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Cereijo AE, Ferretti MV, Iglesias AA, Álvarez HM, Asencion Diez MD. Study of two glycosyltransferases related to polysaccharide biosynthesis in Rhodococcus jostii RHA1. Biol Chem 2024; 405:325-340. [PMID: 38487862 DOI: 10.1515/hsz-2023-0339] [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: 11/02/2023] [Accepted: 02/23/2024] [Indexed: 05/04/2024]
Abstract
The bacterial genus Rhodococcus comprises organisms performing oleaginous behaviors under certain growth conditions and ratios of carbon and nitrogen availability. Rhodococci are outstanding producers of biofuel precursors, where lipid and glycogen metabolisms are closely related. Thus, a better understanding of rhodococcal carbon partitioning requires identifying catalytic steps redirecting sugar moieties to storage molecules. Here, we analyzed two GT4 glycosyl-transferases from Rhodococcus jostii (RjoGlgAb and RjoGlgAc) annotated as α-glucan-α-1,4-glucosyl transferases, putatively involved in glycogen synthesis. Both enzymes were produced in Escherichia coli cells, purified to homogeneity, and kinetically characterized. RjoGlgAb and RjoGlgAc presented the "canonical" glycogen synthase activity and were actives as maltose-1P synthases, although to a different extent. Then, RjoGlgAc is a homologous enzyme to the mycobacterial GlgM, with similar kinetic behavior and glucosyl-donor preference. RjoGlgAc was two orders of magnitude more efficient to glucosylate glucose-1P than glycogen, also using glucosamine-1P as a catalytically efficient aglycon. Instead, RjoGlgAb exhibited both activities with similar kinetic efficiency and preference for short-branched α-1,4-glucans. Curiously, RjoGlgAb presented a super-oligomeric conformation (higher than 15 subunits), representing a novel enzyme with a unique structure-to-function relationship. Kinetic results presented herein constitute a hint to infer on polysaccharides biosynthesis in rhodococci from an enzymological point of view.
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Affiliation(s)
- Antonela Estefania Cereijo
- Laboratorio de Enzimología Molecular, 603337 Instituto de Agrobiotecnología del Litoral (UNL-CONICET) & Facultad de Bioquímica y Ciencias Biológicas , Santa Fe, Argentina
| | - María Victoria Ferretti
- Laboratorio de Enzimología Molecular, 603337 Instituto de Agrobiotecnología del Litoral (UNL-CONICET) & Facultad de Bioquímica y Ciencias Biológicas , Santa Fe, Argentina
| | - Alberto Alvaro Iglesias
- Laboratorio de Enzimología Molecular, 603337 Instituto de Agrobiotecnología del Litoral (UNL-CONICET) & Facultad de Bioquímica y Ciencias Biológicas , Santa Fe, Argentina
| | - Héctor Manuel Álvarez
- Instituto de Biociencias de la Patagonia (INBIOP), 28226 Universidad Nacional de la Patagonia San Juan Bosco y CONICET , Km 4-Ciudad Universitaria 9000, Comodoro Rivadavia, Chubut, Argentina
| | - Matías Damian Asencion Diez
- Laboratorio de Enzimología Molecular, 603337 Instituto de Agrobiotecnología del Litoral (UNL-CONICET) & Facultad de Bioquímica y Ciencias Biológicas , Santa Fe, Argentina
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Guo L, Liu M, Bi Y, Qi Q, Xian M, Zhao G. Using a synthetic machinery to improve carbon yield with acetylphosphate as the core. Nat Commun 2023; 14:5286. [PMID: 37648707 PMCID: PMC10468489 DOI: 10.1038/s41467-023-41135-7] [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: 05/15/2023] [Accepted: 08/23/2023] [Indexed: 09/01/2023] Open
Abstract
In microbial cell factory, CO2 release during acetyl-CoA production from pyruvate significantly decreases the carbon atom economy. Here, we construct and optimize a synthetic carbon conserving pathway named as Sedoheptulose-1,7-bisphosphatase Cycle with Trifunctional PhosphoKetolase (SCTPK) in Escherichia coli. This cycle relies on a generalist phosphoketolase Xfspk and converts glucose into the stoichiometric amounts of acetylphosphate (AcP). Furthermore, genetic circuits responding to AcP positively or negatively are created. Together with SCTPK, they constitute a gene-metabolic oscillator that regulates Xfspk and enzymes converting AcP into valuable chemicals in response to intracellular AcP level autonomously, allocating metabolic flux rationally and improving the carbon atom economy of bioconversion process. Using this synthetic machinery, mevalonate is produced with a yield higher than its native theoretical yield, and the highest titer and yield of 3-hydroxypropionate via malonyl-CoA pathway are achieved. This study provides a strategy for improving the carbon yield of microbial cell factories.
