1
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Roncarati D, Vannini A, Scarlato V. Temperature sensing and virulence regulation in pathogenic bacteria. Trends Microbiol 2024:S0966-842X(24)00180-X. [PMID: 39164134 DOI: 10.1016/j.tim.2024.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 07/16/2024] [Accepted: 07/23/2024] [Indexed: 08/22/2024]
Abstract
Pathogenic bacteria can detect a variety of environmental signals, including temperature changes. While sudden and significant temperature variations act as danger signals that trigger a protective heat-shock response, minor temperature fluctuations typically signal to the pathogen that it has moved from one environment to another, such as entering a specific niche within a host during infection. These latter temperature fluctuations are utilized by pathogens to coordinate the expression of crucial virulence factors. Here, we elucidate the critical role of temperature in governing the expression of virulence factors in bacterial pathogens. Moreover, we outline the molecular mechanisms used by pathogens to detect temperature fluctuations, focusing on systems that employ proteins and nucleic acids as sensory devices. We also discuss the potential implications and the extent of the risk that climate change poses to human pathogenic diseases.
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Affiliation(s)
- Davide Roncarati
- Department of Pharmacy and Biotechnology (FaBiT), Alma Mater Studiorum - University of Bologna, Bologna, Italy.
| | - Andrea Vannini
- Department of Pharmacy and Biotechnology (FaBiT), Alma Mater Studiorum - University of Bologna, Bologna, Italy
| | - Vincenzo Scarlato
- Department of Pharmacy and Biotechnology (FaBiT), Alma Mater Studiorum - University of Bologna, Bologna, Italy
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2
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Gola KK, Patel A, Sen S. Tradeoffs in the design of RNA thermometers. Phys Biol 2024; 21:044001. [PMID: 38949434 DOI: 10.1088/1478-3975/ad5d6b] [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: 02/14/2024] [Accepted: 07/01/2024] [Indexed: 07/02/2024]
Abstract
The synthesis of RNA thermometers is aimed at achieving temperature responses with desired thresholds and sensitivities. Although previous works have generated thermometers with a variety of thresholds and sensitivities as well as guidelines for design, possible constraints in the achievable thresholds and sensitivities remain unclear. We addressed this issue using a two-state model and its variants, as well as melt profiles generated from thermodynamic computations. In the two-state model, we found that the threshold was inversely proportional to the sensitivity, in the case of a fixed energy difference between the two states. Notably, this constraint could persist in variations of the two-state model with sequentially unfolding states and branched parallel pathways. Furthermore, the melt profiles generated from a library of thermometers exhibited a similar constraint. These results should inform the design of RNA thermometers as well as other responses that are mediated in a similar fashion.
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Affiliation(s)
- Krishan Kumar Gola
- Department of Electrical Engineering, Indian Institute of Technology Delhi, New Delhi, Delhi 110016, India
| | - Abhilash Patel
- Department of Electrical Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Shaunak Sen
- Department of Electrical Engineering, Indian Institute of Technology Delhi, New Delhi, Delhi 110016, India
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3
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Monck C, Elani Y, Ceroni F. Genetically programmed synthetic cells for thermo-responsive protein synthesis and cargo release. Nat Chem Biol 2024:10.1038/s41589-024-01673-7. [PMID: 38969863 DOI: 10.1038/s41589-024-01673-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 06/06/2024] [Indexed: 07/07/2024]
Abstract
Synthetic cells containing genetic programs and protein expression machinery are increasingly recognized as powerful counterparts to engineered living cells in the context of biotechnology, therapeutics and cellular modelling. So far, genetic regulation of synthetic cell activity has been largely confined to chemical stimuli; to unlock their potential in applied settings, engineering stimuli-responsive synthetic cells under genetic regulation is imperative. Here we report the development of temperature-sensitive synthetic cells that control protein production by exploiting heat-responsive mRNA elements. This is achieved by combining RNA thermometer technology, cell-free protein expression and vesicle-based synthetic cell design to create cell-sized capsules able to initiate synthesis of both soluble proteins and membrane proteins at defined temperatures. We show that the latter allows for temperature-controlled cargo release phenomena with potential implications for biomedicine. Platforms like the one presented here can pave the way for customizable, genetically programmed synthetic cells under thermal control to be used in biotechnology.
