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Kim J, Seo M, Lim Y, Kim J. START: A Versatile Platform for Bacterial Ligand Sensing with Programmable Performances. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2402029. [PMID: 39075726 PMCID: PMC11423158 DOI: 10.1002/advs.202402029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 05/31/2024] [Indexed: 07/31/2024]
Abstract
Recognition of signaling molecules for coordinated regulation of target genes is a fundamental process for biological systems. Cells often rely on transcription factors to accomplish these intricate tasks, yet the subtle conformational changes of protein structures, coupled with the complexity of intertwined protein interaction networks, pose challenges for repurposing these for bioengineering applications. This study introduces a novel platform for ligand-responsive gene regulation, termed START (Synthetic Trans-Acting Riboswitch with Triggering RNA). Inspired by the bacterial ligand sensing system, riboswitch, and the synthetic gene regulator, toehold switch, the START platform enables the implementation of synthetic biosensors for various ligands. Rational sequence design with targeted domain optimization yields high-performance STARTs with a dynamic range up to 67.29-fold and a tunable ligand sensitivity, providing a simple and intuitive strategy for sensor engineering. The START platform also exhibits modularity and composability to allow flexible genetic circuit construction, enabling seamless implementation of OR, AND, and NOT Boolean logic gates for multiple ligand inputs. The START design principle is capable of broadening the suite of synthetic biosensors for diverse chemical and protein ligands, providing a novel riboregulator chassis for synthetic biology and bioengineering applications.
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Affiliation(s)
- Jeongwon Kim
- Department of Life SciencesPohang University of Science and TechnologyPohang37673South Korea
| | - Minchae Seo
- Department of Life SciencesPohang University of Science and TechnologyPohang37673South Korea
| | - Yelin Lim
- Department of Life SciencesPohang University of Science and TechnologyPohang37673South Korea
| | - Jongmin Kim
- Department of Life SciencesPohang University of Science and TechnologyPohang37673South Korea
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2
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Dykeman EC. Design of a self-regulating mRNA gene circuit. Sci Rep 2024; 14:19421. [PMID: 39169208 PMCID: PMC11339067 DOI: 10.1038/s41598-024-70363-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 08/16/2024] [Indexed: 08/23/2024] Open
Abstract
Protein expression in vivo is predominately controlled via regulatory feedback mechanisms that adjust the level of mRNA transcription. However for positive sense single-stranded RNA viruses, protein expression is often controlled via secondary structural elements, such as internal ribosomal entry sites, that are encoded within the mRNA. The self-regulation of mRNA translation observed in this class of viruses suggests that it may be possible to design mRNAs that self-regulate their protein expression, enabling the creation of mRNAs for vaccines and other synthetic biology applications where protein levels in the cell can be tightly controlled without feedback to a transcriptional mechanism. As a proof of concept, I design a polycistronic mRNA based on bacteriophage MS2, where the upstream gene is capable of repressing synthesis of the downstream gene. Using a computational tool that simulates ribosome kinetics and the co-translational folding of the mRNA in response, I show that mutations to the mRNA can be identified which enhance the efficiency of the translation and the repression of the downstream gene. The results of this study open up the possibility of designing bespoke mRNA gene circuits in which the amount of protein synthesised in cells are self-regulated for therapeutic or antigenic purposes.
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Affiliation(s)
- Eric C Dykeman
- Department of Mathematics, University of York, York, YO10 5DD, UK.
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3
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Huang H, Lin Z, He D, Hong L, Li Y. RiboDiffusion: tertiary structure-based RNA inverse folding with generative diffusion models. Bioinformatics 2024; 40:i347-i356. [PMID: 38940178 PMCID: PMC11211841 DOI: 10.1093/bioinformatics/btae259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2024] Open
Abstract
MOTIVATION RNA design shows growing applications in synthetic biology and therapeutics, driven by the crucial role of RNA in various biological processes. A fundamental challenge is to find functional RNA sequences that satisfy given structural constraints, known as the inverse folding problem. Computational approaches have emerged to address this problem based on secondary structures. However, designing RNA sequences directly from 3D structures is still challenging, due to the scarcity of data, the nonunique structure-sequence mapping, and the flexibility of RNA conformation. RESULTS In this study, we propose RiboDiffusion, a generative diffusion model for RNA inverse folding that can learn the conditional distribution of RNA sequences given 3D backbone structures. Our model consists of a graph neural network-based structure module and a Transformer-based sequence module, which iteratively transforms random sequences into desired sequences. By tuning the sampling weight, our model allows for a trade-off between sequence recovery and diversity to explore more candidates. We split test sets based on RNA clustering with different cut-offs for sequence or structure similarity. Our model outperforms baselines in sequence recovery, with an average relative improvement of 11% for sequence similarity splits and 16% for structure similarity splits. Moreover, RiboDiffusion performs consistently well across various RNA length categories and RNA types. We also apply in silico folding to validate whether the generated sequences can fold into the given 3D RNA backbones. Our method could be a powerful tool for RNA design that explores the vast sequence space and finds novel solutions to 3D structural constraints. AVAILABILITY AND IMPLEMENTATION The source code is available at https://github.com/ml4bio/RiboDiffusion.
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Affiliation(s)
- Han Huang
- Department of Computer Science and Engineering, CUHK, Hong Kong SAR, 999077, China
- School of Computer Science and Engineering, Beihang University, Beijing, 100191, China
| | - Ziqian Lin
- Department of Computer Science and Engineering, CUHK, Hong Kong SAR, 999077, China
- School of Artificial Intelligence, Nanjing University, Nanjing, 210023, China
| | - Dongchen He
- Department of Computer Science and Engineering, CUHK, Hong Kong SAR, 999077, China
| | - Liang Hong
- Department of Computer Science and Engineering, CUHK, Hong Kong SAR, 999077, China
| | - Yu Li
- Department of Computer Science and Engineering, CUHK, Hong Kong SAR, 999077, China
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4
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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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5
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Lv Y, Chang J, Zhang W, Dong H, Chen S, Wang X, Zhao A, Zhang S, Alam MA, Wang S, Du C, Xu J, Wang W, Xu P. Improving Microbial Cell Factory Performance by Engineering SAM Availability. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:3846-3871. [PMID: 38372640 DOI: 10.1021/acs.jafc.3c09561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Methylated natural products are widely spread in nature. S-Adenosyl-l-methionine (SAM) is the secondary abundant cofactor and the primary methyl donor, which confer natural products with structural and functional diversification. The increasing demand for SAM-dependent natural products (SdNPs) has motivated the development of microbial cell factories (MCFs) for sustainable and efficient SdNP production. Insufficient and unsustainable SAM availability hinders the improvement of SdNP MCF performance. From the perspective of developing MCF, this review summarized recent understanding of de novo SAM biosynthesis and its regulatory mechanism. SAM is just the methyl mediator but not the original methyl source. Effective and sustainable methyl source supply is critical for efficient SdNP production. We compared and discussed the innate and relatively less explored alternative methyl sources and identified the one involving cheap one-carbon compound as more promising. The SAM biosynthesis is synergistically regulated on multilevels and is tightly connected with ATP and NAD(P)H pools. We also covered the recent advancement of metabolic engineering in improving intracellular SAM availability and SdNP production. Dynamic regulation is a promising strategy to achieve accurate and dynamic fine-tuning of intracellular SAM pool size. Finally, we discussed the design and engineering constraints underlying construction of SAM-responsive genetic circuits and envisioned their future applications in developing SdNP MCFs.
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Affiliation(s)
- Yongkun Lv
- School of Chemical Engineering, Zhengzhou University, No. 100 Science Avenue, Zhengzhou 450001, China
| | - Jinmian Chang
- School of Chemical Engineering, Zhengzhou University, No. 100 Science Avenue, Zhengzhou 450001, China
| | - Weiping Zhang
- Bloomage Biotechnology Corporation Limited, 678 Tianchen Street, Jinan, Shandong 250101, China
| | - Hanyu Dong
- School of Chemical Engineering, Zhengzhou University, No. 100 Science Avenue, Zhengzhou 450001, China
| | - Song Chen
- School of Chemical Engineering, Zhengzhou University, No. 100 Science Avenue, Zhengzhou 450001, China
| | - Xian Wang
- School of Chemical Engineering, Zhengzhou University, No. 100 Science Avenue, Zhengzhou 450001, China
| | - Anqi Zhao
- School of Life Sciences, Zhengzhou University, No. 100 Science Avenue, Zhengzhou, 450001, China
| | - Shen Zhang
- School of Chemical Engineering, Zhengzhou University, No. 100 Science Avenue, Zhengzhou 450001, China
| | - Md Asraful Alam
- School of Chemical Engineering, Zhengzhou University, No. 100 Science Avenue, Zhengzhou 450001, China
| | - Shilei Wang
- School of Chemical Engineering, Zhengzhou University, No. 100 Science Avenue, Zhengzhou 450001, China
| | - Chaojun Du
- Nanyang Research Institute of Zhengzhou University, Nanyang Institute of Technology, No. 80 Changjiang Road, Nanyang 473004, China
| | - Jingliang Xu
- School of Chemical Engineering, Zhengzhou University, No. 100 Science Avenue, Zhengzhou 450001, China
- National Key Laboratory of Biobased Transportation Fuel Technology, No. 100 Science Avenue, Zhengzhou 450001, China
| | - Weigao Wang
- Department of Chemical Engineering, Stanford University, 443 Via Ortega, Palo Alto, California 94305, United States
| | - Peng Xu
- Department of Chemical Engineering, Guangdong Technion-Israel Institute of Technology (GTIIT), Shantou, Guangdong 515063, China
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6
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Cautereels C, Smets J, Bircham P, De Ruysscher D, Zimmermann A, De Rijk P, Steensels J, Gorkovskiy A, Masschelein J, Verstrepen KJ. Combinatorial optimization of gene expression through recombinase-mediated promoter and terminator shuffling in yeast. Nat Commun 2024; 15:1112. [PMID: 38326309 PMCID: PMC10850122 DOI: 10.1038/s41467-024-44997-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 01/12/2024] [Indexed: 02/09/2024] Open
Abstract
Microbes are increasingly employed as cell factories to produce biomolecules. This often involves the expression of complex heterologous biosynthesis pathways in host strains. Achieving maximal product yields and avoiding build-up of (toxic) intermediates requires balanced expression of every pathway gene. However, despite progress in metabolic modeling, the optimization of gene expression still heavily relies on trial-and-error. Here, we report an approach for in vivo, multiplexed Gene Expression Modification by LoxPsym-Cre Recombination (GEMbLeR). GEMbLeR exploits orthogonal LoxPsym sites to independently shuffle promoter and terminator modules at distinct genomic loci. This approach facilitates creation of large strain libraries, in which expression of every pathway gene ranges over 120-fold and each strain harbors a unique expression profile. When applied to the biosynthetic pathway of astaxanthin, an industrially relevant antioxidant, a single round of GEMbLeR improved pathway flux and doubled production titers. Together, this shows that GEMbLeR allows rapid and efficient gene expression optimization in heterologous biosynthetic pathways, offering possibilities for enhancing the performance of microbial cell factories.
