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Liu R, Deng M, Zhang N, Li Y, Jia L, Niu D. NADK-mediated proline synthesis enhances high-salinity tolerance in the razor clam. Comp Biochem Physiol A Mol Integr Physiol 2024; 291:111610. [PMID: 38408517 DOI: 10.1016/j.cbpa.2024.111610] [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: 01/16/2024] [Revised: 02/23/2024] [Accepted: 02/23/2024] [Indexed: 02/28/2024]
Abstract
Euryhaline organisms can accumulate organic osmolytes to maintain osmotic balance between their internal and external environments. Proline is a pivotal organic small molecule and plays an important role in osmoregulation that enables marine shellfish to tolerate high-salinity conditions. During high-salinity challenge, NAD kinase (NADK) is involved in de novo synthesis of NADP(H) in living organisms, which serves as a reducing agent for the biosynthetic reactions. However, the role of shellfish NADK in proline biosynthesis remains elusive. In this study, we show the modulation of NADK on proline synthesis in the razor clam (Sinonovacula constricta) in response to osmotic stress. Under acute hypersaline conditions, gill tissues exhibited a significant increase in the expression of ScNADK. To elucidate the role of ScNADK in proline biosynthesis, we performed dsRNA interference in the expression of ScNADK in gill tissues to assess proline content and the expression levels of key enzyme genes involved in proline biosynthesis. The results indicate that the knock-down of ScNADK led to a significant decrease in proline content (P<0.01), as well as the expression levels of two proline synthetase genes P5CS and P5CR involved in the glutamate pathway. Razor clams preferred to use ornithine as substrate for proline synthesis when the glutamate pathway is blocked. Exogenous administration of proline greatly improved cell viability and mitigated cell apoptosis in gills. In conclusion, our results demonstrate the important role of ScNADK in augmenting proline production under high-salinity stress, by which the razor clam is able to accommodate salinity variations in the ecological niche.
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Affiliation(s)
- Ruiqi Liu
- Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding, Shanghai Ocean University, Shanghai 201306, China
| | - Min Deng
- Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding, Shanghai Ocean University, Shanghai 201306, China
| | - Na Zhang
- Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding, Shanghai Ocean University, Shanghai 201306, China
| | - Yifeng Li
- Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding, Shanghai Ocean University, Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Liang Jia
- Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding, Shanghai Ocean University, Shanghai 201306, China.
| | - Donghong Niu
- Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding, Shanghai Ocean University, Shanghai 201306, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Huaihai Institute of Technology, Lianyungang 222005, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China.
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2
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Ito S, Watanabe A, Osanai T. Regulation of L-aspartate oxidase contributes to NADP+ biosynthesis in Synechocystis sp. PCC 6803. PLANT PHYSIOLOGY 2024; 194:945-957. [PMID: 37936332 DOI: 10.1093/plphys/kiad580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/11/2023] [Accepted: 10/16/2023] [Indexed: 11/09/2023]
Abstract
Cyanobacteria have been promoted as a biomass resource that can contribute to carbon neutrality. Synechocystis sp. PCC 6803 is a model cyanobacterium that is widely used in various studies. NADP+ and NAD+ are electron receptors involved in energy metabolism. The NADP+/NAD+ ratio in Synechocystis sp. PCC 6803 is markedly higher than that in the heterotrophic bacterium Escherichia coli. In Synechocystis sp. PCC 6803, NADP+ primarily functions as an electron receptor during the light reaction of photosynthesis, and NADP+ biosynthesis is essential for photoautotrophic growth. Generally, the regulatory enzyme of NADP+ biosynthesis is NAD kinase, which catalyzes the phosphorylation of NAD+. However, a previous study suggested that the regulation of another enzyme contributes to NADP+ biosynthesis in Synechocystis sp. PCC 6803 under photoautotrophic conditions. L-Aspartate oxidase is the first enzyme in NAD(P)+ biosynthesis. In this study, we biochemically characterized Synechocystis sp. PCC 6803 L-aspartate oxidase and determined the phenotype of a Synechocystis sp. PCC 6803 mutant overexpressing L-aspartate oxidase. The catalytic efficiency of L-aspartate oxidase from Synechocystis sp. PCC 6803 was lower than that of L-aspartate oxidases and NAD kinases from other organisms. L-Aspartate oxidase activity was affected by different metabolites such as NADP+ and ATP. The L-aspartate oxidase-overexpressing strain grew faster than the wild-type strain under photoautotrophic conditions. The L-aspartate oxidase-overexpressing strain accumulated NADP+ under photoautotrophic conditions. These results indicate that the regulation of L-aspartate oxidase contributes to NADP+ biosynthesis in Synechocystis sp. PCC 6803 under photoautotrophic conditions. These findings provide insight into the regulatory mechanism of cyanobacterial NADP+ biosynthesis.
