1
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Joshi SHN, Jenkins C, Ulaeto D, Gorochowski TE. Accelerating Genetic Sensor Development, Scale-up, and Deployment Using Synthetic Biology. BIODESIGN RESEARCH 2024; 6:0037. [PMID: 38919711 PMCID: PMC11197468 DOI: 10.34133/bdr.0037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 04/23/2024] [Indexed: 06/27/2024] Open
Abstract
Living cells are exquisitely tuned to sense and respond to changes in their environment. Repurposing these systems to create engineered biosensors has seen growing interest in the field of synthetic biology and provides a foundation for many innovative applications spanning environmental monitoring to improved biobased production. In this review, we present a detailed overview of currently available biosensors and the methods that have supported their development, scale-up, and deployment. We focus on genetic sensors in living cells whose outputs affect gene expression. We find that emerging high-throughput experimental assays and evolutionary approaches combined with advanced bioinformatics and machine learning are establishing pipelines to produce genetic sensors for virtually any small molecule, protein, or nucleic acid. However, more complex sensing tasks based on classifying compositions of many stimuli and the reliable deployment of these systems into real-world settings remain challenges. We suggest that recent advances in our ability to precisely modify nonmodel organisms and the integration of proven control engineering principles (e.g., feedback) into the broader design of genetic sensing systems will be necessary to overcome these hurdles and realize the immense potential of the field.
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Affiliation(s)
| | - Christopher Jenkins
- CBR Division, Defence Science and Technology Laboratory, Porton Down, Wiltshire SP4 0JQ, UK
| | - David Ulaeto
- CBR Division, Defence Science and Technology Laboratory, Porton Down, Wiltshire SP4 0JQ, UK
| | - Thomas E. Gorochowski
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
- BrisEngBio,
School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
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2
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Graham AJ, Partipilo G, Dundas CM, Miniel Mahfoud IE, Halwachs KN, Holwerda AJ, Simmons TR, FitzSimons TM, Coleman SM, Rinehart R, Chiu D, Tyndall AE, Sajbel KC, Rosales AM, Keitz BK. Transcriptional regulation of living materials via extracellular electron transfer. Nat Chem Biol 2024:10.1038/s41589-024-01628-y. [PMID: 38783133 DOI: 10.1038/s41589-024-01628-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 04/19/2024] [Indexed: 05/25/2024]
Abstract
Engineered living materials combine the advantages of biological and synthetic systems by leveraging genetic and metabolic programming to control material-wide properties. Here, we demonstrate that extracellular electron transfer (EET), a microbial respiration process, can serve as a tunable bridge between live cell metabolism and synthetic material properties. In this system, EET flux from Shewanella oneidensis to a copper catalyst controls hydrogel cross-linking via two distinct chemistries to form living synthetic polymer networks. We first demonstrate that synthetic biology-inspired design rules derived from fluorescence parameterization can be applied toward EET-based regulation of polymer network mechanics. We then program transcriptional Boolean logic gates to govern EET gene expression, which enables design of computational polymer networks that mechanically respond to combinations of molecular inputs. Finally, we control fibroblast morphology using EET as a bridge for programmed material properties. Our results demonstrate how rational genetic circuit design can emulate physiological behavior in engineered living materials.
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Affiliation(s)
- Austin J Graham
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Gina Partipilo
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Christopher M Dundas
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Ismar E Miniel Mahfoud
- Interdisciplinary Life Sciences Graduate Program, University of Texas at Austin, Austin, TX, USA
| | - Kathleen N Halwachs
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Alexis J Holwerda
- Interdisciplinary Life Sciences Graduate Program, University of Texas at Austin, Austin, TX, USA
| | - Trevor R Simmons
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Thomas M FitzSimons
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Sarah M Coleman
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Rebecca Rinehart
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Darian Chiu
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Avery E Tyndall
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, USA
| | - Kenneth C Sajbel
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Adrianne M Rosales
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Benjamin K Keitz
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, USA.
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3
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Chan CTY, Kennedy V, Kinshuk S. A domain swapping strategy to create modular transcriptional regulators for novel topology in genetic network. Biotechnol Adv 2024; 72:108345. [PMID: 38513775 PMCID: PMC11135624 DOI: 10.1016/j.biotechadv.2024.108345] [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: 11/03/2023] [Revised: 02/23/2024] [Accepted: 03/18/2024] [Indexed: 03/23/2024]
Abstract
Transcriptional regulators generate connections between biological signals and genetic outputs. They are used robustly for sensing input signals in building genetic circuits. However, each regulator can only generate a fixed connection, which generates constraints in linking multiple signals for more complex processes. Recent studies discovered that a domain swapping strategy can be applied to various regulator families to create modular regulators for new signal-output connections, significantly broadening possibilities in circuit design. Here we review the development of this emerging strategy, the use of resulting modular regulators for creating novel genetic response behaviors, and current limitations and solutions for further advancing the design of modular regulators.
