1
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Yue XJ, Wang JR, Zhao JN, Pan Z, Li YZ. Determination of the chromosomal position effects for plug-and-play application in the Myxococcus xanthus chassis cells. Synth Syst Biotechnol 2024; 9:540-548. [PMID: 38680947 PMCID: PMC11046052 DOI: 10.1016/j.synbio.2024.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 03/30/2024] [Accepted: 04/08/2024] [Indexed: 05/01/2024] Open
Abstract
The chromosomal position effect can significantly affect the transgene expression, which may provide an efficient strategy for the inauguration of alien genes in new hosts, but has been less explored rationally. The bacterium Myxococcus xanthus harbors a large circular high-GC genome, and the position effect in this chassis may result in a thousand-fold expression variation of alien natural products. In this study, we conducted transposon insertion at TA sites on the M. xanthus genome, and used enrichment and dilution indexes to respectively appraise high and low expression potentials of alien genes at insertion sites. The enrichment sites are characteristically distributed along the genome, and the dilution sites are overlapped well with the horizontal transfer genes. We experimentally demonstrated the enrichment sites as high expression integration sites (HEISs), and the dilution sites unsuitable for gene integration expression. This work highlights that HEISs are the plug-and-play sites for efficient expression of integrated genes.
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Affiliation(s)
- Xin-jing Yue
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, PR China
| | - Jia-rui Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, PR China
| | - Jun-ning Zhao
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, PR China
| | - Zhuo Pan
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, PR China
| | - Yue-zhong Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, PR China
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2
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Lautenschläger N, Schmidt K, Schiffer C, Wulff TF, Hahnke K, Finstermeier K, Mansour M, Elsholz AKW, Charpentier E. Expanding the genetic toolbox for the obligate human pathogen Streptococcus pyogenes. Front Bioeng Biotechnol 2024; 12:1395659. [PMID: 38911550 PMCID: PMC11190166 DOI: 10.3389/fbioe.2024.1395659] [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: 03/04/2024] [Accepted: 05/06/2024] [Indexed: 06/25/2024] Open
Abstract
Genetic tools form the basis for the study of molecular mechanisms. Despite many recent advances in the field of genetic engineering in bacteria, genetic toolsets remain scarce for non-model organisms, such as the obligatory human pathogen Streptococcus pyogenes. To overcome this limitation and enable the straightforward investigation of gene functions in S. pyogenes, we have developed a comprehensive genetic toolset. By adapting and combining different tools previously applied in other Gram-positive bacteria, we have created new replicative and integrative plasmids for gene expression and genetic manipulation, constitutive and inducible promoters as well as fluorescence reporters for S. pyogenes. The new replicative plasmids feature low- and high-copy replicons combined with different resistance cassettes and a standardized multiple cloning site for rapid cloning procedures. We designed site-specific integrative plasmids and verified their integration by nanopore sequencing. To minimize the effect of plasmid integration on bacterial physiology, we screened publicly available RNA-sequencing datasets for transcriptionally silent sites. We validated this approach by designing the integrative plasmid pSpy0K6 targeting the transcriptionally silent gene SPy_1078. Analysis of the activity of different constitutive promoters indicated a wide variety of strengths, with the lactococcal promoter P 23 showing the strongest activity and the synthetic promoter P xylS2 showing the weakest activity. Further, we assessed the functionality of three inducible regulatory elements including a zinc- and an IPTG-inducible promoter as well as an erythromycin-inducible riboswitch that showed low-to-no background expression and high inducibility. Additionally, we demonstrated the applicability of two codon-optimized fluorescent proteins, mNeongreen and mKate2, as reporters in S. pyogenes. We therefore adapted the chemically defined medium called RPMI4Spy that showed reduced autofluorescence and enabled efficient signal detection in plate reader assays and fluorescence microscopy. Finally, we developed a plasmid-based system for genome engineering in S. pyogenes featuring the counterselection marker pheS*, which enabled the scarless deletion of the sagB gene. This new toolbox simplifies previously laborious genetic manipulation procedures and lays the foundation for new methodologies to study gene functions in S. pyogenes, leading to a better understanding of its virulence mechanisms and physiology.
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Affiliation(s)
| | - Katja Schmidt
- Max Planck Unit for the Science of Pathogens, Berlin, Germany
| | | | - Thomas F. Wulff
- Max Planck Unit for the Science of Pathogens, Berlin, Germany
| | - Karin Hahnke
- Max Planck Unit for the Science of Pathogens, Berlin, Germany
| | | | - Moïse Mansour
- Max Planck Unit for the Science of Pathogens, Berlin, Germany
| | | | - Emmanuelle Charpentier
- Max Planck Unit for the Science of Pathogens, Berlin, Germany
- Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
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3
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Sheng Y, Zhang S, Li X, Wang S, Liu T, Wang C, Yan L. Phenotypic and genomic insights into mutant with high nattokinase-producing activity induced by carbon ion beam irradiation of Bacillus subtilis. Int J Biol Macromol 2024; 271:132398. [PMID: 38754670 DOI: 10.1016/j.ijbiomac.2024.132398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 05/01/2024] [Accepted: 05/13/2024] [Indexed: 05/18/2024]
Abstract
Nattokinase (NK) is found in fermented foods and has high fibrinolytic activity, which makes it promising for biological applications. In this study, a mutant strain (Bacillus subtilis ZT-S1, 5529.56 ± 183.59 U/mL) with high NK-producing activity was obtained using 12C6+ heavy ion beam mutagenesis for the first time. The surface morphology of B. subtilis is also altered by changes in functional groups caused by heavy ion beams. Furthermore, B. subtilis ZT-S1 required more carbon and nitrogen sources and reached stabilization phase later. Comparative genome analysis revealed that most of the mutant implicated genes (oppA, appA, kinA, spoIIP) were related to spore formation. And the affected rpoA is related to the synthesis of the NK-coding gene aprE. In addition, the B. subtilis ZT-S1 obtained by mutagenesis had good genetic stability. This study further explores the factors affecting NK activity and provides a promising microbial resource for NK production in commercial applications.
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Affiliation(s)
- Yanan Sheng
- College of Food, Heilongjiang Bayi Agricultural University, Daqing 163319, PR China
| | - Shuang Zhang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, China
| | - Xintong Li
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, China
| | - Shicheng Wang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, China
| | - Tao Liu
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, China
| | - Changyuan Wang
- College of Food, Heilongjiang Bayi Agricultural University, Daqing 163319, PR China
| | - Lei Yan
- College of Food, Heilongjiang Bayi Agricultural University, Daqing 163319, PR China; Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang 163319, China.
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4
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Peng Q, Bao W, Geng B, Yang S. Biosensor-assisted CRISPRi high-throughput screening to identify genetic targets in Zymomonas mobilis for high d-lactate production. Synth Syst Biotechnol 2024; 9:242-249. [PMID: 38390372 PMCID: PMC10883783 DOI: 10.1016/j.synbio.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/04/2024] [Accepted: 02/04/2024] [Indexed: 02/24/2024] Open
Abstract
Lactate is an important monomer for the synthesis of poly-lactate (PLA), which is a substitute for the petrochemical plastics. To achieve the goal of high lactate titer, rate, and yield for commercial production, efficient lactate production pathway is needed as well as genetic targets that affect high lactate production and tolerance. In this study, an LldR-based d-lactate biosensor with a broad dynamic range was first applied into Zymomonas mobilis to select mutant strains with strong GFP fluorescence, which could be the mutant strains with increased d-lactate production. Then, LldR-based d-lactate biosensor was combined with a genome-wide CRISPR interference (CRISPRi) library targeting the entire genome to generate thousands of mutants with gRNA targeting different genetic targets across the whole genome. Specifically, two mutant libraries were selected containing 105 and 104 mutants with different interference sites from two rounds of fluorescence-activated cell sorting (FACS), respectively. Two genetic targets of ZMO1323 and ZMO1530 were characterized and confirmed to be associated with the increased d-lactate production, further knockout of ZMO1323 and ZMO1530 resulted in a 15% and 21% increase of d-lactate production, respectively. This work thus not only established a high-throughput approach that combines genome-scale CRISPRi and biosensor-assisted screening to identify genetic targets associated with d-lactate production in Z. mobilis, but also provided a feasible high-throughput screening approach for rapid identification of genetic targets associated with strain performance for other industrial microorganisms.
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Affiliation(s)
- Qiqun Peng
- State Key Laboratory of Biocatalysis and Enzyme Engineering, and School of Life Sciences, Hubei University, Wuhan, 430062, China
| | - Weiwei Bao
- State Key Laboratory of Biocatalysis and Enzyme Engineering, and School of Life Sciences, Hubei University, Wuhan, 430062, China
| | - Binan Geng
- State Key Laboratory of Biocatalysis and Enzyme Engineering, and School of Life Sciences, Hubei University, Wuhan, 430062, China
| | - Shihui Yang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, and School of Life Sciences, Hubei University, Wuhan, 430062, China
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5
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Buson F, Gao Y, Wang B. Genetic Parts and Enabling Tools for Biocircuit Design. ACS Synth Biol 2024; 13:697-713. [PMID: 38427821 DOI: 10.1021/acssynbio.3c00691] [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: 03/03/2024]
Abstract
Synthetic biology aims to engineer biological systems for customized tasks through the bottom-up assembly of fundamental building blocks, which requires high-quality libraries of reliable, modular, and standardized genetic parts. To establish sets of parts that work well together, synthetic biologists created standardized part libraries in which every component is analyzed in the same metrics and context. Here we present a state-of-the-art review of the currently available part libraries for designing biocircuits and their gene expression regulation paradigms at transcriptional, translational, and post-translational levels in Escherichia coli. We discuss the necessary facets to integrate these parts into complex devices and systems along with the current efforts to catalogue and standardize measurement data. To better display the range of available parts and to facilitate part selection in synthetic biology workflows, we established biopartsDB, a curated database of well-characterized and useful genetic part and device libraries with detailed quantitative data validated by the published literature.
