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Barbier I, Kusumawardhani H, Chauhan L, Harlapur PV, Jolly MK, Schaerli Y. Synthetic Gene Circuits Combining CRISPR Interference and CRISPR Activation in E. coli: Importance of Equal Guide RNA Binding Affinities to Avoid Context-Dependent Effects. ACS Synth Biol 2023; 12:3064-3071. [PMID: 37813387 PMCID: PMC10594877 DOI: 10.1021/acssynbio.3c00375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Indexed: 10/11/2023]
Abstract
Gene expression control based on clustered regularly interspaced short palindromic repeats (CRISPR) has emerged as a powerful approach for constructing synthetic gene circuits. While the use of CRISPR interference (CRISPRi) is already well-established in prokaryotic circuits, CRISPR activation (CRISPRa) is less mature, and a combination of the two in the same circuits is only just emerging. Here, we report that combining CRISPRi with SoxS-based CRISPRa in Escherichia coli can lead to context-dependent effects due to different affinities in the formation of CRISPRa and CRISPRi complexes, resulting in loss of predictable behavior. We show that this effect can be avoided by using the same scaffold guide RNA structure for both complexes.
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Affiliation(s)
- Içvara Barbier
- Department
of Fundamental Microbiology, University
of Lausanne, 1015 Lausanne, Switzerland
| | | | - Lakshya Chauhan
- Department
of Fundamental Microbiology, University
of Lausanne, 1015 Lausanne, Switzerland
- Department
of Bioengineering, Indian Institute of Science, 560012 Bengaluru, India
| | | | - Mohit Kumar Jolly
- Department
of Bioengineering, Indian Institute of Science, 560012 Bengaluru, India
| | - Yolanda Schaerli
- Department
of Fundamental Microbiology, University
of Lausanne, 1015 Lausanne, Switzerland
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2
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Fábrega MJ, Knödlseder N, Nevot G, Sanvicente M, Toloza L, Santos-Moreno J, Güell M. Establishing a Cell-Free Transcription-Translation Platform for Cutibacterium acnes to Prototype Engineered Metabolic and Synthetic Biology. ACS Biomater Sci Eng 2023; 9:5101-5110. [PMID: 34971313 PMCID: PMC10498419 DOI: 10.1021/acsbiomaterials.1c00894] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In the past few years, new bacterial-cell-free transcription-translation systems have emerged as potent and quick platforms for protein production as well as for prototyping of DNA regulatory elements, genetic circuits, and metabolic pathways. The Gram-positive commensal Cutibacterium acnes is one of the most abundant bacteria present in the human skin microbiome. However, it has recently been reported that some C. acnes phylotypes can be associated with common inflammatory skin conditions, such as acne vulgaris, whereas others seem to play a protective role, acting as possible "skin probiotics". This fact has made C. acnes become a bacterial model of interest for the cosmetic industry. In the present study we report for the first time the development and optimization of a C. acnes-based cell-free system (CFS) that is able to produce 85 μg/mL firefly luciferase. We highlight the importance of harvesting the bacterial pellet in mid log phase and maintaining CFS reactions at 30 °C and physiological pH to obtain the optimal yield. Additionally, a C. acnes promoter library was engineered to compare coupled in vitro TX-TL activities, and a temperature biosensor was tested, demonstrating the wide range of applications of this toolkit in the synthetic biology field.