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Affiliation(s)
- Clement T Y Chan
- Department of Biomedical Engineering, University of North Texas, TX 76207, USA; BioDiscovery Institute, University of North Texas, TX 76207, USA.
| | - Vincenzo Kennedy
- Department of Biomedical Engineering, University of North Texas, TX 76207, USA
| | - Sahaj Kinshuk
- Department of Biomedical Engineering, University of North Texas, TX 76207, USA
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4
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Huang BD, Kim D, Yu Y, Wilson CJ. Engineering intelligent chassis cells via recombinase-based MEMORY circuits. Nat Commun 2024; 15:2418. [PMID: 38499601 PMCID: PMC10948884 DOI: 10.1038/s41467-024-46755-1] [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: 10/16/2023] [Accepted: 03/08/2024] [Indexed: 03/20/2024] Open
Abstract
Synthetic biologists seek to engineer intelligent living systems capable of decision-making, communication, and memory. Separate technologies exist for each tenet of intelligence; however, the unification of all three properties in a living system has not been achieved. Here, we engineer completely intelligent Escherichia coli strains that harbor six orthogonal and inducible genome-integrated recombinases, forming Molecularly Encoded Memory via an Orthogonal Recombinase arraY (MEMORY). MEMORY chassis cells facilitate intelligence via the discrete multi-input regulation of recombinase functions enabling inheritable DNA inversions, deletions, and genomic insertions. MEMORY cells can achieve programmable and permanent gain (or loss) of functions extrachromosomally or from a specific genomic locus, without the loss or modification of the MEMORY platform - enabling the sequential programming and reprogramming of DNA circuits within the cell. We demonstrate all three tenets of intelligence via a probiotic (Nissle 1917) MEMORY strain capable of information exchange with the gastrointestinal commensal Bacteroides thetaiotaomicron.
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Affiliation(s)
- Brian D Huang
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, GA, 30332-0100, Georgia
| | - Dowan Kim
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, GA, 30332-0100, Georgia
| | - Yongjoon Yu
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, GA, 30332-0100, Georgia
| | - Corey J Wilson
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, GA, 30332-0100, Georgia.
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5
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Buson F, Gao Y, Wang B. Genetic Parts and Enabling Tools for Biocircuit Design. ACS Synth Biol 2024; 13:697-713. [PMID: 38427821 DOI: 10.1021/acssynbio.3c00691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2024]
Abstract
Synthetic biology aims to engineer biological systems for customized tasks through the bottom-up assembly of fundamental building blocks, which requires high-quality libraries of reliable, modular, and standardized genetic parts. To establish sets of parts that work well together, synthetic biologists created standardized part libraries in which every component is analyzed in the same metrics and context. Here we present a state-of-the-art review of the currently available part libraries for designing biocircuits and their gene expression regulation paradigms at transcriptional, translational, and post-translational levels in Escherichia coli. We discuss the necessary facets to integrate these parts into complex devices and systems along with the current efforts to catalogue and standardize measurement data. To better display the range of available parts and to facilitate part selection in synthetic biology workflows, we established biopartsDB, a curated database of well-characterized and useful genetic part and device libraries with detailed quantitative data validated by the published literature.
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Affiliation(s)
- Felipe Buson
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310058, China
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, U.K
| | - Yuanli Gao
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310058, China
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, U.K
| | - Baojun Wang
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310058, China
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6
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Gao Y, Zhou Y, Ji X, Graham AJ, Dundas CM, Miniel Mahfoud IE, Tibbett BM, Tan B, Partipilo G, Dodabalapur A, Rivnay J, Keitz BK. A hybrid transistor with transcriptionally controlled computation and plasticity. Nat Commun 2024; 15:1598. [PMID: 38383505 PMCID: PMC10881478 DOI: 10.1038/s41467-024-45759-1] [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: 09/20/2023] [Accepted: 02/02/2024] [Indexed: 02/23/2024] Open
Abstract
Organic electrochemical transistors (OECTs) are ideal devices for translating biological signals into electrical readouts and have applications in bioelectronics, biosensing, and neuromorphic computing. Despite their potential, developing programmable and modular methods for living systems to interface with OECTs has proven challenging. Here we describe hybrid OECTs containing the model electroactive bacterium Shewanella oneidensis that enable the transduction of biological computations to electrical responses. Specifically, we fabricated planar p-type OECTs and demonstrated that channel de-doping is driven by extracellular electron transfer (EET) from S. oneidensis. Leveraging this mechanistic understanding and our ability to control EET flux via transcriptional regulation, we used plasmid-based Boolean logic gates to translate biological computation into current changes within the OECT. Finally, we demonstrated EET-driven changes to OECT synaptic plasticity. This work enables fundamental EET studies and OECT-based biosensing and biocomputing systems with genetically controllable and modular design elements.