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Affiliation(s)
- Felipe Buson
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310058, China
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, U.K
| | - Yuanli Gao
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310058, China
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, U.K
| | - Baojun Wang
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310058, China
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6
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Chromosomal Position of Ribosomal Protein Genes Affects Long-Term Evolution of Vibrio cholerae. mBio 2023; 14:e0343222. [PMID: 36861972 PMCID: PMC10127744 DOI: 10.1128/mbio.03432-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
It is unclear how gene order within the chromosome influences genome evolution. Bacteria cluster transcription and translation genes close to the replication origin (oriC). In Vibrio cholerae, relocation of s10-spc-α locus (S10), the major locus of ribosomal protein genes, to ectopic genomic positions shows that its relative distance to the oriC correlates to a reduction in growth rate, fitness, and infectivity. To test the long-term impact of this trait, we evolved 12 populations of V. cholerae strains bearing S10 at an oriC-proximal or an oriC-distal location for 1,000 generations. During the first 250 generations, positive selection was the main force driving mutation. After 1,000 generations, we observed more nonadaptative mutations and hypermutator genotypes. Populations fixed inactivating mutations at many genes linked to virulence: flagellum, chemotaxis, biofilm, and quorum sensing. Throughout the experiment, all populations increased their growth rates. However, those bearing S10 close to oriC remained the fittest, indicating that suppressor mutations cannot compensate for the genomic position of the main ribosomal protein locus. Selection and sequencing of the fastest-growing clones allowed us to characterize mutations inactivating, among other sites, flagellum master regulators. Reintroduction of these mutations into the wild-type context led to a ≈10% growth improvement. In conclusion, the genomic location of ribosomal protein genes conditions the evolutionary trajectory of V. cholerae. While genomic content is highly plastic in prokaryotes, gene order is an underestimated factor that conditions cellular physiology and evolution. A lack of suppression enables artificial gene relocation as a tool for genetic circuit reprogramming. IMPORTANCE The bacterial chromosome harbors several entangled processes such as replication, transcription, DNA repair, and segregation. Replication begins bidirectionally at the replication origin (oriC) until the terminal region (ter) organizing the genome along the ori-ter axis gene order along this axis could link genome structure to cell physiology. Fast-growing bacteria cluster translation genes near oriC. In Vibrio cholerae, moving them away was feasible but at the cost of losing fitness and infectivity. Here, we evolved strains harboring ribosomal genes close or far from oriC. Growth rate differences persisted after 1,000 generations. No mutation was able to compensate for the growth defect, showing that ribosomal gene location conditions their evolutionary trajectory. Despite the high plasticity of bacterial genomes, evolution has sculpted gene order to optimize the ecological strategy of the microorganism. We observed growth rate improvement throughout the evolution experiment that occurred at expense of energetically costly processes such the flagellum biosynthesis and virulence-related functions. From the biotechnological point of view, manipulation of gene order enables altering bacterial growth with no escape events.
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7
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Ye B, Tao Q, Yan X. A transposon system for random insertion of a gene expression cassette into the chromosome of Bacillus subtilis. J Biotechnol 2023; 361:66-73. [PMID: 36494011 DOI: 10.1016/j.jbiotec.2022.11.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
Bacillus subtilis is a robust industrial workhorse for the production of heterologous proteins. Chromosomal integration-based protein production has advantages over plasmid-based methods. Considering that the expression level of a gene is affected by its location in the chromosome, it is important to find an optimal integration site for the gene to be expressed. This work establishes a method for random insertion of a gene expression cassette into chromosomes, enabling the screening of optimal integration sites for high-level protein production. Specifically, a gene expression cassette and a chloromycetin-resistance marker are assembled into a transposon. This transposon is inserted between the promoter and the ribosomal binding site of the zeocin-resistance marker in the chromosome, which blocks the transcription of the zeocin-resistance gene. Transposase Himar1-mediated transposition of this transposon activates the zeocin-resistance marker, which can be selected on plates containing both chloromycetin and zeocin. The transposition frequency was over 10-5. This method was used to select proper insertion sites for the expression cassette of methyl parathion hydrolase (MPH). Compared with the common integration site amyE, the expression level of MPH was increased up to 50 % at the yjbH site.
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Affiliation(s)
- Bin Ye
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China; Institute of Microbe and Host Health, College of Agriculture and Forestry, Linyi University, Linyi, Shandong 276000, PR China
| | - Qing Tao
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Xin Yan
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
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8
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Teufel M, Henkel W, Sobetzko P. The role of replication-induced chromosomal copy numbers in spatio-temporal gene regulation and evolutionary chromosome plasticity. Front Microbiol 2023; 14:1119878. [PMID: 37152747 PMCID: PMC10157177 DOI: 10.3389/fmicb.2023.1119878] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 03/31/2023] [Indexed: 05/09/2023] Open
Abstract
For a coherent response to environmental changes, bacterial evolution has formed a complex transcriptional regulatory system comprising classical DNA binding proteins sigma factors and modulation of DNA topology. In this study, we investigate replication-induced gene copy numbers - a regulatory concept that is unlike the others not based on modulation of promoter activity but on replication dynamics. We show that a large fraction of genes are predominantly affected by transient copy numbers and identify cellular functions and central pathways governed by this mechanism in Escherichia coli. Furthermore, we show quantitatively that the previously observed spatio-temporal expression pattern between different growth phases mainly emerges from transient chromosomal copy numbers. We extend the analysis to the plant pathogen Dickeya dadantii and the biotechnologically relevant organism Vibrio natriegens. The analysis reveals a connection between growth phase dependent gene expression and evolutionary gene migration in these species. A further extension to the bacterial kingdom indicates that chromosome evolution is governed by growth rate related transient copy numbers.
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Affiliation(s)
- Marc Teufel
- Synthetic Microbiology Center Marburg (SYNMIKRO), Philipps Universität Marburg, Marburg, Germany
| | - Werner Henkel
- Transmission Systems Group, Jacobs University Bremen, Bremen, Germany
| | - Patrick Sobetzko
- Synthetic Microbiology Center Marburg (SYNMIKRO), Philipps Universität Marburg, Marburg, Germany
- DynAMic Department, Universitè de Lorraine, INRAE, Nancy, France
- *Correspondence: Patrick Sobetzko
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9
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Scholz SA, Lindeboom CD, Freddolino PL. Genetic context effects can override canonical cis regulatory elements in Escherichia coli. Nucleic Acids Res 2022; 50:10360-10375. [PMID: 36134716 PMCID: PMC9561378 DOI: 10.1093/nar/gkac787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 08/10/2022] [Accepted: 09/02/2022] [Indexed: 11/12/2022] Open
Abstract
Recent experiments have shown that in addition to control by cis regulatory elements, the local chromosomal context of a gene also has a profound impact on its transcription. Although this chromosome-position dependent expression variation has been empirically mapped at high-resolution, the underlying causes of the variation have not been elucidated. Here, we demonstrate that 1 kb of flanking, non-coding synthetic sequences with a low frequency of guanosine and cytosine (GC) can dramatically reduce reporter expression compared to neutral and high GC-content flanks in Escherichia coli. Natural and artificial genetic context can have a similarly strong effect on reporter expression, regardless of cell growth phase or medium. Despite the strong reduction in the maximal expression level from the fully-induced reporter, low GC synthetic flanks do not affect the time required to reach the maximal expression level after induction. Overall, we demonstrate key determinants of transcriptional propensity that appear to act as tunable modulators of transcription, independent of regulatory sequences such as the promoter. These findings provide insight into the regulation of naturally occurring genes and an independent control for optimizing expression of synthetic biology constructs.
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Affiliation(s)
- Scott A Scholz
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Chase D Lindeboom
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter L Freddolino
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
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10
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Moschner C, Wedd C, Bakshi S. The context matrix: Navigating biological complexity for advanced biodesign. Front Bioeng Biotechnol 2022; 10:954707. [PMID: 36082163 PMCID: PMC9445834 DOI: 10.3389/fbioe.2022.954707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 06/29/2022] [Indexed: 12/05/2022] Open
Abstract
Synthetic biology offers many solutions in healthcare, production, sensing and agriculture. However, the ability to rationally engineer synthetic biosystems with predictable and robust functionality remains a challenge. A major reason is the complex interplay between the synthetic genetic construct, its host, and the environment. Each of these contexts contains a number of input factors which together can create unpredictable behaviours in the engineered biosystem. It has become apparent that for the accurate assessment of these contextual effects a more holistic approach to design and characterisation is required. In this perspective article, we present the context matrix, a conceptual framework to categorise and explore these contexts and their net effect on the designed synthetic biosystem. We propose the use and community-development of the context matrix as an aid for experimental design that simplifies navigation through the complex design space in synthetic biology.
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11
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Zhang Y, Wang Y, Li J, Wang C, Du G, Kang Z. Construction of Strong Promoters by Assembling Sigma Factor Binding Motifs. Methods Mol Biol 2022; 2461:137-147. [PMID: 35727448 DOI: 10.1007/978-1-0716-2152-3_9] [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: 04/18/2023]
Abstract
Development of strong promoters is of growing interest in the field of biotechnology and synthetic biology. Here we present a protocol for the construction of strong prokaryotic promoters that can be recognized by designated multiple sigma factors by interlocking their cognate binding motifs on DNA strands. Strong and stress responsive promoters for Escherichia coli and Bacillus subtilis have been created following the presented protocol. Customized promoters could be easily developed for fine-tuning gene expression or overproducing enzymes with prokaryotic cell factories.
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Affiliation(s)
- Yonglin Zhang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Yang Wang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
| | - Jianghua Li
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Wuxi, China
| | - Chao Wang
- The Science Center for Future Foods, Jiangnan University, Wuxi, China
| | - Guocheng Du
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Wuxi, China
| | - Zhen Kang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China.
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Wuxi, China.
- The Science Center for Future Foods, Jiangnan University, Wuxi, China.
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12
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Intelligent host engineering for metabolic flux optimisation in biotechnology. Biochem J 2021; 478:3685-3721. [PMID: 34673920 PMCID: PMC8589332 DOI: 10.1042/bcj20210535] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 09/22/2021] [Accepted: 09/24/2021] [Indexed: 12/13/2022]
Abstract
Optimising the function of a protein of length N amino acids by directed evolution involves navigating a 'search space' of possible sequences of some 20N. Optimising the expression levels of P proteins that materially affect host performance, each of which might also take 20 (logarithmically spaced) values, implies a similar search space of 20P. In this combinatorial sense, then, the problems of directed protein evolution and of host engineering are broadly equivalent. In practice, however, they have different means for avoiding the inevitable difficulties of implementation. The spare capacity exhibited in metabolic networks implies that host engineering may admit substantial increases in flux to targets of interest. Thus, we rehearse the relevant issues for those wishing to understand and exploit those modern genome-wide host engineering tools and thinking that have been designed and developed to optimise fluxes towards desirable products in biotechnological processes, with a focus on microbial systems. The aim throughput is 'making such biology predictable'. Strategies have been aimed at both transcription and translation, especially for regulatory processes that can affect multiple targets. However, because there is a limit on how much protein a cell can produce, increasing kcat in selected targets may be a better strategy than increasing protein expression levels for optimal host engineering.