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Affiliation(s)
- Shoki Ito
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Atsuko Watanabe
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Takashi Osanai
- School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
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3
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Kugler A, Stensjö K. Optimal energy and redox metabolism in the cyanobacterium Synechocystis sp. PCC 6803. NPJ Syst Biol Appl 2023; 9:47. [PMID: 37739963 PMCID: PMC10516873 DOI: 10.1038/s41540-023-00307-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 09/01/2023] [Indexed: 09/24/2023] Open
Abstract
Understanding energy and redox homeostasis and carbon partitioning is crucial for systems metabolic engineering of cell factories. Carbon metabolism alone cannot achieve maximal accumulation of metabolites in production hosts, since an efficient production of target molecules requires energy and redox balance, in addition to carbon flow. The interplay between cofactor regeneration and heterologous production in photosynthetic microorganisms is not fully explored. To investigate the optimality of energy and redox metabolism, while overproducing alkenes-isobutene, isoprene, ethylene and 1-undecene, in the cyanobacterium Synechocystis sp. PCC 6803, we applied stoichiometric metabolic modelling. Our network-wide analysis indicates that the rate of NAD(P)H regeneration, rather than of ATP, controls ATP/NADPH ratio, and thereby bioproduction. The simulation also implies that energy and redox balance is interconnected with carbon and nitrogen metabolism. Furthermore, we show that an auxiliary pathway, composed of serine, one-carbon and glycine metabolism, supports cellular redox homeostasis and ATP cycling. The study revealed non-intuitive metabolic pathways required to enhance alkene production, which are mainly driven by a few key reactions carrying a high flux. We envision that the presented comparative in-silico metabolic analysis will guide the rational design of Synechocystis as a photobiological production platform of target chemicals.
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Affiliation(s)
- Amit Kugler
- Microbial Chemistry, Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, SE-751 20, Uppsala, Sweden
| | - Karin Stensjö
- Microbial Chemistry, Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, SE-751 20, Uppsala, Sweden.
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4
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Theodosiou E, Tüllinghoff A, Toepel J, Bühler B. Exploitation of Hetero- and Phototrophic Metabolic Modules for Redox-Intensive Whole-Cell Biocatalysis. Front Bioeng Biotechnol 2022; 10:855715. [PMID: 35497353 PMCID: PMC9043136 DOI: 10.3389/fbioe.2022.855715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 03/09/2022] [Indexed: 11/13/2022] Open
Abstract
The successful realization of a sustainable manufacturing bioprocess and the maximization of its production potential and capacity are the main concerns of a bioprocess engineer. A main step towards this endeavor is the development of an efficient biocatalyst. Isolated enzyme(s), microbial cells, or (immobilized) formulations thereof can serve as biocatalysts. Living cells feature, beside active enzymes, metabolic modules that can be exploited to support energy-dependent and multi-step enzyme-catalyzed reactions. Metabolism can sustainably supply necessary cofactors or cosubstrates at the expense of readily available and cheap resources, rendering external addition of costly cosubstrates unnecessary. However, for the development of an efficient whole-cell biocatalyst, in depth comprehension of metabolic modules and their interconnection with cell growth, maintenance, and product formation is indispensable. In order to maximize the flux through biosynthetic reactions and pathways to an industrially relevant product and respective key performance indices (i.e., titer, yield, and productivity), existing metabolic modules can be redesigned and/or novel artificial ones established. This review focuses on whole-cell bioconversions that are coupled to heterotrophic or phototrophic metabolism and discusses metabolic engineering efforts aiming at 1) increasing regeneration and supply of redox equivalents, such as NAD(P/H), 2) blocking competing fluxes, and 3) increasing the availability of metabolites serving as (co)substrates of desired biosynthetic routes.