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Affiliation(s)
- María-José Fábrega
- Department of Experimental
and Health Sciences, Pompeu Fabra University, Carrer del Dr. Aiguader 88, 00803 Barcelona, Spain
| | - Nastassia Knödlseder
- Department of Experimental
and Health Sciences, Pompeu Fabra University, Carrer del Dr. Aiguader 88, 00803 Barcelona, Spain
| | - Guillermo Nevot
- Department of Experimental
and Health Sciences, Pompeu Fabra University, Carrer del Dr. Aiguader 88, 00803 Barcelona, Spain
| | - Marta Sanvicente
- Department of Experimental
and Health Sciences, Pompeu Fabra University, Carrer del Dr. Aiguader 88, 00803 Barcelona, Spain
| | - Lorena Toloza
- Department of Experimental
and Health Sciences, Pompeu Fabra University, Carrer del Dr. Aiguader 88, 00803 Barcelona, Spain
| | - Javier Santos-Moreno
- Department of Experimental
and Health Sciences, Pompeu Fabra University, Carrer del Dr. Aiguader 88, 00803 Barcelona, Spain
| | - Marc Güell
- Department of Experimental
and Health Sciences, Pompeu Fabra University, Carrer del Dr. Aiguader 88, 00803 Barcelona, Spain
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3
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Zhou LY, Zhang S, Li LY, Yang GY, Zeng L. Optimization of mammalian expression vector by cis-regulatory element combinations. Mol Genet Genomics 2023:10.1007/s00438-023-02042-0. [PMID: 37318628 DOI: 10.1007/s00438-023-02042-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 05/31/2023] [Indexed: 06/16/2023]
Abstract
The regulation of gene expression in mammalian cells by combining various cis-regulatory features has rarely been discussed. In this study, we constructed expression vectors containing various combinations of regulatory elements to examine the regulation of gene expression by different combinations of cis-regulatory elements. The effects of four promoters (CMV promoter, PGK promoter, Polr2a promoter, and EF-1α core promoter), two enhancers (CMV enhancer and SV40 enhancer), two introns (EF-1α intron A and hybrid intron), two terminators (CYC1 terminator and TEF terminator), and their different combinations on downstream gene expression were compared in various mammalian cells using fluorescence microscopy to observe fluorescence, quantitative real-time PCR (qRT-PCR), and western blot. The receptor binding domain (RBD) sequence from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein was used to replace the eGFP sequence in the expression vector and the RBD expression was detected by qRT-PCR and western blot. The results showed that protein expression can be regulated by optimizing the combination of cis-acting elements. The vector with the CMV enhancer, EF-1α core promoter, and TEF terminator was found to express approximately threefold higher eGFP than the unmodified vector in different animal cells, as well as 2.63-fold higher recombinant RBD protein than the original vector in HEK-293T cells. Moreover, we suggest that combinations of multiple regulatory elements capable of regulating gene expression do not necessarily exhibit synergistic effects to enhance expression further. Overall, our findings provide insights into biological applications that require the regulation of gene expression and will help to optimize expression vectors for biosynthesis and other fields. Additionally, we provide valuable insights into the production of RBD proteins, which may aid in developing reagents for diagnosis and treatment during the COVID-19 pandemic.
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Affiliation(s)
- Lu-Yu Zhou
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Biochemistry and Nutrition, Henan Agricultural University, Ministry of Agriculture and Rural Affairs, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Growth and Development, The Education Department of Henan Province, Zhengzhou, 450046, Henan, People's Republic of China
| | - Shuang Zhang
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Biochemistry and Nutrition, Henan Agricultural University, Ministry of Agriculture and Rural Affairs, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Growth and Development, The Education Department of Henan Province, Zhengzhou, 450046, Henan, People's Republic of China
| | - Li-Yun Li
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Biochemistry and Nutrition, Henan Agricultural University, Ministry of Agriculture and Rural Affairs, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Growth and Development, The Education Department of Henan Province, Zhengzhou, 450046, Henan, People's Republic of China
| | - Guo-Yu Yang
- Key Laboratory of Animal Biochemistry and Nutrition, Henan Agricultural University, Ministry of Agriculture and Rural Affairs, Zhengzhou, 450046, Henan, People's Republic of China
- Key Laboratory of Animal Growth and Development, The Education Department of Henan Province, Zhengzhou, 450046, Henan, People's Republic of China
| | - Lei Zeng
- College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, 450046, Henan, People's Republic of China.