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Affiliation(s)
- Carolina Monck
- Department of Chemical Engineering, Imperial College London, London, UK
- Imperial College Centre for Synthetic Biology, London, UK
- fabriCELL, Imperial College London, London, UK
| | - Yuval Elani
- Department of Chemical Engineering, Imperial College London, London, UK.
- Imperial College Centre for Synthetic Biology, London, UK.
- fabriCELL, Imperial College London, London, UK.
| | - Francesca Ceroni
- Department of Chemical Engineering, Imperial College London, London, UK.
- Imperial College Centre for Synthetic Biology, London, UK.
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4
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Chung KP, Loiacono FV, Neupert J, Wu M, Bock R. An RNA thermometer in the chloroplast genome of Chlamydomonas facilitates temperature-controlled gene expression. Nucleic Acids Res 2023; 51:11386-11400. [PMID: 37855670 PMCID: PMC10639063 DOI: 10.1093/nar/gkad816] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/01/2023] [Accepted: 09/20/2023] [Indexed: 10/20/2023] Open
Abstract
Riboregulators such as riboswitches and RNA thermometers provide simple, protein-independent tools to control gene expression at the post-transcriptional level. In bacteria, RNA thermometers regulate protein synthesis in response to temperature shifts. Thermometers outside of the bacterial world are rare, and in organellar genomes, no RNA thermometers have been identified to date. Here we report the discovery of an RNA thermometer in a chloroplast gene of the unicellular green alga Chlamydomonas reinhardtii. The thermometer, residing in the 5' untranslated region of the psaA messenger RNA forms a hairpin-type secondary structure that masks the Shine-Dalgarno sequence at 25°C. At 40°C, melting of the secondary structure increases accessibility of the Shine-Dalgarno sequence to initiating ribosomes, thus enhancing protein synthesis. By targeted nucleotide substitutions and transfer of the thermometer into Escherichia coli, we show that the secondary structure is necessary and sufficient to confer the thermometer properties. We also demonstrate that the thermometer provides a valuable tool for inducible transgene expression from the Chlamydomonas plastid genome, in that a simple temperature shift of the algal culture can greatly increase recombinant protein yields.
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Affiliation(s)
- Kin Pan Chung
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - F Vanessa Loiacono
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Juliane Neupert
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Mengting Wu
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Department Organelle Biology, Biotechnology and Molecular Ecophysiology, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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5
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Developing New Tools to Fight Human Pathogens: A Journey through the Advances in RNA Technologies. Microorganisms 2022; 10:microorganisms10112303. [DOI: 10.3390/microorganisms10112303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 11/12/2022] [Accepted: 11/15/2022] [Indexed: 11/22/2022] Open
Abstract
A long scientific journey has led to prominent technological advances in the RNA field, and several new types of molecules have been discovered, from non-coding RNAs (ncRNAs) to riboswitches, small interfering RNAs (siRNAs) and CRISPR systems. Such findings, together with the recognition of the advantages of RNA in terms of its functional performance, have attracted the attention of synthetic biologists to create potent RNA-based tools for biotechnological and medical applications. In this review, we have gathered the knowledge on the connection between RNA metabolism and pathogenesis in Gram-positive and Gram-negative bacteria. We further discuss how RNA techniques have contributed to the building of this knowledge and the development of new tools in synthetic biology for the diagnosis and treatment of diseases caused by pathogenic microorganisms. Infectious diseases are still a world-leading cause of death and morbidity, and RNA-based therapeutics have arisen as an alternative way to achieve success. There are still obstacles to overcome in its application, but much progress has been made in a fast and effective manner, paving the way for the solid establishment of RNA-based therapies in the future.
