1
|
Pöschel L, Gehr E, Jordan P, Sonntag F, Buchhaupt M. Expression of toxic genes in Methylorubrum extorquens with a tightly repressed, cumate-inducible promoter. Antonie Van Leeuwenhoek 2023; 116:1285-1294. [PMID: 37751033 PMCID: PMC10645615 DOI: 10.1007/s10482-023-01880-7] [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: 06/23/2023] [Accepted: 09/11/2023] [Indexed: 09/27/2023]
Abstract
Methylorubrum extorquens is an important model methylotroph and has enormous potential for the development of C1-based microbial cell factories. During strain construction, regulated promoters with a low background expression level are important genetic tools for expression of potentially toxic genes. Here we present an accordingly optimised promoter, which can be used for that purpose. During construction and testing of terpene production strains harbouring a recombinant mevalonate pathway, strong growth defects were observed which made strain development impossible. After isolation and characterisation of suppressor mutants, we discovered a variant of the cumate-inducible promoter PQ2148 used in this approach. Deletion of 28 nucleotides resulted in an extremely low background expression level, but also reduced the maximal expression strength to about 30% of the original promoter. This tightly repressed promoter version is a powerful module for controlled expression of potentially toxic genes in M. extorquens.
Collapse
Affiliation(s)
- Laura Pöschel
- DECHEMA-Forschungsinstitut, Microbial Biotechnology, Theodor-Heuss-Allee 25, 60486, Frankfurt Am Main, Germany
- Faculty of Biological Sciences, Goethe University Frankfurt Am Main, Max-Von-Laue-Str. 9, 60438, Frankfurt Am Main, Germany
| | - Elisabeth Gehr
- DECHEMA-Forschungsinstitut, Microbial Biotechnology, Theodor-Heuss-Allee 25, 60486, Frankfurt Am Main, Germany
| | - Paulina Jordan
- DECHEMA-Forschungsinstitut, Microbial Biotechnology, Theodor-Heuss-Allee 25, 60486, Frankfurt Am Main, Germany
| | - Frank Sonntag
- DECHEMA-Forschungsinstitut, Microbial Biotechnology, Theodor-Heuss-Allee 25, 60486, Frankfurt Am Main, Germany
| | - Markus Buchhaupt
- DECHEMA-Forschungsinstitut, Microbial Biotechnology, Theodor-Heuss-Allee 25, 60486, Frankfurt Am Main, Germany.
| |
Collapse
|
2
|
Phan UT, Jeon BW, Kim YH. Microbial engineering of Methylorubrum extorquens AM1 to enhance CO 2 conversion into formate. Enzyme Microb Technol 2023; 168:110264. [PMID: 37244213 DOI: 10.1016/j.enzmictec.2023.110264] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 05/22/2023] [Accepted: 05/22/2023] [Indexed: 05/29/2023]
Abstract
Methylorubrum extorquens AM1 has the potential to consume C1 feedstock to produce a wide range of biomaterials, from bioplastic to pharmaceutical. However, the synthetic biology tools for engineering M. extorquens AM1 need to be employed for precise control of recombinant enzyme expression. In this study, we presented an approach to improve the expression level of formate dehydrogenase 1 from M. extorquens AM1 (MeFDH1) using an efficient terminator and 5'-untranslated region (5'-UTR) design for enhanced carbon dioxide (CO2) conversion activity of whole-cell biocatalyst. The rrnB terminator significantly increased mRNA levels of MeFDH1 alpha and beta subunits by 8.2-fold and 11-fold, respectively, compared to the T7 terminator. Moreover, enzyme production was 1.6-fold higher with 2.1 mg/wet cell weight (WCW) using rrnB terminator. Homologous 5'-untranslated regions (5'-UTR) determined based on proteomics data and UTR designer also influenced the expression level of MeFDH1. The 5'-UTR of the formaldehyde activating enzyme (fae) was the strongest, with 2.5-fold higher expression than that of the control sequence (T7g-10L). Furthermore, the electrochemical reaction of recombinant strains as whole-cell biocatalysts was investigated for their applicability to CO2 conversion, showing enhanced formate productivity. The recombinant strain containing the 5'-UTR sequence of fae exhibited formate productivity of 5.0 mM/h, 2.3-fold higher than that of the control strain (T7). Overall, this study suggested practical applications for CO2 conversion into bioavailable formate and provided valuable insights for recombinant expression systems in methylotrophic strains.
Collapse
Affiliation(s)
- Uyen Thu Phan
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, the Republic of Korea
| | - Byoung Wook Jeon
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, the Republic of Korea
| | - Yong Hwan Kim
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, the Republic of Korea.
| |
Collapse
|
3
|
Singh HB, Kang MK, Kwon M, Kim SW. Developing methylotrophic microbial platforms for a methanol-based bioindustry. Front Bioeng Biotechnol 2022; 10:1050740. [PMID: 36507257 PMCID: PMC9727194 DOI: 10.3389/fbioe.2022.1050740] [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: 09/22/2022] [Accepted: 11/11/2022] [Indexed: 11/24/2022] Open
Abstract
Methanol, a relatively cheap and renewable single-carbon feedstock, has gained considerable attention as a substrate for the bio-production of commodity chemicals. Conventionally produced from syngas, along with emerging possibilities of generation from methane and CO2, this C1 substrate can serve as a pool for sequestering greenhouse gases while supporting a sustainable bio-economy. Methylotrophic organisms, with the inherent ability to use methanol as the sole carbon and energy source, are competent candidates as platform organisms. Accordingly, methanol bioconversion pathways have been an attractive target for biotechnological and bioengineering interventions in developing microbial cell factories. This review summarizes the recent advances in methanol-based production of various bulk and value-added chemicals exploiting the native and synthetic methylotrophic organisms. Finally, the current challenges and prospects of streamlining these methylotrophic platforms are discussed.