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Affiliation(s)
- Yang Gao
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
| | - Yuchen Zhou
- Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, TX, 78712, USA
- Microelectronics Research Center, University of Texas at Austin, Austin, TX, 78758, USA
| | - Xudong Ji
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
- Simpson Querrey Institute, Northwestern University, Chicago, IL, 60611, USA
| | - Austin J Graham
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Christopher M Dundas
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Ismar E Miniel Mahfoud
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
| | - Bailey M Tibbett
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
| | - Benjamin Tan
- Microelectronics Research Center, University of Texas at Austin, Austin, TX, 78758, USA
- Department of Chemistry, University of Texas at Austin, Austin, TX, 78712, USA
| | - Gina Partipilo
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
| | - Ananth Dodabalapur
- Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, TX, 78712, USA
- Microelectronics Research Center, University of Texas at Austin, Austin, TX, 78758, USA
| | - Jonathan Rivnay
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
- Simpson Querrey Institute, Northwestern University, Chicago, IL, 60611, USA
| | - Benjamin K Keitz
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA.
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7
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Tan Y, Liang J, Lai M, Wan S, Luo X, Li F. Advances in synthetic biology toolboxes paving the way for mechanistic understanding and strain engineering of gut commensal Bacteroides spp. and Clostridium spp. Biotechnol Adv 2023; 69:108272. [PMID: 37844770 DOI: 10.1016/j.biotechadv.2023.108272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 10/10/2023] [Accepted: 10/13/2023] [Indexed: 10/18/2023]
Abstract
The gut microbiota plays a significant role in influencing human immunity, metabolism, development, and behavior by producing a wide range of metabolites. While there is accumulating data on several microbiota-derived small molecules that contribute to host health and disease, our knowledge regarding the molecular mechanisms underlying metabolite-mediated microbe-host interactions remains limited. This is primarily due to the lack of efficient genetic tools for most commensal bacteria, especially those belonging to the dominant phyla Bacteroides spp. and Clostridium spp., which hinders the application of synthetic biology to these gut commensal bacteria. In this review, we provide an overview of recent advances in synthetic biology tools developed for the two dominant genera, as well as their applications in deciphering the mechanisms of microbe-host interactions mediated by microbiota-derived small molecules. We also discuss the potential biomedical applications of engineering commensal bacteria using these toolboxes. Finally, we share our perspective on the future development of synthetic biology tools for a better understanding of small molecule-mediated microbe-host interactions and their engineering for biomedical purposes.
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Affiliation(s)
- Yang Tan
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China; Shandong Energy Institute, Qingdao 266101, China; Qingdao New Energy Shandong Laboratory, Qingdao 266101, China.
| | - Jing Liang
- Center for Synthetic Biochemistry, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Mingchi Lai
- College of Life Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Sai Wan
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China; Shandong Energy Institute, Qingdao 266101, China; Qingdao New Energy Shandong Laboratory, Qingdao 266101, China
| | - Xiaozhou Luo
- Center for Synthetic Biochemistry, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Fuli Li
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China; Shandong Energy Institute, Qingdao 266101, China; Qingdao New Energy Shandong Laboratory, Qingdao 266101, China.
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8
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Short AE, Kim D, Milner PT, Wilson CJ. Next generation synthetic memory via intercepting recombinase function. Nat Commun 2023; 14:5255. [PMID: 37644045 PMCID: PMC10465543 DOI: 10.1038/s41467-023-41043-w] [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: 04/19/2023] [Accepted: 08/22/2023] [Indexed: 08/31/2023] Open
Abstract
Here we present a technology to facilitate synthetic memory in a living system via repurposing Transcriptional Programming (i.e., our decision-making technology) parts, to regulate (intercept) recombinase function post-translation. We show that interception synthetic memory can facilitate programmable loss-of-function via site-specific deletion, programmable gain-of-function by way of site-specific inversion, and synthetic memory operations with nested Boolean logical operations. We can expand interception synthetic memory capacity more than 5-fold for a single recombinase, with reconfiguration specificity for multiple sites in parallel. Interception synthetic memory is ~10-times faster than previous generations of recombinase-based memory. We posit that the faster recombination speed of our next-generation memory technology is due to the post-translational regulation of recombinase function. This iteration of synthetic memory is complementary to decision-making via Transcriptional Programming - thus can be used to develop intelligent synthetic biological systems for myriad applications.
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Affiliation(s)
- Andrew E Short
- Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, Atlanta, GA, USA
| | - Dowan Kim
- Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, Atlanta, GA, USA
| | - Prasaad T Milner
- Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, Atlanta, GA, USA
| | - Corey J Wilson
- Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, Atlanta, GA, USA.
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9
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Gao Y, Zhou Y, Ji X, Graham AJ, Dundas CM, Mahfoud IEM, Tibbett BM, Tan B, Partipilo G, Dodabalapur A, Rivnay J, Keitz BK. A Hybrid Transistor with Transcriptionally Controlled Computation and Plasticity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.16.553547. [PMID: 37645977 PMCID: PMC10462107 DOI: 10.1101/2023.08.16.553547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Organic electrochemical transistors (OECTs) are ideal devices for translating biological signals into electrical readouts and have applications in bioelectronics, biosensing, and neuromorphic computing. Despite their potential, developing programmable and modular methods for living systems to interface with OECTs has proven challenging. Here we describe hybrid OECTs containing the model electroactive bacterium Shewanella oneidensis that enable the transduction of biological computations to electrical responses. Specifically, we fabricated planar p-type OECTs and demonstrated that channel de-doping is driven by extracellular electron transfer (EET) from S. oneidensis. Leveraging this mechanistic understanding and our ability to control EET flux via transcriptional regulation, we used plasmid-based Boolean logic gates to translate biological computation into current changes within the OECT. Finally, we demonstrated EET-driven changes to OECT synaptic plasticity. This work enables fundamental EET studies and OECT-based biosensing and biocomputing systems with genetically controllable and modular design elements.