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Affiliation(s)
- Eleni Theodosiou
- Institute of Applied Biosciences, Centre for Research and Technology Hellas, Thessaloniki, Greece
| | - Adrian Tüllinghoff
- Department of Solar Materials, Helmholtz Centre for Environmental Research GmbH—UFZ, Leipzig, Germany
| | - Jörg Toepel
- Department of Solar Materials, Helmholtz Centre for Environmental Research GmbH—UFZ, Leipzig, Germany
| | - Bruno Bühler
- Department of Solar Materials, Helmholtz Centre for Environmental Research GmbH—UFZ, Leipzig, Germany
- *Correspondence: Bruno Bühler,
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5
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Ishikawa Y, Cassan C, Kadeer A, Yuasa K, Sato N, Sonoike K, Kaneko Y, Miyagi A, Takahashi H, Ishikawa T, Yamaguchi M, Nishiyama Y, Hihara Y, Gibon Y, Kawai-Yamada M. The NAD Kinase Slr0400 Functions as a Growth Repressor in Synechocystis sp. PCC 6803. PLANT & CELL PHYSIOLOGY 2021; 62:668-677. [PMID: 33560438 DOI: 10.1093/pcp/pcab023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 02/04/2021] [Indexed: 06/12/2023]
Abstract
NADP+, the phosphorylated form of nicotinamide adenine dinucleotide (NAD), plays an essential role in many cellular processes. NAD kinase (NADK), which is conserved in all living organisms, catalyzes the phosphorylation of NAD+ to NADP+. However, the physiological role of phosphorylation of NAD+ to NADP+ in the cyanobacterium Synechocystis remains unclear. In this study, we report that slr0400, an NADK-encoding gene in Synechocystis, functions as a growth repressor under light-activated heterotrophic growth conditions and light and dark cycle conditions in the presence of glucose. We show, via characterization of NAD(P)(H) content and enzyme activity, that NAD+ accumulation in slr0400-deficient mutant results in the unsuppressed activity of glycolysis and tricarboxylic acid (TCA) cycle enzymes. In determining whether Slr0400 functions as a typical NADK, we found that constitutive expression of slr0400 in an Arabidopsis nadk2-mutant background complements the pale-green phenotype. Moreover, to determine the physiological background behind the growth advantage of mutants lacking slr04000, we investigated the photobleaching phenotype of slr0400-deficient mutant under high-light conditions. Photosynthetic analysis found in the slr0400-deficient mutant resulted from malfunctions in the Photosystem II (PSII) photosynthetic machinery. Overall, our results suggest that NADP(H)/NAD(H) maintenance by slr0400 plays a significant role in modulating glycolysis and the TCA cycle to repress the growth rate and maintain the photosynthetic capacity.
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Affiliation(s)
- Yuuma Ishikawa
- Institute for Molecular Physiology and Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University Düsseldorf, Düsseldorf 40225, Germany
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya, 464-8601 Japan
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Cedric Cassan
- UMR1332 Biologie du Fruit et Pathologie and Plateforme Métabolome, Centre de Génomique Fonctionnelle Bordeaux, INRA-Bordeaux and Bordeaux University, Villenave d'Ornon, France
| | - Aikeranmu Kadeer
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Koki Yuasa
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Nozomu Sato
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Kintake Sonoike
- Faculty of Education and Integrated Arts and Sciences, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480 Japan
| | - Yasuko Kaneko
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Atsuko Miyagi
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Hiroko Takahashi
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Toshiki Ishikawa
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Masatoshi Yamaguchi
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Yoshitaka Nishiyama
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Yukako Hihara
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
| | - Yves Gibon
- UMR1332 Biologie du Fruit et Pathologie and Plateforme Métabolome, Centre de Génomique Fonctionnelle Bordeaux, INRA-Bordeaux and Bordeaux University, Villenave d'Ornon, France
| | - Maki Kawai-Yamada
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama City, Saitama, 338-8570 Japan
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6
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Tanaka K, Shimakawa G, Tabata H, Kusama S, Miyake C, Nakanishi S. Quantification of NAD(P)H in cyanobacterial cells by a phenol extraction method. PHOTOSYNTHESIS RESEARCH 2021; 148:57-66. [PMID: 33934289 PMCID: PMC8154815 DOI: 10.1007/s11120-021-00835-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Accepted: 04/12/2021] [Indexed: 05/05/2023]
Abstract
In photosynthetic organisms, it is recognized that the intracellular redox ratio of NADPH is regulated within an appropriate range for the cooperative function of a wide variety of physiological processes. However, despite its importance, there is large variability in the values of the NADPH fraction [NADPH/(NADPH + NADP+)] quantitatively estimated to date. In the present study, the light response of the NADPH fraction was investigated by applying a novel NADP(H) extraction method using phenol / chloroform / isoamyl alcohol (PCI) in the cyanobacterium Synechocystis sp. PCC 6803. The light response of NADP(H) observed using PCI extraction was qualitatively consistent with the NAD(P)H fluorescence time course measured in vivo. Moreover, the results obtained by PCI extraction and the fluorescence-based methods were also consistent in a mutant lacking the ability to oxidize NAD(P)H in the respiratory chain, and exhibiting a unique NADPH light response. These observations indicate that the PCI extraction method allowed quantitative determination of NADP(H) redox. Notably, the PCI extraction method showed that not all NADP(H) was oxidized or reduced by light-dark transition. Specifically, the fraction of NADPH was 42% in the dark-adapted cell, and saturated at 68% in light conditions.