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Affiliation(s)
- Likun Guo
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Min Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Yujia Bi
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Qingsheng Qi
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Mo Xian
- CAS Key Lab of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
| | - Guang Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China.
- CAS Key Lab of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
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Cao M, Cheng Q, Cai B, Chen Y, Wei Y, Qi D, Li Y, Yan L, Li X, Long W, Liu Q, Xie J, Wang W. Antifungal Mechanism of Metabolites from Newly Isolated Streptomyces sp. Y1-14 against Banana Fusarium Wilt Disease Using Metabolomics. J Fungi (Basel) 2022; 8:jof8121291. [PMID: 36547623 PMCID: PMC9784640 DOI: 10.3390/jof8121291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/03/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022] Open
Abstract
Banana Fusarium wilt caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) is one of the most destructive banana diseases in the world, which limits the development of the banana industry. Compared with traditional physical and chemical practices, biological control becomes a promising safe and efficient strategy. In this study, strain Y1-14 with strong antagonistic activity against Foc TR4 was isolated from the rhizosphere soil of a banana plantation, where no disease symptom was detected for more than ten years. The strain was identified as Streptomyces according to the morphological, physiological, and biochemical characteristics and the phylogenetic tree of 16S rRNA. Streptomyces sp. Y1-14 also showed a broad-spectrum antifungal activity against the selected 12 plant pathogenic fungi. Its extracts inhibited the growth and spore germination of Foc TR4 by destroying the integrity of the cell membrane and the ultrastructure of mycelia. Twenty-three compounds were identified by gas chromatography-mass spectrometry (GC-MS). The antifungal mechanism was investigated further by metabolomic analysis. Strain Y1-14 extracts significantly affect the carbohydrate metabolism pathway of Foc TR4 by disrupting energy metabolism.
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Affiliation(s)
- Miaomiao Cao
- College of Horticulture/College of Tropical Crops, Hainan University, Haikou 570228, China
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Qifeng Cheng
- College of Horticulture/College of Tropical Crops, Hainan University, Haikou 570228, China
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Bingyu Cai
- College of Horticulture/College of Tropical Crops, Hainan University, Haikou 570228, China
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Yufeng Chen
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Yongzan Wei
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Dengfeng Qi
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Yuqi Li
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- College of Horticulture, China Agricultural University, Beijing 100083, China
| | - Liu Yan
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- College of Horticulture, China Agricultural University, Beijing 100083, China
| | - Xiaojuan Li
- College of Horticulture/College of Tropical Crops, Hainan University, Haikou 570228, China
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Weiqiang Long
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- College of Horticulture and Forestry Sciences/Faculty of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Qiao Liu
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- College of Horticulture and Forestry Sciences/Faculty of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Jianghui Xie
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Correspondence: (J.X.); (W.W.)
| | - Wei Wang
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Correspondence: (J.X.); (W.W.)