Collapse
Affiliation(s)
- Hawaibam Birla Singh
- Division of Applied Life Science (BK21 Four), ABC-RLRC, PMBBRC, Gyeongsang National University, Jinju, South Korea
| | - Min-Kyoung Kang
- Division of Applied Life Science (BK21 Four), ABC-RLRC, PMBBRC, Gyeongsang National University, Jinju, South Korea
| | - Moonhyuk Kwon
- Division of Life Science, ABC-RLRC, PMBBRC, Gyeongsang National University, Jinju, South Korea,*Correspondence: Moonhyuk Kwon, ; Seon-Won Kim,
| | - Seon-Won Kim
- Division of Applied Life Science (BK21 Four), ABC-RLRC, PMBBRC, Gyeongsang National University, Jinju, South Korea,*Correspondence: Moonhyuk Kwon, ; Seon-Won Kim,
| |
Collapse
|
4
|
Piñero-Lambea C, Garcia-Ramallo E, Miravet-Verde S, Burgos R, Scarpa M, Serrano L, Lluch-Senar M. SURE editing: combining oligo-recombineering and programmable insertion/deletion of selection markers to efficiently edit the Mycoplasma pneumoniae genome. Nucleic Acids Res 2022; 50:e127. [PMID: 36215032 PMCID: PMC9825166 DOI: 10.1093/nar/gkac836] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 08/03/2022] [Accepted: 09/28/2022] [Indexed: 01/29/2023] Open
Abstract
The development of advanced genetic tools is boosting microbial engineering which can potentially tackle wide-ranging challenges currently faced by our society. Here we present SURE editing, a multi-recombinase engineering rationale combining oligonucleotide recombineering with the selective capacity of antibiotic resistance via transient insertion of selector plasmids. We test this method in Mycoplasma pneumoniae, a bacterium with a very inefficient native recombination machinery. Using SURE editing, we can seamlessly generate, in a single step, a wide variety of genome modifications at high efficiencies, including the largest possible deletion of this genome (30 Kb) and the targeted complementation of essential genes in the deletion of a region of interest. Additional steps can be taken to remove the selector plasmid from the edited area, to obtain markerless or even scarless edits. Of note, SURE editing is compatible with different site-specific recombinases for mediating transient plasmid integration. This battery of selector plasmids can be used to select different edits, regardless of the target sequence, which significantly reduces the cloning load associated to genome engineering projects. Given the proven functionality in several microorganisms of the machinery behind the SURE editing logic, this method is likely to represent a valuable advance for the synthetic biology field.
Collapse
Affiliation(s)
| | | | - Samuel Miravet-Verde
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Raul Burgos
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | | | - Luis Serrano
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain,Universitat Pompeu Fabra (UPF), Barcelona 08002, Spain,ICREA, Pg. Lluís Companys 23, Barcelona 08010, Spain
| | - Maria Lluch-Senar
- Correspondence may also be addressed to Maria Lluch-Senar. Tel: +34 661963680;
| |
Collapse
|
5
|
Pan-genome Analysis Reveals Comparative Genomic Features of Central Metabolic Pathways in Methylorubrum extorquens. BIOTECHNOL BIOPROC E 2022. [DOI: 10.1007/s12257-022-0154-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
|
6
|
Yang H, Qu J, Zou W, Shen W, Chen X. An overview and future prospects of recombinant protein production in Bacillus subtilis. Appl Microbiol Biotechnol 2021; 105:6607-6626. [PMID: 34468804 DOI: 10.1007/s00253-021-11533-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/12/2021] [Accepted: 08/15/2021] [Indexed: 12/27/2022]
Abstract
Bacillus subtilis is a well-characterized Gram-positive bacterium and a valuable host for recombinant protein production because of its efficient secretion ability, high yield, and non-toxicity. Here, we comprehensively review the recent studies on recombinant protein production in B. subtilis to update and supplement other previous reviews. We have focused on several aspects, including optimization of B. subtilis strains, enhancement and regulation of expression, improvement of secretion level, surface display of proteins, and fermentation optimization. Among them, optimization of B. subtilis strains mainly involves undirected chemical/physical mutagenesis and selection and genetic manipulation; enhancement and regulation of expression comprises autonomous plasmid and integrated expression, promoter regulation and engineering, and fine-tuning gene expression based on proteases and molecular chaperones; improvement of secretion level predominantly involves secretion pathway and signal peptide screening and optimization; surface display of proteins includes surface display of proteins on spores or vegetative cells; and fermentation optimization incorporates medium optimization, process condition optimization, and feeding strategy optimization. Furthermore, we propose some novel methods and future challenges for recombinant protein production in B. subtilis.Key points• A comprehensive review on recombinant protein production in Bacillus subtilis.• Novel techniques facilitate recombinant protein expression and secretion.• Surface display of proteins has significant potential for different applications.
Collapse
Affiliation(s)
- Haiquan Yang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
| | - Jinfeng Qu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Wei Zou
- College of Bioengineering, Sichuan University of Science & Engineering, Yibin, 644000, Sichuan, China
| | - Wei Shen
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Xianzhong Chen
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
| |
Collapse
|
7
|
Kozaeva E, Volkova S, Matos MRA, Mezzina MP, Wulff T, Volke DC, Nielsen LK, Nikel PI. Model-guided dynamic control of essential metabolic nodes boosts acetyl-coenzyme A-dependent bioproduction in rewired Pseudomonas putida. Metab Eng 2021; 67:373-386. [PMID: 34343699 DOI: 10.1016/j.ymben.2021.07.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/23/2021] [Accepted: 07/29/2021] [Indexed: 01/16/2023]
Abstract
Pseudomonas putida is evolutionarily endowed with features relevant for bioproduction, especially under harsh operating conditions. The rich metabolic versatility of this species, however, comes at the price of limited formation of acetyl-coenzyme A (CoA) from sugar substrates. Since acetyl-CoA is a key metabolic precursor for a number of added-value products, in this work we deployed an in silico-guided rewiring program of central carbon metabolism for upgrading P. putida as a host for acetyl-CoA-dependent bioproduction. An updated kinetic model, integrating fluxomics and metabolomics datasets in addition to manually-curated information of enzyme mechanisms, identified targets that would lead to increased acetyl-CoA levels. Based on these predictions, a set of plasmids based on clustered regularly interspaced short palindromic repeats (CRISPR) and dead CRISPR-associated protein 9 (dCas9) was constructed to silence genes by CRISPR interference (CRISPRi). Dynamic reduction of gene expression of two key targets (gltA, encoding citrate synthase, and the essential accA gene, encoding subunit A of the acetyl-CoA carboxylase complex) mediated an 8-fold increase in the acetyl-CoA content of rewired P. putida. Poly(3-hydroxybutyrate) (PHB) was adopted as a proxy of acetyl-CoA availability, and two synthetic pathways were engineered for biopolymer accumulation. By including cell morphology as an extra target for the CRISPRi approach, fully rewired P. putida strains programmed for PHB accumulation had a 5-fold increase in PHB titers in bioreactor cultures using glucose. Thus, the strategy described herein allowed for rationally redirecting metabolic fluxes in P. putida from central metabolism towards product biosynthesis-especially relevant when deletion of essential pathways is not an option.
