1
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Landau J, Cuba Samaniego C, Giordano G, Franco E. Computational characterization of recombinase circuits for periodic behaviors. iScience 2022; 26:105624. [PMID: 36619981 PMCID: PMC9812718 DOI: 10.1016/j.isci.2022.105624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 06/17/2022] [Accepted: 11/15/2022] [Indexed: 11/23/2022] Open
Abstract
Recombinases are site-specific proteins found in nature that are capable of rearranging DNA. This function has made them promising gene editing tools in synthetic biology, as well as key elements in complex artificial gene circuits implementing Boolean logic. However, since DNA rearrangement is irreversible, it is still unclear how to use recombinases to build dynamic circuits like oscillators. In addition, this goal is challenging because a few molecules of recombinase are enough for promoter inversion, generating inherent stochasticity at low copy number. Here, we propose six different circuit designs for recombinase-based oscillators operating at a single copy number. We model them in a stochastic setting, leveraging the Gillespie algorithm for extensive simulations, and show that they can yield coherent periodic behaviors. Our results support the experimental realization of recombinase-based oscillators and, more generally, the use of recombinases to generate dynamic behaviors in synthetic biology.
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Affiliation(s)
- Judith Landau
- California State University, Los Angeles, Los Angeles, CA, USA
| | | | - Giulia Giordano
- Department of Industrial Engineering, University of Trento, Trento, Italy
| | - Elisa Franco
- University of California, Los Angeles, Los Angeles, CA, USA
- Corresponding author
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2
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Sootla A, Delalez N, Alexis E, Norman A, Steel H, Wadhams GH, Papachristodoulou A. Dichotomous feedback: a signal sequestration-based feedback mechanism for biocontroller design. J R Soc Interface 2022; 19:20210737. [PMID: 35440202 PMCID: PMC9019519 DOI: 10.1098/rsif.2021.0737] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We introduce a new design framework for implementing negative feedback regulation in synthetic biology, which we term ‘dichotomous feedback’. Our approach is different from current methods, in that it sequesters existing fluxes in the process to be controlled, and in this way takes advantage of the process’s architecture to design the control law. This signal sequestration mechanism appears in many natural biological systems and can potentially be easier to realize than ‘molecular sequestration’ and other comparison motifs that are nowadays common in biomolecular feedback control design. The loop is closed by linking the strength of signal sequestration to the process output. Our feedback regulation mechanism is motivated by two-component signalling systems, where a second response regulator could be competing with the natural response regulator thus sequestering kinase activity. Here, dichotomous feedback is established by increasing the concentration of the second response regulator as the level of the output of the natural process increases. Extensive analysis demonstrates how this type of feedback shapes the signal response, attenuates intrinsic noise while increasing robustness and reducing crosstalk.
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Affiliation(s)
- Aivar Sootla
- Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, UK
| | - Nicolas Delalez
- Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, UK
| | - Emmanouil Alexis
- Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, UK
| | - Arthur Norman
- Department of Biochemistry, University of Oxford, Oxford OX1 3PJ, UK
| | - Harrison Steel
- Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, UK
| | - George H Wadhams
- Department of Biochemistry, University of Oxford, Oxford OX1 3PJ, UK
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3
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Kudithipudi D, Aguilar-Simon M, Babb J, Bazhenov M, Blackiston D, Bongard J, Brna AP, Chakravarthi Raja S, Cheney N, Clune J, Daram A, Fusi S, Helfer P, Kay L, Ketz N, Kira Z, Kolouri S, Krichmar JL, Kriegman S, Levin M, Madireddy S, Manicka S, Marjaninejad A, McNaughton B, Miikkulainen R, Navratilova Z, Pandit T, Parker A, Pilly PK, Risi S, Sejnowski TJ, Soltoggio A, Soures N, Tolias AS, Urbina-Meléndez D, Valero-Cuevas FJ, van de Ven GM, Vogelstein JT, Wang F, Weiss R, Yanguas-Gil A, Zou X, Siegelmann H. Biological underpinnings for lifelong learning machines. NAT MACH INTELL 2022. [DOI: 10.1038/s42256-022-00452-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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4
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Dey S, Singh A. Diverse role of decoys on emergence and precision of oscillations in a biomolecular clock. Biophys J 2021; 120:5564-5574. [PMID: 34774502 PMCID: PMC8715246 DOI: 10.1016/j.bpj.2021.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 08/11/2021] [Accepted: 11/05/2021] [Indexed: 01/14/2023] Open
Abstract