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13
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Bayer CN, Rennig M, Ehrmann AK, Nørholm MHH. A standardized genome architecture for bacterial synthetic biology (SEGA). Nat Commun 2021; 12:5876. [PMID: 34620865 PMCID: PMC8497626 DOI: 10.1038/s41467-021-26155-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 09/21/2021] [Indexed: 02/08/2023] Open
Abstract
Chromosomal recombinant gene expression offers a number of advantages over plasmid-based synthetic biology. However, the methods applied for bacterial genome engineering are still challenging and far from being standardized. Here, in an attempt to realize the simplest recombinant genome technology imaginable and facilitate the transition from recombinant plasmids to genomes, we create a simplistic methodology and a comprehensive strain collection called the Standardized Genome Architecture (SEGA). In its simplest form, SEGA enables genome engineering by combining only two reagents: a DNA fragment that can be ordered from a commercial vendor and a stock solution of bacterial cells followed by incubation on agar plates. Recombinant genomes are identified by visual inspection using green-white colony screening akin to classical blue-white screening for recombinant plasmids. The modular nature of SEGA allows precise multi-level control of transcriptional, translational, and post-translational regulation. The SEGA architecture simultaneously supports increased standardization of genetic designs and a broad application range by utilizing well-characterized parts optimized for robust performance in the context of the bacterial genome. Ultimately, its adaption and expansion by the scientific community should improve predictability and comparability of experimental outcomes across different laboratories.
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Affiliation(s)
- Carolyn N Bayer
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Maja Rennig
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark.
| | - Anja K Ehrmann
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Morten H H Nørholm
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark.
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14
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The spatial position effect: synthetic biology enters the era of 3D genomics. Trends Biotechnol 2021; 40:539-548. [PMID: 34607694 DOI: 10.1016/j.tibtech.2021.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 11/23/2022]
Abstract
Microbial cell factories are critical to achieving green biomanufacturing. A position effect occurs when a synthetic gene circuit is expressed from different positions in the chassis strain genome. Here, we propose the concept of the 'spatial position effect,' which uses technologies in 3D genomics to reveal the spatial structure characteristics of the 3D genome of the chassis. On this basis, we propose to rationally design the integration sites of synthetic gene circuits, use reporter genes for preliminary screening, and integrate synthetic gene circuits into promising sites for further experiments. This approach can produce stable and efficient chassis strains for green biomanufacturing. The proposed spatial position effect brings synthetic biology into the era of 3D genomics.
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15
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Wekesa CS, Furch ACU, Oelmüller R. Isolation and Characterization of High-Efficiency Rhizobia From Western Kenya Nodulating With Common Bean. Front Microbiol 2021; 12:697567. [PMID: 34566909 PMCID: PMC8461304 DOI: 10.3389/fmicb.2021.697567] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 08/12/2021] [Indexed: 11/29/2022] Open
Abstract
Common bean is one of the primary protein sources in third-world countries. They form nodules with nitrogen-fixing rhizobia, which have to be adapted to the local soils. Commercial rhizobial strains such as Rhizobium tropici CIAT899 are often used in agriculture. However, this strain failed to significantly increase the common bean yield in many places, including Kenya, due to the local soils' low pH. We isolated two indigenous rhizobial strains from the nodules of common bean from two fields in Western Kenya that have never been exposed to commercial inocula. We then determined their ability to fix nitrogen in common beans, solubilize phosphorus, and produce indole acetic acid. In greenhouse experiments, common bean plants inoculated with two isolates, B3 and S2 in sterile vermiculite, performed better than those inoculated with CIAT899 or plants grown with nitrogen fertilizer alone. In contrast to CIAT899, both isolates grew in the media with pH 4.8. Furthermore, isolate B3 had higher phosphate solubilization ability and produced more indole acetic acid than the other two rhizobia. Genome analyses revealed that B3 and S2 are different strains of Rhizobium phaseoli. We recommend fieldwork studies in Kenyan soils to test the efficacy of the two isolates in the natural environment in an effort to produce inoculants specific for these soils.
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Affiliation(s)
| | | | - Ralf Oelmüller
- Department of Plant Physiology, Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich-Schiller-University Jena, Jena, Germany
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16
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Abstract
Bacterial protein synthesis rates have evolved to maintain preferred stoichiometries at striking precision, from the components of protein complexes to constituents of entire pathways. Setting relative protein production rates to be well within a factor of two requires concerted tuning of transcription, RNA turnover, and translation, allowing many potential regulatory strategies to achieve the preferred output. The last decade has seen a greatly expanded capacity for precise interrogation of each step of the central dogma genome-wide. Here, we summarize how these technologies have shaped the current understanding of diverse bacterial regulatory architectures underpinning stoichiometric protein synthesis. We focus on the emerging expanded view of bacterial operons, which encode diverse primary and secondary mRNA structures for tuning protein stoichiometry. Emphasis is placed on how quantitative tuning is achieved. We discuss the challenges and open questions in the application of quantitative, genome-wide methodologies to the problem of precise protein production. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- James C Taggart
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; ,
| | - Jean-Benoît Lalanne
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; , .,Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.,Current affiliation: Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA;
| | - Gene-Wei Li
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA; ,
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17
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Amemiya HM, Schroeder J, Freddolino PL. Nucleoid-associated proteins shape chromatin structure and transcriptional regulation across the bacterial kingdom. Transcription 2021; 12:182-218. [PMID: 34499567 PMCID: PMC8632127 DOI: 10.1080/21541264.2021.1973865] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/15/2021] [Accepted: 08/18/2021] [Indexed: 01/21/2023] Open
Abstract
Genome architecture has proven to be critical in determining gene regulation across almost all domains of life. While many of the key components and mechanisms of eukaryotic genome organization have been described, the interplay between bacterial DNA organization and gene regulation is only now being fully appreciated. An increasing pool of evidence has demonstrated that the bacterial chromosome can reasonably be thought of as chromatin, and that bacterial chromosomes contain transcriptionally silent and transcriptionally active regions analogous to heterochromatin and euchromatin, respectively. The roles played by histones in eukaryotic systems appear to be shared across a range of nucleoid-associated proteins (NAPs) in bacteria, which function to compact, structure, and regulate large portions of bacterial chromosomes. The broad range of extant NAPs, and the extent to which they differ from species to species, has raised additional challenges in identifying and characterizing their roles in all but a handful of model bacteria. Here we review the regulatory roles played by NAPs in several well-studied bacteria and use the resulting state of knowledge to provide a working definition for NAPs, based on their function, binding pattern, and expression levels. We present a screening procedure which can be applied to any species for which transcriptomic data are available. Finally, we note that NAPs tend to play two major regulatory roles - xenogeneic silencers and developmental regulators - and that many unrecognized potential NAPs exist in each bacterial species examined.
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Affiliation(s)
- Haley M. Amemiya
- University of Michigan Medical School, Ann Arbor, MI, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Jeremy Schroeder
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter L. Freddolino
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
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18
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Hao N, Chen Q, Dodd IB, Shearwin KE. The pIT5 Plasmid Series, an Improved Toolkit for Repeated Genome Integration in E. coli. ACS Synth Biol 2021; 10:1633-1639. [PMID: 34190535 DOI: 10.1021/acssynbio.1c00215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We describe a new set of tools for inserting DNA into the bacterial chromosome. The system uses site-specific recombination reactions carried out by bacteriophage integrases to integrate plasmids at up to eight phage attachment sites in E. coli MG1655. The introduction of mutant loxP sites in the integrating plasmids allows repeated removal of antibiotic resistance genes and other plasmid sequences without danger of inducing chromosomal rearrangements. The protocol for Cre-mediated antibiotic resistance gene removal is greatly simplified by introducing the Cre plasmid by phage infection. Finally, we have also developed a set of four independently inducible expression modules with tight control and high dynamic range which can be inserted at specific chromosomal locations.
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Affiliation(s)
- Nan Hao
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
- CSIRO Synthetic Biology Future Science Platform, Canberra, ACT 2601, Australia
| | - Qinqin Chen
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Ian B. Dodd
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Keith E. Shearwin
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
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19
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Dienstbier A, Amman F, Petráčková D, Štipl D, Čapek J, Zavadilová J, Fabiánová K, Držmíšek J, Kumar D, Wildung M, Pouchnik D, Večerek B. Comparative Omics Analysis of Historic and Recent Isolates of Bordetella pertussis and Effects of Genome Rearrangements on Evolution. Emerg Infect Dis 2021; 27:57-68. [PMID: 33350934 PMCID: PMC7774529 DOI: 10.3201/eid2701.191541] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Despite high vaccination coverage, pertussis is increasing in many industrialized countries, including the Czech Republic. To better understand Bordetella pertussis resurgence, we analyzed historic strains and recent clinical isolates by using a comparative omics approach. Whole-genome sequencing showed that historic and recent isolates of B. pertussis have substantial variation in genome organization and form separate phylogenetic clusters. Subsequent RNA sequence analysis and liquid chromatography with mass tandem spectrometry analyses showed that these variations translated into discretely separated transcriptomic and proteomic profiles. When compared with historic strains, recent isolates showed increased expression of flagellar genes and genes involved in lipopolysaccharide biosynthesis and decreased expression of polysaccharide capsule genes. Compared with reference strain Tohama I, all strains had increased expression and production of the type III secretion system apparatus. We detected the potential link between observed effects and insertion sequence element–induced changes in gene context only for a few genes.