Collapse
Affiliation(s)
- Ekaterina Kozaeva
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Svetlana Volkova
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Marta R A Matos
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Mariela P Mezzina
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Tune Wulff
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Daniel C Volke
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Lars K Nielsen
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kongens Lyngby, Denmark; Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Pablo I Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kongens Lyngby, Denmark.
| |
Collapse
|
8
|
Carrillo M, Wagner M, Petit F, Dransfeld A, Becker A, Erb TJ. Design and Control of Extrachromosomal Elements in Methylorubrum extorquens AM1. ACS Synth Biol 2019; 8:2451-2456. [PMID: 31584803 PMCID: PMC6862569 DOI: 10.1021/acssynbio.9b00220] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
![]()
Genetic
tools are a prerequisite to engineer cellular factories
for synthetic biology and biotechnology. Methylorubrum extorquens AM1 is an important platform organism of a future C1-bioeconomy.
However, its application is currently limited by the availability
of genetic tools. Here we systematically tested repABC regions to maintain extrachromosomal DNA in M. extorquens. We used three elements to construct mini-chromosomes that are stably
inherited at single copy number and can be shuttled between Escherichia coli and M. extorquens. These mini-chromosomes are compatible among each other and with
high-copy number plasmids of M. extorquens.
We also developed a set of inducible promoters of wide expression
range, reaching levels exceeding those currently available, notably
the PmxaF-promoter. In
summary, we provide a set of tools to control the dynamic expression
and copy number of genetic elements in M. extorquens, which opens new ways to unleash the metabolic and biotechnological
potential of this organism for future applications.
Collapse
Affiliation(s)
- Martina Carrillo
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
| | - Marcel Wagner
- LOEWE Center for Synthetic Microbiology, 35043 Marburg, Germany
| | - Florian Petit
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
| | - Amelie Dransfeld
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
- LOEWE Center for Synthetic Microbiology, 35043 Marburg, Germany
| | - Anke Becker
- LOEWE Center for Synthetic Microbiology, 35043 Marburg, Germany
| | - Tobias J. Erb
- Department of Biochemistry & Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
- LOEWE Center for Synthetic Microbiology, 35043 Marburg, Germany
| |
Collapse
|
9
|
Seo SO, Schmidt-Dannert C. Development of a synthetic cumate-inducible gene expression system for Bacillus. Appl Microbiol Biotechnol 2018; 103:303-313. [DOI: 10.1007/s00253-018-9485-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/24/2018] [Accepted: 10/24/2018] [Indexed: 10/27/2022]
|
10
|
Schada von Borzyskowski L, Carrillo M, Leupold S, Glatter T, Kiefer P, Weishaupt R, Heinemann M, Erb TJ. An engineered Calvin-Benson-Bassham cycle for carbon dioxide fixation in Methylobacterium extorquens AM1. Metab Eng 2018; 47:423-433. [DOI: 10.1016/j.ymben.2018.04.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 03/21/2018] [Accepted: 04/02/2018] [Indexed: 10/17/2022]
|
11
|
Schada von Borzyskowski L, Sonntag F, Pöschel L, Vorholt JA, Schrader J, Erb TJ, Buchhaupt M. Replacing the Ethylmalonyl-CoA Pathway with the Glyoxylate Shunt Provides Metabolic Flexibility in the Central Carbon Metabolism of Methylobacterium extorquens AM1. ACS Synth Biol 2018; 7:86-97. [PMID: 29216425 DOI: 10.1021/acssynbio.7b00229] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ethylmalonyl-CoA pathway (EMCP) is an anaplerotic reaction sequence in the central carbon metabolism of numerous Proteo- and Actinobacteria. The pathway features several CoA-bound mono- and dicarboxylic acids that are of interest as platform chemicals for the chemical industry. The EMCP, however, is essential for growth on C1 and C2 carbon substrates and therefore cannot be simply interrupted to drain these intermediates. In this study, we aimed at reengineering central carbon metabolism of the Alphaproteobacterium Methylobacterium extorquens AM1 for the specific production of EMCP derivatives in the supernatant. Establishing a heterologous glyoxylate shunt in M. extorquens AM1 restored wild type-like growth in several EMCP knockout strains on defined minimal medium with acetate as carbon source. We further engineered one of these strains that carried a deletion of the gene encoding crotonyl-CoA carboxylase/reductase to demonstrate in a proof-of-concept the specific production of crotonic acid in the supernatant on a defined minimal medium. Our experiments demonstrate that it is in principle possible to further exploit the EMCP by establishing an alternative central carbon metabolic pathway in M. extorquens AM1, opening many possibilities for the biotechnological production of EMCP-derived compounds in future.