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Wu W, Dijkstra P, Hungate BA, Shi L, Dippold MA. In situ diversity of metabolism and carbon use efficiency among soil bacteria. SCIENCE ADVANCES 2022; 8:eabq3958. [PMID: 36332015 PMCID: PMC9635821 DOI: 10.1126/sciadv.abq3958] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
The central carbon (C) metabolic network harvests energy to power the cell and feed biosynthesis for growth. In pure cultures, bacteria use some but not all of the network's major pathways, such as glycolysis and pentose phosphate and Entner-Doudoroff pathways. However, how these pathways are used in microorganisms in intact soil communities is unknown. Here, we analyzed the incorporation of 13C from glucose isotopomers into phospholipid fatty acids. We showed that groups of Gram-positive and Gram-negative bacteria in an intact agricultural soil used different pathways to metabolize glucose. They also differed in C use efficiency (CUE), the efficiency with which a substrate is used for biosynthesis. Our results provide experimental evidence for diversity among microbes in the organization of their central carbon metabolic network and CUE under in situ conditions. These results have important implications for our understanding of how community composition affects soil C cycling and organic matter formation.
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Affiliation(s)
- Weichao Wu
- Biogeochemistry of Agroecosystem, University of Goettingen, Goettingen, Germany
- Department of Environmental Science, Stockholm University, Stockholm, Sweden
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Science, Shanghai Ocean University, Shanghai, China
| | - Paul Dijkstra
- Center for Ecosystem Science and Society and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Bruce A. Hungate
- Center for Ecosystem Science and Society and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Lingling Shi
- Key Laboratory of Economics Plants and Biotechnology, Institute of Botany, Chinese Academy of Sciences, Kunming, China
- World Agroforestry Centre, China and East-Asia Office, Kunming, China
- Geo-Biosphere Interactions, Department of Geosciences, University of Tuebingen, Tuebingen, Germany
| | - Michaela A. Dippold
- Biogeochemistry of Agroecosystem, University of Goettingen, Goettingen, Germany
- Geo-Biosphere Interactions, Department of Geosciences, University of Tuebingen, Tuebingen, Germany
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Orsi E, Claassens NJ, Nikel PI, Lindner SN. Optimizing microbial networks through metabolic bypasses. Biotechnol Adv 2022; 60:108035. [PMID: 36096403 DOI: 10.1016/j.biotechadv.2022.108035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 09/01/2022] [Accepted: 09/05/2022] [Indexed: 01/29/2023]
Abstract
Metabolism has long been considered as a relatively stiff set of biochemical reactions. This somewhat outdated and dogmatic view has been challenged over the last years, as multiple studies exposed unprecedented plasticity of metabolism by exploring rational and evolutionary modifications within the metabolic network of cell factories. Of particular importance is the emergence of metabolic bypasses, which consist of enzymatic reaction(s) that support unnatural connections between metabolic nodes. Such novel topologies can be generated through the introduction of heterologous enzymes or by upregulating native enzymes (sometimes relying on promiscuous activities thereof). Altogether, the adoption of bypasses resulted in an expansion in the capacity of the host's metabolic network, which can be harnessed for bioproduction. In this review, we discuss modifications to the canonical architecture of central carbon metabolism derived from such bypasses towards six optimization purposes: stoichiometric gain, overcoming kinetic limitations, solving thermodynamic barriers, circumventing toxic intermediates, uncoupling product synthesis from biomass formation, and altering redox cofactor specificity. The metabolic costs associated with bypass-implementation are likewise discussed, including tailoring their design towards improving bioproduction.
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Affiliation(s)
- Enrico Orsi
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany; The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
| | - Nico J Claassens
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, the Netherlands
| | - Pablo I Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Steffen N Lindner
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany; Department of Biochemistry, Charité Universitätsmedizin, Virchowweg 6, 10117 Berlin, Germany.