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6
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Xiong LL, Garrett MA, Buss MT, Kornfield JA, Shapiro MG. Tunable Temperature-Sensitive Transcriptional Activation Based on Lambda Repressor. ACS Synth Biol 2022; 11:2518-2522. [PMID: 35708251 PMCID: PMC9295150 DOI: 10.1021/acssynbio.2c00093] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Temperature is a
versatile input signal for the control of engineered
cellular functions. Sharp induction of gene expression with heat has
been established using bacteria- and phage-derived temperature-sensitive
transcriptional repressors with tunable switching temperatures. However,
few temperature-sensitive transcriptional activators have been reported
that enable direct gene induction with cooling. Such activators would
expand the application space for temperature control. In this technical
note, we show that temperature-dependent versions of the Lambda phage
repressor CI can serve as tunable cold-actuated transactivators. Natively,
CI serves as both a repressor and activator of transcription. Previously,
thermolabile mutants of CI, known as the TcI family, were used to
repress the cognate promoters PR and PL. We hypothesized that TcI
mutants can also serve as temperature-sensitive activators of transcription
at CI’s natural PRM promoter, creating cold-inducible operons
with a tunable response to temperature. Indeed, we demonstrate temperature-responsive
activation by two variants of TcI with set points at 35.5 and 38.5
°C in E. coli. In addition, we show that
TcI can serve as both an activator and a repressor of different genes
in the same genetic circuit, leading to opposite thermal responses.
Transcriptional activation by TcI expands the toolbox for control
of cellular function using globally or locally applied thermal inputs.
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Affiliation(s)
- Lealia L Xiong
- Division of Engineering and Applied Sciences, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, United States
| | - Michael A Garrett
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, United States
| | - Marjorie T Buss
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, United States
| | - Julia A Kornfield
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, United States
| | - Mikhail G Shapiro
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, United States.,Howard Hughes Medical Institute, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, United States
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7
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Gao Y, Thiele W, Saleh O, Scossa F, Arabi F, Zhang H, Sampathkumar A, Kühn K, Fernie A, Bock R, Schöttler MA, Zoschke R. Chloroplast translational regulation uncovers nonessential photosynthesis genes as key players in plant cold acclimation. THE PLANT CELL 2022; 34:2056-2079. [PMID: 35171295 PMCID: PMC9048916 DOI: 10.1093/plcell/koac056] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 02/12/2022] [Indexed: 05/04/2023]
Abstract
Plants evolved efficient multifaceted acclimation strategies to cope with low temperatures. Chloroplasts respond to temperature stimuli and participate in temperature sensing and acclimation. However, very little is known about the involvement of chloroplast genes and their expression in plant chilling tolerance. Here we systematically investigated cold acclimation in tobacco seedlings over 2 days of exposure to low temperatures by examining responses in chloroplast genome copy number, transcript accumulation and translation, photosynthesis, cell physiology, and metabolism. Our time-resolved genome-wide investigation of chloroplast gene expression revealed substantial cold-induced translational regulation at both the initiation and elongation levels, in the virtual absence of changes at the transcript level. These cold-triggered dynamics in chloroplast translation are widely distinct from previously described high light-induced effects. Analysis of the gene set responding significantly to the cold stimulus suggested nonessential plastid-encoded subunits of photosynthetic protein complexes as novel players in plant cold acclimation. Functional characterization of one of these cold-responsive chloroplast genes by reverse genetics demonstrated that the encoded protein, the small cytochrome b6f complex subunit PetL, crucially contributes to photosynthetic cold acclimation. Together, our results uncover an important, previously underappreciated role of chloroplast translational regulation in plant cold acclimation.