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20
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Radical genome remodelling accompanied the emergence of a novel host-restricted bacterial pathogen. PLoS Pathog 2021; 17:e1009606. [PMID: 34015034 PMCID: PMC8171923 DOI: 10.1371/journal.ppat.1009606] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 06/02/2021] [Accepted: 05/03/2021] [Indexed: 11/19/2022] Open
Abstract
The emergence of new pathogens is a major threat to public and veterinary health. Changes in bacterial habitat such as a switch in host or disease tropism are typically accompanied by genetic diversification. Staphylococcus aureus is a multi-host bacterial species associated with human and livestock infections. A microaerophilic subspecies, Staphylococcus aureus subsp. anaerobius, is responsible for Morel’s disease, a lymphadenitis restricted to sheep and goats. However, the evolutionary history of S. aureus subsp. anaerobius and its relatedness to S. aureus are unknown. Population genomic analyses of clinical S. aureus subsp. anaerobius isolates revealed a highly conserved clone that descended from a S. aureus progenitor about 1000 years ago before differentiating into distinct lineages that contain African and European isolates. S. aureus subsp. anaerobius has undergone limited clonal expansion, with a restricted population size, and an evolutionary rate 10-fold slower than S. aureus. The transition to its current restricted ecological niche involved acquisition of a pathogenicity island encoding a ruminant host-specific effector of abscess formation, large chromosomal re-arrangements, and the accumulation of at least 205 pseudogenes, resulting in a highly fastidious metabolism. Importantly, expansion of ~87 insertion sequences (IS) located largely in intergenic regions provided distinct mechanisms for the control of expression of flanking genes, including a novel mechanism associated with IS-mediated anti-anti-sense decoupling of ancestral gene repression. Our findings reveal the remarkable evolutionary trajectory of a host-restricted bacterial pathogen that resulted from extensive remodelling of the S. aureus genome through an array of diverse mechanisms in parallel. The emergence of new pathogens is a major threat to public and veterinary health. Some bacteria such as Staphylococcus aureus, have the capacity to infect many different host species including humans and livestock while others such as the closely-related S. aureus subsp. anaerobius, associated with a single type of pathology called Morel’s disease in small ruminants, are highly niche-restricted. However, our understanding of the genetic basis for such differences in bacterial host-tropism is very limited. Here, we discovered that S. aureus subsp. anaerobius evolved from an S. aureus ancestor and underwent an array of extensive changes to its genome that accompanied the transition to its current restricted lifestyle. We observed genome decay involving loss of function of hundreds of genes, large intra-chromosomal rearrangements affecting most of the genome, acquisition of a pathogenicity island, and expansion of large numbers of insertion sequences that are inserted at intergenic sites around the genome. Importantly, we found that IS elements affect the expression of neighbouring genes in different ways including a novel mechanism of IS-enabled disruption of ancestral gene repression. Taken together, we provide a remarkable example of radical genomic changes associated with evolutionary transition from a multi-host to highly restricted host ecology.
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21
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Nagy-Staron A, Tomasek K, Caruso Carter C, Sonnleitner E, Kavčič B, Paixão T, Guet CC. Local genetic context shapes the function of a gene regulatory network. eLife 2021; 10:e65993. [PMID: 33683203 PMCID: PMC7968929 DOI: 10.7554/elife.65993] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 02/19/2021] [Indexed: 11/13/2022] Open
Abstract
Gene expression levels are influenced by multiple coexisting molecular mechanisms. Some of these interactions such as those of transcription factors and promoters have been studied extensively. However, predicting phenotypes of gene regulatory networks (GRNs) remains a major challenge. Here, we use a well-defined synthetic GRN to study in Escherichia coli how network phenotypes depend on local genetic context, i.e. the genetic neighborhood of a transcription factor and its relative position. We show that one GRN with fixed topology can display not only quantitatively but also qualitatively different phenotypes, depending solely on the local genetic context of its components. Transcriptional read-through is the main molecular mechanism that places one transcriptional unit (TU) within two separate regulons without the need for complex regulatory sequences. We propose that relative order of individual TUs, with its potential for combinatorial complexity, plays an important role in shaping phenotypes of GRNs.
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Affiliation(s)
- Anna Nagy-Staron
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Kathrin Tomasek
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | | | - Elisabeth Sonnleitner
- Department of MicrobiologyImmunobiology and Genetics, Max F. Perutz Laboratories, Center Of Molecular Biology, University of ViennaViennaAustria
| | - Bor Kavčič
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Tiago Paixão
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Calin C Guet
- Institute of Science and Technology AustriaKlosterneuburgAustria
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22
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Comprehensive study on Escherichia coli genomic expression: Does position really matter? Metab Eng 2020; 62:10-19. [PMID: 32795614 DOI: 10.1016/j.ymben.2020.07.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 07/20/2020] [Accepted: 07/20/2020] [Indexed: 12/14/2022]
Abstract
As a biorefinery platform host, Escherichia coli has been used extensively to produce metabolites of commercial interest. Integration of foreign DNA onto the bacterial genome allows for stable expression overcoming the need for plasmid expression and its associated instability. Despite the development of numerous tools and genome editing technologies, the question of where to incorporate a synthetic pathway remains unanswered. To address this issue, we studied the genomic expression in E. coli and linked it not only to 26 rationally selected genomic locations, but also to the gene direction in relation to the DNA replication fork, to the carbon and nitrogen source, to DNA folding and supercoiling, and to metabolic burden. To enable these experiments, we have designed a fluorescent expression cassette to eliminate specific local effects on gene expression. Overall it can be concluded that although the expression range obtained by changing the genomic location of a pathway is small compared to the range typically seen in promoter-RBS libraries, the effect of culture medium, environmental stress and metabolic burden can be substantial. The characterization of multiple effects on genomic expression, and the associated libraries of well-characterized strains, will only stimulate and improve the creation of stable production hosts fit for industrial settings.
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23
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Park Y, Espah Borujeni A, Gorochowski TE, Shin J, Voigt CA. Precision design of stable genetic circuits carried in highly-insulated E. coli genomic landing pads. Mol Syst Biol 2020; 16:e9584. [PMID: 32812710 PMCID: PMC7436927 DOI: 10.15252/msb.20209584] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 07/07/2020] [Accepted: 07/22/2020] [Indexed: 01/02/2023] Open
Abstract
Genetic circuits have many applications, from guiding living therapeutics to ordering process in a bioreactor, but to be useful they have to be genetically stable and not hinder the host. Encoding circuits in the genome reduces burden, but this decreases performance and can interfere with native transcription. We have designed genomic landing pads in Escherichia coli at high-expression sites, flanked by ultrastrong double terminators. DNA payloads >8 kb are targeted to the landing pads using phage integrases. One landing pad is dedicated to carrying a sensor array, and two are used to carry genetic circuits. NOT/NOR gates based on repressors are optimized for the genome and characterized in the landing pads. These data are used, in conjunction with design automation software (Cello 2.0), to design circuits that perform quantitatively as predicted. These circuits require fourfold less RNA polymerase than when carried on a plasmid and are stable for weeks in a recA+ strain without selection. This approach enables the design of synthetic regulatory networks to guide cells in environments or for applications where plasmid use is infeasible.
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Affiliation(s)
- Yongjin Park
- Synthetic Biology CenterDepartment of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
| | - Amin Espah Borujeni
- Synthetic Biology CenterDepartment of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
| | - Thomas E Gorochowski
- Synthetic Biology CenterDepartment of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
- Broad Institute of MIT and HarvardCambridgeMAUSA
| | - Jonghyeon Shin
- Synthetic Biology CenterDepartment of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
| | - Christopher A Voigt
- Synthetic Biology CenterDepartment of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
- Broad Institute of MIT and HarvardCambridgeMAUSA
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24
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Chromosome Engineering To Generate Plasmid-Free Phenylalanine- and Tyrosine-Overproducing Escherichia coli Strains That Can Be Applied in the Generation of Aromatic-Compound-Producing Bacteria. Appl Environ Microbiol 2020; 86:AEM.00525-20. [PMID: 32414798 DOI: 10.1128/aem.00525-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 05/11/2020] [Indexed: 12/25/2022] Open
Abstract
Many phenylalanine- and tyrosine-producing strains have used plasmid-based overexpression of pathway genes. The resulting strains achieved high titers and yields of phenylalanine and tyrosine. Chromosomally engineered, plasmid-free producers have shown lower titers and yields than plasmid-based strains, but the former are advantageous in terms of cultivation cost and public health/environmental risk. Therefore, we engineered here the Escherichia coli chromosome to create superior phenylalanine- and tyrosine-overproducing strains that did not depend on plasmid-based expression. Integration into the E. coli chromosome of two central metabolic pathway genes (ppsA and tktA) and eight shikimate pathway genes (aroA, aroB, aroC, aroD, aroE, aroGfbr , aroL, and pheAfbr ), controlled by the T7lac promoter, resulted in excellent titers and yields of phenylalanine; the superscript "fbr" indicates that the enzyme encoded by the gene was feedback resistant. The generated strain could be changed to be a superior tyrosine-producing strain by replacing pheAfbr with tyrAfbr A rational approach revealed that integration of seven genes (ppsA, tktA, aroA, aroB, aroC, aroGfbr , and pheAfbr ) was necessary as the minimum gene set for high-yield phenylalanine production in E. coli MG1655 (tyrR, adhE, ldhA, pykF, pflDC, and ascF deletant). The phenylalanine- and tyrosine-producing strains were further applied to generate phenyllactic acid-, 4-hydroxyphenyllactic acid-, tyramine-, and tyrosol-producing strains; yield of these aromatic compounds increased proportionally to the increase in phenylalanine and tyrosine yields.IMPORTANCE Plasmid-free strains for aromatic compound production are desired in the aspect of industrial application. However, the yields of phenylalanine and tyrosine have been considerably lower in plasmid-free strains than in plasmid-based strains. The significance of this research is that we succeeded in generating superior plasmid-free phenylalanine- and tyrosine-producing strains by engineering the E. coli chromosome, which was comparable to that in plasmid-based strains. The generated strains have a potential to generate superior strains for the production of aromatic compounds. Actually, we demonstrated that four kinds of aromatic compounds could be produced from glucose with high yields (e.g., 0.28 g tyrosol/g glucose).
