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Nastouli A, Sweeney J, Harasek M, Karabelas AJ, Patsios SI. Development of a hybrid bio-purification process of lactic acid solutions employing an engineered E. coli strain in a membrane bioreactor. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:48. [PMID: 38555439 PMCID: PMC10981347 DOI: 10.1186/s13068-024-02497-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 03/22/2024] [Indexed: 04/02/2024]
Abstract
BACKGROUND A potential alternative to lactic acid production through sugar fermentation is its recovery from grass silage leachate. The separation and purification of lactic acid from fermentation broths remain a key issue, as it amounts to up to 80% of its industrial production cost. In this study, a genetically engineered E. coli strain (A1:ldhA), that cannot catabolize lactic acid, has been used to selectively remove impurities from a synthetic medium comprising typical components (i.e., glucose and acetic acid) of green grass silage leachate. A systematic approach has been followed to provide a proof-of-concept for a bio-purification process of lactic acid solutions in a membrane bioreactor operating in semi-continuous mode. RESULTS The synthetic medium composition was initially optimized in shake-flasks experiments, followed by scale-up in bench-scale bioreactor. Complete (i.e., 100%) and 60.4% removal for glucose and acetic acid, respectively, has been achieved in batch bioreactor experiments with a synthetic medium comprising 0.5 g/L glucose and 0.5 g/L acetic acid as carbon sources, and 10 g/L lactic acid; no lactic acid catabolism was observed in all batch fermentation tests. Afterwards, a hybrid biotechnological process combining semi-continuous bioreactor fermentation and ultrafiltration membrane separation (membrane bioreactor) was applied to in-situ separate purified medium from the active cells. The process was assessed under different semi-continuous operating conditions, resulting in a bacteria-free effluent and 100% glucose and acetic acid depletion, with no lactic acid catabolism, thus increasing the purity of the synthetic lactic acid solution. CONCLUSIONS The study clearly demonstrated that a bio-purification process for lactic acid employing the engineered E. coli strain cultivated in a membrane bioreactor is a technically feasible concept, paving the way for further technological advancement.
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Affiliation(s)
- Alexandra Nastouli
- Laboratory of Natural Resources and Renewable Energies, Chemical Process and Energy Resources Institute (CPERI), Centre for Research and Technology-Hellas (CERTH), Thermi, Thessaloniki, Greece
- Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria
| | - Joseph Sweeney
- School of Biosystems and Food Engineering, University College Dublin (UCD), Belfield, Dublin, Ireland
| | - Michael Harasek
- Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Vienna, Austria
| | - Anastasios J Karabelas
- Laboratory of Natural Resources and Renewable Energies, Chemical Process and Energy Resources Institute (CPERI), Centre for Research and Technology-Hellas (CERTH), Thermi, Thessaloniki, Greece
| | - Sotiris I Patsios
- Laboratory of Natural Resources and Renewable Energies, Chemical Process and Energy Resources Institute (CPERI), Centre for Research and Technology-Hellas (CERTH), Thermi, Thessaloniki, Greece.
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Zhang H, Hu W, Liu R, Bartlam M, Wang Y. Low and high nucleic acid content bacteria play discrepant roles in response to various carbon supply modes. Environ Microbiol 2023; 25:3703-3718. [PMID: 37964717 DOI: 10.1111/1462-2920.16539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 10/31/2023] [Indexed: 11/16/2023]
Abstract
Planktonic bacteria can be grouped into 'high nucleic acid content (HNA) bacteria' and 'low nucleic acid content (LNA) bacteria.' Nutrient input modes vary in environments, causing nutrient availability heterogeneity. We incubated them with equal amounts of total glucose added in a continuous/pulsed mode. The pulse-treated LNA bacteria exhibited twice the cell abundance and four times the viability of the continuous-treated LNA, while HNA did not show an adaptation to pulsed treatment. In structural equation modelling, LNA bacteria had higher path coefficients than HNA, between growth and carbon-saving metabolic pathways, intracellular ATP and the inorganic energy storage polymer, polyphosphate, indicating their low-cost growth, and flexible energy storage and utilisation. After incubation, the pulse-treated LNA bacteria contained more proteins and polysaccharides (0.00064, 0.0012 ng cell-1 ) than the continuous-treated LNA (0.00014, 0.00014 ng cell-1 ), conferring endurance and rapid response to pulses. Compared to LNA, HNA keystone taxa had stronger correlations with the primary glucose metabolism step, glycolysis, and occupied leading positions to explain the random forest model. They are essential to introduce glucose into the element cycling of the whole community under both treatments. Our work outlines a systematic bacterial response to carbon input.