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Affiliation(s)
- Yang Gao
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Wolfram Thiele
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Omar Saleh
- Institut für Biologie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), 06120, Germany
| | - Federico Scossa
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
- Council for Agricultural Research and Economics, Research Center for Genomics and Bioinformatics (CREA-GB), Rome, 00178, Italy
| | - Fayezeh Arabi
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Hongmou Zhang
- Institute of Optical Sensor Systems, German Aerospace Center (DLR), Berlin, 12489, Germany
| | - Arun Sampathkumar
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Kristina Kühn
- Institut für Biologie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), 06120, Germany
| | - Alisdair Fernie
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Ralph Bock
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Mark A Schöttler
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
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8
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Gao Y, Thiele W, Saleh O, Scossa F, Arabi F, Zhang H, Sampathkumar A, Kühn K, Fernie A, Bock R, Schöttler MA, Zoschke R. Chloroplast translational regulation uncovers nonessential photosynthesis genes as key players in plant cold acclimation. THE PLANT CELL 2022; 34:2056-2079. [PMID: 35171295 DOI: 10.1093/plcell/koac056%jtheplantcell] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 02/12/2022] [Indexed: 05/28/2023]
Abstract
Plants evolved efficient multifaceted acclimation strategies to cope with low temperatures. Chloroplasts respond to temperature stimuli and participate in temperature sensing and acclimation. However, very little is known about the involvement of chloroplast genes and their expression in plant chilling tolerance. Here we systematically investigated cold acclimation in tobacco seedlings over 2 days of exposure to low temperatures by examining responses in chloroplast genome copy number, transcript accumulation and translation, photosynthesis, cell physiology, and metabolism. Our time-resolved genome-wide investigation of chloroplast gene expression revealed substantial cold-induced translational regulation at both the initiation and elongation levels, in the virtual absence of changes at the transcript level. These cold-triggered dynamics in chloroplast translation are widely distinct from previously described high light-induced effects. Analysis of the gene set responding significantly to the cold stimulus suggested nonessential plastid-encoded subunits of photosynthetic protein complexes as novel players in plant cold acclimation. Functional characterization of one of these cold-responsive chloroplast genes by reverse genetics demonstrated that the encoded protein, the small cytochrome b6f complex subunit PetL, crucially contributes to photosynthetic cold acclimation. Together, our results uncover an important, previously underappreciated role of chloroplast translational regulation in plant cold acclimation.
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Affiliation(s)
- Yang Gao
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Wolfram Thiele
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Omar Saleh
- Institut für Biologie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), 06120, Germany
| | - Federico Scossa
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
- Council for Agricultural Research and Economics, Research Center for Genomics and Bioinformatics (CREA-GB), Rome, 00178, Italy
| | - Fayezeh Arabi
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Hongmou Zhang
- Institute of Optical Sensor Systems, German Aerospace Center (DLR), Berlin, 12489, Germany
| | - Arun Sampathkumar
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Kristina Kühn
- Institut für Biologie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), 06120, Germany
| | - Alisdair Fernie
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Ralph Bock
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Mark A Schöttler
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Reimo Zoschke
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
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9
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Dykstra PB, Kaplan M, Smolke CD. Engineering synthetic RNA devices for cell control. Nat Rev Genet 2022; 23:215-228. [PMID: 34983970 PMCID: PMC9554294 DOI: 10.1038/s41576-021-00436-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2021] [Indexed: 12/16/2022]
Abstract
The versatility of RNA in sensing and interacting with small molecules, proteins and other nucleic acids while encoding genetic instructions for protein translation makes it a powerful substrate for engineering biological systems. RNA devices integrate cellular information sensing, processing and actuation of specific signals into defined functions and have yielded programmable biological systems and novel therapeutics of increasing sophistication. However, challenges centred on expanding the range of analytes that can be sensed and adding new mechanisms of action have hindered the full realization of the field's promise. Here, we describe recent advances that address these limitations and point to a significant maturation of synthetic RNA-based devices.
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Affiliation(s)
- Peter B. Dykstra
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Matias Kaplan
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Christina D. Smolke
- Department of Bioengineering, Stanford University, Stanford, CA, USA.,Chan Zuckerberg Biohub, San Francisco, CA, USA.,
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10
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Sharma A, Alajangi HK, Pisignano G, Sood V, Singh G, Barnwal RP. RNA thermometers and other regulatory elements: Diversity and importance in bacterial pathogenesis. WILEY INTERDISCIPLINARY REVIEWS. RNA 2022; 13:e1711. [PMID: 35037405 DOI: 10.1002/wrna.1711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 11/09/2021] [Accepted: 12/16/2021] [Indexed: 01/11/2023]
Abstract
Survival of microorganisms depends to a large extent on environmental conditions and the occupied host. By adopting specific strategies, microorganisms can thrive in the surrounding environment and, at the same time, preserve their viability. Evading the host defenses requires several mechanisms compatible with the host survival which include the production of RNA thermometers to regulate the expression of genes responsible for heat or cold shock as well as of those involved in virulence. Microorganisms have developed a variety of molecules in response to the environmental changes in temperature and even more specifically to the host they invade. Among all, RNA-based regulatory mechanisms are the most common ones, highlighting the importance of such molecules in gene expression control and novel drug development by suitable structure-based alterations. This article is categorized under: RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry RNA in Disease and Development > RNA in Disease RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems.