Biomolecular clocks are key drivers of oscillatory dynamics in diverse biological processes including cell-cycle regulation, circadian rhythms, and pattern formation during development. A minimal clock implementation is based on the classical Goodwin oscillator, in which a repressor protein inhibits its own synthesis via time-delayed negative feedback. Clock motifs, however, do not exist in isolation; its components are open to interacting with the complex environment inside cells. For example, there are ubiquitous high-affinity binding sites along the genome, known as decoys, where transcription factors such as repressor proteins can potentially interact. This binding affects the availability of transcription factors and has often been ignored in theoretical studies. How does such genomic decoy binding impact the clock's robustness and precision? To address this question, we systematically analyze deterministic and stochastic models of the Goodwin oscillator in the presence of reversible binding of the repressor to a finite number of decoy sites. Our analysis reveals that the relative stability of decoy-bound repressors compared to the free repressor plays distinct roles on the emergence and precision of oscillations. Interestingly, active degradation of the bound repressor can induce sustained oscillations that are otherwise absent without decoys. In contrast, decoy abundances can kill oscillation dynamics if the bound repressor is protected from degradation. Taking into account low copy-number fluctuations in clock components, we show that the degradation of the bound repressors enhances precision by attenuating noise in both the amplitude and period of oscillations. Overall, these results highlight the versatile role of otherwise hidden decoys in shaping the stochastic dynamics of biological clocks and emphasize the importance of synthetic decoys in designing robust clocks.
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Affiliation(s)
- Supravat Dey
- Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware,Corresponding author
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware,Department of Biomedical Engineering, University of Delaware, Newark, Delaware
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5
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Gyorgy A. Context-Dependent Stability and Robustness of Genetic Toggle Switches with Leaky Promoters. Life (Basel) 2021; 11:life11111150. [PMID: 34833026 PMCID: PMC8624834 DOI: 10.3390/life11111150] [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: 09/30/2021] [Revised: 10/21/2021] [Accepted: 10/26/2021] [Indexed: 01/22/2023] Open
Abstract
Multistable switches are ubiquitous building blocks in both systems and synthetic biology. Given their central role, it is thus imperative to understand how their fundamental properties depend not only on the tunable biophysical properties of the switches themselves, but also on their genetic context. To this end, we reveal in this article how these factors shape the essential characteristics of toggle switches implemented using leaky promoters such as their stability and robustness to noise, both at single-cell and population levels. In particular, our results expose the roles that competition for scarce transcriptional and translational resources, promoter leakiness, and cell-to-cell heterogeneity collectively play. For instance, the interplay between protein expression from leaky promoters and the associated cost of relying on shared cellular resources can give rise to tristable dynamics even in the absence of positive feedback. Similarly, we demonstrate that while promoter leakiness always acts against multistability, resource competition can be leveraged to counteract this undesirable phenomenon. Underpinned by a mechanistic model, our results thus enable the context-aware rational design of multistable genetic switches that are directly translatable to experimental considerations, and can be further leveraged during the synthesis of large-scale genetic systems using computer-aided biodesign automation platforms.
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Affiliation(s)
- Andras Gyorgy
- Division of Engineering, New York University Abu Dhabi, Abu Dhabi P.O. Box 129188, United Arab Emirates
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6
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Cuba Samaniego C, Franco E. Ultrasensitive molecular controllers for quasi-integral feedback. Cell Syst 2021; 12:272-288.e3. [PMID: 33539724 DOI: 10.1016/j.cels.2021.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 09/22/2020] [Accepted: 01/11/2021] [Indexed: 12/24/2022]
Abstract
Feedback control has enabled the success of automated technologies by mitigating the effects of variability, unknown disturbances, and noise. While it is known that biological feedback loops reduce the impact of noise and help shape kinetic responses, many questions remain about how to design molecular integral controllers. Here, we propose a modular strategy to build molecular quasi-integral feedback controllers, which involves following two design principles. The first principle is to utilize an ultrasensitive response, which determines the gain of the controller and influences the steady-state error. The second is to use a tunable threshold of the ultrasensitive response, which determines the equilibrium point of the system. We describe a reaction network, named brink controller, that satisfies these conditions by combining molecular sequestration and an activation/deactivation cycle. With computational models, we examine potential biological implementations of brink controllers, and we illustrate different example applications.
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Affiliation(s)
- Christian Cuba Samaniego
- Mechanical and Aerospace Engineering, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Elisa Franco
- Mechanical and Aerospace Engineering, University of California at Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA; Bioengineering, University of California at Los Angeles, Los Angeles, CA 90095, USA; Mechanical Engineering, University of California at Riverside, Riverside, CA 92521, USA.