- Key Laboratory of Animal Biochemistry and Nutrition, Henan Agricultural University, Ministry of Agriculture and Rural Affairs, Zhengzhou, 450046, Henan, People's Republic of China.
- Key Laboratory of Animal Growth and Development, The Education Department of Henan Province, Zhengzhou, 450046, Henan, People's Republic of China.
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4
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Santos-Moreno J, Tasiudi E, Kusumawardhani H, Stelling J, Schaerli Y. Robustness and innovation in synthetic genotype networks. Nat Commun 2023; 14:2454. [PMID: 37117168 PMCID: PMC10147661 DOI: 10.1038/s41467-023-38033-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 04/13/2023] [Indexed: 04/30/2023] Open
Abstract
Genotype networks are sets of genotypes connected by small mutational changes that share the same phenotype. They facilitate evolutionary innovation by enabling the exploration of different neighborhoods in genotype space. Genotype networks, first suggested by theoretical models, have been empirically confirmed for proteins and RNAs. Comparative studies also support their existence for gene regulatory networks (GRNs), but direct experimental evidence is lacking. Here, we report the construction of three interconnected genotype networks of synthetic GRNs producing three distinct phenotypes in Escherichia coli. Our synthetic GRNs contain three nodes regulating each other by CRISPR interference and governing the expression of fluorescent reporters. The genotype networks, composed of over twenty different synthetic GRNs, provide robustness in face of mutations while enabling transitions to innovative phenotypes. Through realistic mathematical modeling, we quantify robustness and evolvability for the complete genotype-phenotype map and link these features mechanistically to GRN motifs. Our work thereby exemplifies how GRN evolution along genotype networks might be driving evolutionary innovation.
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Affiliation(s)
- Javier Santos-Moreno
- Department of Fundamental Microbiology, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland
- Department of Medicine and Life Sciences, Pompeu Fabra University, 00803, Barcelona, Spain
| | - Eve Tasiudi
- Department of Biosystems Science and Engineering, ETH Zurich and SIB Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Hadiastri Kusumawardhani
- Department of Fundamental Microbiology, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland
| | - Joerg Stelling
- Department of Biosystems Science and Engineering, ETH Zurich and SIB Swiss Institute of Bioinformatics, Basel, Switzerland.
| | - Yolanda Schaerli
- Department of Fundamental Microbiology, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland.
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English MA, Alcantar MA, Collins JJ. A self‐propagating, barcoded transposon system for the dynamic rewiring of genomic networks. Mol Syst Biol 2023:e11398. [DOI: 10.15252/msb.202211398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/29/2023] Open
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6
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CRISPR-Based Genetic Switches and Other Complex Circuits: Research and Application. Life (Basel) 2021; 11:life11111255. [PMID: 34833131 PMCID: PMC8621321 DOI: 10.3390/life11111255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/14/2021] [Accepted: 11/15/2021] [Indexed: 12/26/2022] Open
Abstract
CRISPR-based enzymes have offered a unique capability to the design of genetic switches, with advantages in designability, modularity and orthogonality. CRISPR-based genetic switches operate on multiple levels of life, including transcription and translation. In both prokaryotic and eukaryotic cells, deactivated CRISPR endonuclease and endoribonuclease have served in genetic switches for activating or repressing gene expression, at both transcriptional and translational levels. With these genetic switches, more complex circuits have been assembled to achieve sophisticated functions including inducible switches, non-linear response and logical biocomputation. As more CRISPR enzymes continue to be excavated, CRISPR-based genetic switches will be used in a much wider range of applications.