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Affiliation(s)
- Yang Gao
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
| | - Yuchen Zhou
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
- Microelectronics Research Center, The University of Texas at Austin, Austin, TX, 78758, USA
| | - Xudong Ji
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
- Simpson Querrey Institute, Northwestern University, Chicago, IL, 60611, USA
| | - Austin J. Graham
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Christopher M. Dundas
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Ismar E. Miniel Mahfoud
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
| | - Bailey M. Tibbett
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
| | - Benjamin Tan
- Microelectronics Research Center, The University of Texas at Austin, Austin, TX, 78758, USA
- Department of Chemistry, University of Texas at Austin, Austin, TX, 78712, USA
| | - Gina Partipilo
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
| | - Ananth Dodabalapur
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
- Microelectronics Research Center, The University of Texas at Austin, Austin, TX, 78758, USA
| | - Jonathan Rivnay
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
- Simpson Querrey Institute, Northwestern University, Chicago, IL, 60611, USA
| | - Benjamin K. Keitz
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
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10
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Hersey AN, Kay VE, Lee S, Realff MJ, Wilson CJ. Engineering allosteric transcription factors guided by the LacI topology. Cell Syst 2023; 14:645-655. [PMID: 37591203 DOI: 10.1016/j.cels.2023.04.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 02/26/2023] [Accepted: 04/26/2023] [Indexed: 08/19/2023]
Abstract
Allosteric transcription factors (aTFs) are used in a myriad of processes throughout biology and biotechnology. aTFs have served as the workhorses for developments in synthetic biology, fundamental research, and protein manufacturing. One of the most utilized TFs is the lactose repressor (LacI). In addition to being an exceptional tool for gene regulation, LacI has also served as an outstanding model system for understanding allosteric communication. In this perspective, we will use the LacI TF as the principal exemplar for engineering alternate functions related to allostery-i.e., alternate protein DNA interactions, alternate protein-ligand interactions, and alternate phenotypic mechanisms. In addition, we will summarize the design rules and heuristics for each design goal and demonstrate how the resulting design rules and heuristics can be extrapolated to engineer other aTFs with a similar topology-i.e., from the broader LacI/GalR family of TFs.
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Affiliation(s)
- Ashley N Hersey
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, Atlanta, GA, USA
| | - Valerie E Kay
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, Atlanta, GA, USA
| | - Sumin Lee
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, Atlanta, GA, USA
| | - Matthew J Realff
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, Atlanta, GA, USA
| | - Corey J Wilson
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, Atlanta, GA, USA.
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11
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Alba Burbano D, Cardiff RAL, Tickman BI, Kiattisewee C, Maranas CJ, Zalatan JG, Carothers JM. Engineering activatable promoters for scalable and multi-input CRISPRa/i circuits. Proc Natl Acad Sci U S A 2023; 120:e2220358120. [PMID: 37463216 PMCID: PMC10374173 DOI: 10.1073/pnas.2220358120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 06/13/2023] [Indexed: 07/20/2023] Open
Abstract
Dynamic, multi-input gene regulatory networks (GRNs) are ubiquitous in nature. Multilayer CRISPR-based genetic circuits hold great promise for building GRNs akin to those found in naturally occurring biological systems. We develop an approach for creating high-performing activatable promoters that can be assembled into deep, wide, and multi-input CRISPR-activation and -interference (CRISPRa/i) GRNs. By integrating sequence-based design and in vivo screening, we engineer activatable promoters that achieve up to 1,000-fold dynamic range in an Escherichia coli-based cell-free system. These components enable CRISPRa GRNs that are six layers deep and four branches wide. We show the generalizability of the promoter engineering workflow by improving the dynamic range of the light-dependent EL222 optogenetic system from 6-fold to 34-fold. Additionally, high dynamic range promoters enable CRISPRa systems mediated by small molecules and protein-protein interactions. We apply these tools to build input-responsive CRISPRa/i GRNs, including feedback loops, logic gates, multilayer cascades, and dynamic pulse modulators. Our work provides a generalizable approach for the design of high dynamic range activatable promoters and enables classes of gene regulatory functions in cell-free systems.