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Affiliation(s)
- Charlotte Cautereels
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Jolien Smets
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Peter Bircham
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Dries De Ruysscher
- Molecular Biotechnology of Plants and Micro-organisms, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, box 2438, Leuven, 3001, Belgium
- Laboratory for Biomolecular Discovery & Engineering, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
| | - Anna Zimmermann
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Peter De Rijk
- Neuromics Support Facility, VIB Center for Molecular Neurology, VIB, Antwerp, 2610, Belgium
- Neuromics Support Facility, Department of Biomedical Sciences, University of Antwerp, Antwerp, 2610, Belgium
| | - Jan Steensels
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Anton Gorkovskiy
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium
| | - Joleen Masschelein
- Molecular Biotechnology of Plants and Micro-organisms, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, box 2438, Leuven, 3001, Belgium
- Laboratory for Biomolecular Discovery & Engineering, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium
| | - Kevin J Verstrepen
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Leuven, 3001, Belgium.
- Laboratory of Genetics and Genomics, Center of Microbial and Plant Genetics, Department M2S, KU Leuven, Gaston Geenslaan 1, Leuven, 3001, Belgium.
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7
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Gao Y, Wang L, Wang B. Customizing cellular signal processing by synthetic multi-level regulatory circuits. Nat Commun 2023; 14:8415. [PMID: 38110405 PMCID: PMC10728147 DOI: 10.1038/s41467-023-44256-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 12/05/2023] [Indexed: 12/20/2023] Open
Abstract
As synthetic biology permeates society, the signal processing circuits in engineered living systems must be customized to meet practical demands. Towards this mission, novel regulatory mechanisms and genetic circuits with unprecedented complexity have been implemented over the past decade. These regulatory mechanisms, such as transcription and translation control, could be integrated into hybrid circuits termed "multi-level circuits". The multi-level circuit design will tremendously benefit the current genetic circuit design paradigm, from modifying basic circuit dynamics to facilitating real-world applications, unleashing our capabilities to customize cellular signal processing and address global challenges through synthetic biology.
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Affiliation(s)
- 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, UK
| | - Lei Wang
- Center of Synthetic Biology and Integrated Bioengineering & School of Engineering, Westlake University, Hangzhou, 310030, China.
| | - Baojun Wang
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, 310058, China.
- Research Center for Biological Computation, Zhejiang Lab, Hangzhou, 311100, China.
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8
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Sieg JP, Jolley EA, Huot MJ, Babitzke P, Bevilacqua P. In vivo-like nearest neighbor parameters improve prediction of fractional RNA base-pairing in cells. Nucleic Acids Res 2023; 51:11298-11317. [PMID: 37855684 PMCID: PMC10639048 DOI: 10.1093/nar/gkad807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 09/11/2023] [Accepted: 09/27/2023] [Indexed: 10/20/2023] Open
Abstract
We conducted a thermodynamic analysis of RNA stability in Eco80 artificial cytoplasm, which mimics in vivo conditions, and compared it to transcriptome-wide probing of mRNA. Eco80 contains 80% of Escherichia coli metabolites, with biological concentrations of metal ions, including 2 mM free Mg2+ and 29 mM metabolite-chelated Mg2+. Fluorescence-detected binding isotherms (FDBI) were used to conduct a thermodynamic analysis of 24 RNA helices and found that these helices, which have an average stability of -12.3 kcal/mol, are less stable by ΔΔGo37 ∼1 kcal/mol. The FDBI data was used to determine a set of Watson-Crick free energy nearest neighbor parameters (NNPs), which revealed that Eco80 reduces the stability of three NNPs. This information was used to adjust the NN model using the RNAstructure package. The in vivo-like adjustments have minimal effects on the prediction of RNA secondary structures determined in vitro and in silico, but markedly improve prediction of fractional RNA base pairing in E. coli, as benchmarked with our in vivo DMS and EDC RNA chemical probing data. In summary, our thermodynamic and chemical probing analyses of RNA helices indicate that RNA secondary structures are less stable in cells than in artificially stable in vitro buffer conditions.
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Affiliation(s)
- Jacob P Sieg
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
- Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Elizabeth A Jolley
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
- Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Melanie J Huot
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Paul Babitzke
- Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Philip C Bevilacqua
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
- Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
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9
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Liu B, Samaniego CC, Bennett MR, Franco E, Chappell J. A portable regulatory RNA array design enables tunable and complex regulation across diverse bacteria. Nat Commun 2023; 14:5268. [PMID: 37644054 PMCID: PMC10465534 DOI: 10.1038/s41467-023-40785-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 08/10/2023] [Indexed: 08/31/2023] Open
Abstract
A lack of composable and tunable gene regulators has hindered efforts to engineer non-model bacteria and consortia. Toward addressing this, we explore the broad-host potential of small transcription activating RNA (STAR) and propose a design strategy to achieve tunable gene control. First, we demonstrate that STARs optimized for E. coli function across different Gram-negative species and can actuate using phage RNA polymerase, suggesting that RNA systems acting at the level of transcription are portable. Second, we explore an RNA design strategy that uses arrays of tandem and transcriptionally fused RNA regulators to precisely alter regulator concentration from 1 to 8 copies. This provides a simple means to predictably tune output gain across species and does not require access to large regulatory part libraries. Finally, we show RNA arrays can be used to achieve tunable cascading and multiplexing circuits across species, analogous to the motifs used in artificial neural networks.
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Affiliation(s)
- Baiyang Liu
- Graduate Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, TX, USA
| | - Christian Cuba Samaniego
- Department of Mechanical and Aerospace Engineering, Bioengineering, Molecular Biology Institute, University of California at Los Angeles, Los Angeles, CA, USA
| | - Matthew R Bennett
- Department of Biosciences, Rice University, Houston, TX, USA
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Elisa Franco
- Department of Mechanical and Aerospace Engineering, Bioengineering, Molecular Biology Institute, University of California at Los Angeles, Los Angeles, CA, USA
| | - James Chappell
- Department of Biosciences, Rice University, Houston, TX, USA.
- Department of Bioengineering, Rice University, Houston, TX, USA.
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10
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Riley AT, Robson JM, Green AA. Generative and predictive neural networks for the design of functional RNA molecules. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.14.549043. [PMID: 37503279 PMCID: PMC10370010 DOI: 10.1101/2023.07.14.549043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
RNA is a remarkably versatile molecule that has been engineered for applications in therapeutics, diagnostics, and in vivo information-processing systems. However, the complex relationship between the sequence and structural properties of an RNA molecule and its ability to perform specific functions often necessitates extensive experimental screening of candidate sequences. Here we present a generalized neural network architecture that utilizes the sequence and structure of RNA molecules (SANDSTORM) to inform functional predictions. We demonstrate that this approach achieves state-of-the-art performance across several distinct RNA prediction tasks, while learning interpretable abstractions of RNA secondary structure. We paired these predictive models with generative adversarial RNA design networks (GARDN), allowing the generative modelling of novel mRNA 5' untranslated regions and toehold switch riboregulators exhibiting a predetermined fitness. This approach enabled the design of novel toehold switches with a 43-fold increase in experimentally characterized dynamic range compared to those designed using classic thermodynamic algorithms. SANDSTORM and GARDN thus represent powerful new predictive and generative tools for the development of diagnostic and therapeutic RNA molecules with improved function.
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Affiliation(s)
- Aidan T. Riley
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
- Biological Design Center, Boston University, Boston, MA 02215, USA
| | - James M. Robson
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
- Biological Design Center, Boston University, Boston, MA 02215, USA
| | - Alexander A. Green
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
- Biological Design Center, Boston University, Boston, MA 02215, USA
- Molecular Biology, Cell Biology & Biochemistry Program, Graduate School of Arts and Sciences, Boston University, Boston, MA 02215, USA
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11
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Wang CH, Hou J, Deng HK, Wang LJ. Microbial Production of Mevalonate. J Biotechnol 2023; 370:1-11. [PMID: 37209831 DOI: 10.1016/j.jbiotec.2023.05.005] [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] [Received: 02/01/2023] [Revised: 04/20/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023]
Abstract
Mevalonate, an important intermediate product of the mevalonate pathway, has a broad spectrum of applications. With the rapid growth of metabolic engineering and synthetic biology, mevalonate biosynthesis by microorganisms is feasible and holds great promise in the future. In this review, we summarize the applications of mevalonate and its derivatives and describe the biosynthesis pathways of mevalonate. The current status of mevalonate biosynthesis is also detailed with an emphasis on metabolic engineering strategies to enhance mevalonate production in typical industrial organisms, including Escherichia coli, Saccharomyces cerevisiae, and Pseudomonas putida, suggesting new insights for the efficient production of biosynthesized mevalonate.
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Affiliation(s)
- Cong-Han Wang
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo, China
| | - Jie Hou
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo, China
| | - Hong-Kuan Deng
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo, China.
| | - Li-Juan Wang
- School of Life Sciences and Medicine, Shandong University of Technology, Zibo, China; College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China.
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12
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Gyorgy A, Menezes A, Arcak M. A blueprint for a synthetic genetic feedback optimizer. Nat Commun 2023; 14:2554. [PMID: 37137895 PMCID: PMC10156725 DOI: 10.1038/s41467-023-37903-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 04/05/2023] [Indexed: 05/05/2023] Open
Abstract
Biomolecular control enables leveraging cells as biomanufacturing factories. Despite recent advancements, we currently lack genetically encoded modules that can be deployed to dynamically fine-tune and optimize cellular performance. Here, we address this shortcoming by presenting the blueprint of a genetic feedback module to optimize a broadly defined performance metric by adjusting the production and decay rate of a (set of) regulator species. We demonstrate that the optimizer can be implemented by combining available synthetic biology parts and components, and that it can be readily integrated with existing pathways and genetically encoded biosensors to ensure its successful deployment in a variety of settings. We further illustrate that the optimizer successfully locates and tracks the optimum in diverse contexts when relying on mass action kinetics-based dynamics and parameter values typical in Escherichia coli.