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7
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Currin A, Parker S, Robinson CJ, Takano E, Scrutton NS, Breitling R. The evolving art of creating genetic diversity: From directed evolution to synthetic biology. Biotechnol Adv 2021; 50:107762. [PMID: 34000294 PMCID: PMC8299547 DOI: 10.1016/j.biotechadv.2021.107762] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 04/21/2021] [Accepted: 04/25/2021] [Indexed: 12/31/2022]
Abstract
The ability to engineer biological systems, whether to introduce novel functionality or improved performance, is a cornerstone of biotechnology and synthetic biology. Typically, this requires the generation of genetic diversity to explore variations in phenotype, a process that can be performed at many levels, from single molecule targets (i.e., in directed evolution of enzymes) to whole organisms (e.g., in chassis engineering). Recent advances in DNA synthesis technology and automation have enhanced our ability to create variant libraries with greater control and throughput. This review highlights the latest developments in approaches to create such a hierarchy of diversity from the enzyme level to entire pathways in vitro, with a focus on the creation of combinatorial libraries that are required to navigate a target's vast design space successfully to uncover significant improvements in function.
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Affiliation(s)
- Andrew Currin
- Manchester Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, United Kingdom.
| | - Steven Parker
- Manchester Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, United Kingdom
| | - Christopher J Robinson
- Manchester Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, United Kingdom
| | - Eriko Takano
- Manchester Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, United Kingdom
| | - Nigel S Scrutton
- Manchester Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, United Kingdom
| | - Rainer Breitling
- Manchester Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM), Manchester Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, United Kingdom.
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8
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Santos-Moreno J, Schaerli Y. CRISPR-based gene expression control for synthetic gene circuits. Biochem Soc Trans 2020; 48:1979-1993. [PMID: 32964920 PMCID: PMC7609024 DOI: 10.1042/bst20200020] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/27/2020] [Accepted: 08/28/2020] [Indexed: 12/22/2022]
Abstract
Synthetic gene circuits allow us to govern cell behavior in a programmable manner, which is central to almost any application aiming to harness engineered living cells for user-defined tasks. Transcription factors (TFs) constitute the 'classic' tool for synthetic circuit construction but some of their inherent constraints, such as insufficient modularity, orthogonality and programmability, limit progress in such forward-engineering endeavors. Here we review how CRISPR (clustered regularly interspaced short palindromic repeats) technology offers new and powerful possibilities for synthetic circuit design. CRISPR systems offer superior characteristics over TFs in many aspects relevant to a modular, predictable and standardized circuit design. Thus, the choice of CRISPR technology as a framework for synthetic circuit design constitutes a valid alternative to complement or replace TFs in synthetic circuits and promises the realization of more ambitious designs.
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Affiliation(s)
- Javier Santos-Moreno
- Department of Fundamental Microbiology, University of Lausanne, Biophore Building, 1015 Lausanne, Switzerland
| | - Yolanda Schaerli
- Department of Fundamental Microbiology, University of Lausanne, Biophore Building, 1015 Lausanne, Switzerland
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9
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Farquhar KS, Flohr H, Charlebois DA. Advancing Antimicrobial Resistance Research Through Quantitative Modeling and Synthetic Biology. Front Bioeng Biotechnol 2020; 8:583415. [PMID: 33072732 PMCID: PMC7530828 DOI: 10.3389/fbioe.2020.583415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/02/2020] [Indexed: 11/13/2022] Open
Abstract
Antimicrobial resistance (AMR) is an emerging global health crisis that is undermining advances in modern medicine and, if unmitigated, threatens to kill 10 million people per year worldwide by 2050. Research over the last decade has demonstrated that the differences between genetically identical cells in the same environment can lead to drug resistance. Fluctuations in gene expression, modulated by gene regulatory networks, can lead to non-genetic heterogeneity that results in the fractional killing of microbial populations causing drug therapies to fail; this non-genetic drug resistance can enhance the probability of acquiring genetic drug resistance mutations. Mathematical models of gene networks can elucidate general principles underlying drug resistance, predict the evolution of resistance, and guide drug resistance experiments in the laboratory. Cells genetically engineered to carry synthetic gene networks regulating drug resistance genes allow for controlled, quantitative experiments on the role of non-genetic heterogeneity in the development of drug resistance. In this perspective article, we emphasize the contributions that mathematical, computational, and synthetic gene network models play in advancing our understanding of AMR to discover effective therapies against drug-resistant infections.