Collapse
Affiliation(s)
| | - Frank Sonntag
- DECHEMA Research Institute, Theodor-Heuss-Allee 25, 60486 Frankfurt am Main, Germany
| | - Laura Pöschel
- DECHEMA Research Institute, Theodor-Heuss-Allee 25, 60486 Frankfurt am Main, Germany
| | - Julia A. Vorholt
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
| | - Jens Schrader
- DECHEMA Research Institute, Theodor-Heuss-Allee 25, 60486 Frankfurt am Main, Germany
| | - Tobias J. Erb
- Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
- Center for Synthetic Microbiology, SYNMIKRO, 35043 Marburg, Germany
| | - Markus Buchhaupt
- DECHEMA Research Institute, Theodor-Heuss-Allee 25, 60486 Frankfurt am Main, Germany
| |
Collapse
|
12
|
Liang WF, Sun MY, Cui LY, Zhang C, Xing XH. Cre/loxP-Mediated Multicopy Integration of the Mevalonate Operon into the Genome of Methylobacterium extorquens AM1. Appl Biochem Biotechnol 2017; 185:565-577. [PMID: 29243041 DOI: 10.1007/s12010-017-2673-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 11/30/2017] [Indexed: 01/08/2023]
Abstract
Methylobacterium extorquens AM1 is the model strain for methylotrophic bacteria that metabolize methanol as the sole carbon and energy source. Genetically modified M. extorquens AM1 is used as a methylotrophic cell factory (MeCF) for high value-added chemical production. We tested the Cre-loxP recombination system for its ability to mediate multicopy gene integration of the mvt3 operon (mvt3) in M. extorquens AM1. mvt3 controls the expression of the first three enzymes of the mevalonate synthesis pathway. We assayed for Cre-mediated multigene integration by screening for multicopy mutants via their survival in culture with a high kanamycin concentration (600 μg/mL). We identified mutant strains in which the mevalonate titer was increased by up to 1.9-fold compared with M2 (M. extorquens AM1ΔcelABCΔattTn7::mvt3::loxP) and confirmed mvt3 integration at 2-3 copies per genome. This result demonstrates the feasibility of multicopy integration in M. extorquens AM1 mediated by Cre-loxP recombination and its potential for improving the output of M. extorquens AM1 metabolic pathways, e.g., optimization of terpenoid synthesis.
Collapse
Affiliation(s)
- Wei-Fan Liang
- Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Center for Synthetic and Systems Biology, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, People's Republic of China
- Guangdong Hainabiotech CO., LTD, Foshan, 511400, People's Republic of China
| | - Ming-Yang Sun
- Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Center for Synthetic and Systems Biology, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, People's Republic of China
| | - Lan-Yu Cui
- Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Center for Synthetic and Systems Biology, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, People's Republic of China
| | - Chong Zhang
- Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Center for Synthetic and Systems Biology, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, People's Republic of China.
| | - Xin-Hui Xing
- Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Center for Synthetic and Systems Biology, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, People's Republic of China
| |
Collapse
|
13
|
Cui LY, Liang WF, Zhu WL, Sun MY, Zhang C, Xing XH. Medium redesign for stable cultivation and high production of mevalonate by recombinant Methtylobacterium extorquens AM1 with mevalonate synthetic pathway. Biochem Eng J 2017. [DOI: 10.1016/j.bej.2016.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
14
|
Production of 2-Hydroxyisobutyric Acid from Methanol by Methylobacterium extorquens AM1 Expressing (R)-3-Hydroxybutyryl Coenzyme A-Isomerizing Enzymes. Appl Environ Microbiol 2017; 83:AEM.02622-16. [PMID: 27836853 DOI: 10.1128/aem.02622-16] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 11/08/2016] [Indexed: 01/05/2023] Open
Abstract
The biotechnological production of the methyl methacrylate precursor 2-hydroxyisobutyric acid (2-HIBA) via bacterial poly-3-hydroxybutyrate (PHB) overflow metabolism requires suitable (R)-3-hydroxybutyryl coenzyme A (CoA)-specific coenzyme B12-dependent mutases (RCM). Here, we characterized a predicted mutase from Bacillus massiliosenegalensis JC6 as a mesophilic RCM closely related to the thermophilic enzyme previously identified in Kyrpidia tusciae DSM 2912 (M.-T. Weichler et al., Appl Environ Microbiol 81:4564-4572, 2015, https://doi.org/10.1128/AEM.00716-15). Using both RCM variants, 2-HIBA production from methanol was studied in fed-batch bioreactor experiments with recombinant Methylobacterium extorquens AM1. After complete nitrogen consumption, the concomitant formation of PHB and 2-HIBA was achieved, indicating that both sets of RCM genes were successfully expressed. However, although identical vector systems and incubation conditions were chosen, the metabolic activity of the variant bearing the RCM genes from strain DSM 2912 was severely inhibited, likely due to the negative effects caused by heterologous expression. In contrast, the biomass yield of the variant expressing the JC6 genes was close to the wild-type performance, and 2-HIBA titers of 2.1 g liter-1 could be demonstrated. In this case, up to 24% of the substrate channeled into overflow metabolism was converted to the mutase product, and maximal combined 2-HIBA plus PHB yields from methanol of 0.11 g g-1 were achieved. Reverse transcription-quantitative PCR analysis revealed that metabolic genes, such as methanol dehydrogenase and acetoacetyl-CoA reductase genes, are strongly downregulated after exponential growth, which currently prevents a prolonged overflow phase, thus preventing higher product yields with strain AM1. IMPORTANCE In this study, we genetically modified a methylotrophic bacterium in order to channel intermediates of its overflow metabolism to the C4 carboxylic acid 2-hydroxyisobutyric acid, a precursor of acrylic glass. This has implications for biotechnology, as it shows that reduced C1 substrates, such as methanol and formic acid, can be alternative feedstocks for producing today's commodities. We found that product titers and yields depend more on host physiology than on the activity of the introduced heterologous function modifying the overflow metabolism. In addition, we show that the fitness of recombinant strains substantially varies when they express orthologous genes from different origins. Further studies are needed to extend the overflow production phase in methylotrophic microorganisms for the implementation of biotechnological processes.