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Affiliation(s)
- Hui Zhang
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
| | - Wei Hu
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
| | - Ruidan Liu
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
| | - Mark Bartlam
- College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
| | - Yingying Wang
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai International Advanced Research Institute (Shenzhen Futian), Nankai University, Tianjin, China
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Wang L, Zhang K, Gao S, Zhang M, Liu T, Cai B, Wang L, Su L, Wu J, Chen S. High-Yield Synthesis of 2'-Fucosyllactose from Glycerol and Glucose in Engineered Escherichia coli. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:15237-15248. [PMID: 37795855 DOI: 10.1021/acs.jafc.3c05015] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
2'-Fucosyllactose (2'-FL) is vital for the growth and development of newborns. In this study, we developed a synthesis pathway for 2'-FL in Escherichia coli BL21 (DE3). Then, we optimized the solubility of α-1,2-fucosyltransferase, thereby enhancing the production yield of 2'-FL. Based on this finding, we further enhanced the expression of guanosine inosine kinase Gsk and knocked out the isocitrate lyase regulator gene iclR. This strategy reduced the formation of byproduct acetate during the metabolic process and alleviated carbon source overflow effects in the strain, resulting in further improvement of the yield of 2'-FL. In a 3 L bioreactor, employing fed-batch fermentation with glycerol and glucose as substrates, the engineered strain BWLAI-RSZL exhibited impressive 2'-FL titers of 121.9 and 111.56 g/L, along with productivity levels of 1.57 and 1.31 g/L/h, respectively. The reported 2'-FL titers reached a groundbreaking level, irrespective of the carbon source employed (glycerol or glucose), highlighting the significant potential for large-scale industrial synthesis of 2'-FL.
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Affiliation(s)
- Luyao Wang
- State Key Laboratory of Food Science and Resources, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology Ministry of Education, and International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Kang Zhang
- State Key Laboratory of Food Science and Resources, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology Ministry of Education, and International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Shengqi Gao
- State Key Laboratory of Food Science and Resources, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology Ministry of Education, and International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Mengwei Zhang
- State Key Laboratory of Food Science and Resources, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology Ministry of Education, and International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Tongle Liu
- State Key Laboratory of Food Science and Resources, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology Ministry of Education, and International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Bohan Cai
- State Key Laboratory of Food Science and Resources, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology Ministry of Education, and International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Lei Wang
- State Key Laboratory of Food Science and Resources, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology Ministry of Education, and International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Lingqia Su
- State Key Laboratory of Food Science and Resources, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology Ministry of Education, and International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jing Wu
- State Key Laboratory of Food Science and Resources, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology Ministry of Education, and International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Sheng Chen
- State Key Laboratory of Food Science and Resources, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Industrial Biotechnology Ministry of Education, and International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
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Gu P, Li F, Huang Z. Engineering Escherichia coli for Isobutanol Production from Xylose or Glucose-Xylose Mixture. Microorganisms 2023; 11:2573. [PMID: 37894231 PMCID: PMC10609591 DOI: 10.3390/microorganisms11102573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 10/11/2023] [Accepted: 10/12/2023] [Indexed: 10/29/2023] Open
Abstract
Aiming to overcome the depletion of fossil fuels and serious environmental pollution, biofuels such as isobutanol have garnered increased attention. Among different synthesis methods, the microbial fermentation of isobutanol from raw substrate is a promising strategy due to its low cost and environmentally friendly and optically pure products. As an important component of lignocellulosics and the second most common sugar in nature, xylose has become a promising renewable resource for microbial production. However, bottlenecks in xylose utilization limit its wide application as substrates. In this work, an isobutanol synthetic pathway from xylose was first constructed in E. coli MG1655 through the combination of the Ehrlich and Dahms pathways. The engineering of xylose transport and electron transport chain complexes further improved xylose assimilation and isobutanol production. By optimizing xylose supplement concentration, the recombinant E. coli strain BWL4 could produce 485.35 mg/L isobutanol from 20 g/L of xylose. To our knowledge, this is the first report related to isobutanol production using xylose as a sole carbon source in E. coli. Additionally, a glucose-xylose mixture was utilized as the carbon source. The Entner-Doudorof pathway was used to assimilate glucose, and the Ehrlich pathway was applied for isobutanol production. After carefully engineering the recombinant E. coli, strain BWL9 could produce 528.72 mg/L isobutanol from a mixture of 20 g/L glucose and 10 g/L xylose. The engineering strategies applied in this work provide a useful reference for the microbial production of isobutanol from xylose or glucose-xylose mixture.