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Ma X, Mi Y, Zhao C, Wei Q. A comprehensive review on carbon source effect of microalgae lipid accumulation for biofuel production. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:151387. [PMID: 34740661 DOI: 10.1016/j.scitotenv.2021.151387] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/12/2021] [Accepted: 10/29/2021] [Indexed: 06/13/2023]
Abstract
Energy is a major driving force for the economic development. Due to the scarcity of fossil fuels and negative impact on the environment, it is important to develop renewable and sustainable energy sources for humankind. Microalgae as the primary feedstock for biodiesel has shown great application potential. However, lipid yield from microalgae is limited by the upstream cost, which restrain the realization of large-scale biofuel production. The modification of lipid-rich microalgae cell has become the focus over the last few decades to improve the lipid content and productivity of microalgae. Carbon is a vital nutrient that regulates the growth and metabolism of microalgae. Different carbon sources are assimilated by microalgae cells via different pathways. Inorganic carbon sources are mainly used through the CO2-concentrating mechanisms (CCMs), while organic carbon sources are absorbed by microalgae mainly through the Pentose Phosphate (PPP) Pathway and the Embden-Meyerhof-Pranas (EMP) pathway. Therefore, the addition of carbon source has a significant impact on the production of microalgae biomass and lipid accumulation. In this paper, mechanisms of lipid synthesis and carbon uptake of microalgae were introduced, and the effects of different carbon conditions (types, concentrations, and addition methods) on lipid accumulation in microalgal biomass production and biodiesel production were comprehensively discussed. This review also highlights the recent advances in microalgae lipid cultivation with large-scale commercialization and the development prospects of biodiesel production. Current challenges and constructive suggestions are proposed on cost-benefit concerns in large-scale production of microalgae biodiesel.
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Affiliation(s)
- Xiangmeng Ma
- School of Resources, Environment and Materials, Guangxi University, Nanning, Guangxi 530004, China; Guangxi Key Laboratory of Electrochemical Energy Materials, Nanning, Guangxi 530004, China
| | - Yuwei Mi
- School of Resources, Environment and Materials, Guangxi University, Nanning, Guangxi 530004, China
| | - Chen Zhao
- China Construction Fifth Engineering Division Corp., Ltd, 9 Kaixuan Rd, Liangqing District, Nanning, Guangxi 530000, China
| | - Qun Wei
- School of Resources, Environment and Materials, Guangxi University, Nanning, Guangxi 530004, China.
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Fuchino K, Wasser D, Soppa J. Genome Copy Number Quantification Revealed That the Ethanologenic Alpha-Proteobacterium Zymomonas mobilis Is Polyploid. Front Microbiol 2021; 12:705895. [PMID: 34408736 PMCID: PMC8365228 DOI: 10.3389/fmicb.2021.705895] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/07/2021] [Indexed: 11/20/2022] Open
Abstract
The alpha-proteobacterium Zymomonas mobilis is a promising biofuel producer, based on its native metabolism that efficiently converts sugars to ethanol. Therefore, it has a high potential for industrial-scale biofuel production. Two previous studies suggested that Z. mobilis strain Zm4 might not be monoploid. However, a systematic analysis of the genome copy number is still missing, in spite of the high potential importance of Z. mobilis. To get a deep insight into the ploidy level of Z. mobilis and its regulation, the genome copy numbers of three strains were quantified. The analyses revealed that, during anaerobic growth, the lab strain Zm6, the Zm6 type strain obtained from DSMZ (German Collection of Microorganisms), and the lab strain Zm4, have copy numbers of 18.9, 22.3 and 16.2, respectively, of an origin-adjacent region. The copy numbers of a terminus-adjacent region were somewhat lower with 9.3, 15.8, and 12.9, respectively. The values were similar throughout the growth curves, and they were only slightly downregulated in late stationary phase. During aerobic growth, the copy numbers of the lab strain Zm6 were much higher with around 40 origin-adjacent copies and 17 terminus-adjacent copies. However, the cells were larger during aerobic growth, and the copy numbers per μm3 cell volume were rather similar. Taken together, this first systematic analysis revealed that Z. mobilis is polyploid under regular laboratory growth conditions. The copy number is constant during growth, in contrast to many other polyploid bacteria. This knowledge should be considered in further engineering of the strain for industrial applications.