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Affiliation(s)
- Kenya Tanaka
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan
| | - Ginga Shimakawa
- Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan
| | - Hiro Tabata
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan
| | - Shoko Kusama
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan
| | - Chikahiro Miyake
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Shuji Nakanishi
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan.
- Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan.
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7
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Song X, Diao J, Yao J, Cui J, Sun T, Chen L, Zhang W. Engineering a Central Carbon Metabolism Pathway to Increase the Intracellular Acetyl-CoA Pool in Synechocystis sp. PCC 6803 Grown under Photomixotrophic Conditions. ACS Synth Biol 2021; 10:836-846. [PMID: 33779148 DOI: 10.1021/acssynbio.0c00629] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In cyanobacteria, photomixotrophic growth is considered as a promising strategy to achieve both high cell density and product accumulation. However, the conversion of glucose to acetyl coenzyme A (acetyl-CoA) in the native glycolytic pathway is insufficient, which decreases the carbon utilization and productivity of engineered cyanobacteria under photomixotrophic conditions. To increase the carbon flux from glucose to key intracellular precursor acetyl-CoA in Synechocystis sp. PCC 6803 (hereafter, Synechocystis 6803) under photomixotrophic conditions, a synthetic nonoxidative cyclic glycolysis (NOG) pathway was introduced into the wild type strain, which successfully increased the intracellular pool of acetyl-CoA by approximately 1-fold. To minimize the competition for glucose, the native Embden-Meyerhof-Parnas (EMP) and Entner-Doudoroff (ED) pathways were knocked out, respectively. Notably, eliminating the native ED pathway in the engineered strain carrying the NOG pathway further increased the intracellular pool of acetyl-CoA up to 2.8-fold. Another carbon consuming pathway in Synechocystis 6803, the glycogen biosynthesis pathway, was additionally knocked out in the above-mentioned engineered strain, which enabled an increase of the intracellular acetyl-CoA pool by up to 3.5-fold when compared with the wild type strain. Finally, the content of intracellular lipids was analyzed as an index of the productive capacity of the engineered Synechocystis 6803 cell factory under photomixotrophic conditions. The results showed the total lipids yield increased about 26% compared to the wild type (from 15.71% to 34.12%, g/g glucose), demonstrating that this integrated approach could represent a general strategy not only for the improvement of the intracellular concentration of acetyl-CoA, but also for the production of value-added chemicals that require acetyl-CoA as a key precursor in cyanobacteria.
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Affiliation(s)
- Xinyu Song
- Center for Biosafety Research and Strategy, Tianjin University, Tianjin 300072, People’s Republic of China
- Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- Law School of Tianjin University, Tianjin 300072, P.R. China
| | - Jinjin Diao
- Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, People’s Republic of China
| | - Jiaqi Yao
- Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, People’s Republic of China
| | - Jinyu Cui
- Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, People’s Republic of China
| | - Tao Sun
- Center for Biosafety Research and Strategy, Tianjin University, Tianjin 300072, People’s Republic of China
- Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- Law School of Tianjin University, Tianjin 300072, P.R. China
| | - Lei Chen
- Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, People’s Republic of China
| | - Weiwen Zhang
- Center for Biosafety Research and Strategy, Tianjin University, Tianjin 300072, People’s Republic of China
- Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, People’s Republic of China
- Law School of Tianjin University, Tianjin 300072, P.R. China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, People’s Republic of China
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8
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Yuasa K, Shikata T, Ichikawa T, Tamura Y, Nishiyama Y. Nutrient deficiency stimulates the production of superoxide in the noxious red-tide-forming raphidophyte Chattonella antiqua. HARMFUL ALGAE 2020; 99:101938. [PMID: 33218451 DOI: 10.1016/j.hal.2020.101938] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 09/14/2020] [Accepted: 10/22/2020] [Indexed: 06/11/2023]
Abstract
