7099-103. [PMID: 3313386 PMCID: PMC299237 DOI: 10.1073/pnas.84.20.7099] [Citation(s) in RCA: 310] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In addition to the reaction-center chlorophyll, at least two other organic cofactors are involved in the photosynthetic oxygen-evolution process. One of these cofactors, called "Z," transfers electrons from the site of water oxidation to the reaction center of photosystem II. The other species, "D," has an uncertain function but gives rise to the stable EPR signal known as signal II. Z+. and D+. have identical EPR spectra and are generally assumed to arise from species with the same chemical structure. Results from a variety of experiments have suggested that Z and D are plastoquinones or plastoquinone derivatives. In general, however, the evidence to support this assignment is indirect. To address this situation, we have developed more direct methods to assign the structure of the Z+./D+. radicals. By selective in vivo deuteration of the methyl groups of plastoquinone in cyanobacteria, we show that hyperfine couplings from the methyl protons cannot be responsible for the partially resolved structure seen in the D+. EPR spectrum. That is, we verify by extraction and mass spectrometry that quinones are labeled in algae fed deuterated methionine, but no change is observed in the line shape of signal II. Considering the spectral properties of the D+. radical, a tyrosine origin is a reasonable alternative. In a second series of experiments, we have found that deuteration of tyrosine does indeed narrow the D+. signal. Extraction and mass spectral analysis of the quinones in these cultures show that they are not labeled by tyrosine. These results eliminate a plastoquinone origin for D+.; we conclude instead that D+., and most likely Z+., are tyrosine radicals.
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Affiliation(s)
- B A Barry
- Department of Chemistry, Michigan State University, East Lansing 48824-1322
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24
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Fiske MJ, Whitaker RJ, Jensen RA. Hidden overflow pathway to L-phenylalanine in Pseudomonas aeruginosa. J Bacteriol 1983; 154:623-31. [PMID: 6132913 PMCID: PMC217509 DOI: 10.1128/jb.154.2.623-631.1983] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Pseudomonas aeruginosa is representative of a large group of pseudomonad bacteria that possess coexisting alternative pathways to L-phenylalanine (as well as to L-tyrosine). These multiple flow routes to aromatic end products apparently account for the inordinate resistance of P. aeruginosa to end product analogs. Manipulation of carbon source nutrition produced a physiological state of sensitivity to p-fluorophenylalanine and m-fluorophenylalanine, each a specific antimetabolite of L-phenylalanine. Analog-resistant mutants obtained fell into two classes. One type lacked feedback sensitivity of prephenate dehydratase and was the most dramatic excretor of L-phenylalanine. The presence of L-tyrosine curbed phenylalanine excretion to one-third, a finding explained by potent early-pathway regulation of 3-deoxy-D-arabinoheptulosonate 7-phosphate (DAHP) synthase-Tyr (a DAHP synthase subject to allosteric inhibition by L-tyrosine). The second class of regulatory mutants possessed a completely feedback-resistant DAHP synthase-Tyr, the major species (greater than 90%) of two isozymes. Deregulation of DAHP synthase-Tyr resulted in the escape of most chorismate molecules produced into an unregulated overflow route consisting of chorismate mutase (monofunctional), prephenate aminotransferase, and arogenate dehydratase. In the wild type the operation of the overflow pathway is restrained by factors that restrict early-pathway flux. These factors include the highly potent feedback control of DAHP synthase isozymes by end products as well as the strikingly variable abilities of different carbon source nutrients to supply the aromatic pathway with beginning substrates. Even in the wild type, where all allosteric regulation in intact, some phenylalanine overflow was found on glucose-based medium, but not on fructose-based medium. This carbon source-dependent difference was much more exaggerated in each class of regulatory mutants.
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25
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Hall GC, Flick MB, Jensen RA. Regulation of the aromatic pathway in the cyanobacterium Synechococcus sp. strain Pcc6301 (Anacystis nidulans). J Bacteriol 1983; 153:423-8. [PMID: 6129240 PMCID: PMC217389 DOI: 10.1128/jb.153.1.423-428.1983] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
A pattern of allosteric control for aromatic biosynthesis in cyanobacteria relies upon early-pathway regulation as the major control point for the entire branched pathway. In Synechococcus sp. strain PCC6301 (Anacystis nidulans), two enzymes which form precursors for L-phenylalanine biosynthesis are subject to control by feedback inhibition. 3-Deoxy-D-arabino-heptulosonate 7-phosphate synthase (first pathway enzyme) is feedback inhibited by L-tyrosine, whereas prephenate dehydratase (enzyme step 9) is feedback inhibited by L-phenylalanine and allosterically activated by L-tyrosine. Mutants lacking feedback inhibition of prephenate dehydratase excreted relatively modest quantities of L-phenylalanine. In contrast, mutants deregulated in allosteric control of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase excreted large quantities of L-phenylalanine (in addition to even greater quantities of L-tyrosine). Clearly, in the latter mutants, the elevated levels of prephenate must overwhelm the inhibition of prephenate dehydratase by L-phenylalanine, an effect assisted by increased intracellular L-tyrosine, an allosteric activator. The results show that early-pathway flow regulated in vivo by 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase is the dominating influence upon metabolite flow-through to L-phenylalanine. L-Tyrosine biosynthesis exemplifies such early-pathway control even more simply, since 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase is the sole regulatory enzyme subject to end-product control by L-tyrosine.