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Affiliation(s)
- Andras Gyorgy
- Division of Engineering, New York University Abu Dhabi, Abu Dhabi, UAE.
| | - Amor Menezes
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA
| | - Murat Arcak
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, USA
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13
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Vezeau GE, Gadila LR, Salis HM. Automated design of protein-binding riboswitches for sensing human biomarkers in a cell-free expression system. Nat Commun 2023; 14:2416. [PMID: 37105971 PMCID: PMC10140043 DOI: 10.1038/s41467-023-38098-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Cell-free genetically encoded biosensors have been developed to detect small molecules and nucleic acids, but they have yet to be reliably engineered to detect proteins. Here we develop an automated platform to convert protein-binding RNA aptamers into riboswitch sensors that operate within low-cost cell-free assays. We demonstrate the platform by engineering 35 protein-sensing riboswitches for human monomeric C-reactive protein, human interleukin-32γ, and phage MS2 coat protein. The riboswitch sensors regulate output expression levels by up to 16-fold with input protein concentrations within the human serum range. We identify two distinct mechanisms governing riboswitch-mediated regulation of translation rates and leverage computational analysis to refine the protein-binding aptamer regions, improving design accuracy. Overall, we expand the cell-free sensor toolbox and demonstrate how computational design is used to develop protein-sensing riboswitches with future applications as low-cost medical diagnostics.
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Affiliation(s)
- Grace E Vezeau
- Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Lipika R Gadila
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Howard M Salis
- Department of Agricultural and Biological Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, 16802, USA.
- Huck Institute Bioinformatics and Genomics Graduate Program, Pennsylvania State University, University Park, PA, 16802, USA.
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14
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Liu B, Samaniego CC, Bennett MR, Franco E, Chappell J. A portable regulatory RNA array design enables tunable and complex regulation across diverse bacteria. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.24.529951. [PMID: 36865180 PMCID: PMC9980294 DOI: 10.1101/2023.02.24.529951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
A lack of composable and tunable gene regulators has hindered efforts to engineer non-model bacteria and consortia. To address this, we explore the broad-host potential of small transcription activating RNA (STAR) and propose a novel design strategy to achieve tunable gene control. First, we demonstrate that STARs optimized for E. coli function across different Gram-negative species and can actuate using phage RNA polymerase, suggesting that RNA systems acting at the level of transcription are portable. Second, we explore a novel RNA design strategy that uses arrays of tandem and transcriptionally fused RNA regulators to precisely alter regulator concentration from 1 to 8 copies. This provides a simple means to predictably tune output gain across species and does not require access to large regulatory part libraries. Finally, we show RNA arrays can be used to achieve tunable cascading and multiplexing circuits across species, analogous to the motifs used in artificial neural networks.
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Affiliation(s)
- Baiyang Liu
- Graduate Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, TX, USA
| | - Christian Cuba Samaniego
- Department of Mechanical and Aerospace Engineering, Bioengineering, and Molecular Biology Institute, University of California at Los Angeles, CA, USA
| | - Matthew R. Bennett
- Department of Biosciences, Rice University, Houston, TX, USA
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Elisa Franco
- Department of Mechanical and Aerospace Engineering, Bioengineering, and Molecular Biology Institute, University of California at Los Angeles, CA, USA
| | - James Chappell
- Department of Biosciences, Rice University, Houston, TX, USA
- Department of Bioengineering, Rice University, Houston, TX, USA
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15
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Satta A, Esquirol L, Ebert BE. Current Metabolic Engineering Strategies for Photosynthetic Bioproduction in Cyanobacteria. Microorganisms 2023; 11:455. [PMID: 36838420 PMCID: PMC9964548 DOI: 10.3390/microorganisms11020455] [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: 12/12/2022] [Revised: 02/04/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Cyanobacteria are photosynthetic microorganisms capable of using solar energy to convert CO2 and H2O into O2 and energy-rich organic compounds, thus enabling sustainable production of a wide range of bio-products. More and more strains of cyanobacteria are identified that show great promise as cell platforms for the generation of bioproducts. However, strain development is still required to optimize their biosynthesis and increase titers for industrial applications. This review describes the most well-known, newest and most promising strains available to the community and gives an overview of current cyanobacterial biotechnology and the latest innovative strategies used for engineering cyanobacteria. We summarize advanced synthetic biology tools for modulating gene expression and their use in metabolic pathway engineering to increase the production of value-added compounds, such as terpenoids, fatty acids and sugars, to provide a go-to source for scientists starting research in cyanobacterial metabolic engineering.
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Affiliation(s)
- Alessandro Satta
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD 4072, Australia
- Department of Biology, University of Padua, 35100 Padua, Italy
| | - Lygie Esquirol
- Centre for Cell Factories and Biopolymers, Griffith Institute for Drug Discovery, Griffith University, Natha, QLD 4111, Australia
| | - Birgitta E. Ebert
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD 4072, Australia
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16
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Yin G, Peng A, Zhang L, Wang Y, Du G, Chen J, Kang Z. Design of artificial small regulatory trans-RNA for gene knockdown in Bacillus subtilis. Synth Syst Biotechnol 2022; 8:61-68. [DOI: 10.1016/j.synbio.2022.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/03/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022] Open
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17
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Romantseva E, Alperovich N, Ross D, Lund SP, Strychalski EA. Effects of DNA template preparation on variability in cell-free protein production. Synth Biol (Oxf) 2022; 7:ysac015. [PMID: 36046152 PMCID: PMC9425043 DOI: 10.1093/synbio/ysac015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 07/01/2022] [Accepted: 08/12/2022] [Indexed: 08/08/2023] Open
Abstract
DNA templates for protein production remain an unexplored source of variability in the performance of cell-free expression (CFE) systems. To characterize this variability, we investigated the effects of two common DNA extraction methodologies, a postprocessing step and manual versus automated preparation on protein production using CFE. We assess the concentration of the DNA template, the quality of the DNA template in terms of physical damage and the quality of the DNA solution in terms of purity resulting from eight DNA preparation workflows. We measure the variance in protein titer and rate of protein production in CFE reactions associated with the biological replicate of the DNA template, the technical replicate DNA solution prepared with the same workflow and the measurement replicate of nominally identical CFE reactions. We offer practical guidance for preparing and characterizing DNA templates to achieve acceptable variability in CFE performance.
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Affiliation(s)
| | - Nina Alperovich
- National Institute of Standards and Technology, Gaithersburg, MD USA
| | - David Ross
- National Institute of Standards and Technology, Gaithersburg, MD USA
| | - Steven P Lund
- National Institute of Standards and Technology, Gaithersburg, MD USA
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18
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Ryan J, Hong S, Foo M, Kim J, Tang X. Model-Based Investigation of the Relationship between Regulation Level and Pulse Property of I1-FFL Gene Circuits. ACS Synth Biol 2022; 11:2417-2428. [PMID: 35729788 PMCID: PMC9295143 DOI: 10.1021/acssynbio.2c00109] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mathematical models are powerful tools in guiding the construction of synthetic biological circuits, given their capability of accurately capturing and predicting circuit dynamics. Recent innovations in RNA technology have enabled the development of a variety of new tools for regulating gene expression at both the transcription and translation levels. However, the effects of different regulation levels on the circuit dynamics remain largely unexplored. In this study, we focus on the type 1 incoherent feed-forward loop (I1-FFL) gene circuit with four different variations (TX, TL, HY-1, HY-2), to investigate how regulation at the transcription and translation levels affect the circuit dynamics. We develop a mechanistic model for each of the four circuits and deploy sensitivity analysis to investigate the circuits' dynamics in terms of pulse generation. Based on the analysis, we observe that the repression regulation mechanism dominates the characteristics of the pulse as compared to the activation regulation mechanism and find that the I1-FFL with transcription repression has a higher chance of generating a pulse meeting the desired criteria. The experimental results in Escherichia coli also confirm our findings from the computational analysis. We expect our findings to facilitate future experimental construction of gene circuits with insights on the selection of appropriate transcription and translation regulation tools.
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Affiliation(s)
- Jordan Ryan
- Cain
Department of Chemical Engineering, Louisiana
State University, Baton
Rouge, Louisiana 70803, United States
| | - Seongho Hong
- Department
of Life Sciences, Pohang University of Science
and Technology (POSTECH), Pohang, Gyeongbuk 37673, South Korea
| | - Mathias Foo
- School
of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Jongmin Kim
- Department
of Life Sciences, Pohang University of Science
and Technology (POSTECH), Pohang, Gyeongbuk 37673, South Korea
| | - Xun Tang
- Cain
Department of Chemical Engineering, Louisiana
State University, Baton
Rouge, Louisiana 70803, United States
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19
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A microfluidic optimal experimental design platform for forward design of cell-free genetic networks. Nat Commun 2022; 13:3626. [PMID: 35750678 PMCID: PMC9232554 DOI: 10.1038/s41467-022-31306-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 06/14/2022] [Indexed: 12/20/2022] Open
Abstract
Cell-free protein synthesis has been widely used as a “breadboard” for design of synthetic genetic networks. However, due to a severe lack of modularity, forward engineering of genetic networks remains challenging. Here, we demonstrate how a combination of optimal experimental design and microfluidics allows us to devise dynamic cell-free gene expression experiments providing maximum information content for subsequent non-linear model identification. Importantly, we reveal that applying this methodology to a library of genetic circuits, that share common elements, further increases the information content of the data resulting in higher accuracy of model parameters. To show modularity of model parameters, we design a pulse decoder and bistable switch, and predict their behaviour both qualitatively and quantitatively. Finally, we update the parameter database and indicate that network topology affects parameter estimation accuracy. Utilizing our methodology provides us with more accurate model parameters, a necessity for forward engineering of complex genetic networks. Characterization of cell-free genetic networks is inherently difficult. Here the authors use optimal experimental design and microfluidics to improve characterization, demonstrating modularity and predictability of parts in applied test cases.