The raphidophyte Chattonella antiqua is a single-celled alga that forms 'red tides' in coastal areas. C. antiqua produces superoxide anions (O2-), the excessive production of which has been associated with fish mortality. It is suggested that putative NADPH oxidase in the outer membrane oxidizes intracellular NADPH to produce O2- and secrete it externally. Earlier studies revealed that photosynthetic electron transport, a major producer of NADPH in photosynthetic organisms, is involved in the production of O2- in C. antiqua but the details of the O2- production mechanism have yet to be elucidated. Since nutrient deficiency adversely affects the formation of blooms of C. antiqua, in this study, we examined the effects of nutrient deficiency on O2- production in C. antiqua. When cells were grown under nitrogen (N)- or phosphorus (P)-deficient conditions, the production of O2- was stimulated. In particular, the extracellular levels of O2- under N- or P-deficient conditions were high during the dark period when photosynthetic activities in terms of actual quantum efficiency and photochemical quenching were low. The extracellular levels of O2- under the nutrient-deficient conditions were unaffected by the presence of 3-(3,4-dichlorophenyl)-1,1‑dimethylurea (DCMU), an inhibitor of photosynthetic electron transport, but decreased when the nutrients were present. Furthermore, the intracellular ratio of NADPH to NADP+ under N- or P-deficient conditions was higher than that under nutrient-replete conditions. These observations suggest that another metabolic pathway, independent of photosynthesis, provides NADPH for the production of O2- under nutrient deficiency.
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Affiliation(s)
- Koki Yuasa
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
| | - Tomoyuki Shikata
- Fisheries Technology Institute, Japan Fisheries Research and Education Agency, 2-17-5 Maruishi, Hatsukaichi, Hiroshima 738-8635, Japan.
| | - Takayoshi Ichikawa
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
| | - Yu Tamura
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
| | - Yoshitaka Nishiyama
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
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9
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Unconventional biochemical regulation of the oxidative pentose phosphate pathway in the model cyanobacterium Synechocystis sp. PCC 6803. Biochem J 2020; 477:1309-1321. [PMID: 32227111 DOI: 10.1042/bcj20200038] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/11/2020] [Accepted: 03/30/2020] [Indexed: 01/05/2023]
Abstract
Metabolite production from carbon dioxide using sugar catabolism in cyanobacteria has been in the spotlight recently. Synechocystis sp. PCC 6803 (Synechocystis 6803) is the most studied cyanobacterium for metabolite production. Previous in vivo analyses revealed that the oxidative pentose phosphate (OPP) pathway is at the core of sugar catabolism in Synechocystis 6803. However, the biochemical regulation of the OPP pathway enzymes in Synechocystis 6803 remains unknown. Therefore, we characterized a key enzyme of the OPP pathway, glucose-6-phosphate dehydrogenase (G6PDH), and related enzymes from Synechocystis 6803. Synechocystis 6803 G6PDH was inhibited by citrate in the oxidative tricarboxylic acid (TCA) cycle. Citrate has not been reported as an inhibitor of G6PDH before. Similarly, 6-phosphogluconate dehydrogenase, the other enzyme from Synechocystis 6803 that catalyzes the NADPH-generating reaction in the OPP pathway, was inhibited by citrate. To understand the physiological significance of this inhibition, we characterized succinic semialdehyde dehydrogenase (SSADH) from Synechocystis 6803 (SySSADH), which catalyzes one of the NAD(P)H generating reactions in the oxidative TCA cycle. Similar to isocitrate dehydrogenase from Synechocystis 6803, SySSADH specifically catalyzed the NADPH-generating reaction and was not inhibited by citrate. The activity of SySSADH was lower than that of other bacterial SSADHs. Previous and this studies revealed that unlike the OPP pathway, the oxidative TCA cycle is a pathway with low efficiency in NADPH generation in Synechocystis 6803. It has, thus, been suggested that to avoid NADPH overproduction, the OPP pathway dehydrogenase activity is repressed when the flow of the oxidative TCA cycle increases in Synechocystis 6803.
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He P, Cai X, Chen K, Fu X. Identification of small RNAs involved in nitrogen fixation in Anabaena sp. PCC 7120 based on RNA-seq under steady state conditions. ANN MICROBIOL 2020. [DOI: 10.1186/s13213-020-01557-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Abstract
Purpose
Anabaena sp. PCC7120 is a genetically tractable model organism for nitrogen fixation and photosynthesis research. The importance of small regulatory RNAs (sRNAs) as mediators of a number of cellular processes in bacteria has begun to be recognized. Bacterial sRNA binds to target genes through base pairing, and play a regulatory role. Many studies have shown that bacterial sRNA can regulate cell stress response, carbon and nitrogen fixation, and so on. However, little is known about sRNAs in Anabaena sp. PCC 7120 regarded to nitrogen fixation under later steady state.