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Affiliation(s)
- Akanksha Sharma
- Department of Biophysics, Panjab University, Chandigarh, India.,University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India
| | - Hema Kumari Alajangi
- Department of Biophysics, Panjab University, Chandigarh, India.,University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India
| | | | - Vikas Sood
- Department of Biochemistry, Jamia Hamdard, New Delhi, India
| | - Gurpal Singh
- University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India
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11
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Chee WKD, Yeoh JW, Dao VL, Poh CL. Thermogenetics: Applications come of age. Biotechnol Adv 2022; 55:107907. [PMID: 35041863 DOI: 10.1016/j.biotechadv.2022.107907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/13/2021] [Accepted: 01/09/2022] [Indexed: 12/20/2022]
Abstract
Temperature is a ubiquitous physical cue that is non-invasive, penetrative and easy to apply. In the growing field of thermogenetics, through beneficial repurposing of natural thermosensing mechanisms, synthetic biology is bringing new opportunities to design and build robust temperature-sensitive (TS) sensors which forms a thermogenetic toolbox of well characterised biological parts. Recent advancements in technological platforms available have expedited the discovery of novel or de novo thermosensors which are increasingly deployed in many practical temperature-dependent biomedical, industrial and biosafety applications. In all, the review aims to convey both the exhilarating recent technological developments underlying the advancement of thermosensors and the exciting opportunities the nascent thermogenetic field holds for biomedical and biotechnology applications.
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Affiliation(s)
- Wai Kit David Chee
- Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore; NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, 28 Medical Drive, Singapore 117456, Singapore
| | - Jing Wui Yeoh
- Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore; NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, 28 Medical Drive, Singapore 117456, Singapore
| | - Viet Linh Dao
- Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore; NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, 28 Medical Drive, Singapore 117456, Singapore
| | - Chueh Loo Poh
- Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore; NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, 28 Medical Drive, Singapore 117456, Singapore.
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12
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Smith JM, Chowdhry R, Booth MJ. Controlling Synthetic Cell-Cell Communication. Front Mol Biosci 2022; 8:809945. [PMID: 35071327 PMCID: PMC8766733 DOI: 10.3389/fmolb.2021.809945] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 12/13/2021] [Indexed: 11/28/2022] Open
Abstract
Synthetic cells, which mimic cellular function within a minimal compartment, are finding wide application, for instance in studying cellular communication and as delivery devices to living cells. However, to fully realise the potential of synthetic cells, control of their function is vital. An array of tools has already been developed to control the communication of synthetic cells to neighbouring synthetic cells or living cells. These tools use either chemical inputs, such as small molecules, or physical inputs, such as light. Here, we examine these current methods of controlling synthetic cell communication and consider alternative mechanisms for future use.
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Affiliation(s)
| | | | - Michael J. Booth
- Chemistry Research Laboratory, University of Oxford, Oxford, United Kingdom
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13
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Sen S, Patel A, Gola KK. Design of a Toolbox of RNA Thermometers. Methods Mol Biol 2022; 2518:125-133. [PMID: 35666443 DOI: 10.1007/978-1-0716-2421-0_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
RNA thermometers are RNA regulatory elements that convert temperature into a functional biological response through a temperature-induced conformational change. These regulatory elements have been investigated in numerous natural contexts and have been designed for synthetic biology as well. A basic challenge has been the design of an RNA thermometer whose final activity in response to temperature matches a prespecified response, in terms of its sensitivity, threshold, and leakiness. This chapter provides a methodology for the design of a toolbox of RNA thermometers. We describe considerations for the conceptual design, a computational assessment, and strategies for experimental synthesis and measurement.