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20
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Engineering Toehold-Mediated Switches for Native RNA Detection and Regulation in Bacteria. J Mol Biol 2022; 434:167689. [PMID: 35717997 DOI: 10.1016/j.jmb.2022.167689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 05/19/2022] [Accepted: 06/09/2022] [Indexed: 01/24/2023]
Abstract
RNA switches are versatile tools in synthetic biology for sensing and regulation applications. The discoveries of RNA-mediated translational and transcriptional control have facilitated the development of complexde novodesigns of RNA switches. Specifically, RNA toehold-mediated switches, in which binding to the toehold sensing domain controls the transition between switch states via strand displacement, have been extensively adapted for coupling systems responses to specifictrans-RNA inputs. This review highlights some of the challenges associated with applying these switches for native RNA detectionin vivo, including transferability between organisms. The applicability and design considerations of toehold-mediated switches are discussed by highlighting twelve recently developed switch designs. This review finishes with future perspectives to address current gaps in the field, particularly regarding the power of structural prediction algorithms for improved in vivo functionality of RNA switches.
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21
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Nguyen MTA, Pothoulakis G, Andersen ES. Synthetic Translational Regulation by Protein-Binding RNA Origami Scaffolds. ACS Synth Biol 2022; 11:1710-1718. [PMID: 35438978 PMCID: PMC9127956 DOI: 10.1021/acssynbio.1c00608] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rational design approaches for the regulation of gene expression are expanding the synthetic biology toolbox. However, only a few tools for regulating gene expression at the translational level have been developed. Here, we devise an approach for translational regulation using the MS2 and PP7 aptamer and coat-protein pairs in Escherichia coli. The aptamers are used as operators in transcription units that encode proteins fused to their cognate coat proteins, which leads to self-repression. RNA origami scaffolds that contain up to four aptamers serve as an alternate binder to activate translation. With this system, we demonstrate that the increase in expression of a reporter protein is dependent on both the concentration and number of aptamers on RNA origami scaffolds. We also demonstrate regulation of multiple proteins using a single MS2 coat protein fusion and apply this method to regulate the relative expression of enzymes of the branched pathway for deoxyviolacein biosynthesis.
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Affiliation(s)
| | | | - Ebbe S. Andersen
- Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark
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22
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Falgenhauer E, Mückl A, Schwarz-Schilling M, Simmel FC. Transcriptional Interference in Toehold Switch-Based RNA Circuits. ACS Synth Biol 2022; 11:1735-1745. [PMID: 35412304 DOI: 10.1021/acssynbio.1c00486] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Gene regulation based on regulatory RNA is an important mechanism in cells and is increasingly used for regulatory circuits in synthetic biology. Toehold switches are rationally designed post-transcriptional riboregulators placed in the 5' untranslated region of mRNA molecules. In the inactive state of a toehold switch, the ribosome-binding site is inaccessible to the ribosome. In the presence of a trigger RNA molecule, protein production is turned on. Using antisense RNA against trigger molecules (antitrigger RNA), gene expression can also be switched off again. We here study the utility of antisense transcription in this context, which enables a particularly compact circuit design. Our circuits utilize two inducible promoters that separately regulate trigger and antitrigger transcription, whereas their cognate toehold switch, regulating the expression of a reporter protein, is transcribed from a constitutive promoter. We explore various design options for the arrangement of the promoters and demonstrate that the resulting dynamic behavior is influenced by transcriptional interference (TI) effects depending on the promoter distance. Our experimental results are consistent with previous findings that enhanced local RNA polymerase concentrations due to active promoters in close proximity lead to an increase in transcriptional activity of the strongest promoter in the circuits. We observed that the range of this effect is larger when the participating promoters are stronger. Based on this insight, we combined two promoter arrangements for the realization of a genetic circuit comprised of two toehold switches, two triggers, and two antitriggers that function as a two-input two-output logic gate.
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Affiliation(s)
- Elisabeth Falgenhauer
- Physics Department - E14 and ZNN/WSI, TU Munich, Am Coulombwall 4a, 85748 Garching, Germany
| | - Andrea Mückl
- Physics Department - E14 and ZNN/WSI, TU Munich, Am Coulombwall 4a, 85748 Garching, Germany
| | | | - Friedrich C. Simmel
- Physics Department - E14 and ZNN/WSI, TU Munich, Am Coulombwall 4a, 85748 Garching, Germany
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23
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van der Linden AJ, Pieters PA, Bartelds MW, Nathalia BL, Yin P, Huck WTS, Kim J, de Greef TFA. DNA Input Classification by a Riboregulator-Based Cell-Free Perceptron. ACS Synth Biol 2022; 11:1510-1520. [PMID: 35381174 PMCID: PMC9016768 DOI: 10.1021/acssynbio.1c00596] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ability to recognize molecular patterns is essential for the continued survival of biological organisms, allowing them to sense and respond to their immediate environment. The design of synthetic gene-based classifiers has been explored previously; however, prior strategies have focused primarily on DNA strand-displacement reactions. Here, we present a synthetic in vitro transcription and translation (TXTL)-based perceptron consisting of a weighted sum operation (WSO) coupled to a downstream thresholding function. We demonstrate the application of toehold switch riboregulators to construct a TXTL-based WSO circuit that converts DNA inputs into a GFP output, the concentration of which correlates to the input pattern and the corresponding weights. We exploit the modular nature of the WSO circuit by changing the output protein to the Escherichia coli σ28-factor, facilitating the coupling of the WSO output to a downstream reporter network. The subsequent introduction of a σ28 inhibitor enabled thresholding of the WSO output such that the expression of the downstream reporter protein occurs only when the produced σ28 exceeds this threshold. In this manner, we demonstrate a genetically implemented perceptron capable of binary classification, i.e., the expression of a single output protein only when the desired minimum number of inputs is exceeded.
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Affiliation(s)
- Ardjan J. van der Linden
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Pascal A. Pieters
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Mart W. Bartelds
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Bryan L. Nathalia
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Peng Yin
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, United States
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Wilhelm T. S. Huck
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Jongmin Kim
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Republic of Korea
| | - Tom F. A. de Greef
- Laboratory of Chemical Biology and Institute for Complex Molecular Systems, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Computational Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
- Center for Living Technologies, Eindhoven-Wageningen-Utrecht Alliance, 3584 CB Utrecht, The Netherlands
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24
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Cellular Computational Logic Using Toehold Switches. Int J Mol Sci 2022; 23:ijms23084265. [PMID: 35457085 PMCID: PMC9033136 DOI: 10.3390/ijms23084265] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/09/2022] [Accepted: 04/10/2022] [Indexed: 11/16/2022] Open
Abstract
The development of computational logic that carries programmable and predictable features is one of the key requirements for next-generation synthetic biological devices. Despite considerable progress, the construction of synthetic biological arithmetic logic units presents numerous challenges. In this paper, utilizing the unique advantages of RNA molecules in building complex logic circuits in the cellular environment, we demonstrate the RNA-only bitwise logical operation of XOR gates and basic arithmetic operations, including a half adder, a half subtractor, and a Feynman gate, in Escherichia coli. Specifically, de-novo-designed riboregulators, known as toehold switches, were concatenated to enhance the functionality of an OR gate, and a previously utilized antisense RNA strategy was further optimized to construct orthogonal NIMPLY gates. These optimized synthetic logic gates were able to be seamlessly integrated to achieve final arithmetic operations on small molecule inputs in cells. Toehold-switch-based ribocomputing devices may provide a fundamental basis for synthetic RNA-based arithmetic logic units or higher-order systems in cells.
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25
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Dykstra PB, Kaplan M, Smolke CD. Engineering synthetic RNA devices for cell control. Nat Rev Genet 2022; 23:215-228. [PMID: 34983970 PMCID: PMC9554294 DOI: 10.1038/s41576-021-00436-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2021] [Indexed: 12/16/2022]
Abstract
The versatility of RNA in sensing and interacting with small molecules, proteins and other nucleic acids while encoding genetic instructions for protein translation makes it a powerful substrate for engineering biological systems. RNA devices integrate cellular information sensing, processing and actuation of specific signals into defined functions and have yielded programmable biological systems and novel therapeutics of increasing sophistication. However, challenges centred on expanding the range of analytes that can be sensed and adding new mechanisms of action have hindered the full realization of the field's promise. Here, we describe recent advances that address these limitations and point to a significant maturation of synthetic RNA-based devices.
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Affiliation(s)
- Peter B. Dykstra
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Matias Kaplan
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Christina D. Smolke
- Department of Bioengineering, Stanford University, Stanford, CA, USA.,Chan Zuckerberg Biohub, San Francisco, CA, USA.,
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26
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Schaffter SW, Strychalski EA. Cotranscriptionally encoded RNA strand displacement circuits. SCIENCE ADVANCES 2022; 8:eabl4354. [PMID: 35319994 PMCID: PMC8942360 DOI: 10.1126/sciadv.abl4354] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 02/01/2022] [Indexed: 05/21/2023]
Abstract
Engineered molecular circuits that process information in biological systems could address emerging human health and biomanufacturing needs. However, such circuits can be difficult to rationally design and scale. DNA-based strand displacement reactions have demonstrated the largest and most computationally powerful molecular circuits to date but are limited in biological systems due to the difficulty in genetically encoding components. Here, we develop scalable cotranscriptionally encoded RNA strand displacement (ctRSD) circuits that are rationally programmed via base pairing interactions. ctRSD circuits address the limitations of DNA-based strand displacement circuits by isothermally producing circuit components via transcription. We demonstrate circuit programmability in vitro by implementing logic and amplification elements, as well as multilayer cascades. Furthermore, we show that circuit kinetics are accurately predicted by a simple model of coupled transcription and strand displacement, enabling model-driven design. We envision ctRSD circuits will enable the rational design of powerful molecular circuits that operate in biological systems, including living cells.