Methods
To provide a comprehensive study of sRNAs in this model organism, the sRNA (< 200 nt) extracted from Anabaena sp. PCC 7120 under nitrogen step-down treatment of 12 days, together with the sRNA from the control, was analyzed using deep RNA sequencing. Possible target genes regulated by all identified putative sRNAs were predicted by IntaRNA and further analyzed for functional categorizations for biological pathways.
Result
Totally, 14,132 transcripts were produced from the de novo assembly. Among them, transcripts that are located either in the intergenic region or antisense strand were kept, which resulted in 1219 sRNA candidates, for further analysis. RPKM-based differential expression analysis showed that 418 sRNAs were significantly differentially expressed between the samples from control (nitrogen addition, N+) and nitrogen depletion, (N−). Among them, 303 sRNAs were significantly upregulated, whereas 115 sRNAs were significantly downregulated. RT-PCR of 18 randomly chosen sRNAs showed a similar pattern as RNA-seq result, which confirmed the reliability of the RNA-seq data. In addition, the possible target genes regulated by unique sRNAs of Anabaena sp. PCC 7120 under nitrogen addition (N+) condition or that under nitrogen depletion (N−) condition were analyzed for functional categorization and biological pathways, which provided the evidences that sRNAs were indeed involved in many different metabolic pathways.
Conclusion
The information from the present study provides a valuable reference for understanding the sRNA-mediated regulation of the nitrogen fixation in Anabaena PCC 7120 under steady state conditions.
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Abstract
Glucose is an important building component in organisms and a central molecule of energy metabolism. It is also a key signaling molecule involved in regulation of many physiologic processes, including organism morphogenesis, anabolism and catabolism, pest and disease stress, environmental stress response. The signal transduction pathway mediated by heterotrimeric G proteins is one of the most important pathways for Arabidopsis to recognize, perceive and transduce external stimuli. AtRGS1 (Arabidopsis thaliana regulator of G-protein signaling) metabolism is currently thought to be through endosome.This paper introduces relationship between autophagy and RGS1.
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Affiliation(s)
- Yue Jiao
- Ministry of Education Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
- CONTACT Wenli Chen: Ministry of Education Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Wenxue Lei
- Ministry of Education Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Wan Xu
- Ministry of Education Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Wen-Li Chen
- Ministry of Education Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
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Ishikawa Y, Kawai-Yamada M. Physiological Significance of NAD Kinases in Cyanobacteria. FRONTIERS IN PLANT SCIENCE 2019; 10:847. [PMID: 31316540 PMCID: PMC6610520 DOI: 10.3389/fpls.2019.00847] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 06/13/2019] [Indexed: 05/04/2023]
Abstract
Unicellular cyanobacteria are thought to be the evolutionary ancestors of plant chloroplasts and are widely used both for chemical production and as model organisms in studies of photosynthesis. Although most research focused on increasing reducing power (that is, NADPH) as target of metabolic engineering, the physiological roles of NAD(P)(H) in cyanobacteria poorly understood. In cyanobacteria such as the model species Synechocystis sp. PCC 6803, most metabolic pathways share a single compartment. This complex metabolism raises the question of how cyanobacteria control the amounts of the redox pairs NADH/NAD+ and NADPH/NADP+ in the cyanobacterial metabolic pathways. For example, photosynthetic and respiratory electron transport chains share several redox components in the thylakoid lumen, including plastoquinone, cytochrome b6f (cyt b6f), and the redox carriers plastocyanin and cytochrome c6. In the case of photosynthesis, NADP+ acts as an important electron mediator on the acceptor-side of photosystem I (PSI) in the linear electron chain as well as in the plant chloroplast. Meanwhile, in respiration, most electrons derived from NADPH and NADH are transferred by NAD(P)H dehydrogenases. Therefore, it is expected that Synechocystis employs unique NAD(P)(H) -pool control mechanisms to regulate the mixed metabolic systems involved in photosynthesis and respiration. This review article summarizes the current state of knowledge of NAD(P)(H) metabolism in Synechocystis. In particular, we focus on the physiological function in Synechocystis of NAD kinase, the enzyme that phosphorylates NAD+ to NADP+.
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