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Affiliation(s)
| | - Harold Flohr
- Department of Physics, University of Alberta, Edmonton, AB, Canada
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10
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Abstract
Gene expression control based on CRISPRi (clustered regularly interspaced short palindromic repeats interference) has emerged as a powerful tool for creating synthetic gene circuits, both in prokaryotes and in eukaryotes; yet, its lack of cooperativity has been pointed out as a potential obstacle for dynamic or multistable synthetic circuit construction. Here we use CRISPRi to build a synthetic oscillator (“CRISPRlator”), bistable network (toggle switch) and stripe pattern-forming incoherent feed-forward loop (IFFL). Our circuit designs, conceived to feature high predictability and orthogonality, as well as low metabolic burden and context-dependency, allow us to achieve robust circuit behaviors in Escherichia coli populations. Mathematical modeling suggests that unspecific binding in CRISPRi is essential to establish multistability. Our work demonstrates the wide applicability of CRISPRi in synthetic circuits and paves the way for future efforts towards engineering more complex synthetic networks, boosted by the advantages of CRISPR technology. Synthetic circuits based on CRISPRi have not achieved multistable and dynamic behaviors. Here the authors build an oscillator, a toggle switch and an incoherent feed-forward loop using CRISPRi, and provide a mathematical model suggesting that unspecific binding in CRISPRi enables multistability.
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11
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Gräwe A, Ranglack J, Weyrich A, Stein V. iFLinkC: an iterative functional linker cloning strategy for the combinatorial assembly and recombination of linker peptides with functional domains. Nucleic Acids Res 2020; 48:e24. [PMID: 31925441 PMCID: PMC7039005 DOI: 10.1093/nar/gkz1210] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 12/10/2019] [Accepted: 12/18/2019] [Indexed: 02/02/2023] Open
Abstract
Recent years have witnessed increasing efforts to engineer artificial biological functions through recombination of modular-organized toolboxes of protein scaffolds and parts. A critical, yet frequently neglected aspect concerns the identity of peptide linkers or spacers connecting individual domains which remain poorly understood and challenging to assemble. Addressing these limitations, iFlinkC comprises a highly scalable DNA assembly process that facilitates the combinatorial recombination of functional domains with linkers of varying length and flexibility, thereby overcoming challenges with high GC-content and the repeat nature of linker elements. The capacity of iFLinkC is demonstrated in the construction of synthetic protease switches featuring PDZ-FN3-based affinity clamps and single-chain FKBP12-FRB receptors as allosteric inputs. Library screening experiments demonstrate that linker space is highly plastic as the induction of allosterically regulated protease switches can vary from >150-fold switch-ON to >13-fold switch-OFF solely depending on the identity of the connecting linkers and relative orientation of functional domains. In addition, Pro-rich linkers yield the most potent switches contradicting the conventional use of flexible Gly-Ser linkers. Given the ease and efficiency how functional domains can be readily recombined with any type of linker, iFLinkC is anticipated to be widely applicable to the assembly of any type of fusion protein.
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Affiliation(s)
- Alexander Gräwe
- Fachbereich Biologie, Technische Universität Darmstadt, 64287 Darmstadt, Germany.,Centre for Synthetic Biology, Technische Universität Darmstadt, 64283 Darmstadt, Germany
| | - Jan Ranglack
- Fachbereich Biologie, Technische Universität Darmstadt, 64287 Darmstadt, Germany.,Centre for Synthetic Biology, Technische Universität Darmstadt, 64283 Darmstadt, Germany
| | - Anastasia Weyrich
- Fachbereich Biologie, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Viktor Stein
- Fachbereich Biologie, Technische Universität Darmstadt, 64287 Darmstadt, Germany.,Centre for Synthetic Biology, Technische Universität Darmstadt, 64283 Darmstadt, Germany
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