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7
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8
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Shannon B, Zamora-Chimal CG, Postiglione L, Salzano D, Grierson CS, Marucci L, Savery NJ, di Bernardo M. In Vivo Feedback Control of an Antithetic Molecular-Titration Motif in Escherichia coli Using Microfluidics. ACS Synth Biol 2020; 9:2617-2624. [PMID: 32966743 DOI: 10.1021/acssynbio.0c00105] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We study both in silico and in vivo the real-time feedback control of a molecular titration motif that has been earmarked as a fundamental component of antithetic and multicellular feedback control schemes in E. coli. We show that an external feedback control strategy can successfully regulate the average fluorescence output of a bacterial cell population to a desired constant level in real-time. We also provide in silico evidence that the same strategy can be used to track a time-varying reference signal where the set-point is switched to a different value halfway through the experiment. We use the experimental data to refine and parametrize an in silico model of the motif that can be used as an error computation module in future embedded or multicellular control experiments.
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Affiliation(s)
- Barbara Shannon
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, U.K
- BrisSynBio, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, U.K
| | - Criseida G. Zamora-Chimal
- Department of Engineering Mathematics, University of Bristol, Bristol BS8 1UB, U.K
- BrisSynBio, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, U.K
| | - Lorena Postiglione
- Department of Engineering Mathematics, University of Bristol, Bristol BS8 1UB, U.K
| | - Davide Salzano
- Department of Electrical Engineering and Information Technology, University of Naples Federico II, 80125 Naples, Italy
| | - Claire S. Grierson
- School of Biological Sciences, University of Bristol, Bristol BS8 1UH, U.K
- BrisSynBio, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, U.K
| | - Lucia Marucci
- Department of Engineering Mathematics, University of Bristol, Bristol BS8 1UB, U.K
- BrisSynBio, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, U.K
| | - Nigel J. Savery
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, U.K
- BrisSynBio, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, U.K
| | - Mario di Bernardo
- Department of Engineering Mathematics, University of Bristol, Bristol BS8 1UB, U.K
- Department of Electrical Engineering and Information Technology, University of Naples Federico II, 80125 Naples, Italy
- BrisSynBio, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, U.K
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9
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Agrawal DK, Marshall R, Noireaux V, Sontag ED. In vitro implementation of robust gene regulation in a synthetic biomolecular integral controller. Nat Commun 2019; 10:5760. [PMID: 31848346 PMCID: PMC6917713 DOI: 10.1038/s41467-019-13626-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 11/18/2019] [Indexed: 12/20/2022] Open
Abstract
Feedback mechanisms play a critical role in the maintenance of cell homeostasis in the presence of disturbances and uncertainties. Motivated by the need to tune the dynamics and improve the robustness of gene circuits, biological engineers have proposed various designs that mimic natural molecular feedback control mechanisms. However, practical and predictable implementations have proved challenging because of the complexity of synthesis and analysis of complex biomolecular networks. Here, we analyze and experimentally validate a synthetic biomolecular controller executed in vitro. The controller ensures that gene expression rate tracks an externally imposed reference level, and achieves this goal even in the presence of certain kinds of disturbances. Our design relies upon an analog of the well-known principle of integral feedback in control theory. We implement the controller in an Escherichia coli cell-free transcription-translation system, which allows rapid prototyping and implementation. Modeling and theory guide experimental implementation with well-defined operational predictability.
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Affiliation(s)
- Deepak K Agrawal
- Department of Bioengineering, Northeastern University, Boston, MA, USA
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, USA
| | - Ryan Marshall
- 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.
| | - Eduardo D Sontag
- Department of Bioengineering, Northeastern University, Boston, MA, USA.
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, USA.
- Laboratory of Systems Pharmacology, Program in Therapeutic Science, Harvard Medical School, Boston MA, USA.