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Affiliation(s)
- Shaunak Sen
- Department of Electrical Engineering, IIT Delhi, New Delhi, India.
| | - Abhilash Patel
- Department of Bioengineering, Imperial College, London, UK
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14
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Aratboni HA, Rafiei N, Khorashad LK, Lerma-Escalera AI, Balderas-Cisneros FDJ, Liu Z, Alemzadeh A, Shaji S, Morones-Ramírez JR. LED control of gene expression in a nanobiosystem composed of metallic nanoparticles and a genetically modified E. coli strain. J Nanobiotechnology 2021; 19:190. [PMID: 34174890 PMCID: PMC8236197 DOI: 10.1186/s12951-021-00937-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 06/12/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Within the last decade, genetic engineering and synthetic biology have revolutionized society´s ability to mass-produce complex biological products within genetically-modified microorganisms containing elegantly designed genetic circuitry. However, many challenges still exist in developing bioproduction processes involving genetically modified microorganisms with complex or multiple gene circuits. These challenges include the development of external gene expression regulation methods with the following characteristics: spatial-temporal control and scalability, while inducing minimal permanent or irreversible system-wide conditions. Different stimuli have been used to control gene expression and mitigate these challenges, and they can be characterized by the effect they produce in the culture media conditions. Invasive stimuli that cause permanent, irreversible changes (pH and chemical inducers), non-invasive stimuli that cause partially reversible changes (temperature), and non-invasive stimuli that cause reversible changes in the media conditions (ultrasound, magnetic fields, and light). METHODS Opto-control of gene expression is a non-invasive external trigger that complies with most of the desired characteristics of an external control system. However, the disadvantage relies on the design of the biological photoreceptors and the necessity to design them to respond to a different wavelength for every bioprocess needed to be controlled or regulated in the microorganism. Therefore, this work proposes using biocompatible metallic nanoparticles as external controllers of gene expression, based on their ability to convert light into heat and the capacity of nanotechnology to easily design a wide array of nanostructures capable of absorbing light at different wavelengths and inducing plasmonic photothermal heating. RESULTS Here, we designed a nanobiosystem that can be opto-thermally triggered using LED light. The nanobiosystem is composed of biocompatible gold nanoparticles and a genetically modified E. coli with a plasmid that allows mCherry fluorescent protein production at 37 °C in response to an RNA thermometer. CONCLUSIONS The LED-triggered photothermal protein production system here designed offers a new, cheaper, scalable switchable method, non-destructive for living organisms, and contribute toward the evolution of bioprocess production systems.
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Affiliation(s)
- Hossein Alishah Aratboni
- Universidad Autónoma de Nuevo León, UANL. Facultad de Ciencias Químicas, Av. Universidad s/n. CD. Universitaria, San Nicolás de los Garza, 66451, Nuevo León, México
- Centro de Investigación en Biotecnología y Nanotecnología, Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León. Parque de Investigación e Innovación Tecnológica, Km. 10 autopista al Aeropuerto Internacional Mariano Escobedo, 66629, Apodaca, Nuevo León, México
| | - Nahid Rafiei
- Universidad Autónoma de Nuevo León, UANL. Facultad de Ciencias Químicas, Av. Universidad s/n. CD. Universitaria, San Nicolás de los Garza, 66451, Nuevo León, México
- Centro de Investigación en Biotecnología y Nanotecnología, Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León. Parque de Investigación e Innovación Tecnológica, Km. 10 autopista al Aeropuerto Internacional Mariano Escobedo, 66629, Apodaca, Nuevo León, México
- Department of Crop Production and Plant Breeding, School of Agriculture, Shiraz University, Km. 12 Shiraz-Isfahan highway, Bajgah area, 71441-65186, Shiraz, Iran
| | - Larousse Khosravi Khorashad
- Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Albert Isaac Lerma-Escalera
- Universidad Autónoma de Nuevo León, UANL. Facultad de Ciencias Químicas, Av. Universidad s/n. CD. Universitaria, San Nicolás de los Garza, 66451, Nuevo León, México
- Centro de Investigación en Biotecnología y Nanotecnología, Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León. Parque de Investigación e Innovación Tecnológica, Km. 10 autopista al Aeropuerto Internacional Mariano Escobedo, 66629, Apodaca, Nuevo León, México
| | - Francisco de Jesús Balderas-Cisneros
- Universidad Autónoma de Nuevo León, UANL. Facultad de Ciencias Químicas, Av. Universidad s/n. CD. Universitaria, San Nicolás de los Garza, 66451, Nuevo León, México
- Centro de Investigación en Biotecnología y Nanotecnología, Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León. Parque de Investigación e Innovación Tecnológica, Km. 10 autopista al Aeropuerto Internacional Mariano Escobedo, 66629, Apodaca, Nuevo León, México
| | - Zhaowei Liu
- Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Abbas Alemzadeh
- Department of Crop Production and Plant Breeding, School of Agriculture, Shiraz University, Km. 12 Shiraz-Isfahan highway, Bajgah area, 71441-65186, Shiraz, Iran.