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Affiliation(s)
- Katsuya Fuchino
- Institute for Molecular Biosciences, Goethe-University, Frankfurt, Germany.,Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Trondheim, Norway
| | - Daniel Wasser
- Institute for Molecular Biosciences, Goethe-University, Frankfurt, Germany
| | - Jörg Soppa
- Institute for Molecular Biosciences, Goethe-University, Frankfurt, Germany
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Li B, Cai D, Chen S. Metabolic Engineering of Central Carbon Metabolism of Bacillus licheniformis for Enhanced Production of Poly-γ-glutamic Acid. Appl Biochem Biotechnol 2021; 193:3540-3552. [PMID: 34312784 DOI: 10.1007/s12010-021-03619-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 07/12/2021] [Indexed: 01/17/2023]
Abstract
Poly-γ-glutamic acid (γ-PGA) is an anionic polymer with wide-ranging applications in the areas of medicine, light chemical industry, wastewater treatment, and agriculture. However, the production cost of γ-PGA is high for the requirement of adding the expensive precursor L-glutamic acid during fermentation, which hinders its widespread application. In this study, in order to improve γ-PGA yield, central carbon metabolism was engineered to enhance the carbon flux of tricarboxylic acid (TCA) cycle and glutamic acid synthesis in a γ-PGA production strain Bacillus licheniformis WX-02. Firstly, pyruvate dehydrogenase (PdhABCD) and citrate synthase (CitA) were overexpressed to strengthen the flux of pyruvate into TCA cycle, resulting in 34.93% and 11.14% increase of γ-PGA yield in B. licheniformis WX-02, respectively. Secondly, the carbon flux to glyoxylate shunt was rewired via varying the expression of isocitrate lyase (AceA), and a 23.24% increase of γ-PGA yield was obtained in AceA down-regulated strain WXPbacAaceBA. Thirdly, deletion of pyruvate formate-lyase gene pflB led to a 30.70% increase of γ-PGA yield. Finally, combinatorial metabolic engineering was applied, and γ-PGA titer was enhanced to 12.02 g/L via overexpressing pdhABCD and citA, repressing aceA, and deleting pflB, with a 69.30% improvement compared to WX-02. Collectively, metabolic engineering of central carbon metabolism is an effective strategy for enhanced γ-PGA production in B. licheniformis, and this research provided a promising strain for industrial production of γ-PGA.
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Affiliation(s)
- Bichan Li
- Fujian Provincial Key Laboratory of Eco-Industrial Green Technology, College of Ecological and Resource Engineering, Wuyi University, Wuyishan, 354300, People's Republic of China.,State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China
| | - Dongbo Cai
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, College of Life Sciences, Hubei University, Wuhan, 430062, People's Republic of China
| | - Shouwen Chen
- Fujian Provincial Key Laboratory of Eco-Industrial Green Technology, College of Ecological and Resource Engineering, Wuyi University, Wuyishan, 354300, People's Republic of China. .,State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, College of Life Sciences, Hubei University, Wuhan, 430062, People's Republic of China.
