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Mao C, Zheng H, Chen Y, Yuan P, Sun D. Development of a Type I-E CRISPR-Based Programmable Repression System for Fine-Tuning Metabolic Flux toward D-Pantothenic Acid in Bacillus subtilis. ACS Synth Biol 2024; 13:2480-2491. [PMID: 39083228 DOI: 10.1021/acssynbio.4c00256] [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] [Indexed: 08/17/2024]
Abstract
The CRISPR-based regulation tools enable fine-tuning of gene transcription, showing potential in areas of biomanufacturing and live therapeutics. However, the cell toxicity and PAM specificity of existing CRISPR-based regulation systems limit their broad application. The development of new and less-toxic CRISPR-controlled expression systems remains highly desirable for expanding the application scope of CRISPR-based tools. Here, we reconstituted the type I CRISPR-Cas system from Escherichia coli to finely tune gene expression in Bacillus subtilis. Through engineering the 5' untranslated region (UTR) of mRNAs of cas genes, we remarkably improved the efficacy of the type I CRISPRi system. The improved type I CRISPRi system was applied in engineering the D-pantothenic acid (DPA)-producing B. subtilis, which was generated by strengthening the metabolic flux toward β-alanine and (R)-pantoate via enhancing expression of key enzymes at both transcriptional and translational levels. Through controlling the expression of pdhA with the CRISPRi system for fine-tuning the metabolic flux toward DPA and the TCA cycle, we elevated the DPA titer to 0.88 g/L in shake flasks and 12.81 g/L in fed-batch fermentations without the addition of the precursor β-alanine. The type I CRISPRi system and the strategy for fine-tuning metabolic flux reported here not only enrich the CRISPR toolbox in B. subtilis and facilitate DPA production through microbial fermentation but also provide a paradigm for programming important organisms to produce value-added chemicals with cheap raw materials.
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Affiliation(s)
- Chengyao Mao
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - Han Zheng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - Yifeng Chen
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - Panhong Yuan
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - Dongchang Sun
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
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Yuan P, Xu M, Mao C, Zheng H, Sun D. Dynamically Regulating Glucose Uptake to Reduce Overflow Metabolism with a Quorum-Sensing Circuit for the Efficient Synthesis of d-Pantothenic Acid in Bacillus subtilis. ACS Synth Biol 2023; 12:2983-2995. [PMID: 37664894 DOI: 10.1021/acssynbio.3c00315] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
In response to a high concentration of glucose, Bacillus subtilis, a microbial chassis for producing many industrial metabolites, rapidly takes up glucose using the phosphotransferase system (PTS), leading to overflow metabolism, a common phenomenon observed in many bacteria. Although overflow metabolism affects cell growth and reduces the production of many metabolites, effective strategies that reduce overflow metabolism while maintaining normal cell growth remain to be developed. Here, we used a quorum sensing (QS)-mediated circuit to tune the glucose uptake rate and thereby relieve overflow metabolism in an engineered B. subtilis for producing d-pantothenic acid (DPA). A low-efficiency non-PTS system was used for glucose uptake at the early growth stages to avoid a rapid glycolytic flux, while an efficient PTS system, which was activated by a QS circuit, was automatically activated at the late growth stages after surpassing a threshold cell density. This strategy was successfully applied as a modular metabolic engineering process for the high production of DPA. By enhancing the translation levels of key enzymes (3-methyl-2-oxobutanoate hydroxymethytransferase, pantothenate synthetase, aspartate 1-decarboxylase proenzyme, 2-dehydropantoate 2-reductase, dihydroxy-acid dehydratase, and acetolactate synthase) with engineered 5'-untranslated regions (UTRs) of mRNAs, the metabolic flux was promoted in the direction of DPA production, elevating the yield of DPA to 5.11 g/L in shake flasks. Finally, the engineered B. subtilis produced 21.52 g/L of DPA in fed-batch fermentations. Our work not only revealed a new strategy for reducing overflow metabolism by adjusting the glucose uptake rate in combination with promoting the translation of key metabolic enzymes through engineering the 5'-UTR of mRNAs but also showed its power in promoting the bioproduction of DPA in B. subtilis, exhibiting promising application prospects.