Collapse
|
15
|
Mustakhimov II, But SY, Reshetnikov AS, Khmelenina VN, Trotsenko YA. Homo- and heterologous reporter proteins for evaluation of promoter activity in Methylomicrobium alcaliphilum 20Z. APPL BIOCHEM MICRO+ 2016. [DOI: 10.1134/s0003683816030157] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
16
|
Cui J, Good NM, Hu B, Yang J, Wang Q, Sadilek M, Yang S. Metabolomics Revealed an Association of Metabolite Changes and Defective Growth in Methylobacterium extorquens AM1 Overexpressing ecm during Growth on Methanol. PLoS One 2016; 11:e0154043. [PMID: 27116459 PMCID: PMC4846091 DOI: 10.1371/journal.pone.0154043] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 04/07/2016] [Indexed: 11/18/2022] Open
Abstract
Methylobacterium extorquens AM1 is a facultative methylotroph capable of growth on both single-carbon and multi-carbon compounds. The ethylmalonyl-CoA (EMC) pathway is one of the central assimilatory pathways in M. extorquens during growth on C1 and C2 substrates. Previous studies had shown that ethylmalonyl-CoA mutase functioned as a control point during the transition from growth on succinate to growth on ethylamine. In this study we overexpressed ecm, phaA, mcmAB and found that upregulating ecm by expressing it from the strong constitutive mxaF promoter caused a 27% decrease in growth rate on methanol compared to the strain with an empty vector. Targeted metabolomics demonstrated that most of the central intermediates in the ecm over-expressing strain did not change significantly compared to the control strain; However, poly-β-hydroxybutyrate (PHB) was 4.5-fold lower and 3-hydroxybutyryl-CoA was 1.6-fold higher. Moreover, glyoxylate, a toxic and highly regulated essential intermediate, was determined to be 2.6-fold higher when ecm was overexpressed. These results demonstrated that overexpressing ecm can manipulate carbon flux through the EMC pathway and divert it from the carbon and energy storage product PHB, leading to an accumulation of glyoxylate. Furthermore, untargeted metabolomics discovered two unusual metabolites, alanine (Ala)-meso-diaminopimelic acid (mDAP) and Ala-mDAP-Ala, each over 45-fold higher in the ecm over-expressing strain. These two peptides were also found to be highly produced in a dose-dependent manner when glyoxylate was added to the control strain. Overall, this work has explained a direct association of ecm overexpression with glyoxylate accumulation up to a toxic level, which inhibits cell growth on methanol. This research provides useful insight for manipulating the EMC pathway for efficiently producing high-value chemicals in M. extorquens.
Collapse
Affiliation(s)
- Jinyu Cui
- School of Life Science, Qingdao Agricultural University, Shandong Province Key Laboratory of Applied Mycology, and Qingdao International Center on Microbes Utilizing Biogas, Qingdao, Shandong Province, China
| | - Nathan M. Good
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Bo Hu
- Kemin Industries, KI Research & Development, Des Moines, Iowa, United States of America
| | - Jing Yang
- School of Life Science, Qingdao Agricultural University, Shandong Province Key Laboratory of Applied Mycology, and Qingdao International Center on Microbes Utilizing Biogas, Qingdao, Shandong Province, China
| | - Qianwen Wang
- Central Laboratory, Qingdao Agricultural University, Qingdao, Shandong Province, China
| | - Martin Sadilek
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Song Yang
- School of Life Science, Qingdao Agricultural University, Shandong Province Key Laboratory of Applied Mycology, and Qingdao International Center on Microbes Utilizing Biogas, Qingdao, Shandong Province, China
- Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin, China
- * E-mail:
| |
Collapse
|
17
|
Chaudhary AK, Lee EY. Tightly regulated and high level expression vector construction for Escherichia coli BL21 (DE3). J IND ENG CHEM 2015. [DOI: 10.1016/j.jiec.2015.07.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
18
|
Bioconversion of methanol to value-added mevalonate by engineered Methylobacterium extorquens AM1 containing an optimized mevalonate pathway. Appl Microbiol Biotechnol 2015; 100:2171-82. [DOI: 10.1007/s00253-015-7078-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 09/20/2015] [Accepted: 10/12/2015] [Indexed: 12/21/2022]
|
19
|
Schada von Borzyskowski L, Remus-Emsermann M, Weishaupt R, Vorholt JA, Erb TJ. A set of versatile brick vectors and promoters for the assembly, expression, and integration of synthetic operons in Methylobacterium extorquens AM1 and other alphaproteobacteria. ACS Synth Biol 2015; 4:430-43. [PMID: 25105793 DOI: 10.1021/sb500221v] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The discipline of synthetic biology requires standardized tools and genetic elements to construct novel functionalities in microorganisms; yet, many model systems still lack such tools. Here, we describe a novel set of vectors that allows the convenient construction of synthetic operons in Methylobacterium extorquens AM1, an important alphaproteobacterial model organism for methylotrophy and a promising platform organism for methanol-based biotechnology. In addition, we provide a set of constitutive alphaproteobacterial promoters of different strengths that were characterized in detail by two approaches: on the single-cell scale and on the cell population level. Finally, we describe a straightforward strategy to deliver synthetic constructs to the genome of M. extorquens AM1 and other Alphaproteobacteria. This study defines a new standard to systematically characterize genetic parts for their use in M. extorquens AM1 by using single-cell fluorescence microscopy and opens the toolbox for synthetic biological applications in M. extorquens AM1 and other alphaproteobacterial model systems.