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26
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Riccardi G, Sanangelantoni AM, Sarasini A, Ciferri O. Altered methionyl-tRNA synthetase in a Spirulina platensis mutant resistant to ethionine. J Bacteriol 1982; 151:1053-5. [PMID: 7096264 PMCID: PMC220363 DOI: 10.1128/jb.151.2.1053-1055.1982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Compared with the parental strain, a Spirulina platensis mutant that is resistant to ethionine incorporated methionine into protein at a reduced rate, whereas ethionine incorporation was practically nil. The methionyl-tRNA synthetase present in crude extracts from the resistant strain showed a reduced affinity for methionine and ethionine.
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27
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Byng GS, Kane JF, Jensen RA. Diversity in the routing and regulation of complex biochemical pathways as indicators of microbial relatedness. Crit Rev Microbiol 1982; 9:227-52. [PMID: 7049576 DOI: 10.3109/10408418209104491] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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28
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Hall GC, Flick MB, Gherna RL, Jensen RA. Biochemical diversity for biosynthesis of aromatic amino acids among the cyanobacteria. J Bacteriol 1982; 149:65-78. [PMID: 6119309 PMCID: PMC216593 DOI: 10.1128/jb.149.1.65-78.1982] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
We examined the enzymology and regulatory patterns of the aromatic amino acid pathway in 48 strains of cyanobacteria including representatives from each of the five major grouping. Extensive diversity was found in allosteric inhibition patterns of 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase, not only between the major groupings but also within several of the generic groupings. Unimetabolite inhibition by phenylalanine occurred in approximately half of the strains examined; in the other strains unimetabolite inhibition by tyrosine and cumulative, concerted, and additive patterns were found. The additive patterns suggest the presence of regulatory isozymes. Even though both arogenate and prephenate dehydrogenase activities were found in some strains, it seems clear that the arogenate pathway to tyrosine is a common trait that has been highly conserved among cyanobacteria. No arogenate dehydratase activities were found. In general, prephenate dehydratase activities were activated by tyrosine and inhibited by phenylalanine. Chorismate mutase, arogenate dehydrogenase, and shikimate dehydrogenase were nearly always unregulated. Most strains preferred NADP as the cofactor for the dehydrogenase activities. The diversity in the allosteric inhibition patterns for 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase, cofactor specificities, and the presence or absence of prephenate dehydrogenase activity allowed the separation of subgroupings within several of the form genera, namely, Synechococcus, Synechocystis, Anabaena, Nostoc, and Calothrix.
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29
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Riccardi G, Sanangelantoni A, Carbonera D, Savi A, Ciferri O. Characterization of mutants ofSpirulina platensisresistant to amino acid analogues. FEMS Microbiol Lett 1981. [DOI: 10.1111/j.1574-6968.1981.tb07668.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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30
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Hall GC, Jensen RA. Regulatory isozymes of 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase in the cyanobacterium Anabaena sp. strain ATCC 29151. J Bacteriol 1981; 148:361-4. [PMID: 6116697 PMCID: PMC216200 DOI: 10.1128/jb.148.1.361-364.1981] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Two regulatory isozymes of 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase from the cyanobacterium Anabaena sp. strain ATCC 29151 were separated via gel filtration. One isozyme (Mr = 205,000) was sensitive to phenylalanine inhibition, and the other (Mr = 60,000) was sensitive to tyrosine inhibition. The tyrosine-sensitive isozyme from wild-type cells was unstable to gel filtration, whereas the corresponding isozyme from an analog-resistant mutant was insensitive to tyrosine inhibition and was stable.
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31
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Hall GC, Jensen RA. Isolation of cyanobacterial auxotrophs by direct selection of regulatory-mutant phenotypes. Curr Microbiol 1981. [DOI: 10.1007/bf01642397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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