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25
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Lato DF, Golding GB. Spatial Patterns of Gene Expression in Bacterial Genomes. J Mol Evol 2020; 88:510-520. [PMID: 32506154 PMCID: PMC7324424 DOI: 10.1007/s00239-020-09951-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 05/08/2020] [Indexed: 01/06/2023]
Abstract
Gene expression in bacteria is a remarkably controlled and intricate process impacted by many factors. One such factor is the genomic position of a gene within a bacterial genome. Genes located near the origin of replication generally have a higher expression level, increased dosage, and are often more conserved than genes located farther from the origin of replication. The majority of the studies involved with these findings have only noted this phenomenon in a single gene or cluster of genes that was re-located to pre-determined positions within a bacterial genome. In this work, we look at the overall expression levels from eleven bacterial data sets from Escherichia coli, Bacillus subtilis, Streptomyces, and Sinorhizobium meliloti. We have confirmed that gene expression tends to decrease when moving away from the origin of replication in majority of the replicons analysed in this study. This study sheds light on the impact of genomic location on molecular trends such as gene expression and highlights the importance of accounting for spatial trends in bacterial molecular analysis.
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Affiliation(s)
- Daniella F Lato
- Department of Biology, McMaster Univeristy, 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada
| | - G Brian Golding
- Department of Biology, McMaster Univeristy, 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada.
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26
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Shuffling type of biological evolution based on horizontal gene transfer and the biosphere gene pool hypothesis. Biosystems 2020; 193-194:104131. [DOI: 10.1016/j.biosystems.2020.104131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 03/12/2020] [Accepted: 03/12/2020] [Indexed: 02/08/2023]
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27
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Yubero P, Poyatos JF. The Impact of Global Transcriptional Regulation on Bacterial Gene Order. iScience 2020; 23:101029. [PMID: 32283521 PMCID: PMC7155222 DOI: 10.1016/j.isci.2020.101029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 12/15/2019] [Accepted: 03/27/2020] [Indexed: 12/04/2022] Open
Abstract
Bacterial gene expression depends on the allocation of limited transcriptional resources provided a particular growth rate and growth condition. Early studies in a few genes suggested this global regulation to generate a unifying hyperbolic expression pattern. Here, we developed a large-scale method that generalizes these experiments to quantify the response to growth of over 700 genes that a priori do not exhibit any specific control. We distinguish a core subset following a promoter-specific hyperbolic response. Within this group, we sort genes with regard to their responsiveness to the global regulatory program to show that those with a particularly sensitive linear response are located near the origin of replication. We then find evidence that this genomic architecture is biologically significant by examining position conservation of E. coli genes in 100 bacteria. The response to the transcriptional resources of the cell results in an additional feature contributing to bacterial genome organization. Cell physiology determines a global transcriptional regulatory program Constitutive genes show a differential response to this global regulation The most responsive constitutive genes are located near the origin of replication Global transcriptional regulation acts as a gene position conservation force
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Affiliation(s)
- Pablo Yubero
- Logic of Genomic Systems Laboratory, CNB - CSIC, Madrid 28049, Spain
| | - Juan F Poyatos
- Logic of Genomic Systems Laboratory, CNB - CSIC, Madrid 28049, Spain.
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28
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Spencer GWK, Chua SMH, Erpf PE, Wizrah MSI, Dyba TG, Condon ND, Fraser JA. Broadening the spectrum of fluorescent protein tools for use in the encapsulated human fungal pathogen Cryptococcus neoformans. Fungal Genet Biol 2020; 138:103365. [PMID: 32145317 DOI: 10.1016/j.fgb.2020.103365] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 12/31/2022]
Abstract
Green fluorescent protein (GFP) and its counterparts are modern molecular biology research tools indispensable in many experimental systems. Within fungi, researchers studying Saccharomyces cerevisiae and other model ascomycetes have access to a wide variety of fluorescent proteins. Unfortunately, many of these tools have not crossed the phylum divide into the Basidiomycota, where only GFP S65T, Venus, Ds-Red, and mCherry are currently available. To address this, we searched the literature for potential candidates to be expressed in the human fungal pathogen Cryptococcus neoformans and identified a suite of eight more modern fluorescent proteins that span the visible spectrum. A single copy of each fluorophore was heterologously expressed in Safe Haven 1 and their fluorescence intensities compared in this encapsulated yeast. mTurquoise2, mTFP1, Clover, mNeonGreen, mRuby3, and Citrine were highly visible under the microscope, whereas Superfolder GFP and mMaroon1 were not. Expressed fluorophores did not impact growth or virulence as demonstrated by an in vitro spotting assay and murine inhalation model, respectively.
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Affiliation(s)
- Garrick W K Spencer
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia; School of Chemistry & Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Sheena M H Chua
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia; School of Chemistry & Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Paige E Erpf
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia; School of Chemistry & Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Maha S I Wizrah
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia; School of Chemistry & Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Taylor G Dyba
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia; School of Chemistry & Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Nicholas D Condon
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072 Australia
| | - James A Fraser
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia; School of Chemistry & Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.
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29
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Kosmidis K, Jablonski KP, Muskhelishvili G, Hütt MT. Chromosomal origin of replication coordinates logically distinct types of bacterial genetic regulation. NPJ Syst Biol Appl 2020; 6:5. [PMID: 32066730 PMCID: PMC7026169 DOI: 10.1038/s41540-020-0124-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 01/21/2020] [Indexed: 01/16/2023] Open
Abstract
For a long time it has been hypothesized that bacterial gene regulation involves an intricate interplay of the transcriptional regulatory network (TRN) and the spatial organization of genes in the chromosome. Here we explore this hypothesis both on a structural and on a functional level. On the structural level, we study the TRN as a spatially embedded network. On the functional level, we analyze gene expression patterns from a network perspective (“digital control”), as well as from the perspective of the spatial organization of the chromosome (“analog control”). Our structural analysis reveals the outstanding relevance of the symmetry axis defined by the origin (Ori) and terminus (Ter) of replication for the network embedding and, thus, suggests the co-evolution of two regulatory infrastructures, namely the transcriptional regulatory network and the spatial arrangement of genes on the chromosome, to optimize the cross-talk between two fundamental biological processes: genomic expression and replication. This observation is confirmed by the functional analysis based on the differential gene expression patterns of more than 4000 pairs of microarray and RNA-Seq datasets for E. coli from the Colombos Database using complex network and machine learning methods. This large-scale analysis supports the notion that two logically distinct types of genetic control are cooperating to regulate gene expression in a complementary manner. Moreover, we find that the position of the gene relative to the Ori is a feature of very high predictive value for gene expression, indicating that the Ori–Ter symmetry axis coordinates the action of distinct genetic control mechanisms.
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Affiliation(s)
- Kosmas Kosmidis
- Division of Theoretical Physics, Physics Department, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece.,PharmaInformatics Unit, Research Center ATHENA, Athens, Greece
| | - Kim Philipp Jablonski
- Department of Life Sciences and Chemistry, Jacobs University, Bremen, Germany.,Department of Biosystems Science and Engineering, ETH Zürich, Zürich, Switzerland
| | | | - Marc-Thorsten Hütt
- Department of Life Sciences and Chemistry, Jacobs University, Bremen, Germany.
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Travers A, Muskhelishvili G. Chromosomal Organization and Regulation of Genetic Function in Escherichia coli Integrates the DNA Analog and Digital Information. EcoSal Plus 2020; 9:10.1128/ecosalplus.ESP-0016-2019. [PMID: 32056535 PMCID: PMC11168577 DOI: 10.1128/ecosalplus.esp-0016-2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Indexed: 12/22/2022]
Abstract
In this article, we summarize our current understanding of the bacterial genetic regulation brought about by decades of studies using the Escherichia coli model. It became increasingly evident that the cellular genetic regulation system is organizationally closed, and a major challenge is to describe its circular operation in quantitative terms. We argue that integration of the DNA analog information (i.e., the probability distribution of the thermodynamic stability of base steps) and digital information (i.e., the probability distribution of unique triplets) in the genome provides a key to understanding the organizational logic of genetic control. During bacterial growth and adaptation, this integration is mediated by changes of DNA supercoiling contingent on environmentally induced shifts in intracellular ionic strength and energy charge. More specifically, coupling of dynamic alterations of the local intrinsic helical repeat in the structurally heterogeneous DNA polymer with structural-compositional changes of RNA polymerase holoenzyme emerges as a fundamental organizational principle of the genetic regulation system. We present a model of genetic regulation integrating the genomic pattern of DNA thermodynamic stability with the gene order and function along the chromosomal OriC-Ter axis, which acts as a principal coordinate system organizing the regulatory interactions in the genome.
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Affiliation(s)
- Andrew Travers
- Department of Biochemistry, University of Cambridge, Cambridge, UK
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
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31
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Katashkina JI, Kazieva ED, Tajima Y, Mashko SV. Increased Isoprene Production by the Recombinant Pantoea ananatis Strain due to the Balanced Amplification of Mevalonate Pathway Genes. APPL BIOCHEM MICRO+ 2019. [DOI: 10.1134/s0003683819090023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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32
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Stoof R, Wood A, Goñi-Moreno Á. A Model for the Spatiotemporal Design of Gene Regulatory Circuits †. ACS Synth Biol 2019; 8:2007-2016. [PMID: 31429541 DOI: 10.1021/acssynbio.9b00022] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mathematical modeling assists the design of synthetic regulatory networks by providing a detailed mechanistic understanding of biological systems. Models that can predict the performance of a design are fundamental for synthetic biology since they minimize iterations along the design-build-test lifecycle. Such predictability depends crucially on what assumptions (i.e., biological simplifications) the model considers. Here, we challenge a common assumption when it comes to the modeling of bacterial-based gene regulation: considering negligible the effects of intracellular physical space. It is commonly assumed that molecules, such as transcription factors (TF), are homogeneously distributed inside a cell, so there is no need to model their diffusion. We describe a mathematical model that accounts for molecular diffusion and show how simulations of network performance are decisively affected by the distance between its components. Specifically, the model focuses on the search by a TF for its target promoter. The combination of local searches, via one-dimensional sliding along the chromosome, and global searches, via three-dimensional diffusion through the cytoplasm, determine TF-promoter interplay. Previous experimental results with engineered bacteria in which the distance between TF source and target was minimized or enlarged were successfully reproduced by the spatially resolved model we introduce here. This suggests that the spatial specification of the circuit alone can be exploited as a design parameter in synthetic biology to select programmable output levels.