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Affiliation(s)
- Pengfei Gu
- School of Biological Science and Technology, University of Jinan, Jinan 250022, China;
| | - Fangfang Li
- Yantai Food and Drug Control and Test Center, Yantai 264003, China;
| | - Zhaosong Huang
- School of Biological Science and Technology, University of Jinan, Jinan 250022, China;
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Yan J, Yang B, Xue X, Li J, Li Y, Li A, Ding P, Cao B. Transcriptome Analysis Reveals the Effect of PdhR in Plesiomonas shigelloides. Int J Mol Sci 2023; 24:14473. [PMID: 37833920 PMCID: PMC10572922 DOI: 10.3390/ijms241914473] [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: 08/29/2023] [Revised: 09/19/2023] [Accepted: 09/21/2023] [Indexed: 10/15/2023] Open
Abstract
The pyruvate dehydrogenase complex regulator (PdhR) was originally identified as a repressor of the pdhR-aceEF-lpd operon, which encodes the pyruvate dehydrogenase complex (PDHc) and PdhR itself. According to previous reports, PdhR plays a regulatory role in the physiological and metabolic pathways of bacteria. At present, the function of PdhR in Plesiomonas shigelloides is still poorly understood. In this study, RNA sequencing (RNA-Seq) of the wild-type strain and the ΔpdhR mutant strains was performed for comparison to identify the PdhR-controlled pathways, revealing that PdhR regulates ~7.38% of the P. shigelloides transcriptome. We found that the deletion of pdhR resulted in the downregulation of practically all polar and lateral flagella genes in P. shigelloides; meanwhile, motility assay and transmission electron microscopy (TEM) confirmed that the ΔpdhR mutant was non-motile and lacked flagella. Moreover, the results of RNA-seq and quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) showed that PdhR positively regulated the expression of the T3SS cluster, and the ΔpdhR mutant significantly reduced the ability of P. shigelloides to infect Caco-2 cells compared with the WT. Consistent with previous research, pyruvate-sensing PdhR directly binds to its promoter and inhibits pdhR-aceEF-lpd operon expression. In addition, we identified two additional downstream genes, metR and nuoA, that are directly negatively regulated by PdhR. Furthermore, we also demonstrated that ArcA was identified as being located upstream of pdhR and lpdA and directly negatively regulating their expression. Overall, we revealed the function and regulatory pathway of PdhR, which will allow for a more in-depth investigation into P. shigelloides pathogenicity as well as the complex regulatory network.
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Affiliation(s)
- Junxiang Yan
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin 300457, China
| | - Bin Yang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin 300457, China
| | - Xinke Xue
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin 300457, China
| | - Jinghao Li
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin 300457, China
| | - Yuehua Li
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin 300457, China
| | - Ang Li
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300353, China
- College of Pharmacy Laboratory of Molecular Drug Research, Nankai University, Tianjin 300353, China
| | - Peng Ding
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin 300457, China
| | - Boyang Cao
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China
- Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, TEDA College, Nankai University, Tianjin 300457, China
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Exploiting Catabolite Repression and Stringent Response to Control Delay and Multimodality of Bioluminescence Signal by Metal Whole-Cell Biosensors: Interplay between Metal Bioavailability and Nutritional Medium Conditions. BIOSENSORS 2022; 12:bios12050327. [PMID: 35624628 PMCID: PMC9139025 DOI: 10.3390/bios12050327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 05/09/2022] [Accepted: 05/10/2022] [Indexed: 12/02/2022]
Abstract
The time-dependent response of metal-detecting whole-cell luminescent bacterial sensors is impacted by metal speciation/bioavailability in solution. The comprehensive understanding of such connections requires the consideration of the bacterial energy metabolism at stake and the effects of supplied food on cells’ capability to convert bioaccumulated metals into light. Accordingly, we investigated the time response (48 h assay) of PzntA-luxCDABE Escherichia coli Cd biosensors in media differing with respect to sources of amino acids (tryptone or Lysogeny Broth) and carbon (glucose, xylose and mixtures thereof). We show that the resulting coupling between the stringent cell response and glucose/xylose-mediated catabolite repressions lead to well-defined multimodalities and shapes of the bioluminescence signal over time. Based on a recent theory for the time–response of metal-sensing luminescent bacteria, successful theoretical reconstructions of the bioluminescence signals are reported under all Cd concentrations (0–20 nM) and nutritive conditions examined. This analysis leads to the evaluation of time-dependent cell photoactivity and qualitative information on metal speciation/bioavailability in solution. Biosensor performance and the position, shape, number, and magnitude of detected peaks are discussed in relation to the metabolic pathways operative during the successive light emission modes identified here over time. Altogether, the results clarify the contributions of metal/nutrient bio-availabilities and food quality to cell response typology.