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Affiliation(s)
- Diego Alba Burbano
- Department of Chemical Engineering, University of Washington, Seattle, WA98195
- Center for Synthetic Biology, University of Washington, Seattle, WA98195
| | - Ryan A. L. Cardiff
- Center for Synthetic Biology, University of Washington, Seattle, WA98195
- Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA98195
| | - Benjamin I. Tickman
- Center for Synthetic Biology, University of Washington, Seattle, WA98195
- Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA98195
| | - Cholpisit Kiattisewee
- Center for Synthetic Biology, University of Washington, Seattle, WA98195
- Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA98195
| | - Cassandra J. Maranas
- Center for Synthetic Biology, University of Washington, Seattle, WA98195
- Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA98195
| | - Jesse G. Zalatan
- Center for Synthetic Biology, University of Washington, Seattle, WA98195
- Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA98195
- Department of Chemistry, University of Washington, Seattle, WA98195
| | - James M. Carothers
- Department of Chemical Engineering, University of Washington, Seattle, WA98195
- Center for Synthetic Biology, University of Washington, Seattle, WA98195
- Molecular Engineering & Sciences Institute, University of Washington, Seattle, WA98195
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12
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Milner PT, Zhang Z, Herde ZD, Vedire NR, Zhang F, Realff MJ, Wilson CJ. Performance Prediction of Fundamental Transcriptional Programs. ACS Synth Biol 2023; 12:1094-1108. [PMID: 36935615 PMCID: PMC10127286 DOI: 10.1021/acssynbio.2c00593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2023]
Abstract
Transcriptional programming leverages systems of engineered transcription factors to impart decision-making (e.g., Boolean logic) in chassis cells. The number of components used to construct said decision-making systems is rapidly increasing, making an exhaustive experimental evaluation of iterations of biological circuits impractical. Accordingly, we posited that a predictive tool is needed to guide and accelerate the design of transcriptional programs. The work described here involves the development and experimental characterization of a large collection of network-capable single-INPUT logical operations─i.e., engineered BUFFER (repressor) and engineered NOT (antirepressor) logical operations. Using this single-INPUT data and developed metrology, we were able to model and predict the performances of all fundamental two-INPUT compressed logical operations (i.e., compressed AND gates and compressed NOR gates). In addition, we were able to model and predict the performance of compressed mixed phenotype logical operations (A NIMPLY B gates and complementary B NIMPLY A gates). These results demonstrate that single-INPUT data is sufficient to accurately predict both the qualitative and quantitative performance of a complex circuit. Accordingly, this work has set the stage for the predictive design of transcriptional programs of greater complexity.
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Affiliation(s)
- Prasaad T Milner
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-2000, United States
| | - Ziqiao Zhang
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-2000, United States
| | - Zachary D Herde
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-2000, United States
| | - Namratha R Vedire
- School of Computer Science, Georgia Institute of Technology, Atlanta, Georgia 30332-2000, United States
| | - Fumin Zhang
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-2000, United States
| | - Matthew J Realff
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-2000, United States
| | - Corey J Wilson
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-2000, United States
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13
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Huang Y, Lin X, Yu S, Chen R, Chen W. Intestinal Engineered Probiotics as Living Therapeutics: Chassis Selection, Colonization Enhancement, Gene Circuit Design, and Biocontainment. ACS Synth Biol 2022; 11:3134-3153. [PMID: 36094344 DOI: 10.1021/acssynbio.2c00314] [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: 01/24/2023]
Abstract
Intestinal probiotics are often used for the in situ treatment of diseases, such as metabolic disorders, tumors, and chronic inflammatory infections. Recently, there has been an increased emphasis on intelligent, customized treatments with a focus on long-term efficacy; however, traditional probiotic therapy has not kept up with this trend. The use of synthetic biology to construct gut-engineered probiotics as live therapeutics is a promising avenue in the treatment of specific diseases, such as phenylketonuria and inflammatory bowel disease. These studies generally involve a series of fundamental design issues: choosing an engineered chassis, improving the colonization ability of engineered probiotics, designing functional gene circuits, and ensuring the safety of engineered probiotics. In this review, we summarize the relevant past research, the progress of current research, and discuss the key issues that restrict the widespread application of intestinal engineered probiotic living therapeutics.
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Affiliation(s)
- Yan Huang
- Team SZU-China at iGEM 2021, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
| | - Xiaojun Lin
- Team SZU-China at iGEM 2021, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
| | - Siyang Yu
- Team SZU-China at iGEM 2021, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
| | - Ruiyue Chen
- Team SZU-China at iGEM 2021, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Weizhao Chen
- Team SZU-China at iGEM 2021, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China.,Shenzhen Key Laboratory for Microbial Gene Engineering, Shenzhen University, Shenzhen 518060, China
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14
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Moschner C, Wedd C, Bakshi S. The context matrix: Navigating biological complexity for advanced biodesign. Front Bioeng Biotechnol 2022; 10:954707. [PMID: 36082163 PMCID: PMC9445834 DOI: 10.3389/fbioe.2022.954707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 06/29/2022] [Indexed: 12/05/2022] Open
Abstract
Synthetic biology offers many solutions in healthcare, production, sensing and agriculture. However, the ability to rationally engineer synthetic biosystems with predictable and robust functionality remains a challenge. A major reason is the complex interplay between the synthetic genetic construct, its host, and the environment. Each of these contexts contains a number of input factors which together can create unpredictable behaviours in the engineered biosystem. It has become apparent that for the accurate assessment of these contextual effects a more holistic approach to design and characterisation is required. In this perspective article, we present the context matrix, a conceptual framework to categorise and explore these contexts and their net effect on the designed synthetic biosystem. We propose the use and community-development of the context matrix as an aid for experimental design that simplifies navigation through the complex design space in synthetic biology.