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Affiliation(s)
- Ruud Stoof
- School of Computing, Newcastle University, Newcastle upon Tyne NE4 5TG, U.K
| | - Alexander Wood
- School of Computing, Newcastle University, Newcastle upon Tyne NE4 5TG, U.K
| | - Ángel Goñi-Moreno
- School of Computing, Newcastle University, Newcastle upon Tyne NE4 5TG, U.K
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33
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Position effects on promoter activity in Escherichia coli and their consequences for antibiotic-resistance determinants. Biochem Soc Trans 2019; 47:839-845. [PMID: 31189732 DOI: 10.1042/bst20180503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 02/07/2023]
Abstract
The activity of any bacterial promoter is generally supposed to be set by its base sequence and the different transcription factors that bind in the local vicinity. Here, we review recent data indicating that the activity of the Escherichia coli lac operon promoter also depends upon its chromosomal location. Factors that affect promoter activity include the binding of nucleoid-associated proteins to neighbouring sequences, supercoiling and the activity of neighbouring promoters. We suggest that many bacterial promoters might be susceptible to similar position-dependent effects and we review recent data showing that the expression of mobile genes encoding antibiotic-resistance determinants is also location-dependent, both when carried on a bacterial chromosome or a conjugative plasmid.
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34
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Pseudomonas putida rDNA is a favored site for the expression of biosynthetic genes. Sci Rep 2019; 9:7028. [PMID: 31065014 PMCID: PMC6505042 DOI: 10.1038/s41598-019-43405-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 04/24/2019] [Indexed: 11/23/2022] Open
Abstract
Since high-value bacterial secondary metabolites, including antibiotics, are often naturally produced in only low amounts, their efficient biosynthesis typically requires the transfer of entire metabolic pathways into suitable bacterial hosts like Pseudomonas putida. Stable maintenance and sufficient expression of heterologous pathway-encoding genes in host microbes, however, still remain key challenges. In this study, the 21 kb prodigiosin gene cluster from Serratia marcescens was used as a reporter to identify genomic sites in P. putida KT2440 especially suitable for maintenance and expression of pathway genes. After generation of a strain library by random Tn5 transposon-based chromosomal integration of the cluster, 50 strains exhibited strong prodigiosin production. Remarkably, chromosomal integration sites were exclusively identified in the seven rRNA-encoding rrn operons of P. putida. We could further demonstrate that prodigiosin production was mainly dependent on (i) the individual rrn operon where the gene cluster was inserted as well as (ii) the distance between the rrn promoter and the inserted prodigiosin biosynthetic genes. In addition, the recombinant strains showed high stability upon subculturing for many generations. Consequently, our findings demonstrate the general applicability of rDNA loci as chromosomal integration sites for gene cluster expression and recombinant pathway implementation in P. putida KT2440.
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35
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Targeted and Repetitive Chromosomal Integration Enables High-Level Heterologous Gene Expression in Lactobacillus casei. Appl Environ Microbiol 2019; 85:AEM.00033-19. [PMID: 30824448 DOI: 10.1128/aem.00033-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 02/23/2019] [Indexed: 12/18/2022] Open
Abstract
Lactobacillus casei is a potential cell factory for the production of enzymes and bioactive molecules using episomal plasmids, which suffer from genetic instability. While chromosomal integration strategies can provide genetic stability of recombinant proteins, low expression yields limit their application. To address this problem, we developed a two-step integration strategy in Lb. casei by combination of the LCABL_13040-50-60 recombineering system (comprised of LCABL_1340, LCABL_13050, and LCABL_13060) with the Cre/loxP site-specific recombination system, with an efficiency of ∼3.7 × 103 CFU/µg DNA. A gfp gene was successfully integrated into six selected chromosomal sites, and the relative fluorescence intensities (RFUs) of the resulting integrants varied up to ∼3.7-fold depending on the integrated site, among which the LCABL_07270 site gfp integration showed the highest RFU. However, integrants with gfp gene(s) integrated into the LCABL_07270 site showed various RFUs, ranging from 993 ± 89 to 7,289 ± 564 and corresponding to 1 to 13.68 ± 1.08 copies of gfp gene integration. Moreover, the integrant with 13.68 ± 1.08 copies of the gfp gene had a more stable RFU after 63 generations compared to that of a plasmid-engineered strain. To investigate the feasibility of this system for bioactive molecules with high expression levels, the fimbrial adhesin gene, faeG, from Escherichia coli was tested and successfully integrated into the LCABL_07270 site with 5.51 ± 0.25 copies, and the integrated faeG achieved stable expression. All results demonstrate that this two-step integration system could achieve a high yield of heterologous gene expression by repetitive integration at a targeted chromosomal location in Lb. casei IMPORTANCE Lactic acid bacteria (LAB), including Lactobacillus casei, have the potential for overexpression of heterologous proteins, such as bioactive molecules and enzymes. However, traditional genetic tools for expression of these proteins show genetic instability or low yields of the desired product. In this study, we provide a procedure for repetitive integration of genes at various chromosomal locations, achieving high-level and stable expression of proteins in Lb. casei without selective pressure. The protocol developed in this study provides an essential reference for chromosomal overexpression of proteins or bioactive molecules in LAB.
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Scholz SA, Diao R, Wolfe MB, Fivenson EM, Lin XN, Freddolino PL. High-Resolution Mapping of the Escherichia coli Chromosome Reveals Positions of High and Low Transcription. Cell Syst 2019; 8:212-225.e9. [PMID: 30904377 DOI: 10.1016/j.cels.2019.02.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 11/19/2018] [Accepted: 02/11/2019] [Indexed: 01/28/2023]
Abstract
Recent studies on targeted gene integrations in bacteria have demonstrated that chromosomal location can substantially affect a gene's expression level. However, these studies have only provided information on a small number of sites. To measure position effects on transcriptional propensity at high resolution across the genome, we built and analyzed a library of over 144,000 genome-integrated, standardized reporters in a single mixed population of Escherichia coli. We observed more than 20-fold variations in transcriptional propensity across the genome when the length of the chromosome was binned into broad 4 kbp regions; greater variability was observed over smaller regions. Our data reveal peaks of high transcriptional propensity centered on ribosomal RNA operons and core metabolic genes, while prophages and mobile genetic elements were enriched in less transcribable regions. In total, our work supports the hypothesis that E. coli has evolved gene-independent mechanisms for regulating expression from specific regions of its genome.
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Affiliation(s)
- Scott A Scholz
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48103, USA
| | - Rucheng Diao
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48103, USA
| | - Michael B Wolfe
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48103, USA; Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48103, USA
| | - Elayne M Fivenson
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48103, USA
| | - Xiaoxia Nina Lin
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48103, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48103, USA.
| | - Peter L Freddolino
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48103, USA; Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48103, USA.
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37
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Genome Location Dictates the Transcriptional Response to PolC Inhibition in Clostridium difficile. Antimicrob Agents Chemother 2019; 63:AAC.01363-18. [PMID: 30455241 DOI: 10.1128/aac.01363-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/04/2018] [Indexed: 01/08/2023] Open
Abstract
Clostridium difficile is a potentially lethal gut pathogen that causes nosocomial and community-acquired infections. Limited treatment options and reports of reduced susceptibility to current treatment emphasize the necessity for novel antimicrobials. The DNA polymerase of Gram-positive organisms is an attractive target for the development of antimicrobials. ACX-362E [N 2-(3,4-dichlorobenzyl)-7-(2-[1-morpholinyl]ethyl)guanine; MorE-DCBG] is a DNA polymerase inhibitor in preclinical development as a novel therapeutic against C. difficile infection. This synthetic purine shows preferential activity against C. difficile PolC over those of other organisms in vitro and is effective in an animal model of C. difficile infection. In this study, we have determined its efficacy against a large collection of clinical isolates. At concentrations below the MIC, the presumed slowing (or stalling) of replication forks due to ACX-362E leads to a growth defect. We have determined the transcriptional response of C. difficile to replication inhibition and observed an overrepresentation of upregulated genes near the origin of replication in the presence of PolC inhibitors, but not when cells were subjected to subinhibitory concentrations of other antibiotics. This phenomenon can be explained by a gene dosage shift, as we observed a concomitant increase in the ratio between origin-proximal and terminus-proximal gene copy number upon exposure to PolC inhibitors. Moreover, we show that certain genes differentially regulated under PolC inhibition are controlled by the origin-proximal general stress response regulator sigma factor B. Together, these data suggest that genome location both directly and indirectly determines the transcriptional response to replication inhibition in C. difficile.
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38
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Urtecho G, Tripp AD, Insigne KD, Kim H, Kosuri S. Systematic Dissection of Sequence Elements Controlling σ70 Promoters Using a Genomically Encoded Multiplexed Reporter Assay in Escherichia coli. Biochemistry 2018; 58:1539-1551. [PMID: 29388765 DOI: 10.1021/acs.biochem.7b01069] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Promoters are the key drivers of gene expression and are largely responsible for the regulation of cellular responses to time and environment. In Escherichia coli, decades of studies have revealed most, if not all, of the sequence elements necessary to encode promoter function. Despite our knowledge of these motifs, it is still not possible to predict the strength and regulation of a promoter from primary sequence alone. Here we develop a novel multiplexed assay to study promoter function in E. coli by building a site-specific genomic recombination-mediated cassette exchange system that allows for the facile construction and testing of large libraries of genetic designs integrated into precise genomic locations. We build and test a library of 10898 σ70 promoter variants consisting of all combinations of a set of eight -35 elements, eight -10 elements, three UP elements, eight spacers, and eight backgrounds. We find that the -35 and -10 sequence elements can explain approximately 74% of the variance in promoter strength within our data set using a simple log-linear statistical model. Simple neural network models explain >95% of the variance in our data set by capturing nonlinear interactions with the spacer, background, and UP elements.