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Affiliation(s)
- Panhong Yuan
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China
| | - Mengtao Xu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China
| | - Chengyao Mao
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China
| | - Han Zheng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China
| | - Dongchang Sun
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China
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Hu S, Fei M, Fu B, Yu M, Yuan P, Tang B, Yang H, Sun D. Development of probiotic E. coli Nissle 1917 for β-alanine production by using protein and metabolic engineering. Appl Microbiol Biotechnol 2023; 107:2277-2288. [PMID: 36929190 DOI: 10.1007/s00253-023-12477-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 01/18/2023] [Accepted: 03/06/2023] [Indexed: 03/18/2023]
Abstract
β-alanine has been used in food and pharmaceutical industries. Although Escherichia coli Nissle 1917 (EcN) is generally considered safe and engineered as living therapeutics, engineering EcN for producing industrial metabolites has rarely been explored. Here, by protein and metabolic engineering, EcN was engineered for producing β-alanine from glucose. First, an aspartate-α-decarboxylase variant ADCK43Y with improved activity was identified and over-expressed in EcN, promoting the titer of β-alanine from an undetectable level to 0.46 g/L. Second, directing the metabolic flux towards L-aspartate increased the titer of β-alanine to 0.92 g/L. Third, the yield of β-alanine was elevated to 1.19 g/L by blocking conversion of phosphoenolpyruvate to pyruvate, and further increased to 2.14 g/L through optimizing culture medium. Finally, the engineered EcN produced 11.9 g/L β-alanine in fed-batch fermentation. Our work not only shows the potential of EcN as a valuable industrial platform, but also facilitates production of β-alanine via fermentation. KEY POINTS: • Escherichia coli Nissle 1917 (EcN) was engineered as a β-alanine producing cell factory • Identification of a decarboxylase variant ADCK43Y with improved activity • Directing the metabolic flux to L-ASP and expressing ADCK43Y elevated the titer of β-alanine to 11.9 g/L.
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Affiliation(s)
- Shilong Hu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang, China
| | - Mingyue Fei
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang, China
| | - Beibei Fu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang, China
| | - Mingjing Yu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang, China
| | - Panhong Yuan
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang, China
| | - Biao Tang
- Institute of Quality and Standard for Agro-Products, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, Zhejiang, China
| | - Hua Yang
- Institute of Quality and Standard for Agro-Products, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, Zhejiang, China
| | - Dongchang Sun
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, Zhejiang, China.
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Yuan SF, Nair PH, Borbon D, Coleman SM, Fan PH, Lin WL, Alper HS. Metabolic engineering of E. coli for β-alanine production using a multi-biosensor enabled approach. Metab Eng 2022; 74:24-35. [PMID: 36067877 DOI: 10.1016/j.ymben.2022.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 07/18/2022] [Accepted: 08/30/2022] [Indexed: 10/31/2022]
Abstract
β-alanine is an important biomolecule used in nutraceuticals, pharmaceuticals, and chemical synthesis. The relatively eco-friendly bioproduction of β-alanine has recently attracted more interest than petroleum-based chemical synthesis. In this work, we developed two types of in vivo high-throughput screening platforms, wherein one was utilized to identify a novel target ribonuclease E (encoded by rne) as well as a redox-cofactor balancing module that can enhance de novo β-alanine biosynthesis from glucose, and the other was employed for screening fermentation conditions. When combining these approaches with rational upstream and downstream module engineering, an engineered E. coli producer was developed that exhibited 3.4- and 6.6-fold improvement in β-alanine yield (0.85 mol β-alanine/mole glucose) and specific β-alanine production (0.74 g/L/OD600), respectively, compared to the parental strain in a minimal medium. Across all of the strains constructed, the best yielding strain exhibited 1.08 mol β-alanine/mole glucose (equivalent to 81.2% of theoretic yield). The final engineered strain produced 6.98 g/L β-alanine in a batch-mode bioreactor and 34.8 g/L through a whole-cell catalysis. This approach demonstrates the utility of biosensor-enabled high-throughput screening for the production of β-alanine.
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Affiliation(s)
- Shuo-Fu Yuan
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - Priya H Nair
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Dominic Borbon
- Biology, College of Natural Sciences, The University of Texas at Austin, Austin, TX, USA
| | - Sarah M Coleman
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Po-Hsun Fan
- Department of Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA
| | - Wen-Ling Lin
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - Hal S Alper
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA; McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA.
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