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15
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Abstract
Bacteroides species are prominent members of the human gut microbiota. The prevalence and stability of Bacteroides in humans make them ideal candidates to engineer as programmable living therapeutics. Here we report a biotic decision-making technology in a community of Bacteroides (consortium transcriptional programming) with genetic circuit compression. Circuit compression requires systematic pairing of engineered transcription factors with cognate regulatable promoters. In turn, we demonstrate the compression workflow by designing, building, and testing all fundamental two-input logic gates dependent on the inputs isopropyl-β-D-1-thiogalactopyranoside and D-ribose. We then deploy complete sets of logical operations in five human donor Bacteroides, with which we demonstrate sequential gain-of-function control in co-culture. Finally, we couple transcriptional programs with CRISPR interference to achieve loss-of-function regulation of endogenous genes-demonstrating complex control over community composition in co-culture. This work provides a powerful toolkit to program gene expression in Bacteroides for the development of bespoke therapeutic bacteria.
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16
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Abstract
Regulatory processes in biology can be re-conceptualized in terms of logic gates, analogous to those in computer science. Frequently, biological systems need to respond to multiple, sometimes conflicting, inputs to provide the correct output. The language of logic gates can then be used to model complex signal transduction and metabolic processes. Advances in synthetic biology in turn can be used to construct new logic gates, which find a variety of biotechnology applications including in the production of high value chemicals, biosensing, and drug delivery. In this review, we focus on advances in the construction of logic gates that take advantage of biological catalysts, including both protein-based and nucleic acid-based enzymes. These catalyst-based biomolecular logic gates can read a variety of molecular inputs and provide chemical, optical, and electrical outputs, allowing them to interface with other types of biomolecular logic gates or even extend to inorganic systems. Continued advances in molecular modeling and engineering will facilitate the construction of new logic gates, further expanding the utility of biomolecular computing.
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17
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Franklin KA, Shields CE, Haynes KA. Beyond the marks: reader-effectors as drivers of epigenetics and chromatin engineering. Trends Biochem Sci 2022; 47:417-432. [PMID: 35427480 PMCID: PMC9074927 DOI: 10.1016/j.tibs.2022.03.002] [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] [Received: 11/26/2021] [Revised: 02/27/2022] [Accepted: 03/01/2022] [Indexed: 10/18/2022]
Abstract
Chromatin is a system of proteins and DNA that regulates chromosome organization and gene expression in eukaryotes. Essential features that support these processes include biochemical marks on histones and DNA, 'writer' enzymes that generate or remove these marks and proteins that translate the marks into transcriptional regulation: reader-effectors. Here, we review recent studies that reveal how reader-effectors drive chromatin-mediated processes. Advances in proteomics and epigenomics have accelerated the discovery of chromatin marks and their correlation with gene states, outpacing our understanding of the corresponding reader-effectors. Therefore, we summarize the current state of knowledge and open questions about how reader-effectors impact cellular function and human disease and discuss how synthetic biology can deepen our knowledge of reader-effector activity.
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Affiliation(s)
- Kierra A Franklin
- Wallace H. Coulter Department of Biomedical Engineering, Emory University, Atlanta, GA 30322, USA
| | - Cara E Shields
- Wallace H. Coulter Department of Biomedical Engineering, Emory University, Atlanta, GA 30322, USA
| | - Karmella A Haynes
- Wallace H. Coulter Department of Biomedical Engineering, Emory University, Atlanta, GA 30322, USA.
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18
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Moore JC, Ramos I, Van Dien S. OUP accepted manuscript. J Ind Microbiol Biotechnol 2022; 49:6520437. [PMID: 35108392 PMCID: PMC9118995 DOI: 10.1093/jimb/kuab088] [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: 09/20/2021] [Accepted: 12/20/2021] [Indexed: 11/13/2022]
Abstract
Optimization of metabolism to maximize production of bio-based chemicals must consistently balance cellular resources for biocatalyst growth and desired compound synthesis. This mini-review discusses synthetic biology strategies for dynamically controlling expression of genes to enable dual-phase fermentations in which growth and production are separated into dedicated phases. Emphasis is placed on practical examples which can be reliably scaled to commercial production with the current state of technology. Recent case studies are presented, and recommendations are provided for environmental signals and genetic control circuits.