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Affiliation(s)
- Guillaume Urtecho
- Molecular Biology Interdepartmental Doctoral Program , University of California , Los Angeles , California 90095 , United States
| | - Arielle D Tripp
- Department of Molecular, Cell, and Developmental Biology , University of California , Los Angeles , California 90095 , United States
| | - Kimberly D Insigne
- Bioinformatics Interdepartmental Graduate Program , University of California , Los Angeles , California 90095 , United States
| | - Hwangbeom Kim
- Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095 , United States
| | - Sriram Kosuri
- Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095 , United States.,UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, Quantitative and Computational Biology Institute, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, Jonsson Comprehensive Cancer Center , University of California , Los Angeles , California 90095 , United States
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39
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Koma D, Kishida T, Yamanaka H, Moriyoshi K, Nagamori E, Ohmoto T. Escherichia coli chromosome-based T7-dependent constitutive overexpression system and its application to generating a phenylalanine producing strain. J Biosci Bioeng 2018; 126:586-595. [DOI: 10.1016/j.jbiosc.2018.05.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 11/16/2022]
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40
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Abstract
A feature of bacterial chromosomes is that highly expressed essential genes are usually located close to the origin of replication. Because bacteria have overlapping cycles of replication, genes located close to the origin will often be present in multiple copies, and this is thought to be of selective benefit where high levels of expression support high growth rate. However, the magnitude of this selective effect and whether other forces could be at play are poorly understood. To study this, we translocated a highly expressed essential operon, tufB, to different locations and measured growth fitness. We found that transcriptional regulation buffered the effects of translocation and that even under conditions where growth rate was reduced, genetic changes that increased the expression of tufB were easily and rapidly selected. We conclude, at least for tufB, that forces other than gene dosage may be significant in selecting for chromosomal location. Highly expressed genes are commonly located close to the origin of replication of bacterial chromosomes (OriC). This location skew is thought to reflect selective advantages associated with gene dosage effects during the replication cycle. The expression of constitutively expressed genes can vary up to fivefold based on chromosomal location, but it is not clear what level of variation would occur in naturally regulated operons. We tested the magnitude of the chromosome location effect using EF-Tu (tufA, tufB), an abundant protein whose cellular level correlates with, and limits, the maximum growth rate. We translocated the Salmonella tufB operon to four locations across the chromosome. The distance from OriC had only a small effect on growth rate, consistent with this operon having the natural ability to upregulate expression and compensate for reduced gene dosage. In contrast, when the total EF-Tu concentration was limiting for the growth rate (tufA deleted), we observed a strong gene dosage effect when tufB was located further from OriC. However, only a short period of experimental evolution was required before the bacteria adapted to this EF-Tu starvation situation by acquiring genetic changes that increased expression levels from the translocated tufB gene, restoring growth rates. Our findings demonstrate that, at least for the tufB operon, gene dosage is probably not the dominant force selecting for a chromosomal location close to OriC. We suggest that the colocation of highly expressed genes close to OriC might instead be selected because it enhances their coregulation during various growth states, with gene dosage being a secondary benefit.
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41
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Ou B, Garcia C, Wang Y, Zhang W, Zhu G. Techniques for chromosomal integration and expression optimization in Escherichia coli. Biotechnol Bioeng 2018; 115:2467-2478. [PMID: 29981268 DOI: 10.1002/bit.26790] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 06/30/2018] [Accepted: 07/04/2018] [Indexed: 12/31/2022]
Abstract
Due to the inherent expression stability and low metabolic burden to the host cell, the expression of heterologous proteins in the bacterial chromosome in a precise and efficient manner is highly desirable for metabolic engineering and live bacterial applications. However, obtaining suitable chromosome expression levels is particularly challenging. In this minireview, we briefly present the technologies available for the integration of heterologous genes into Escherichia coli chromosomes and strategies to optimize the expression levels of heterologous proteins.
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Affiliation(s)
- Bingming Ou
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.,Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, China.,Diagnostic Medicine/Pathobiology, Kansas State University College of Veterinary Medicine, Manhattan, Kansas
| | - Carolina Garcia
- Diagnostic Medicine/Pathobiology, Kansas State University College of Veterinary Medicine, Manhattan, Kansas
| | - Yejun Wang
- Department of Cell Biology and Genetics, School of Basic Medical Sciences, Shenzhen University Health Science Center, Shenzhen, China
| | - Weiping Zhang
- Diagnostic Medicine/Pathobiology, Kansas State University College of Veterinary Medicine, Manhattan, Kansas
| | - Guoqiang Zhu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-Innovation Center for Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.,Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, China
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42
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Abstract
The ability of bacterial cells to adjust their gene expression program in response to environmental perturbation is often critical for their survival. Recent experimental advances allowing us to quantitatively record gene expression dynamics in single cells and in populations coupled with mathematical modeling enable mechanistic understanding on how these responses are shaped by the underlying regulatory networks. Here, we review how the combination of local and global factors affect dynamical responses of gene regulatory networks. Our goal is to discuss the general principles that allow extrapolation from a few model bacteria to less understood microbes. We emphasize that, in addition to well-studied effects of network architecture, network dynamics are shaped by global pleiotropic effects and cell physiology.
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Affiliation(s)
- David L Shis
- Department of Biosciences, Rice University, Houston, Texas 77005, USA;
| | - Matthew R Bennett
- Department of Biosciences, Rice University, Houston, Texas 77005, USA; .,Department of Bioengineering, Rice University, Houston, Texas 77005, USA
| | - Oleg A Igoshin
- Department of Biosciences, Rice University, Houston, Texas 77005, USA; .,Department of Bioengineering, Rice University, Houston, Texas 77005, USA.,Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
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43
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Engineered promoters enable constant gene expression at any copy number in bacteria. Nat Biotechnol 2018; 36:352-358. [PMID: 29553576 DOI: 10.1038/nbt.4111] [Citation(s) in RCA: 124] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 02/23/2018] [Indexed: 11/09/2022]
Abstract
The internal environment of growing cells is variable and dynamic, making it difficult to introduce reliable parts, such as promoters, for genetic engineering. Here, we applied control-theoretic ideas to design promoters that maintained constant levels of expression at any copy number. Theory predicts that independence to copy number can be achieved by using an incoherent feedforward loop (iFFL) if the negative regulation is perfectly non-cooperative. We engineered iFFLs into Escherichia coli promoters using transcription-activator-like effectors (TALEs). These promoters had near-identical expression in different genome locations and plasmids, even when their copy number was perturbed by genomic mutations or changes in growth medium composition. We applied the stabilized promoters to show that a three-gene metabolic pathway to produce deoxychromoviridans could retain function without re-tuning when the stabilized-promoter-driven genes were moved from a plasmid into the genome.
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44
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Alonso‐Gutierrez J, Koma D, Hu Q, Yang Y, Chan LJG, Petzold CJ, Adams PD, Vickers CE, Nielsen LK, Keasling JD, Lee TS. Toward industrial production of isoprenoids in
Escherichia coli
: Lessons learned from CRISPR‐Cas9 based optimization of a chromosomally integrated mevalonate pathway. Biotechnol Bioeng 2018; 115:1000-1013. [DOI: 10.1002/bit.26530] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 12/18/2017] [Accepted: 12/22/2017] [Indexed: 01/13/2023]
Affiliation(s)
- Jorge Alonso‐Gutierrez
- Joint BioEnergy Institute (JBEI)EmeryvilleCalifornia
- Biological Systems and Engineering DivisionLawrence Berkeley National LaboratoryBerkeleyCalifornia
| | - Daisuke Koma
- Joint BioEnergy Institute (JBEI)EmeryvilleCalifornia
- Biological Systems and Engineering DivisionLawrence Berkeley National LaboratoryBerkeleyCalifornia
- Osaka Municipal Technical Research InstituteOsakaJapan
| | - Qijun Hu
- Joint BioEnergy Institute (JBEI)EmeryvilleCalifornia
- Biological Systems and Engineering DivisionLawrence Berkeley National LaboratoryBerkeleyCalifornia
| | - Yuchen Yang
- Joint BioEnergy Institute (JBEI)EmeryvilleCalifornia
- Biological Systems and Engineering DivisionLawrence Berkeley National LaboratoryBerkeleyCalifornia
| | - Leanne J. G. Chan
- Joint BioEnergy Institute (JBEI)EmeryvilleCalifornia
- Biological Systems and Engineering DivisionLawrence Berkeley National LaboratoryBerkeleyCalifornia
| | - Christopher J. Petzold
- Joint BioEnergy Institute (JBEI)EmeryvilleCalifornia
- Biological Systems and Engineering DivisionLawrence Berkeley National LaboratoryBerkeleyCalifornia
| | - Paul D. Adams
- Joint BioEnergy Institute (JBEI)EmeryvilleCalifornia
- Molecular Biophysics and Integrated Bioimaging DivisionLawrence Berkeley National LaboratoryBerkeleyCalifornia
| | - Claudia E. Vickers
- Australian Institute for Bioengineering and NanotechnologyThe University of QueenslandSt. LuciaQueenslandAustralia
| | - Lars K. Nielsen
- Australian Institute for Bioengineering and NanotechnologyThe University of QueenslandSt. LuciaQueenslandAustralia
| | - Jay D. Keasling
- Joint BioEnergy Institute (JBEI)EmeryvilleCalifornia
- Biological Systems and Engineering DivisionLawrence Berkeley National LaboratoryBerkeleyCalifornia
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of DenmarkHorsholmDenmark
- Department of Chemical and Biomolecular EngineeringUniversity of CaliforniaBerkeleyCalifornia
- Department of BioengineeringUniversity of CaliforniaBerkeleyCalifornia
| | - Taek S. Lee
- Joint BioEnergy Institute (JBEI)EmeryvilleCalifornia
- Biological Systems and Engineering DivisionLawrence Berkeley National LaboratoryBerkeleyCalifornia
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45
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Jeong DE, So Y, Park SY, Park SH, Choi SK. Random knock-in expression system for high yield production of heterologous protein in Bacillus subtilis. J Biotechnol 2017; 266:50-58. [PMID: 29229542 DOI: 10.1016/j.jbiotec.2017.12.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 12/07/2017] [Accepted: 12/07/2017] [Indexed: 10/18/2022]
Abstract
Chromosome-integrated recombinant protein expression in bacteria has advantages for the stable maintenance of genes without any use of antibiotics during large-scale fermentation. Even though different levels of gene expression were reported, depending upon their chromosomal position in bacterial species, only a limited number of integration sites have been used in B. subtilis. In this study, we randomly integrated the GFP and AprE expression cassettes into the B. subtilis genome to determine integration sites that can produce a high yield of heterologous protein expression. Our mariner transposon-based expression cassette integration system was able to find integration sites, which can produce up to 2.9-fold and 1.5-fold increased expression of intracellular GFP and extracellular AprE, respectively, compared to the common integration site amyE. By analyzing the location of integration sites, we observed an adjacent promoter effect, gene dosage effect, and gene knock-out effect all complexly contributing to the increased level of integrated gene expression. Besides obtaining a high yield of heterologous protein expression, our system can also provide a wide-range of expression to expand the systematic application for steady-state metabolic protein production.