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10
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Dey A, Barik D. Dichotomous Nature of Bistability Generated by Negative Cooperativity in Receptor-Ligand Binding. ACS Synth Biol 2019; 8:1294-1302. [PMID: 31132851 DOI: 10.1021/acssynbio.8b00517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Positive cooperativity in receptor-ligand binding plays an important role in cell signaling as it generates an ultrasensitive response, a requirement for nonlinear phenomena such as bistability and oscillations in feedback regulated reaction networks. On the other hand, negative cooperativity typically produces a hyperbolic response and is thus less explored. However, recently negative cooperativity was shown to generate an ultrasensitive response under the condition of strong ligand affinity. In this work, we have used mathematical modeling to investigate the effect of negative cooperativity in receptor-ligand interaction on the bistability in a positive feedback regulatory motif. We systematically investigated the effect of negative cooperativity, modifying the two equilibrium constants of the receptor-ligand binding, on the robustness and tunability of bistability. We show that in the regime where negative cooperativity exhibits robust bistability, positive cooperativity results in poor bistability and vice versa. Further we find that the robustness and tunability of bistability depend crucially on the stability of singly and doubly engaged receptors. Our modeling highlights the ability of negative cooperativity to produce complex phenomena with potential applications in designing synthetic devices or in explaining experimental observations in cell biology.
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Affiliation(s)
- Anupam Dey
- School of Chemistry, University of Hyderabad, Central University
P.O., Hyderabad, 500046 Telangana, India
| | - Debashis Barik
- School of Chemistry, University of Hyderabad, Central University
P.O., Hyderabad, 500046 Telangana, India
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11
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Jeong D, Klocke M, Agarwal S, Kim J, Choi S, Franco E, Kim J. Cell-Free Synthetic Biology Platform for Engineering Synthetic Biological Circuits and Systems. Methods Protoc 2019; 2:E39. [PMID: 31164618 PMCID: PMC6632179 DOI: 10.3390/mps2020039] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 04/12/2019] [Accepted: 05/08/2019] [Indexed: 01/07/2023] Open
Abstract
Synthetic biology brings engineering disciplines to create novel biological systems for biomedical and technological applications. The substantial growth of the synthetic biology field in the past decade is poised to transform biotechnology and medicine. To streamline design processes and facilitate debugging of complex synthetic circuits, cell-free synthetic biology approaches has reached broad research communities both in academia and industry. By recapitulating gene expression systems in vitro, cell-free expression systems offer flexibility to explore beyond the confines of living cells and allow networking of synthetic and natural systems. Here, we review the capabilities of the current cell-free platforms, focusing on nucleic acid-based molecular programs and circuit construction. We survey the recent developments including cell-free transcription-translation platforms, DNA nanostructures and circuits, and novel classes of riboregulators. The links to mathematical models and the prospects of cell-free synthetic biology platforms will also be discussed.
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Affiliation(s)
- Dohyun Jeong
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, 77 Cheongam-ro, Pohang, Gyeongbuk 37673, Korea.
| | - Melissa Klocke
- Department of Mechanical Engineering, University of California at Riverside, 900 University Ave, Riverside, CA 92521, USA.
| | - Siddharth Agarwal
- Department of Mechanical Engineering, University of California at Riverside, 900 University Ave, Riverside, CA 92521, USA.
| | - Jeongwon Kim
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, 77 Cheongam-ro, Pohang, Gyeongbuk 37673, Korea.
| | - Seungdo Choi
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, 77 Cheongam-ro, Pohang, Gyeongbuk 37673, Korea.
| | - Elisa Franco
- Department of Mechanical and Aerospace Engineering, University of California at Los Angeles, 420 Westwood Plaza, Los Angeles, CA 90095, USA.
| | - Jongmin Kim
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, 77 Cheongam-ro, Pohang, Gyeongbuk 37673, Korea.
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12
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Green LN, Subramanian HKK, Mardanlou V, Kim J, Hariadi RF, Franco E. Autonomous dynamic control of DNA nanostructure self-assembly. Nat Chem 2019; 11:510-520. [PMID: 31011170 DOI: 10.1038/s41557-019-0251-8] [Citation(s) in RCA: 147] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Accepted: 03/06/2019] [Indexed: 11/09/2022]
Abstract
Biological cells routinely reconfigure their shape using dynamic signalling and regulatory networks that direct self-assembly processes in time and space, through molecular components that sense, process and transmit information from the environment. A similar strategy could be used to enable life-like behaviours in synthetic materials. Nucleic acid nanotechnology offers a promising route towards this goal through a variety of sensors, logic and dynamic components and self-assembling structures. Here, by harnessing both dynamic and structural DNA nanotechnology, we demonstrate dynamic control of the self-assembly of DNA nanotubes-a well-known class of programmable DNA nanostructures. Nanotube assembly and disassembly is controlled with minimal synthetic gene systems, including an autonomous molecular oscillator. We use a coarse-grained computational model to capture nanotube length distribution dynamics in response to inputs from nucleic acid circuits. We hope that these results may find use for the development of responsive nucleic acid materials, with potential applications in biomaterials science, nanofabrication and drug delivery.