Collapse
Affiliation(s)
- Lennart Schada von Borzyskowski
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zurich, Vladimir-Prelog-Weg
4, 8093 Zurich, Switzerland
| | - Mitja Remus-Emsermann
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zurich, Vladimir-Prelog-Weg
4, 8093 Zurich, Switzerland
| | - Ramon Weishaupt
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zurich, Vladimir-Prelog-Weg
4, 8093 Zurich, Switzerland
| | - Julia A. Vorholt
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zurich, Vladimir-Prelog-Weg
4, 8093 Zurich, Switzerland
| | - Tobias J. Erb
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zurich, Vladimir-Prelog-Weg
4, 8093 Zurich, Switzerland
| |
Collapse
|
20
|
Ochsner AM, Sonntag F, Buchhaupt M, Schrader J, Vorholt JA. Methylobacterium extorquens: methylotrophy and biotechnological applications. Appl Microbiol Biotechnol 2014; 99:517-34. [PMID: 25432674 DOI: 10.1007/s00253-014-6240-3] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/14/2014] [Accepted: 11/16/2014] [Indexed: 01/06/2023]
Abstract
Methylotrophy is the ability to use reduced one-carbon compounds, such as methanol, as a single source of carbon and energy. Methanol is, due to its availability and potential for production from renewable resources, a valuable feedstock for biotechnology. Nature offers a variety of methylotrophic microorganisms that differ in their metabolism and represent resources for engineering of value-added products from methanol. The most extensively studied methylotroph is the Alphaproteobacterium Methylobacterium extorquens. Over the past five decades, the metabolism of M. extorquens has been investigated physiologically, biochemically, and more recently, using complementary omics technologies such as transcriptomics, proteomics, metabolomics, and fluxomics. These approaches, together with a genome-scale metabolic model, facilitate system-wide studies and the development of rational strategies for the successful generation of desired products from methanol. This review summarizes the knowledge of methylotrophy in M. extorquens, as well as the available tools and biotechnological applications.
Collapse
Affiliation(s)
- Andrea M Ochsner
- Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 4, 8093, Zurich, Switzerland
| | | | | | | | | |
Collapse
|
21
|
Gilbert R, Guilbault C, Gagnon D, Bernier A, Bourget L, Elahi SM, Kamen A, Massie B. Establishment and validation of new complementing cells for production of E1-deleted adenovirus vectors in serum-free suspension culture. J Virol Methods 2014; 208:177-88. [DOI: 10.1016/j.jviromet.2014.08.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 08/12/2014] [Accepted: 08/15/2014] [Indexed: 11/17/2022]
|
22
|
Nayak DD, Marx CJ. Genetic and phenotypic comparison of facultative methylotrophy between Methylobacterium extorquens strains PA1 and AM1. PLoS One 2014; 9:e107887. [PMID: 25232997 PMCID: PMC4169470 DOI: 10.1371/journal.pone.0107887] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 08/19/2014] [Indexed: 02/01/2023] Open
Abstract
Methylobacterium extorquens AM1, a strain serendipitously isolated half a century ago, has become the best-characterized model system for the study of aerobic methylotrophy (the ability to grow on reduced single-carbon compounds). However, with 5 replicons and 174 insertion sequence (IS) elements in the genome as well as a long history of domestication in the laboratory, genetic and genomic analysis of M. extorquens AM1 face several challenges. On the contrary, a recently isolated strain - M. extorquens PA1- is closely related to M. extorquens AM1 (100% 16S rRNA identity) and contains a streamlined genome with a single replicon and only 20 IS elements. With the exception of the methylamine dehydrogenase encoding gene cluster (mau), genes known to be involved in methylotrophy are well conserved between M. extorquens AM1 and M. extorquens PA1. In this paper we report four primary findings regarding methylotrophy in PA1. First, with a few notable exceptions, the repertoire of methylotrophy genes between PA1 and AM1 is extremely similar. Second, PA1 grows faster with higher yields compared to AM1 on C1 and multi-C substrates in minimal media, but AM1 grows faster in rich medium. Third, deletion mutants in PA1 throughout methylotrophy modules have the same C1 growth phenotypes observed in AM1. Finally, the precision of our growth assays revealed several unexpected growth phenotypes for various knockout mutants that serve as leads for future work in understanding their basis and generality across Methylobacterium strains.
Collapse
Affiliation(s)
- Dipti D. Nayak
- Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Christopher J. Marx
- Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
- Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, Massachusetts, United States of America
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, Idaho, United States of America
- * E-mail:
| |
Collapse
|
23
|
Novel and tightly regulated resorcinol and cumate-inducible expression systems for Streptomyces and other actinobacteria. Appl Microbiol Biotechnol 2014; 98:8641-55. [DOI: 10.1007/s00253-014-5918-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 06/24/2014] [Accepted: 06/25/2014] [Indexed: 01/07/2023]
|
24
|
New vectors for chromosomal integration enable high-level constitutive or inducible magnetosome expression of fusion proteins in Magnetospirillum gryphiswaldense. Appl Environ Microbiol 2014; 80:2609-16. [PMID: 24532068 DOI: 10.1128/aem.00192-14] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The alphaproteobacterium Magnetospirillum gryphiswaldense biomineralizes magnetosomes, which consist of monocrystalline magnetite cores enveloped by a phospholipid bilayer containing specific proteins. Magnetosomes represent magnetic nanoparticles with unprecedented magnetic and physicochemical characteristics. These make them potentially useful in a number of biotechnological and biomedical applications. Further functionalization can be achieved by expression of foreign proteins via genetic fusion to magnetosome anchor peptides. However, the available genetic tool set for strong and controlled protein expression in magnetotactic bacteria is very limited. Here, we describe versatile vectors for either inducible or high-level constitutive expression of proteins in M. gryphiswaldense. The combination of an engineered native PmamDC promoter with a codon-optimized egfp gene (Mag-egfp) resulted in an 8-fold increase in constitutive expression and in brighter fluorescence. We further demonstrate that the widely used Ptet promoter is functional and tunable in M. gryphiswaldense. Stable and uniform expression of the EGFP and β-glucuronidase (GusA) reporters was achieved by single-copy chromosomal insertion via Tn5-mediated transposition. In addition, gene duplication by Mag-EGFP-EGFP fusions to MamC resulted in further increased magnetosome expression and fluorescence. Between 80 and 210 (for single MamC-Mag-EGFP) and 200 and 520 (for MamC-Mag-EGFP-EGFP) GFP copies were estimated to be expressed per individual magnetosome particle.