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Affiliation(s)
| | - Itzel Ramos
- BP Biosciences Center, San Diego, CA 92121, USA
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19
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May MP, Munsky B. Exploiting Noise, Non-Linearity, and Feedback for Differential Control of Multiple Synthetic Cells with a Single Optogenetic Input. ACS Synth Biol 2021; 10:3396-3410. [PMID: 34793137 PMCID: PMC9875732 DOI: 10.1021/acssynbio.1c00341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Synthetic biology seeks to develop modular biocircuits that combine to produce complex, controllable behaviors. These designs are often subject to noisy fluctuations and uncertainties, and most modern synthetic biology design processes have focused to create robust components to mitigate the noise of gene expression and reduce the heterogeneity of single-cell responses. However, a deeper understanding of noise can achieve control goals that would otherwise be impossible. We explore how an "Optogenetic Maxwell Demon" could selectively amplify noise to control multiple cells using single-input-multiple-output (SIMO) feedback. Using data-constrained stochastic model simulations and theory, we show how an appropriately selected stochastic SIMO controller can drive multiple different cells to different user-specified configurations irrespective of initial conditions. We explore how controllability depends on cells' regulatory structures, the amount of information available to the controller, and the accuracy of the model used. Our results suggest that gene regulation noise, when combined with optogenetic feedback and non-linear biochemical auto-regulation, can achieve synergy to enable precise control of complex stochastic processes.
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Affiliation(s)
- Michael P May
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA, 80523
| | - Brian Munsky
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA, 80523,Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO, USA, 80523
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20
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Biological signal processing filters via engineering allosteric transcription factors. Proc Natl Acad Sci U S A 2021; 118:2111450118. [PMID: 34772815 PMCID: PMC8609624 DOI: 10.1073/pnas.2111450118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2021] [Indexed: 11/18/2022] Open
Abstract
As the size and complexity of genetic circuits increases, scientists and engineers need to find solutions to rapidly optimize flux and reduce the metabolic burden imposed on chassis cells. In this study, we report synthetic biology tools that imbue chassis cells with advanced signal processing functions akin to electrical devices commonly used in wireless transmitters and receivers (i.e., biological BANDPASS and BANDSTOP devices) that can simultaneously reduce metabolic burden. Moreover, this study presents a set of granular and more complete design rules for engineering allosteric transcription factors in the broader LacI/GalR topology. In addition, this study has improved our fundamental understanding of the plasticity and continuum of allosteric communication from the binding pocket to the protein–DNA interaction. Signal processing is critical to a myriad of biological phenomena (natural and engineered) that involve gene regulation. Biological signal processing can be achieved by way of allosteric transcription factors. In canonical regulatory systems (e.g., the lactose repressor), an INPUT signal results in the induction of a given transcription factor and objectively switches gene expression from an OFF state to an ON state. In such biological systems, to revert the gene expression back to the OFF state requires the aggressive dilution of the input signal, which can take 1 or more d to achieve in a typical biotic system. In this study, we present a class of engineered allosteric transcription factors capable of processing two-signal INPUTS, such that a sequence of INPUTS can rapidly transition gene expression between alternating OFF and ON states. Here, we present two fundamental biological signal processing filters, BANDPASS and BANDSTOP, that are regulated by D-fucose and isopropyl-β-D-1-thiogalactopyranoside. BANDPASS signal processing filters facilitate OFF–ON–OFF gene regulation. Whereas, BANDSTOP filters facilitate the antithetical gene regulation, ON–OFF–ON. Engineered signal processing filters can be directed to seven orthogonal promoters via adaptive modular DNA binding design. This collection of signal processing filters can be used in collaboration with our established transcriptional programming structure. Kinetic studies show that our collection of signal processing filters can switch between states of gene expression within a few minutes with minimal metabolic burden—representing a paradigm shift in general gene regulation.
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21
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Anderson DA, Voigt CA. Competitive dCas9 binding as a mechanism for transcriptional control. Mol Syst Biol 2021; 17:e10512. [PMID: 34747560 PMCID: PMC8574044 DOI: 10.15252/msb.202110512] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 10/10/2021] [Accepted: 10/11/2021] [Indexed: 12/24/2022] Open
Abstract
Catalytically dead Cas9 (dCas9) is a programmable transcription factor that can be targeted to promoters through the design of small guide RNAs (sgRNAs), where it can function as an activator or repressor. Natural promoters use overlapping binding sites as a mechanism for signal integration, where the binding of one can block, displace, or augment the activity of the other. Here, we implemented this strategy in Escherichia coli using pairs of sgRNAs designed to repress and then derepress transcription through competitive binding. When designed to target a promoter, this led to 27-fold repression and complete derepression. This system was also capable of ratiometric input comparison over two orders of magnitude. Additionally, we used this mechanism for promoter sequence-independent control by adopting it for elongation control, achieving 8-fold repression and 4-fold derepression. This work demonstrates a new genetic control mechanism that could be used to build analog circuit or implement cis-regulatory logic on CRISPRi-targeted native genes.