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Affiliation(s)
- Leopold N Green
- Bioengineering, University of California, Riverside, CA, USA.,Bioengineering, California Institute of Technology, Pasadena, CA, USA
| | | | - Vahid Mardanlou
- Electrical and Computer Engineering, University of California, Riverside, CA, USA
| | - Jongmin Kim
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA.,Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, Gyeongbuk, Republic of Korea
| | - Rizal F Hariadi
- Department of Physics and the Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Elisa Franco
- Mechanical Engineering, University of California, Riverside, CA, USA. .,Samueli School of Engineering, University of California, Los Angeles, CA, USA.
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13
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Blanchini F, Cuba Samaniego C, Franco E, Giordano G. Homogeneous Time Constants Promote Oscillations in Negative Feedback Loops. ACS Synth Biol 2018; 7:1481-1487. [PMID: 29676894 PMCID: PMC6008730 DOI: 10.1021/acssynbio.7b00442] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
![]()
Biological oscillators are present
in nearly all self-regulating
systems, from individual cells to entire organisms. In any oscillator
structure, a negative feedback loop is necessary, but not sufficient
to guarantee the emergence of periodic behaviors. The likelihood of
oscillations can be improved by careful tuning of the system time
constants and by increasing the loop gain, yet it is unclear whether
there is any general relationship between optimal time constants and
loop gain. This issue is particularly relevant in genetic oscillators
resulting from a chain of different subsequent biochemical events,
each with distinct (and uncertain) kinetics. Using two families of
genetic oscillators as model examples, we show that the loop gain
required for oscillations is minimum when all elements in the loop
have the same time constant. On the contrary, we show that homeostasis
is ensured if a single element is considerably slower than the others.
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Affiliation(s)
- Franco Blanchini
- Dipartimento di Scienze Matematiche, Informatiche e Fisiche, Università degli Studi di Udine, 33100 Udine, Italy
| | - Christian Cuba Samaniego
- Department of Mechanical Engineering, University of California at Riverside, Riverside, California 92521, United States
| | - Elisa Franco
- Department of Mechanical Engineering, University of California at Riverside, Riverside, California 92521, United States
| | - Giulia Giordano
- Delft Center for Systems and Control, Delft University of Technology, 2628 CD Delft, The Netherlands
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14
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Giordano G. Ceramide-transfer protein-mediated ceramide transfer is a structurally tunable flow-inducing mechanism with structural feed-forward loops. ROYAL SOCIETY OPEN SCIENCE 2018; 5:180494. [PMID: 30110462 PMCID: PMC6030332 DOI: 10.1098/rsos.180494] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 05/22/2018] [Indexed: 06/08/2023]
Abstract
This paper considers two models of ceramide-transfer protein (CERT)-mediated ceramide transfer at the trans-Golgi network proposed in the literature, short distance shuttle and neck swinging, and seeks structural (parameter-free) features of the two models, which rely exclusively on the peculiar interaction network and not on specific parameter values. In particular, it is shown that both models can be seen as flow-inducing systems, where the flows between pairs of species are tuned by the concentrations of other species, and suitable external inputs can structurally regulate ceramide transfer. In the short distance shuttle model, the amount of transferred ceramide is structurally tuned by active protein kinase D (PKD), both directly and indirectly, in a coherent feed-forward loop motif. In the neck-swinging model, the amount of transferred ceramide is structurally tuned by active PI4KIIIβ, while active PKD has an ambivalent effect, due to the presence of an incoherent feed-forward loop motif that directly inhibits ceramide transfer and indirectly promotes it; the structural role of active PKD is to favour CERT mobility in the cytosol. It is also shown that the influences among key variables often have structurally determined steady-state signs, which can help falsify the models against experimental traces.