Collapse
|
25
|
Cumate-inducible gene expression system for sphingomonads and other Alphaproteobacteria. Appl Environ Microbiol 2013; 79:6795-802. [PMID: 23995928 DOI: 10.1128/aem.02296-13] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Tunable promoters represent a pivotal genetic tool for a wide range of applications. Here we present such a system for sphingomonads, a phylogenetically diverse group of bacteria that have gained much interest for their potential in bioremediation and their use in industry and for which no dedicated inducible gene expression system has been described so far. A strong, constitutive synthetic promoter was first identified through a genetic screen and subsequently combined with the repressor and the operator sites of the Pseudomonas putida F1 cym/cmt system. The resulting promoter, termed PQ5, responds rapidly to the inducer cumate and shows a maximal induction ratio of 2 to 3 orders of magnitude in the different sphingomonads tested. Moreover, it was also functional in other Alphaproteobacteria, such as the model organisms Caulobacter crescentus, Paracoccus denitrificans, and Methylobacterium extorquens. In the noninduced state, expression from PQ5 is low enough to allow gene depletion analysis, as demonstrated with the essential gene phyP of Sphingomonas sp. strain Fr1. A set of PQ5-based plasmids has been constructed allowing fusions to affinity tags or fluorescent proteins.
Collapse
|
26
|
Chubiz LM, Purswani J, Carroll SM, Marx CJ. A novel pair of inducible expression vectors for use in Methylobacterium extorquens. BMC Res Notes 2013; 6:183. [PMID: 23648175 PMCID: PMC3694467 DOI: 10.1186/1756-0500-6-183] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 03/27/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Due to the ever increasing use of diverse microbial taxa in basic research and industrial settings, there is a growing need for genetic tools to alter the physiology of these organisms. In particular, there is a dearth of inducible expression systems available for bacteria outside commonly used γ-proteobacteria, such as Escherichia coli or Pseudomonas species. To this end, we have sought to develop a pair of inducible expression vectors for use in the α-proteobacterium Methylobacterium extorquens, a model methylotroph. FINDINGS We found that the P(R) promoter from rhizobial phage 16-3 was active in M. extorquens and engineered the promoter to be inducible by either p-isopropyl benzoate (cumate) or anhydrotetracycline. These hybrid promoters, P(R/cmtO) and P(R/tetO), were found to have high levels of expression in M. extorquens with a regulatory range of 10-fold and 30-fold, respectively. Compared to an existing cumate-inducible (10-fold range), high-level expression system for M. extorquens, P(R/cmtO) and P(R/tetO) have 33% of the maximal activity but were able to repress gene expression 3 and 8-fold greater, respectively. Both promoters were observed to exhibit homogeneous, titratable activation dynamics rather than on-off, switch-like behavior. The utility of these promoters was further demonstrated by complementing loss of function of ftfL--essential for growth on methanol--where we show P(R/tetO) is capable of not only fully complementing function but also producing a conditional null phenotype. These promoters have been incorporated into a broad-host-range backbone allowing for potential use in a variety of bacterial hosts. CONCLUSIONS We have developed two novel expression systems for use in M. extorquens. The expression range of these vectors should allow for increased ability to explore cellular physiology in M. extorquens. Further, the P(R/tetO) promoter is capable of producing conditional null phenotypes, previously unattainable in M. extorquens. As both expression systems rely on the use of membrane permeable inducers, we suspect these expression vectors will be useful for ectopic gene expression in numerous proteobacteria.
Collapse
Affiliation(s)
- Lon M Chubiz
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave., Cambridge, MA 02138, USA.
| | | | | | | |
Collapse
|
27
|
Kagawa Y, Mitani Y, Yun HY, Nakashima N, Tamura N, Tamura T. Identification of a methanol-inducible promoter from Rhodococcus erythropolis PR4 and its use as an expression vector. J Biosci Bioeng 2012; 113:596-603. [DOI: 10.1016/j.jbiosc.2011.12.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 12/26/2011] [Accepted: 12/27/2011] [Indexed: 11/26/2022]
|
28
|
Chou HH, Marx CJ. Optimization of gene expression through divergent mutational paths. Cell Rep 2012; 1:133-40. [PMID: 22832162 DOI: 10.1016/j.celrep.2011.12.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 12/09/2011] [Accepted: 12/15/2011] [Indexed: 11/18/2022] Open
Abstract
Adaptation under similar selective pressure often leads to comparable phenotypes. A longstanding question is whether such phenotypic repeatability entails similar (parallelism) or different genotypic changes (convergence). To better understand this, we characterized mutations that optimized expression of a plasmid-borne metabolic pathway during laboratory evolution of a bacterium. Expressing these pathway genes was essential for growth but came with substantial costs. Starting from overexpression, replicate populations founded by this bacterium all evolved to reduce expression. Despite this phenotypic repetitiveness, the underlying mutational spectrum was highly diverse. Analysis of these plasmid mutations identified three distinct means to modulate gene expression: (1) reducing the gene copy number, (2) lowering transcript stability, and (3) integration of the pathway-bearing plasmid into the host genome. Our study revealed diverse molecular changes beneath convergence to a simple phenotype. This complex genotype-phenotype mapping presents a challenge to inferring genetic evolution based solely on phenotypic changes.