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Affiliation(s)
- Da-Eun Jeong
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Younju So
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
| | - Soo-Young Park
- Genofocus Inc., 65 Techno 1-ro, Yuseong-gu, Daejeon 34014, Republic of Korea
| | - Seung-Hwan Park
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
| | - Soo-Keun Choi
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
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Jaruszewicz-Błońska J, Lipniacki T. Genetic toggle switch controlled by bacterial growth rate. BMC SYSTEMS BIOLOGY 2017; 11:117. [PMID: 29197392 PMCID: PMC5712128 DOI: 10.1186/s12918-017-0483-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/09/2017] [Indexed: 01/27/2023]
Abstract
Background In favorable conditions bacterial doubling time is less than 20 min, shorter than DNA replication time. In E. coli a single round of genome replication lasts about 40 min and it must be accomplished about 20 min before cell division. To achieve such fast growth rates bacteria perform multiple replication rounds simultaneously. As a result, when the division time is as short as 20 min E. coli has about 8 copies of origin of replication (ori) and the average copy number of the genes situated close to ori can be 4 times larger than those near the terminus of replication (ter). It implies that shortening of cell cycle may influence dynamics of regulatory pathways involving genes placed at distant loci. Results We analyze this effect in a model of a genetic toggle switch, i.e. a system of two mutually repressing genes, one localized in the vicinity of ori and the other localized in the vicinity of ter. Using a stochastic model that accounts for cell growth and divisions we demonstrate that shortening of the cell cycle can induce switching of the toggle to the state in which expression of the gene placed near ter is suppressed. The toggle bistability causes that the ratio of expression of the competing genes changes more than two orders of magnitude for a two-fold change of the doubling time. The increasing stability of the two toggle states enhances system sensitivity but also its reaction time. Conclusions By fusing the competing genes with fluorescent tags this mechanism could be tested and employed to create an indicator of the doubling time. By manipulating copy numbers of the competing genes and locus of the gene situated near ter, one can obtain equal average expression of both genes for any doubling time T between 20 and 120 min. Such a toggle would accurately report departures of the doubling time from T. Electronic supplementary material The online version of this article (doi:10.1186/s12918-017-0483-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joanna Jaruszewicz-Błońska
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawińskiego 5B, Warsaw, 02-106, Poland.
| | - Tomasz Lipniacki
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawińskiego 5B, Warsaw, 02-106, Poland
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Bury-Moné S, Sclavi B. Stochasticity of gene expression as a motor of epigenetics in bacteria: from individual to collective behaviors. Res Microbiol 2017; 168:503-514. [PMID: 28427910 DOI: 10.1016/j.resmic.2017.03.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 03/07/2017] [Accepted: 03/28/2017] [Indexed: 01/22/2023]
Abstract
Measuring gene expression at the single cell and single molecule level has recently made possible the quantitative measurement of stochasticity of gene expression. This enables identification of the probable sources and roles of noise. Gene expression noise can result in bacterial population heterogeneity, offering specific advantages for fitness and survival in various environments. This trait is therefore selected during the evolution of the species, and is consequently regulated by a specific genetic network architecture. Examples exist in stress-response mechanisms, as well as in infection and pathogenicity strategies, pointing to advantages for multicellularity of bacterial populations.
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Affiliation(s)
- Stéphanie Bury-Moné
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France.
| | - Bianca Sclavi
- LBPA, UMR 8113, CNRS, ENS Paris-Saclay, Université Paris-Saclay, F-94235, Cachan, France.
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The Proximity of Ribosomal Protein Genes to oriC Enhances Vibrio cholerae Fitness in the Absence of Multifork Replication. mBio 2017; 8:mBio.00097-17. [PMID: 28246358 PMCID: PMC5347342 DOI: 10.1128/mbio.00097-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Recent works suggest that bacterial gene order links chromosome structure to cell homeostasis. Comparative genomics showed that, in fast-growing bacteria, ribosomal protein genes (RP) locate near the replication origin (oriC). We recently showed that Vibrio cholerae employs this positional bias as a growth optimization strategy: under fast-growth conditions, multifork replication increases RP dosage and expression. However, RP location may provide advantages in a dosage-independent manner: for example, the physical proximity of the many ribosomal components, in the context of a crowded cytoplasm, may favor ribosome biogenesis. To uncover putative dosage-independent effects, we studied isogenic V. cholerae derivatives in which the major RP locus, S10-spc-α (S10), was relocated to alternative genomic positions. When bacteria grew fast, bacterial fitness was reduced according to the S10 relative distance to oriC The growth of wild-type V. cholerae could not be improved by additional copies of the locus, suggesting a physiologically optimized genomic location. Slow growth is expected to uncouple RP position from dosage, since multifork replication does not occur. Under these conditions, we detected a fitness impairment when S10 was far from oriC Deep sequencing followed by marker frequency analysis in the absence of multifork replication revealed an up to 30% S10 dosage reduction associated with its relocation that closely correlated with fitness alterations. Hence, the impact of S10 location goes beyond a growth optimization strategy during feast periods. RP location may be important during the whole life cycle of this pathogen.IMPORTANCE The role of gene order within the bacterial chromosome is poorly understood. In fast growers, the location of genes linked with the expression of genetic information (i.e., transcription and translation) is biased toward oriC It was proposed that the location of these genes helps to maximize their expression by recruiting multifork replication during fast growth. Our results show that such genomic positioning impacts cell fitness beyond fast-growth conditions, probably across the whole life cycle of fast growers. Thus, the genomic position of key highly expressed genes, such as RP, was finely tuned during the evolution of fast-growing bacteria and may also be important in slow growers. In the near future, many more genes whose genomic position impacts bacterial phenotype will be described. These studies will contribute to discovery the rules of genome organization and application of them for the design of synthetic chromosomes and the creation of artificial life forms.
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Bilyk B, Horbal L, Luzhetskyy A. Chromosomal position effect influences the heterologous expression of genes and biosynthetic gene clusters in Streptomyces albus J1074. Microb Cell Fact 2017; 16:5. [PMID: 28052753 PMCID: PMC5209838 DOI: 10.1186/s12934-016-0619-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 12/20/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Efforts to construct the Streptomyces host strain with enhanced yields of heterologous product have focussed mostly on engineering of primary metabolism and/or the deletion of endogenous biosynthetic gene clusters. However, other factors, such as chromosome compactization, have been shown to have a significant influence on gene expression levels in bacteria and fungi. The expression of genes and biosynthetic gene clusters may vary significantly depending on their location within the chromosome. Little is known about the position effect in actinomycetes, which are important producers of various industrially relevant bioactive molecules. RESULTS To demonstrate an impact of the chromosomal position effect on the heterologous expression of genes and gene clusters in Streptomyces albus J1074, a transposon mutant library with randomly distributed transposon that includes a β-glucuronidase reporter gene was generated. Reporter gene expression levels have been shown to depend on the position on the chromosome. Using a combination of the transposon system and a φC31-based vector, the aranciamycin biosynthetic cluster was introduced randomly into the S. albus genome. The production levels of aranciamycin varied up to eightfold depending on the location of the gene cluster within the chromosome of S. albus J1074. One of the isolated mutant strains with an artificially introduced attachment site produced approximately 50% more aranciamycin than strains with endogenous attBs. CONCLUSIONS In this study, we demonstrate that expression of the reporter gene and aranciamycin biosynthetic cluster in Streptomyces albus J1074 varies up to eightfold depending on its position on the chromosome. The integration of the heterologous cluster into different locations on the chromosome may significantly influence the titre of the produced substance. This knowledge can be used for the more efficient engineering of Actinobacteria via the relocation of the biosynthetic gene clusters and insertion of additional copies of heterologous constructs in a suitable chromosomal position.
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Affiliation(s)
- Bohdan Bilyk
- PharmBioTec GmbH, Science Park 1, 66123, Saarbrücken, Germany.,Helmholtz-Institute for Pharmaceutical Research Saarland, Campus, Building C2.3, 66123, Saarbrücken, Germany
| | - Liliya Horbal
- Department of Pharmaceutical Biotechnology, Saarland University, 66123, Saarbrücken, Germany
| | - Andriy Luzhetskyy
- PharmBioTec GmbH, Science Park 1, 66123, Saarbrücken, Germany. .,Helmholtz-Institute for Pharmaceutical Research Saarland, Campus, Building C2.3, 66123, Saarbrücken, Germany. .,Department of Pharmaceutical Biotechnology, Saarland University, 66123, Saarbrücken, Germany.
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De Paepe B, Peters G, Coussement P, Maertens J, De Mey M. Tailor-made transcriptional biosensors for optimizing microbial cell factories. J Ind Microbiol Biotechnol 2016; 44:623-645. [PMID: 27837353 DOI: 10.1007/s10295-016-1862-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/30/2016] [Indexed: 12/24/2022]
Abstract
Monitoring cellular behavior and eventually properly adapting cellular processes is key to handle the enormous complexity of today's metabolic engineering questions. Hence, transcriptional biosensors bear the potential to augment and accelerate current metabolic engineering strategies, catalyzing vital advances in industrial biotechnology. The development of such transcriptional biosensors typically starts with exploring nature's richness. Hence, in a first part, the transcriptional biosensor architecture and the various modi operandi are briefly discussed, as well as experimental and computational methods and relevant ontologies to search for natural transcription factors and their corresponding binding sites. In the second part of this review, various engineering approaches are reviewed to tune the main characteristics of these (natural) transcriptional biosensors, i.e., the response curve and ligand specificity, in view of specific industrial biotechnology applications, which is illustrated using success stories of transcriptional biosensor engineering.
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Affiliation(s)
- Brecht De Paepe
- Department of Biochemical and Microbial Technology, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Gert Peters
- Department of Biochemical and Microbial Technology, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Pieter Coussement
- Department of Biochemical and Microbial Technology, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Jo Maertens
- Department of Biochemical and Microbial Technology, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Marjan De Mey
- Department of Biochemical and Microbial Technology, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
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