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Affiliation(s)
- Daniel A Anderson
- Synthetic Biology CenterDepartment of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
| | - Christopher A Voigt
- Synthetic Biology CenterDepartment of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
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22
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Jiang XL, Dimas RP, Chan CTY, Morcos F. Coevolutionary methods enable robust design of modular repressors by reestablishing intra-protein interactions. Nat Commun 2021; 12:5592. [PMID: 34552074 PMCID: PMC8458406 DOI: 10.1038/s41467-021-25851-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 09/03/2021] [Indexed: 11/23/2022] Open
Abstract
Genetic sensors with unique combinations of DNA recognition and allosteric response can be created by hybridizing DNA-binding modules (DBMs) and ligand-binding modules (LBMs) from distinct transcriptional repressors. This module swapping approach is limited by incompatibility between DBMs and LBMs from different proteins, due to the loss of critical module-module interactions after hybridization. We determine a design strategy for restoring key interactions between DBMs and LBMs by using a computational model informed by coevolutionary traits in the LacI family. This model predicts the influence of proposed mutations on protein structure and function, quantifying the feasibility of each mutation for rescuing hybrid repressors. We accurately predict which hybrid repressors can be rescued by mutating residues to reinstall relevant module-module interactions. Experimental results confirm that dynamic ranges of gene expression induction were improved significantly in these mutants. This approach enhances the molecular and mechanistic understanding of LacI family proteins, and advances the ability to design modular genetic parts.
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Affiliation(s)
- Xian-Li Jiang
- Department of Biological Sciences, The University of Texas at Dallas, Dallas, TX, USA
- Department of Bioinformatics and Computational Biology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
| | - Rey P Dimas
- Department of Biology, The University of Texas at Tyler, Tyler, TX, USA
| | - Clement T Y Chan
- Department of Biomedical Engineering, University of North Texas, Denton, TX, USA.
- BioDiscovery Institute, University of North Texas, Denton, TX, USA.
| | - Faruck Morcos
- Department of Biological Sciences, The University of Texas at Dallas, Dallas, TX, USA.
- Department of Bioengineering, The University of Texas at Dallas, Dallas, TX, USA.
- Center for Systems Biology, The University of Texas at Dallas, Dallas, TX, USA.
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23
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Rondon R, Wilson CJ. Engineering Alternate Ligand Recognition in the PurR Topology: A System of Novel Caffeine Biosensing Transcriptional Antirepressors. ACS Synth Biol 2021; 10:552-565. [PMID: 33689294 DOI: 10.1021/acssynbio.0c00582] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Recent advances in synthetic biology and protein engineering have increased the number of allosteric transcription factors used to regulate independent promoters. These developments represent an important increase in our biological computing capacity, which will enable us to construct more sophisticated genetic programs for a broad range of biological technologies. However, the majority of these transcription factors are represented by the repressor phenotype (BUFFER), and require layered inversion to confer the antithetical logical function (NOT), requiring additional biological resources. Moreover, these engineered transcription factors typically utilize native ligand binding functions paired with alternate DNA binding functions. In this study, we have advanced the state-of-the-art by engineering and redesigning the PurR topology (a native antirepressor) to be responsive to caffeine, while mitigating responsiveness to the native ligand hypoxanthine-i.e., a deamination product of the input molecule adenine. Importantly, the resulting caffeine responsive transcription factors are not antagonized by the native ligand hypoxanthine. In addition, we conferred alternate DNA binding to the caffeine antirepressors, and to the PurR scaffold, creating 38 new transcription factors that are congruent with our current transcriptional programming structure. Finally, we leveraged this system of transcription factors to create integrated NOR logic and related feedback operations. This study represents the first example of a system of transcription factors (antirepressors) in which both the ligand binding site and the DNA binding functions were successfully engineered in tandem.
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Affiliation(s)
- Ronald Rondon
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, Georgia 30332-0100, United States
| | - Corey J. Wilson
- Georgia Institute of Technology, School of Chemical & Biomolecular Engineering, 311 Ferst Drive, Atlanta, Georgia 30332-0100, United States
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24
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Groseclose TM, Rondon RE, Hersey AN, Milner PT, Kim D, Zhang F, Realff MJ, Wilson CJ. Biomolecular Systems Engineering: Unlocking the Potential of Engineered Allostery via the Lactose Repressor Topology. Annu Rev Biophys 2021; 50:303-321. [PMID: 33606944 DOI: 10.1146/annurev-biophys-090820-101708] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Allosteric function is a critical component of many of the parts used to construct gene networks throughout synthetic biology. In this review, we discuss an emerging field of research and education, biomolecular systems engineering, that expands on the synthetic biology edifice-integrating workflows and strategies from protein engineering, chemical engineering, electrical engineering, and computer science principles. We focus on the role of engineered allosteric communication as it relates to transcriptional gene regulators-i.e., transcription factors and corresponding unit operations. In this review, we (a) explore allosteric communication in the lactose repressor LacI topology, (b) demonstrate how to leverage this understanding of allostery in the LacI system to engineer non-natural BUFFER and NOT logical operations, (c) illustrate how engineering workflows can be used to confer alternate allosteric functions in disparate systems that share the LacI topology, and (d) demonstrate how fundamental unit operations can be directed to form combinational logical operations.
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Affiliation(s)
- Thomas M Groseclose
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA;
| | - Ronald E Rondon
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA;
| | - Ashley N Hersey
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA;
| | - Prasaad T Milner
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA;
| | - Dowan Kim
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA;
| | - Fumin Zhang
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Matthew J Realff
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA;
| | - Corey J Wilson
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA;
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