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27
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Liu B, Cuba Samaniego C, Bennett M, Chappell J, Franco E. RNA Compensation: A Positive Feedback Insulation Strategy for RNA-Based Transcription Networks. ACS Synth Biol 2022; 11:1240-1250. [PMID: 35244392 DOI: 10.1021/acssynbio.1c00540] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The lack of signaling modularity of biomolecular systems poses major challenges toward engineering complex networks. Directional signaling between an upstream and a downstream circuit requires the presence of binding events, which result in the consumption of regulatory molecules and can compromise the operation of the upstream circuit. This issue has been previously addressed by introducing insulation strategies that include high-gain negative feedback and activation-deactivation reaction cycles. In this paper, we focus on RNA-based circuits and propose a new positive-feedback strategy to mitigate signal consumption that we propose occurs for each regulatory event due to irreversible binding of the RNA input to the RNA target. To mitigate this, an extra RNA input is added in tandem with transcription output to compensate the RNA consumption, leading to concentration robustness of the input RNA molecule regardless of the amount of downstream modules. We term this strategy RNA compensation, and it can be applied to systems that have a stringent input-output gain, such as Small Transcription Activating RNAs (STARs). Our theoretical analysis shows that RNA compensation not only eliminates the signaling consumption in individual STAR-based regulators, but also improves the composability of STAR cascades and the modularity of RNA bistable systems.
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Affiliation(s)
- Baiyang Liu
- Graduate Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, Texas 77005, United States
| | - Christian Cuba Samaniego
- Department of Mechanical and Aerospace Engineering, Bioengineering, and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
| | - Matthew Bennett
- Department of Biosciences, Rice University, Houston, Texas 77005, United States
- Department of Bioengineering, Rice University, Houston, Texas 77005, United States
| | - James Chappell
- Department of Biosciences, Rice University, Houston, Texas 77005, United States
- Department of Bioengineering, Rice University, Houston, Texas 77005, United States
| | - Elisa Franco
- Department of Mechanical and Aerospace Engineering, Bioengineering, and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
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28
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Tickman BI, Burbano DA, Chavali VP, Kiattisewee C, Fontana J, Khakimzhan A, Noireaux V, Zalatan JG, Carothers JM. Multi-layer CRISPRa/i circuits for dynamic genetic programs in cell-free and bacterial systems. Cell Syst 2022; 13:215-229.e8. [PMID: 34800362 DOI: 10.1016/j.cels.2021.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/24/2021] [Accepted: 10/26/2021] [Indexed: 11/29/2022]
Abstract
CRISPR-Cas transcriptional circuits hold great promise as platforms for engineering metabolic networks and information processing circuits. Historically, prokaryotic CRISPR control systems have been limited to CRISPRi. Creating approaches to integrate CRISPRa for transcriptional activation with existing CRISPRi-based systems would greatly expand CRISPR circuit design space. Here, we develop design principles for engineering prokaryotic CRISPRa/i genetic circuits with network topologies specified by guide RNAs. We demonstrate that multi-layer CRISPRa/i cascades and feedforward loops can operate through the regulated expression of guide RNAs in cell-free expression systems and E. coli. We show that CRISPRa/i circuits can program complex functions by designing type 1 incoherent feedforward loops acting as fold-change detectors and tunable pulse-generators. By investigating how component characteristics relate to network properties such as depth, width, and speed, this work establishes a framework for building scalable CRISPRa/i circuits as regulatory programs in cell-free expression systems and bacterial hosts. A record of this paper's transparent peer review process is included in the supplemental information.
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Affiliation(s)
- Benjamin I Tickman
- Molecular Engineering & Sciences Institute and Center for Synthetic Biology, University of Washington, Seattle, WA 98195, USA
| | - Diego Alba Burbano
- Molecular Engineering & Sciences Institute and Center for Synthetic Biology, University of Washington, Seattle, WA 98195, USA; Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Venkata P Chavali
- Molecular Engineering & Sciences Institute and Center for Synthetic Biology, University of Washington, Seattle, WA 98195, USA
| | - Cholpisit Kiattisewee
- Molecular Engineering & Sciences Institute and Center for Synthetic Biology, University of Washington, Seattle, WA 98195, USA
| | - Jason Fontana
- Molecular Engineering & Sciences Institute and Center for Synthetic Biology, University of Washington, Seattle, WA 98195, USA
| | - Aset Khakimzhan
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Vincent Noireaux
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jesse G Zalatan
- Molecular Engineering & Sciences Institute and Center for Synthetic Biology, University of Washington, Seattle, WA 98195, USA; Department of Chemistry, University of Washington, Seattle, WA 98195, USA.
| | - James M Carothers
- Molecular Engineering & Sciences Institute and Center for Synthetic Biology, University of Washington, Seattle, WA 98195, USA; Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA.
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29
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Yeom J, Park JS, Jeon YM, Song BS, Yoo SM. Synthetic fused sRNA for the simultaneous repression of multiple genes. Appl Microbiol Biotechnol 2022; 106:2517-2527. [PMID: 35291022 DOI: 10.1007/s00253-022-11867-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 03/03/2022] [Accepted: 03/05/2022] [Indexed: 11/02/2022]
Abstract
Efficient control over multiple gene expression still presents a major challenge. Synthetic sRNA enables targeted gene expression control in trans without directly modifying the chromosome, but its use to simultaneously target multiple genes can often cause cell growth defects because of the need for additional energy for transcription and lowering of their repression efficiency by limiting the amount of Hfq protein. To address these limitations, we present fusion sRNA (fsRNA) that simultaneously regulates the translation of multiple genes efficiently. It is constructed by linking the mRNA-binding modules for multiple targeted genes in one sRNA scaffold via one-pot generation using overlap extension PCR. The repression capacity of fsRNA was demonstrated by the construction of sRNAs to target four endogenous genes: caiF, hybG, ytfR and minD in Escherichia coli. Their cross-reactivity and the effect on cell growth were also investigated. As practical applications, we applied fsRNA to violacein- and protocatechuic acid-producing strains, resulting in increases of 13% violacein and 81% protocatechuic acid, respectively. The developed fsRNA-mediated multiple gene expression regulation system thus enables rapid and efficient development of optimised cell factories for valuable chemicals without cell growth defects and limiting cellular resources.Key points• Synthetic fusion sRNA (fsRNA)-based system was constructed for the repression of multiple target genes.• fsRNA repressed multiple genes by only expressing a single sRNA while minimising the cellular burden.• The application of fsRNA showed the increased production titers of violacein (13%) and protocatechuic acid (81%).
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Affiliation(s)
- Jinho Yeom
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Jong Seong Park
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Yong Min Jeon
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Beom Seop Song
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Seung Min Yoo
- School of Integrative Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea.
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30
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Refactoring transcription factors for metabolic engineering. Biotechnol Adv 2022; 57:107935. [PMID: 35271945 DOI: 10.1016/j.biotechadv.2022.107935] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 02/04/2022] [Accepted: 03/03/2022] [Indexed: 12/19/2022]
Abstract
Due to the ability to regulate target metabolic pathways globally and dynamically, metabolic regulation systems composed of transcription factors have been widely used in metabolic engineering and synthetic biology. This review introduced the categories, action principles, prediction strategies, and related databases of transcription factors. Then, the application of global transcription machinery engineering technology and the transcription factor-based biosensors and quorum sensing systems are overviewed. In addition, strategies for optimizing the transcriptional regulatory tools' performance by refactoring transcription factors are summarized. Finally, the current limitations and prospects of constructing various regulatory tools based on transcription factors are discussed. This review will provide theoretical guidance for the rational design and construction of transcription factor-based metabolic regulation systems.
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31
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Ozer I, Pitoc GA, Layzer JM, Moreno A, Olson LB, Layzer KD, Hucknall AM, Sullenger BA, Chilkoti A. PEG-Like Brush Polymer Conjugate of RNA Aptamer That Shows Reversible Anticoagulant Activity and Minimal Immune Response. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2107852. [PMID: 34994037 DOI: 10.1002/adma.202107852] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/28/2021] [Indexed: 06/14/2023]
Abstract
Ribonucleic acid (RNA) therapeutics are an emerging class of drugs. RNA aptamers are of significant therapeutic and clinical interest because their activity can be easily reversed in vivo-a useful feature that is difficult to achieve using other therapeutic modalities. Despite their therapeutic promise, RNA aptamers are limited by their poor blood circulation. The attachment of polyethylene glycol (PEG) to RNA aptamers addresses this limitation. However, an RNA aptamer-PEG conjugate that is a reversible anticoagulant fails in a clinical trial due to the reactivity of the conjugate with pre-existing PEG antibodies and has cast a pall over PEGylation of aptamers and other biologics, despite its long history of utility in drug delivery. Here, PEG antibody-reactivity of this RNA aptamer is eliminated by conjugating it to a next-generation PEG-like brush polymer-poly[(oligoethylene glycol) methyl ether methacrylate)] (POEGMA). The conjugate retained the drug's therapeutic action and the ability to be easily reversed. Importantly, this conjugate does not bind pre-existing PEG antibodies that are prevalent in humans and does not induce a humoral immune response against the polymer itself in mice. These findings suggest a path to rescuing the PEGylation of RNA therapeutics and vaccines from the deleterious side-effects of PEG.
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Affiliation(s)
- Imran Ozer
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - George A Pitoc
- Department of Surgery, Duke University Medical Center, Durham, NC, 27707, USA
| | - Juliana M Layzer
- Department of Surgery, Duke University Medical Center, Durham, NC, 27707, USA
- Duke Clinical and Translational Science Institute, Durham, NC, 27707, USA
| | - Angelo Moreno
- Department of Surgery, Duke University Medical Center, Durham, NC, 27707, USA
| | - Lyra B Olson
- Department of Surgery, Duke University Medical Center, Durham, NC, 27707, USA
| | - Kyle D Layzer
- Department of Surgery, Duke University Medical Center, Durham, NC, 27707, USA
| | - Angus M Hucknall
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Bruce A Sullenger
- Department of Surgery, Duke University Medical Center, Durham, NC, 27707, USA
| | - Ashutosh Chilkoti
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
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32
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Romantseva EF, Tack DS, Alperovich N, Ross D, Strychalski EA. Best Practices for DNA Template Preparation Toward Improved Reproducibility in Cell-Free Protein Production. Methods Mol Biol 2022; 2433:3-50. [PMID: 34985735 DOI: 10.1007/978-1-0716-1998-8_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Performance variability is a common challenge in cell-free protein production and hinders a wider adoption of these systems for both research and biomanufacturing. While the inherent stochasticity and complexity of biology likely contributes to variability, other systematic factors may also play a role, including the source and preparation of the cell extract, the composition of the supplemental reaction buffer, the facility at which experiments are conducted, and the human operator (Cole et al. ACS Synth Biol 8:2080-2091, 2019). Variability in protein production could also arise from differences in the DNA template-specifically the amount of functional DNA added to a cell-free reaction and the quality of the DNA preparation in terms of contaminants and strand breakage. Here, we present protocols and suggest best practices optimized for DNA template preparation and quantitation for cell-free systems toward reducing variability in cell-free protein production.