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Smaluch K, Wollenhaupt B, Steinhoff H, Kohlheyer D, Grünberger A, Dusny C. Assessing the growth kinetics and stoichiometry of Escherichia coli at the single-cell level. Eng Life Sci 2022; 23:e2100157. [PMID: 36619887 PMCID: PMC9815083 DOI: 10.1002/elsc.202100157] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 03/17/2022] [Accepted: 04/16/2022] [Indexed: 01/11/2023] Open
Abstract
Microfluidic cultivation and single-cell analysis are inherent parts of modern microbial biotechnology and microbiology. However, implementing biochemical engineering principles based on the kinetics and stoichiometry of growth in microscopic spaces remained unattained. We here present a novel integrated framework that utilizes distinct microfluidic cultivation technologies and single-cell analytics to make the fundamental math of process-oriented biochemical engineering applicable at the single-cell level. A combination of non-invasive optical cell mass determination with sub-pg sensitivity, microfluidic perfusion cultivations for establishing physiological steady-states, and picoliter batch reactors, enabled the quantification of all physiological parameters relevant to approximate a material balance in microfluidic reaction environments. We determined state variables (biomass concentration based on single-cell dry weight and mass density), biomass synthesis rates, and substrate affinities of cells grown in microfluidic environments. Based on this data, we mathematically derived the specific kinetics of substrate uptake and growth stoichiometry in glucose-grown Escherichia coli with single-cell resolution. This framework may initiate microscale material balancing beyond the averaged values obtained from populations as a basis for integrating heterogeneous kinetic and stoichiometric single-cell data into generalized bioprocess models and descriptions.
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Affiliation(s)
- Katharina Smaluch
- Department of Solar Materials – Microscale Analysis and EngineeringHelmholtz‐Centre for Environmental Research – UFZ LeipzigLeizpigGermany
| | - Bastian Wollenhaupt
- Microscale BioengineeringIBG‐1: BiotechnologyForschungszentrum Jülich GmbHJülichGermany
| | - Heiko Steinhoff
- Multiscale BioengineeringFaculty of TechnologyBielefeld UniversityBielefeldGermany
| | - Dietrich Kohlheyer
- Microscale BioengineeringIBG‐1: BiotechnologyForschungszentrum Jülich GmbHJülichGermany
| | - Alexander Grünberger
- Multiscale BioengineeringFaculty of TechnologyBielefeld UniversityBielefeldGermany
| | - Christian Dusny
- Department of Solar Materials – Microscale Analysis and EngineeringHelmholtz‐Centre for Environmental Research – UFZ LeipzigLeizpigGermany
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Miyakoshi M, Morita T, Kobayashi A, Berger A, Takahashi H, Gotoh Y, Hayashi T, Tanaka K. Glutamine synthetase mRNA releases sRNA from its 3'UTR to regulate carbon/nitrogen metabolic balance in Enterobacteriaceae. eLife 2022; 11:82411. [PMID: 36440827 PMCID: PMC9731577 DOI: 10.7554/elife.82411] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 11/27/2022] [Indexed: 11/29/2022] Open
Abstract
Glutamine synthetase (GS) is the key enzyme of nitrogen assimilation induced under nitrogen limiting conditions. The carbon skeleton of glutamate and glutamine, 2-oxoglutarate, is supplied from the TCA cycle, but how this metabolic flow is controlled in response to nitrogen availability remains unknown. We show that the expression of the E1o component of 2-oxoglutarate dehydrogenase, SucA, is repressed under nitrogen limitation in Salmonella enterica and Escherichia coli. The repression is exerted at the post-transcriptional level by an Hfq-dependent sRNA GlnZ generated from the 3'UTR of the GS-encoding glnA mRNA. Enterobacterial GlnZ variants contain a conserved seed sequence and primarily regulate sucA through base-pairing far upstream of the translation initiation region. During growth on glutamine as the nitrogen source, the glnA 3'UTR deletion mutants expressed SucA at higher levels than the S. enterica and E. coli wild-type strains, respectively. In E. coli, the transcriptional regulator Nac also participates in the repression of sucA. Lastly, this study clarifies that the release of GlnZ from the glnA mRNA by RNase E is essential for the post-transcriptional regulation of sucA. Thus, the mRNA coordinates the two independent functions to balance the supply and demand of the fundamental metabolites.
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Affiliation(s)
- Masatoshi Miyakoshi
- Department of Infection Biology, Faculty of Medicine, University of TsukubaTsukubaJapan,Transborder Medical Research Center, University of TsukubaTsukubaJapan,International Joint Degree Master’s Program in Agro-Biomedical Science in Food and Health (GIP-TRIAD), University of TsukubaTsukubaJapan
| | - Teppei Morita
- Institute for Advanced Biosciences, Keio UniversityTsuruokaJapan,Graduate School of Media and Governance, Keio UniversityFujisawaJapan
| | - Asaki Kobayashi
- Transborder Medical Research Center, University of TsukubaTsukubaJapan
| | - Anna Berger
- International Joint Degree Master’s Program in Agro-Biomedical Science in Food and Health (GIP-TRIAD), University of TsukubaTsukubaJapan
| | | | - Yasuhiro Gotoh
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu UniversityFukuokaJapan
| | - Tetsuya Hayashi
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu UniversityFukuokaJapan
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of TechnologyYokohamaJapan
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