Collapse
Affiliation(s)
- Hsin-Hung Chou
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | | |
Collapse
|
29
|
Höfer P, Choi YJ, Osborne MJ, Miguez CB, Vermette P, Groleau D. Production of functionalized polyhydroxyalkanoates by genetically modified Methylobacterium extorquens strains. Microb Cell Fact 2010; 9:70. [PMID: 20846434 PMCID: PMC2954876 DOI: 10.1186/1475-2859-9-70] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 09/16/2010] [Indexed: 11/16/2022] Open
Abstract
Background Methylotrophic (methanol-utilizing) bacteria offer great potential as cell factories in the production of numerous products from biomass-derived methanol. Bio-methanol is essentially a non-food substrate, an advantage over sugar-utilizing cell factories. Low-value products as well as fine chemicals and advanced materials are envisageable from methanol. For example, several methylotrophic bacteria, including Methylobacterium extorquens, can produce large quantities of the biodegradable polyester polyhydroxybutyric acid (PHB), the best known polyhydroxyalkanoate (PHA). With the purpose of producing second-generation PHAs with increased value, we have explored the feasibility of using M. extorquens for producing functionalized PHAs containing C-C double bonds, thus, making them amenable to future chemical/biochemical modifications for high value applications. Results Our proprietary M. extorquens ATCC 55366 was found unable to yield functionalized PHAs when fed methanol and selected unsaturated carboxylic acids as secondary substrates. However, cloning of either the phaC1 or the phaC2 gene from P. fluorescens GK13, using an inducible and regulated expression system based on cumate as inducer (the cumate switch), yielded recombinant M. extorquens strains capable of incorporating modest quantities of C-C double bonds into PHA, starting from either C6= and/or C8=. The two recombinant strains gave poor results with C11=. The strain containing the phaC2 gene was better at using C8= and at incorporating C-C double bonds into PHA. Solvent fractioning indicated that the produced polymers were PHA blends that consequently originated from independent actions of the native and the recombinant PHA synthases. Conclusions This work constitutes an example of metabolic engineering applied to the construction of a methanol-utilizing bacterium capable of producing functionalized PHAs containing C-C double bonds. In this regard, the PhaC2 synthase appeared superior to the PhaC1 synthase at utilizing C8= as source of C-C double bonds and at incorporating C-C double bonds into PHA from either C6= or C8=. The M. ex-phaC2 strain is, therefore, a promising biocatalyst for generating advanced (functionalized) PHAs for future high value applications in various fields.
Collapse
Affiliation(s)
- Philipp Höfer
- Microbial and Enzymatic Technology Group, Bioprocess Centre, Biotechnology Research Institute, National Research Council Canada, 6100 Royalmount Avenue, Montréal, Québec, H4P 2R2, Canada
| | | | | | | | | | | |
Collapse
|
30
|
Hölscher T, Breuer U, Adrian L, Harms H, Maskow T. Production of the chiral compound (R)-3-hydroxybutyrate by a genetically engineered methylotrophic bacterium. Appl Environ Microbiol 2010; 76:5585-91. [PMID: 20581197 PMCID: PMC2918973 DOI: 10.1128/aem.01065-10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 06/11/2010] [Indexed: 11/20/2022] Open
Abstract
In this study, a methylotrophic bacterium, Methylobacterium rhodesianum MB 126, was used for the production of the chiral compound (R)-3-hydroxybutyrate (R-3HB) from methanol. R-3HB is formed during intracellular degradation of the storage polymer (R)-3-polyhydroxybutyrate (PHB). Since the monomer R-3HB does not accumulate under natural conditions, M. rhodesianum was genetically modified. The gene (hbd) encoding the R-3HB-degrading enzyme, R-3HB dehydrogenase, was inactivated in M. rhodesianum. The resulting hbd mutant still exhibited low growth rates on R-3HB as the sole source of carbon and energy, indicating the presence of alternative pathways for R-3HB utilization. Therefore, transposon mutagenesis was carried out with the hbd mutant, and a double mutant unable to grow on R-3HB was obtained. This mutant was shown to be defective in lipoic acid synthase (LipA), resulting in an incomplete citric acid cycle. Using the hbd lipA mutant, we produced 3.2 to 3.5 mM R-3HB in batch and 27 mM (2,800 mg liter(-1)) in fed-batch cultures. This was achieved by sequences of cultivation conditions initially favoring growth, then PHB accumulation, and finally PHB degradation.
Collapse
Affiliation(s)
- Tina Hölscher
- UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| | - Uta Breuer
- UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| | - Lorenz Adrian
- UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| | - Hauke Harms
- UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| | - Thomas Maskow
- UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| |
Collapse
|
31
|
Novel, versatile, and tightly regulated expression system for Escherichia coli strains. Appl Environ Microbiol 2010; 76:5058-66. [PMID: 20562288 DOI: 10.1128/aem.00413-10] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel tightly regulated gene expression system was developed for Escherichia coli by applying the regulatory elements of the Pseudomonas putida F1 cym and cmt operons to control target gene expression at the transcriptional level by using p-isopropylbenzoate (cumate) as an inducer. This novel expression system, referred to as the cumate gene switch, includes a specific expression vector, pNEW, that contains a partial T5 phage promoter combined with the Pseudomonas-based synthetic operator and the cymR repressor protein-encoding gene designed to express constitutively in the host strain. The induction of transcription relies on the addition of the exogenous inducer (cumate), which is nontoxic to the culture, water soluble, and inexpensive. The characteristics and potential of the expression system were determined. Using flow cytometry and fed-batch fermentations, we have shown that, with the newly developed cumate-regulated system, (i) higher recombinant product yields can be obtained than with the pET (isopropyl-beta-D-thiogalactopyranoside [IPTG])-induced expression system, (ii) expression is tightly regulated, (iii) addition of cumate quickly results in a fully induced and homogenous protein-expressing population in contrast to the bimodal expression profile of an IPTG-induced population, (iv) expression can be modulated by varying the cumate concentration, and (v) the cumate-induced population remains induced and fully expressing even at 8 h following induction, resulting in high yields of the target protein Furthermore, the cumate gene switch described in this article is applicable to a wide range of E. coli strains.
Collapse
|
32
|
Methanol-based industrial biotechnology: current status and future perspectives of methylotrophic bacteria. Trends Biotechnol 2008; 27:107-15. [PMID: 19111927 DOI: 10.1016/j.tibtech.2008.10.009] [Citation(s) in RCA: 185] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 10/24/2008] [Accepted: 10/29/2008] [Indexed: 11/21/2022]
Abstract
Methanol is one of the building blocks in the chemical industry and can be synthesized either from petrochemical or renewable resources, such as biogas. Bioprocess technology with methylotrophic bacteria is well established, as illustrated by large-scale single-cell protein production in the past. During recent years, the first genomes of methylotrophs have been sequenced and significant progress in elucidating their metabolism has been made. In addition, the tool set for genetic engineering of methylotrophic bacteria has expanded greatly and strategies to produce fine and bulk chemicals with methylotrophs have been described. This review highlights the potential of these bacteria for the development of economically competitive bioprocesses based on methanol as an alternative carbon source, bringing together biological, technical and economic considerations.
Collapse
|