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Cofactor Specificity of Glucose-6-Phosphate Dehydrogenase Isozymes in Pseudomonas putida Reveals a General Principle Underlying Glycolytic Strategies in Bacteria. mSystems 2021; 6:6/2/e00014-21. [PMID: 33727391 PMCID: PMC8546961 DOI: 10.1128/msystems.00014-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glucose-6-phosphate dehydrogenase (G6PDH) is widely distributed in nature and catalyzes the first committing step in the oxidative branch of the pentose phosphate (PP) pathway, feeding either the reductive PP or the Entner-Doudoroff pathway. Besides its role in central carbon metabolism, this dehydrogenase provides reduced cofactors, thereby affecting redox balance. Although G6PDH is typically considered to display specificity toward NADP+, some variants accept NAD+ similarly or even preferentially. Furthermore, the number of G6PDH isozymes encoded in bacterial genomes varies from none to more than four orthologues. On this background, we systematically analyzed the interplay of the three G6PDH isoforms of the soil bacterium Pseudomonas putida KT2440 from genomic, genetic, and biochemical perspectives. P. putida represents an ideal model to tackle this endeavor, as its genome harbors gene orthologues for most dehydrogenases in central carbon metabolism. We show that the three G6PDHs of strain KT2440 have different cofactor specificities and that the isoforms encoded by zwfA and zwfB carry most of the activity, acting as metabolic “gatekeepers” for carbon sources that enter at different nodes of the biochemical network. Moreover, we demonstrate how multiplication of G6PDH isoforms is a widespread strategy in bacteria, correlating with the presence of an incomplete Embden-Meyerhof-Parnas pathway. The abundance of G6PDH isoforms in these species goes hand in hand with low NADP+ affinity, at least in one isozyme. We propose that gene duplication and relaxation in cofactor specificity is an evolutionary strategy toward balancing the relative production of NADPH and NADH. IMPORTANCE Protein families have likely arisen during evolution by gene duplication and divergence followed by neofunctionalization. While this phenomenon is well documented for catabolic activities (typical of environmental bacteria that colonize highly polluted niches), the coexistence of multiple isozymes in central carbon catabolism remains relatively unexplored. We have adopted the metabolically versatile soil bacterium Pseudomonas putida KT2440 as a model to interrogate the physiological and evolutionary significance of coexisting glucose-6-phosphate dehydrogenase (G6PDH) isozymes. Our results show that each of the three G6PDHs in this bacterium display distinct biochemical properties, especially at the level of cofactor preference, impacting bacterial physiology in a carbon source-dependent fashion. Furthermore, the presence of multiple G6PDHs differing in NAD+ or NADP+ specificity in bacterial species strongly correlates with their predominant metabolic lifestyle. Our findings support the notion that multiplication of genes encoding cofactor-dependent dehydrogenases is a general evolutionary strategy toward achieving redox balance according to the growth conditions.
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Abstract
The Embden–Meyerhof–Parnas (EMP) and Entner–Doudoroff (ED) pathways are considered the most abundant catabolic pathways found in microorganisms, and ED enzymes have been shown to also be widespread in cyanobacteria, algae and plants. In a large number of organisms, especially common strains used in molecular biology, these pathways account for the catabolism of glucose. The existence of pathways for other carbohydrates that are relevant to biomass utilization has been recognized as new strains have been characterized among thermophilic bacteria and Archaea that are able to transform simple polysaccharides from biomass to more complex and potentially valuable precursors for industrial microbiology. Many of the variants of the ED pathway have the key dehydratase enzyme involved in the oxidation of sugar derived from different families such as the enolase, IlvD/EDD and xylose-isomerase-like superfamilies. There are the variations in structure of proteins that have the same specificity and generally greater-than-expected substrate promiscuity. Typical biomass lignocellulose has an abundance of xylan, and four different pathways have been described, which include the Weimberg and Dahms pathways initially oxidizing xylose to xylono-gamma-lactone/xylonic acid, as well as the major xylose isomerase pathway. The recent realization that xylan constitutes a large proportion of biomass has generated interest in exploiting the compound for value-added precursors, but few chassis microorganisms can grow on xylose. Arabinose is part of lignocellulose biomass and can be metabolized with similar pathways to xylose, as well as an oxidative pathway. Like enzymes in many non-phosphorylative carbohydrate pathways, enzymes involved in L-arabinose pathways from bacteria and Archaea show metabolic and substrate promiscuity. A similar multiplicity of pathways was observed for other biomass-derived sugars such as L-rhamnose and L-fucose, but D-mannose appears to be distinct in that a non-phosphorylative version of the ED pathway has not been reported. Many bacteria and Archaea are able to grow on mannose but, as with other minor sugars, much of the information has been derived from whole cell studies with additional enzyme proteins being incorporated, and so far, only one synthetic pathway has been described. There appears to be a need for further discovery studies to clarify the general ability of many microorganisms to grow on the rarer sugars, as well as evaluation of the many gene copies displayed by marine bacteria.
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