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Affiliation(s)
- Giulia Giordano
- Delft Center for Systems and Control, Delft University of Technology (TU Delft), 2628 CD Delft, The Netherlands
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15
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Agrawal DK, Tang X, Westbrook A, Marshall R, Maxwell CS, Lucks J, Noireaux V, Beisel CL, Dunlop MJ, Franco E. Mathematical Modeling of RNA-Based Architectures for Closed Loop Control of Gene Expression. ACS Synth Biol 2018; 7:1219-1228. [PMID: 29709170 DOI: 10.1021/acssynbio.8b00040] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Feedback allows biological systems to control gene expression precisely and reliably, even in the presence of uncertainty, by sensing and processing environmental changes. Taking inspiration from natural architectures, synthetic biologists have engineered feedback loops to tune the dynamics and improve the robustness and predictability of gene expression. However, experimental implementations of biomolecular control systems are still far from satisfying performance specifications typically achieved by electrical or mechanical control systems. To address this gap, we present mathematical models of biomolecular controllers that enable reference tracking, disturbance rejection, and tuning of the temporal response of gene expression. These controllers employ RNA transcriptional regulators to achieve closed loop control where feedback is introduced via molecular sequestration. Sensitivity analysis of the models allows us to identify which parameters influence the transient and steady state response of a target gene expression process, as well as which biologically plausible parameter values enable perfect reference tracking. We quantify performance using typical control theory metrics to characterize response properties and provide clear selection guidelines for practical applications. Our results indicate that RNA regulators are well-suited for building robust and precise feedback controllers for gene expression. Additionally, our approach illustrates several quantitative methods useful for assessing the performance of biomolecular feedback control systems.
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Affiliation(s)
- Deepak K. Agrawal
- Biomedical Engineering Department, Boston University, Boston, Massachusetts 02215, United States
| | - Xun Tang
- Department of Mechanical Engineering, University of California at Riverside, Riverside, California 92521, United States
| | - Alexandra Westbrook
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Ryan Marshall
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Colin S. Maxwell
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Julius Lucks
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Vincent Noireaux
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Chase L. Beisel
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
- Helmholtz Institute for RNA-Based Infection Research (HIRI), Josef-Schneider-Str. 2/D15, D-97080 Würzburg, Germany
| | - Mary J. Dunlop
- Biomedical Engineering Department, Boston University, Boston, Massachusetts 02215, United States
| | - Elisa Franco
- Department of Mechanical Engineering, University of California at Riverside, Riverside, California 92521, United States
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16
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Lloyd J, Tran CH, Wadhwani K, Cuba Samaniego C, Subramanian HKK, Franco E. Dynamic Control of Aptamer-Ligand Activity Using Strand Displacement Reactions. ACS Synth Biol 2018; 7:30-37. [PMID: 29028334 DOI: 10.1021/acssynbio.7b00277] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nucleic acid aptamers are an expandable toolkit of sensors and regulators. To employ aptamer regulators within nonequilibrium molecular networks, the aptamer-ligand interactions should be tunable over time, so that functions within a given system can be activated or suppressed on demand. This is accomplished through complementary sequences to aptamers, which achieve programmable aptamer-ligand dissociation by displacing the aptamer from the ligand. We demonstrate the effectiveness of our simple approach on light-up aptamers as well as on aptamers inhibiting viral RNA polymerases, dynamically controlling the functionality of the aptamer-ligand complex. Mathematical models allow us to obtain estimates for the aptamer displacement kinetics. Our results suggest that aptamers, paired with their complement, could be used to build dynamic nucleic acid networks with direct control over a variety of aptamer-controllable enzymes and their downstream pathways.
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Affiliation(s)
- Jonathan Lloyd
- Bioengineering, University of California at Riverside, Riverside, California 92521, United States
| | - Claire H. Tran
- Bioengineering, University of California at Riverside, Riverside, California 92521, United States
| | - Krishen Wadhwani
- Bioengineering, University of California at Riverside, Riverside, California 92521, United States
| | - Christian Cuba Samaniego
- Mechanical
Engineering, University of California at Riverside, Riverside, California 92521, United States
| | - Hari K. K. Subramanian
- Mechanical
Engineering, University of California at Riverside, Riverside, California 92521, United States
| | - Elisa Franco
- Mechanical
Engineering, University of California at Riverside, Riverside, California 92521, United States
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17
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Cuba Samaniego C, Giordano G, Blanchini F, Franco E. Stability analysis of an artificial biomolecular oscillator with non-cooperative regulatory interactions. JOURNAL OF BIOLOGICAL DYNAMICS 2017; 11:102-120. [PMID: 27830588 DOI: 10.1080/17513758.2016.1245790] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Oscillators are essential to fuel autonomous behaviours in molecular systems. Artificial oscillators built with programmable biological molecules such as DNA and RNA are generally easy to build and tune, and can serve as timers for biological computation and regulation. We describe a new artificial nucleic acid biochemical reaction network, and we demonstrate its capacity to exhibit oscillatory solutions. This network can be built in vitro using nucleic acids and three bacteriophage enzymes, and has the potential to be implemented in cells. Numerical simulations suggest that oscillations occur in a realistic range of reaction rates and concentrations.