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Affiliation(s)
| | - Drew S Tack
- National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Nina Alperovich
- National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - David Ross
- National Institute of Standards and Technology, Gaithersburg, MD, USA
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33
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Zambrano RAI, Hernandez-Perez C, Takahashi MK. RNA Structure Prediction, Analysis, and Design: An Introduction to Web-Based Tools. Methods Mol Biol 2022; 2518:253-269. [PMID: 35666450 DOI: 10.1007/978-1-0716-2421-0_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Understanding RNA structure has become critical in the study of RNA in their roles as mediators of biological processes. To aid in these studies, computational algorithms that utilize thermodynamics have been developed to predict RNA secondary structure. Due to the importance of intermolecular interactions, the algorithms have been expanded to determine and predict RNA-RNA hybridization. This chapter discusses popular webservers with the tools for RNA secondary structure prediction, RNA-RNA hybridization, and design. We address key features that distinguish common-functioning programs and their purposes for the interests of the user. Ultimately, we hope this review elucidates web-based tools researchers may take advantage of in their investigations of RNA structure and function.
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Affiliation(s)
| | | | - Melissa K Takahashi
- Department of Biology, California State University Northridge, Northridge, CA, USA.
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34
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Liu B, Chappell J. Computational Design of Small Transcription Activating RNAs (STARs). Methods Mol Biol 2022; 2518:87-97. [PMID: 35666440 DOI: 10.1007/978-1-0716-2421-0_5] [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: 06/15/2023]
Abstract
A major goal of synthetic biology has been to develop libraries of versatile genetic regulators that enable the precise control of gene expression. In recent years, the creation of novel RNA design motifs has allowed for the bottom-up, computational design of large libraries of high-performing and orthogonal RNA regulator systems. One example of this is Small Transcription Activating RNAs (STARs), which function through the conditional formation of terminator hairpins to activate the transcription of targeted genes. STARs have found broad utility for creating synthetic gene circuits, engineering metabolic pathways, and creating new types of diagnostics. Here we describe the method to computationally design, build, and characterize STAR regulators.
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Affiliation(s)
- Baiyang Liu
- Graduate Program in Systems, Synthetic, and Physical Biology, Rice University, Houston, TX, USA
| | - James Chappell
- Department of BioSciences, Rice University, Houston, TX, USA.
- Department of Bioengineering, Rice University, Houston, TX, USA.
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35
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Greco FV, Irvine T, Grierson CS, Gorochowski TE. Design and Assembly of Multilevel Transcriptional and Translational Regulators for Stringent Control of Gene Expression. Methods Mol Biol 2022; 2518:99-110. [PMID: 35666441 DOI: 10.1007/978-1-0716-2421-0_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Precise control of gene expression is crucial when reprogramming the behavior of living cells. However, common inducible systems often lack the ability to stringently control gene expression due to the use of a single type of regulator that can be susceptible to unavoidable biomolecular fluctuations. In contrast, multilevel controllers (MLCs) employ several forms of regulation simultaneously to overcome this issue, ensuring a reduced basal expression while minimally affecting the maximum induced expression level that can be achieved. Here, we show how our publicly available genetic toolkit can be used to simplify the assembly of MLCs for the stringent control of gene expression. We demonstrate how new compatible parts can be designed and explain the rapid end-to-end assembly procedure.
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Affiliation(s)
- F Veronica Greco
- School of Biological Sciences, University of Bristol, Bristol, UK
| | - Thea Irvine
- School of Biological Sciences, University of Bristol, Bristol, UK
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36
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Simmons TR, Ellington AD, Contreras LM. RNP-Based Control Systems for Genetic Circuits in Synthetic Biology Beyond CRISPR. Methods Mol Biol 2022; 2518:1-31. [PMID: 35666436 DOI: 10.1007/978-1-0716-2421-0_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ribonucleoproteins (RNPs) are RNA-protein complexes utilized natively in both prokaryotes and eukaryotes to regulate essential processes within the cell. Over the past few years, many of these native systems have been adapted to provide control over custom genetic targets. Engineered RNP-based control systems allow for fine-tune regulation of desired targets, by providing customizable nucleotide-nucleotide interactions. However, as there have been several engineered RNP systems developed recently, identifying an optimal system for various bioprocesses is challenging. Here, we review the most successful engineered RNP systems and their applications to survey the current state of the field. Additionally, we provide selection criteria to provide users a streamlined method for identifying an RNP control system most useful to their own work. Lastly, we discuss future applications of RNP control systems and how they can be utilized to address the current grand challenges of the synthetic biology community.
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Affiliation(s)
- Trevor R Simmons
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Andrew D Ellington
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Lydia M Contreras
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA.
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37
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Scheifele LZ, Tsotakos N, Wolyniak MJ. Preprint articles as a tool for teaching data analysis and scientific communication. PLoS One 2021; 16:e0261622. [PMID: 34932610 PMCID: PMC8691640 DOI: 10.1371/journal.pone.0261622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 12/06/2021] [Indexed: 11/21/2022] Open
Abstract
The skill of analyzing and interpreting research data is central to the scientific process, yet it is one of the hardest skills for students to master. While instructors can coach students through the analysis of data that they have either generated themselves or obtained from published articles, the burgeoning availability of preprint articles provides a new potential pedagogical tool. We developed a new method in which students use a cognitive apprenticeship model to uncover how experts analyzed a paper and compare the professional’s cognitive approach to their own. Specifically, students first critique research data themselves and then identify changes between the preprint and final versions of the paper that were likely the results of peer review. From this activity, students reported diverse insights into the processes of data presentation, peer review, and scientific publishing. Analysis of preprint articles is therefore a valuable new tool to strengthen students’ information literacy and understanding of the process of science.
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Affiliation(s)
- Lisa Z. Scheifele
- Department of Biology, Loyola University Maryland, Baltimore, Maryland, United States of America
- * E-mail:
| | - Nikolaos Tsotakos
- School of Science, Engineering, and Technology, Penn State Harrisburg, Middletown, Pennsylvania, United States of America
| | - Michael J. Wolyniak
- Department of Biology, Hampden-Sydney College, Hampden-Sydney, Virginia, United States of America
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38
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Methods for the Development of Recombinant Microorganisms for the Production of Natural Products. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2021; 2396:1-17. [PMID: 34786671 DOI: 10.1007/978-1-0716-1822-6_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Metabolic engineering strives to develop microbial strains that are capable of producing a target chemical in a biological organism. There are still many challenges to overcome in order to achieve titers, yields, and productivities necessary for industrial production. The use of recombinant microorganisms to meet these needs is the next step for metabolic engineers. In this chapter, we aim to provide insight on both the applications of metabolic engineering for natural product biosynthesis as well as optimization methods.
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39
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Cai X, Wang Q, Fang Y, Yao D, Zhan Y, An B, Yan B, Cai J. Attenuator LRR - a regulatory tool for modulating gene expression in Gram-positive bacteria. Microb Biotechnol 2021; 14:2538-2551. [PMID: 33720523 PMCID: PMC8601186 DOI: 10.1111/1751-7915.13797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 02/24/2021] [Accepted: 02/24/2021] [Indexed: 11/28/2022] Open
Abstract
With the rapid development of synthetic biology in recent years, particular attention has been paid to RNA devices, especially riboswitches, because of their significant and diverse regulatory roles in prokaryotic and eukaryotic cells. Due to the limited performance and context-dependence of riboswitches, only a few of them (such as theophylline, tetracycline and ciprofloxacin riboswitches) have been utilized as regulatory tools in biotechnology. In the present study, we demonstrated that a ribosome-dependent ribo-regulator, LRR, discovered in our previous work, exhibits an attractive regulatory performance. Specifically, it offers a 60-fold change in expression in the presence of retapamulin and a low level of leaky expression of about 1-2% without antibiotics. Moreover, LRR can be combined with different promoters and performs well in Bacillus thuringiensis, B. cereus, B. amyloliquefaciens, and B. subtilis. Additionally, LRR also functions in the Gram-negative bacterium Escherichia coli. Furthermore, we demonstrate its ability to control melanin metabolism in B. thuringiensis BMB171. Our results show that LRR can be applied to regulate gene expression, construct genetic circuits and tune metabolic pathways, and has great potential for many applications in synthetic biology.
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Affiliation(s)
- Xia Cai
- Department of MicrobiologyCollege of Life SciencesNankai UniversityTianjin300071China
| | - Qian Wang
- Department of MicrobiologyCollege of Life SciencesNankai UniversityTianjin300071China
| | - Yu Fang
- Department of MicrobiologyCollege of Life SciencesNankai UniversityTianjin300071China
| | - Die Yao
- Department of MicrobiologyCollege of Life SciencesNankai UniversityTianjin300071China
| | - Yunda Zhan
- Department of MicrobiologyCollege of Life SciencesNankai UniversityTianjin300071China
| | - Baoju An
- Department of MicrobiologyCollege of Life SciencesNankai UniversityTianjin300071China
| | - Bing Yan
- Department of MicrobiologyCollege of Life SciencesNankai UniversityTianjin300071China
| | - Jun Cai
- Department of MicrobiologyCollege of Life SciencesNankai UniversityTianjin300071China
- Key Laboratory of Molecular Microbiology and TechnologyMinistry of EducationTianjin300071China
- Tianjin Key Laboratory of Microbial Functional GenomicsTianjin300071China
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40
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Lehr FX, Kuzembayeva A, Bailey ME, Kleindienst W, Kabisch J, Koeppl H. Functionalizing Cell-Free Systems with CRISPR-Associated Proteins: Application to RNA-Based Circuit Engineering. ACS Synth Biol 2021; 10:2138-2150. [PMID: 34383464 DOI: 10.1021/acssynbio.0c00386] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cell-free systems have become a compelling choice for the prototyping of synthetic circuits. Many robust protocols for preparing cell-free systems are now available along with toolboxes designed for a variety of applications. Thus far, the production of cell-free extracts has often been decoupled from the production of functionalized proteins. Here, we leveraged a recent protocol for producing an E. coli-based cell-free expression system with two CRISPR-associated proteins, Csy4 and dCas9, expressed prior to harvest. We found that pre-expression did not affect the resulting extract performance, and the final concentrations of the endonucleases matched the level required for synthetic circuit prototyping. We demonstrated the benefits and versatility of dCas9 and Csy4 through the use of RNA circuitry based on a combination of single guide RNAs, small transcriptional activator RNAs, and toehold switches. For instance, we show that Csy4 processing increased 4-fold the dynamic range of a previously published AND-logic gate. Additionally, blending the CRISPR-enhanced extracts enabled us to reduce leakage in a multiple inputs gate, and to extend the type of Boolean functions available for RNA-based circuits, such as NAND-logic. Finally, we reported the use of simultaneous transcriptional and translational reporters in our RNA-based circuits. In particular, the AND-gate mRNA and protein levels were able to be independently monitored in response to transcriptional and translational activators. We hope this work will facilitate the adoption of advanced processing tools for RNA-based circuit prototyping in a cell-free environment.