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Affiliation(s)
| | - Giulia Giordano
- b Department of Automatic Control and LCCC Linnaeus Center , Lund University , Lund , Sweden
| | - Franco Blanchini
- c Mathematics and Computer Science , University of Udine , Udine , Italy
| | - Elisa Franco
- a Mechanical Engineering , University of California at Riverside , Riverside , CA , USA
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18
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Annunziata F, Matyjaszkiewicz A, Fiore G, Grierson CS, Marucci L, di Bernardo M, Savery NJ. An Orthogonal Multi-input Integration System to Control Gene Expression in Escherichia coli. ACS Synth Biol 2017; 6:1816-1824. [PMID: 28723080 DOI: 10.1021/acssynbio.7b00109] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In many biotechnological applications, it is useful for gene expression to be regulated by multiple signals, as this allows the programming of complex behavior. Here we implement, in Escherichia coli, a system that compares the concentration of two signal molecules, and tunes GFP expression proportionally to their relative abundance. The computation is performed via molecular titration between an orthogonal σ factor and its cognate anti-σ factor. We use mathematical modeling and experiments to show that the computation system is predictable and able to adapt GFP expression dynamically to a wide range of combinations of the two signals, and our model qualitatively captures most of these behaviors. We also demonstrate in silico the practical applicability of the system as a reference-comparator, which compares an intrinsic signal (reflecting the state of the system) with an extrinsic signal (reflecting the desired reference state) in a multicellular feedback control strategy.
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Affiliation(s)
- Fabio Annunziata
- School
of Biochemistry, University of Bristol, BS8 1TD, Bristol, U.K
- BrisSynBio, Bristol, BS8 1TQ, U.K
| | - Antoni Matyjaszkiewicz
- Department
of Engineering Mathematics, University of Bristol, BS8 1UB, Bristol, U.K
- BrisSynBio, Bristol, BS8 1TQ, U.K
| | - Gianfranco Fiore
- Department
of Engineering Mathematics, University of Bristol, BS8 1UB, Bristol, U.K
- BrisSynBio, Bristol, BS8 1TQ, U.K
| | - Claire S. Grierson
- School
of Biological Sciences, University of Bristol, BS8 1UH, Bristol, U.K
- BrisSynBio, Bristol, BS8 1TQ, U.K
| | - Lucia Marucci
- Department
of Engineering Mathematics, University of Bristol, BS8 1UB, Bristol, U.K
- BrisSynBio, Bristol, BS8 1TQ, U.K
| | - Mario di Bernardo
- Department
of Engineering Mathematics, University of Bristol, BS8 1UB, Bristol, U.K
- Department
of Electrical Engineering and Information Technology, University of Naples Federico II, 80125, Naples, Italy
- BrisSynBio, Bristol, BS8 1TQ, U.K
| | - Nigel J. Savery
- School
of Biochemistry, University of Bristol, BS8 1TD, Bristol, U.K
- BrisSynBio, Bristol, BS8 1TQ, U.K
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19
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Wong ASY, Huck WTS. Grip on complexity in chemical reaction networks. Beilstein J Org Chem 2017; 13:1486-1497. [PMID: 28845192 PMCID: PMC5550812 DOI: 10.3762/bjoc.13.147] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 07/11/2017] [Indexed: 01/06/2023] Open
Abstract
A new discipline of "systems chemistry" is emerging, which aims to capture the complexity observed in natural systems within a synthetic chemical framework. Living systems rely on complex networks of chemical reactions to control the concentration of molecules in space and time. Despite the enormous complexity in biological networks, it is possible to identify network motifs that lead to functional outputs such as bistability or oscillations. To truly understand how living systems function, we need a complete understanding of how chemical reaction networks (CRNs) create function. We propose the development of a bottom-up approach to design and construct CRNs where we can follow the influence of single chemical entities on the properties of the network as a whole. Ultimately, this approach should allow us to not only understand such complex networks but also to guide and control their behavior.