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Affiliation(s)
- François-Xavier Lehr
- Centre for Synthetic Biology, Technische Universität Darmstadt, Darmstadt 64287, Germany
- Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt 64283, Germany
| | - Alina Kuzembayeva
- Centre for Synthetic Biology, Technische Universität Darmstadt, Darmstadt 64287, Germany
- Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt 64283, Germany
| | - Megan E Bailey
- Centre for Synthetic Biology, Technische Universität Darmstadt, Darmstadt 64287, Germany
- Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt 64283, Germany
| | - Werner Kleindienst
- Centre for Synthetic Biology, Technische Universität Darmstadt, Darmstadt 64287, Germany
| | - Johannes Kabisch
- Centre for Synthetic Biology, Technische Universität Darmstadt, Darmstadt 64287, Germany
| | - Heinz Koeppl
- Centre for Synthetic Biology, Technische Universität Darmstadt, Darmstadt 64287, Germany
- Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt 64283, Germany
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41
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Design and Evaluation of Synthetic RNA-Based Incoherent Feed-Forward Loop Circuits. Biomolecules 2021; 11:biom11081182. [PMID: 34439849 PMCID: PMC8391864 DOI: 10.3390/biom11081182] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/31/2021] [Accepted: 08/06/2021] [Indexed: 11/16/2022] Open
Abstract
RNA-based regulators are promising tools for building synthetic biological systems that provide a powerful platform for achieving a complex regulation of transcription and translation. Recently, de novo-designed synthetic RNA regulators, such as the small transcriptional activating RNA (STAR), toehold switch (THS), and three-way junction (3WJ) repressor, have been utilized to construct RNA-based synthetic gene circuits in living cells. In this work, we utilized these regulators to construct type 1 incoherent feed-forward loop (IFFL) circuits in vivo and explored their dynamic behaviors. A combination of a STAR and 3WJ repressor was used to construct an RNA-only IFFL circuit. However, due to the fast kinetics of RNA–RNA interactions, there was no significant timescale difference between the direct activation and the indirect inhibition, that no pulse was observed in the experiments. These findings were confirmed with mechanistic modeling and simulation results for a wider range of conditions. To increase delay in the inhibition pathway, we introduced a protein synthesis process to the circuit and designed an RNA–protein hybrid IFFL circuit using THS and TetR protein. Simulation results indicated that pulse generation could be achieved with this RNA–protein hybrid model, and this was further verified with experimental realization in E. coli. Our findings demonstrate that while RNA-based regulators excel in speed as compared to protein-based regulators, the fast reaction kinetics of RNA-based regulators could also undermine the functionality of a circuit (e.g., lack of significant timescale difference). The agreement between experiments and simulations suggests that the mechanistic modeling can help debug issues and validate the hypothesis in designing a new circuit. Moreover, the applicability of the kinetic parameters extracted from the RNA-only circuit to the RNA–protein hybrid circuit also indicates the modularity of RNA-based regulators when used in a different context. We anticipate the findings of this work to guide the future design of gene circuits that rely heavily on the dynamics of RNA-based regulators, in terms of both modeling and experimental realization.
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42
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Bao SH, Jiang H, Zhu LY, Yao G, Han PG, Wan XK, Wang K, Song TY, Liu CJ, Wang S, Zhang ZY, Zhang DY, Meng E. A dynamic and multilocus metabolic regulation strategy using quorum-sensing-controlled bacterial small RNA. Cell Rep 2021; 36:109413. [PMID: 34289355 DOI: 10.1016/j.celrep.2021.109413] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 03/30/2021] [Accepted: 06/25/2021] [Indexed: 12/21/2022] Open
Abstract
Metabolic regulation strategies have been developed to redirect metabolic fluxes to production pathways. However, it is difficult to screen out target genes that, when repressed, improve yield without affecting cell growth. Here, we report a strategy using a quorum-sensing system to control small RNA transcription, allowing cell-density-dependent repression of target genes. This strategy is shown with convenient operation, dynamic repression, and availability for simultaneous regulation of multiple genes. The parameters Ai, Am, and RA (3-oxohexanoyl-homoserine lactone [AHL] concentrations at which half of the maximum repression and the maximum repression were reached and value of the maximum repression when AHL was added manually, respectively) are defined and introduced to characterize repression curves, and the variant LuxRI58N is identified as the most suitable tuning factor for shake flask culture. Moreover, it is shown that dynamic overexpression of the Hfq chaperone is the key to combinatorial repression without disruptions on cell growth. To show a broad applicability, the production titers of pinene, pentalenene, and psilocybin are improved by 365.3%, 79.5%, and 302.9%, respectively, by applying combinatorial dynamic repression.
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Affiliation(s)
- Shao-Heng Bao
- State Key Laboratory of NBC Protection for Civilian, Beijing, PRC
| | - Hui Jiang
- State Key Laboratory of NBC Protection for Civilian, Beijing, PRC
| | - Ling-Yun Zhu
- College of Arts and Sciences, National University of Defense Technology, Changsha, PRC
| | - Ge Yao
- State Key Laboratory of NBC Protection for Civilian, Beijing, PRC
| | - Peng-Gang Han
- State Key Laboratory of NBC Protection for Civilian, Beijing, PRC
| | - Xiu-Kun Wan
- State Key Laboratory of NBC Protection for Civilian, Beijing, PRC
| | - Kang Wang
- State Key Laboratory of NBC Protection for Civilian, Beijing, PRC
| | - Tian-Yu Song
- State Key Laboratory of NBC Protection for Civilian, Beijing, PRC
| | - Chang-Jun Liu
- Hunan Key Laboratory of Economic Crops, Genetic Improvement, and Integrated Utilization, School of Life Sciences, Hunan University of Science and Technology, Xiangtan, Hunan 411201, PRC
| | - Shan Wang
- Hunan Key Laboratory of Economic Crops, Genetic Improvement, and Integrated Utilization, School of Life Sciences, Hunan University of Science and Technology, Xiangtan, Hunan 411201, PRC
| | - Zhe-Yang Zhang
- Hunan Key Laboratory of Economic Crops, Genetic Improvement, and Integrated Utilization, School of Life Sciences, Hunan University of Science and Technology, Xiangtan, Hunan 411201, PRC
| | - Dong-Yi Zhang
- Hunan Key Laboratory of Economic Crops, Genetic Improvement, and Integrated Utilization, School of Life Sciences, Hunan University of Science and Technology, Xiangtan, Hunan 411201, PRC; College of Arts and Sciences, National University of Defense Technology, Changsha, PRC.
| | - Er Meng
- Hunan Key Laboratory of Economic Crops, Genetic Improvement, and Integrated Utilization, School of Life Sciences, Hunan University of Science and Technology, Xiangtan, Hunan 411201, PRC.
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43
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Guo L, Lu J, Gao C, Zhang L, Liu L, Chen X. Dynamic control of the distribution of carbon flux between cell growth and butyrate biosynthesis in Escherichia coli. Appl Microbiol Biotechnol 2021; 105:5173-5187. [PMID: 34115183 DOI: 10.1007/s00253-021-11385-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 05/05/2021] [Accepted: 06/02/2021] [Indexed: 12/14/2022]
Abstract
Microbial cell factories offer an economic and environmentally friendly method for the biosynthesis of acetyl-CoA-derived chemicals. However, the static control of carbon flux can cause direct and indirect competition for acetyl-CoA between cell growth and chemical biosynthesis, limiting the efficiency of microbial cell factories. Herein, recombinase-based genetic circuits were developed to achieve the optimal distribution of acetyl-CoA between cell growth and butyrate biosynthesis. First, three dynamic devices-a turn-on switch, a turn-off switch, and a recombinase-based inverter (RBI)-were constructed based on Bxb1 recombinase. Then, the turn-on switch was used to dynamically control the butyrate biosynthetic pathway, which directly improved the consumption of acetyl-CoA. Next, the turn-off switch was applied to dynamically control cell growth, which indirectly enhanced the supply of acetyl-CoA. Finally, an RBI was adopted for the dynamic dual control of the distribution of acetyl-CoA between cell growth and butyrate biosynthesis. The final butyrate production rate was increased to 34 g/L, with a productivity of 0.405 g/L/h. The strategy described herein will pave the way for the development of high-performance microbial cell factories for the production of other desirable chemicals. KEY POINTS: • Competition for acetyl-CoA between cell growth and synthesis limits productivity. • Recombinase-based genetic circuits were developed to dynamic control of acetyl-CoA. • Optimal distribution of acetyl-CoA between cell growth and synthesis was achieved.
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Affiliation(s)
- Liang Guo
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China
- International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Jiaxin Lu
- School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Cong Gao
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China
- International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Linpei Zhang
- School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Liming Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China
- International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Xiulai Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China.
- International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China.
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Abstract
Metabolic engineering reprograms cells to synthesize value-added products. In doing so, endogenous genes are altered and heterologous genes can be introduced to achieve the necessary enzymatic reactions. Dynamic regulation of metabolic flux is a powerful control scheme to alleviate and overcome the competing cellular objectives that arise from the introduction of these production pathways. This review explores dynamic regulation strategies that have demonstrated significant production benefits by targeting the metabolic node corresponding to a specific challenge. We summarize the stimulus-responsive control circuits employed in these strategies that determine the criterion for actuating a dynamic response and then examine the points of control that couple the stimulus-responsive circuit to a shift in metabolic flux.