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Affiliation(s)
- Albert S Y Wong
- Institute for Molecular Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Wilhelm T S Huck
- Institute for Molecular Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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20
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Hakim AS, Omara ST, Syame SM, Fouad EA. Serotyping, antibiotic susceptibility, and virulence genes screening of Escherichia coli isolates obtained from diarrheic buffalo calves in Egyptian farms. Vet World 2017; 10:769-773. [PMID: 28831220 PMCID: PMC5553145 DOI: 10.14202/vetworld.2017.769-773] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 05/23/2017] [Indexed: 01/01/2023] Open
Abstract
AIM In Egypt as in many other countries, river water buffalo (Bubalus bubalis) is considered an important source of high-quality milk and meat supply. The objective of this study was to investigate serotypes, virulence genes, and antibiotic resistance determinants profiles of Escherichia coli isolated from buffalo at some places in Egypt; noticibly, this issue was not discussed in the country yet. MATERIALS AND METHODS A number of 58 rectal samples were collected from diarrheic buffalo calves in different regions in Egypt, and bacteriological investigated for E. coli existence. The E. coli isolates were biochemically, serologicaly identified, tested for antibiotic susceptibility, and polymerase chain reaction (PCR) analyzed for the presence of antibiotic resistance determinants and virulence genes. RESULTS Overall 14 isolates typed as E. coli (24.1%); 6 were belonged to serogroup O78 (10.3%), followed by O125 (4 isolates, 6.9%), then O158 (3 isolates, 5.2%) and one isolate O8 (1.7%), among them, there were 5 E. coli isolates showed a picture of hemolysis (35.7%). The isolates exhibited a high resistance to β lactams over 60%, followed by sulfa (50%) and aminoglucoside (42.8%) group, in the same time the isolates were sensitive to quinolone, trimethoprim-sulfamethoxazole, tetracycline (100%), and cephalosporine groups (71.4%). A multiplex PCR was applied to the 14 E. coli isolates revealed that all were carrying at least one gene, as 10 carried blaTEM (71.4%), 8 Sul1 (57.1%), and 6 aadB (42.8%), and 9 isolates could be considered multidrug resistant (MDR) by an incidence of 64.3%. A PCR survey was stratified for the most important E. coli virulence genes, and showed the presence of Shiga toxins in 9 isolates carried either one or the two Stx genes (64.3%), 5 isolates carried hylA gene (35.7%), and eae in 2 isolates only (14.3%), all isolates carried at least one virulence gene except two (85.7%). CONCLUSION The obtained data displayed that in Egypt, buffalo as well as other ruminants could be a potential source of MDR pathogenic E. coli variants which have a public health importance.
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Affiliation(s)
- Ashraf S Hakim
- Department of Microbiology and Immunology, National Research Centre, Dokki, Cairo, Egypt
| | - Shimaa T Omara
- Department of Microbiology and Immunology, National Research Centre, Dokki, Cairo, Egypt
| | - Sohier M Syame
- Department of Microbiology and Immunology, National Research Centre, Dokki, Cairo, Egypt
| | - Ehab A Fouad
- Department of Microbiology and Immunology, National Research Centre, Dokki, Cairo, Egypt
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21
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Cuba Samaniego C, Franco E. An ultrasensitive biomolecular network for robust feedback control. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/j.ifacol.2017.08.2466] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Wong ASY, Pogodaev AA, Vialshin IN, Helwig B, Huck WTS. Molecular Engineering of Robustness and Resilience in Enzymatic Reaction Networks. J Am Chem Soc 2017; 139:8146-8151. [PMID: 28582616 PMCID: PMC5481813 DOI: 10.1021/jacs.7b00632] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Living systems rely on complex networks of chemical reactions to control the concentrations of molecules in space and time. Despite the enormous complexity in biological networks, it is possible to identify network motifs that lead to functional outputs such as bistability or oscillations. One of the greatest challenges in chemistry is the creation of such functionality from chemical reactions. A key limitation is our lack of understanding of how molecular structure impacts on the dynamics of chemical reaction networks, preventing the design of networks that are robust (i.e., function in a large parameter space) and resilient (i.e., reach their out-of-equilibrium function rapidly). Here we demonstrate that reaction rates of individual reactions in the network can control the dynamics by which the system reaches limit cycle oscillations, thereby gaining information on the key parameters that govern the dynamics of these networks. We envision that these principles will be incorporated into the design of network motifs, enabling chemists to develop "molecular software" to create functional behavior in chemical systems.
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Affiliation(s)
- Albert S Y Wong
- Institute for Molecules and Materials, Radboud University Nijmegen , Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Aleksandr A Pogodaev
- Institute for Molecules and Materials, Radboud University Nijmegen , Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Ilia N Vialshin
- Institute for Molecules and Materials, Radboud University Nijmegen , Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Britta Helwig
- Institute for Molecules and Materials, Radboud University Nijmegen , Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Wilhelm T S Huck
- Institute for Molecules and Materials, Radboud University Nijmegen , Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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