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Affiliation(s)
- Cynthia Ni
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
| | - Christina V Dinh
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
| | - Kristala L J Prather
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA;
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45
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Glasscock CJ, Biggs BW, Lazar JT, Arnold JH, Burdette LA, Valdes A, Kang MK, Tullman-Ercek D, Tyo KEJ, Lucks JB. Dynamic Control of Gene Expression with Riboregulated Switchable Feedback Promoters. ACS Synth Biol 2021; 10:1199-1213. [PMID: 33834762 DOI: 10.1021/acssynbio.1c00015] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
One major challenge in synthetic biology is the deleterious impacts of cellular stress caused by expression of heterologous pathways, sensors, and circuits. Feedback control and dynamic regulation are broadly proposed strategies to mitigate this cellular stress by optimizing gene expression levels temporally and in response to biological cues. While a variety of approaches for feedback implementation exist, they are often complex and cannot be easily manipulated. Here, we report a strategy that uses RNA transcriptional regulators to integrate additional layers of control over the output of natural and engineered feedback responsive circuits. Called riboregulated switchable feedback promoters (rSFPs), these gene expression cassettes can be modularly activated using multiple mechanisms, from manual induction to autonomous quorum sensing, allowing control over the timing, magnitude, and autonomy of expression. We develop rSFPs in Escherichia coli to regulate multiple feedback networks and apply them to control the output of two metabolic pathways. We envision that rSFPs will become a valuable tool for flexible and dynamic control of gene expression in metabolic engineering, biological therapeutic production, and many other applications.
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Affiliation(s)
- Cameron J. Glasscock
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, 113 Ho Plaza, Ithaca, New York 14853, United States
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Bradley W. Biggs
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - John T. Lazar
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Jack H. Arnold
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Lisa A. Burdette
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United States
| | - Aliki Valdes
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Min-Kyoung Kang
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Danielle Tullman-Ercek
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Keith E. J. Tyo
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Julius B. Lucks
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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46
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Minuesa G, Alsina C, Garcia-Martin JA, Oliveros J, Dotu I. MoiRNAiFold: a novel tool for complex in silico RNA design. Nucleic Acids Res 2021; 49:4934-4943. [PMID: 33956139 PMCID: PMC8136780 DOI: 10.1093/nar/gkab331] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/09/2021] [Accepted: 04/21/2021] [Indexed: 12/23/2022] Open
Abstract
Novel tools for in silico design of RNA constructs such as riboregulators are required in order to reduce time and cost to production for the development of diagnostic and therapeutic advances. Here, we present MoiRNAiFold, a versatile and user-friendly tool for de novo synthetic RNA design. MoiRNAiFold is based on Constraint Programming and it includes novel variable types, heuristics and restart strategies for Large Neighborhood Search. Moreover, this software can handle dozens of design constraints and quality measures and improves features for RNA regulation control of gene expression, such as Translation Efficiency calculation. We demonstrate that MoiRNAiFold outperforms any previous software in benchmarking structural RNA puzzles from EteRNA. Importantly, with regard to biologically relevant RNA designs, we focus on RNA riboregulators, demonstrating that the designed RNA sequences are functional both in vitro and in vivo. Overall, we have generated a powerful tool for de novo complex RNA design that we make freely available as a web server (https://moiraibiodesign.com/design/).
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Affiliation(s)
- Gerard Minuesa
- Moirai Biodesign, c/ Baldiri Reixach s/n, Parc Científic de Barcelona (PCB), 08028 Barcelona, Spain
| | - Cristina Alsina
- Moirai Biodesign, c/ Baldiri Reixach s/n, Parc Científic de Barcelona (PCB), 08028 Barcelona, Spain
| | - Juan Antonio Garcia-Martin
- Bioinformatics for Genomics and Proteomics. National Centre for Biotechnology (CNB-CSIC). c/ Darwin 3, 28049 Madrid, Spain
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Universidad Carlos III de Madrid, 28911 Madrid, Spain
| | - Juan Carlos Oliveros
- Bioinformatics for Genomics and Proteomics. National Centre for Biotechnology (CNB-CSIC). c/ Darwin 3, 28049 Madrid, Spain
| | - Ivan Dotu
- Moirai Biodesign, c/ Baldiri Reixach s/n, Parc Científic de Barcelona (PCB), 08028 Barcelona, Spain
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47
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Recent advances in tuning the expression and regulation of genes for constructing microbial cell factories. Biotechnol Adv 2021; 50:107767. [PMID: 33974979 DOI: 10.1016/j.biotechadv.2021.107767] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 04/29/2021] [Accepted: 05/05/2021] [Indexed: 12/14/2022]
Abstract
To overcome environmental problems caused by the use of fossil resources, microbial cell factories have become a promising technique for the sustainable and eco-friendly development of valuable products from renewable resources. Constructing microbial cell factories with high titers, yields, and productivity requires a balance between growth and production; to this end, tuning gene expression and regulation is necessary to optimise and precisely control complicated metabolic fluxes. In this article, we review the current trends and advances in tuning gene expression and regulation and consider their engineering at each of the three stages of gene regulation: genomic, mRNA, and protein. In particular, the technological approaches utilised in a diverse range of genetic-engineering-based tools for the construction of microbial cell factories are reviewed and representative applications of these strategies are presented. Finally, the prospects for strategies and systems for tuning gene expression and regulation are discussed.
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48
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Villegas Kcam MC, Tsong AJ, Chappell J. Rational engineering of a modular bacterial CRISPR-Cas activation platform with expanded target range. Nucleic Acids Res 2021; 49:4793-4802. [PMID: 33823546 PMCID: PMC8096225 DOI: 10.1093/nar/gkab211] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 03/10/2021] [Accepted: 03/19/2021] [Indexed: 11/14/2022] Open
Abstract
CRISPR-Cas activator (CRISPRa) systems that selectively turn on transcription of a target gene are a potentially transformative technology for programming cellular function. While in eukaryotes versatile CRISPRa systems exist, in bacteria these systems suffer from a limited ability to activate different genes due to strict distance-dependent requirements of functional target binding sites, and require greater customization to optimize performance in different genetic and cellular contexts. To address this, we apply a rational protein engineering approach to create a new CRISPRa platform that is highly modular to allow for easy customization and has increased targeting flexibility through harnessing engineered Cas proteins. We first demonstrate that transcription activation domains can be recruited by CRISPR-Cas through noncovalent protein-protein interactions, which allows each component to be encoded on separate and easily interchangeable plasmid elements. We then exploit this modularity to rapidly screen a library of different activation domains, creating new systems with distinct regulatory properties. Furthermore, we demonstrate that by harnessing a library of circularly permuted Cas proteins, we can create CRISPRa systems that have different target binding site requirements, which together, allow for expanded target range.
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Affiliation(s)
| | - Annette J Tsong
- Department of BioSciences, Rice University, 6100 Main Street, MS 140, Houston, TX 77005, USA
| | - James Chappell
- Department of BioSciences, Rice University, 6100 Main Street, MS 140, Houston, TX 77005, USA
- Department of Bioengineering, Rice University, 6100 Main Street, MS 142, Houston, TX 77005, USA
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49
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Yu Q, Ren K, You M. Genetically encoded RNA nanodevices for cellular imaging and regulation. NANOSCALE 2021; 13:7988-8003. [PMID: 33885099 PMCID: PMC8122502 DOI: 10.1039/d0nr08301a] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Nucleic acid-based nanodevices have been widely used in the fields of biosensing and nanomedicine. Traditionally, the majority of these nanodevices were first constructed in vitro using synthetic DNA or RNA oligonucleotides and then delivered into cells. Nowadays, the emergence of genetically encoded RNA nanodevices has provided a promising alternative approach for intracellular analysis and regulation. These genetically encoded RNA-based nanodevices can be directly transcribed and continuously produced inside living cells. A variety of highly precise and programmable nanodevices have been constructed in this way during the last decade. In this review, we will summarize the recent advances in the design and function of these artificial genetically encoded RNA nanodevices. In particular, we will focus on their applications in regulating cellular gene expression, imaging, logic operation, structural biology, and optogenetics. We believe these versatile RNA-based nanodevices will be broadly used in the near future to probe and program cells and other biological systems.
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Affiliation(s)
- Qikun Yu
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA.
| | - Kewei Ren
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA.
| | - Mingxu You
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA.
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50
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Verosloff MS, Corcoran WK, Dolberg TB, Bushhouse DZ, Leonard JN, Lucks JB. RNA Sequence and Structure Determinants of Pol III Transcriptional Termination in Human Cells. J Mol Biol 2021; 433:166978. [PMID: 33811918 DOI: 10.1016/j.jmb.2021.166978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 01/25/2023]
Abstract
The precise mechanism of transcription termination of the eukaryotic RNA polymerase III (Pol III) has been a subject of considerable debate. Although previous studies have clearly shown that multiple uracils at the end of RNA transcripts are required for Pol III termination, the effects of upstream RNA secondary structure in the nascent transcript on transcriptional termination is still unclear. To address this, we developed an in cellulo Pol III transcription termination assay using the recently developed Tornado-Corn RNA aptamer system to create a Pol III-transcribed RNA that produces a detectable fluorescent signal when transcribed in human cells. To study the effects of RNA sequence and structure on Pol III termination, we systematically varied the sequence context upstream of the aptamer and identified sequence characteristics that enhance or diminish termination. For transcription from Pol III type 3 promoters, we found that only poly-U tracts longer than the average length found in the human genome efficiently terminate Pol III transcription without RNA secondary structure elements. We observed that RNA secondary structure elements placed in proximity to shorter poly-U tracts induced termination, and RNA secondary structure by itself was not sufficient to induce termination. For Pol III type 2 promoters, we found that the shorter poly-U tract lengths of 4 uracils were sufficient to induce termination. These findings demonstrate a key role for sequence and structural elements within Pol III-transcribed nascent RNA for efficient transcription termination, and demonstrate a generalizable assay for characterizing Pol III transcription in human cells.
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Affiliation(s)
- Matthew S Verosloff
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, 2204 Tech Drive, Evanston, IL 60208, USA; Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - William K Corcoran
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, 2204 Tech Drive, Evanston, IL 60208, USA; Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - Taylor B Dolberg
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA; Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - David Z Bushhouse
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, 2204 Tech Drive, Evanston, IL 60208, USA; Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - Joshua N Leonard
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA; Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA.
| | - Julius B Lucks
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA; Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA.
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