| | - Sadasivan Shaji
- Universidad Autónoma de Nuevo León, UANL. Facultad de ingeniería mecánica y eléctrica, Universidad s/n. CD. Universitaria, 66451, Nuevo León, San Nicolás de los Garza, México
| | - José Ruben Morones-Ramírez
- Universidad Autónoma de Nuevo León, UANL. Facultad de Ciencias Químicas, Av. Universidad s/n. CD. Universitaria, San Nicolás de los Garza, 66451, Nuevo León, México.
- Centro de Investigación en Biotecnología y Nanotecnología, Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León. Parque de Investigación e Innovación Tecnológica, Km. 10 autopista al Aeropuerto Internacional Mariano Escobedo, 66629, Apodaca, Nuevo León, México.
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15
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Restrepo-Pineda S, Pérez NO, Valdez-Cruz NA, Trujillo-Roldán MA. Thermoinducible expression system for producing recombinant proteins in Escherichia coli: advances and insights. FEMS Microbiol Rev 2021; 45:6223457. [PMID: 33844837 DOI: 10.1093/femsre/fuab023] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 04/09/2021] [Indexed: 12/13/2022] Open
Abstract
Recombinant protein (RP) production from Escherichia coli has been extensively studied to find strategies for increasing product yields. The thermoinducible expression system is commonly employed at the industrial level to produce various RPs which avoids the addition of chemical inducers, thus minimizing contamination risks. Multiple aspects of the molecular origin and biotechnological uses of its regulatory elements (pL/pR promoters and cI857 thermolabile repressor) derived from bacteriophage λ provide knowledge to improve the bioprocesses using this system. Here, we discuss the main aspects of the potential use of the λpL/pR-cI857 thermoinducible system for RP production in E. coli, focusing on the approaches of investigations that have contributed to the advancement of this expression system. Metabolic and physiological changes that occur in the host cells caused by heat stress and by RP overproduction are also described. Therefore, the current scenario and the future applications of systems that use heat to induce RP production is discussed to understand the relationship between the activation of the bacterial heat shock response, RP accumulation, and its possible aggregation to form inclusion bodies.
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Affiliation(s)
- Sara Restrepo-Pineda
- Unidad de Bioprocesos, Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510, Ciudad de México, México
| | - Néstor O Pérez
- Probiomed S.A. de C.V. Planta Tenancingo, Cruce de Carreteras Acatzingo-Zumpahuacan SN, 52400 Tenancingo, Estado de México, México
| | - Norma A Valdez-Cruz
- Unidad de Bioprocesos, Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510, Ciudad de México, México
| | - Mauricio A Trujillo-Roldán
- Unidad de Bioprocesos, Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510, Ciudad de México, México
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16
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Gawroński P, Enroth C, Kindgren P, Marquardt S, Karpiński S, Leister D, Jensen PE, Vinther J, Scharff LB. Light-Dependent Translation Change of Arabidopsis psbA Correlates with RNA Structure Alterations at the Translation Initiation Region. Cells 2021; 10:322. [PMID: 33557293 PMCID: PMC7914831 DOI: 10.3390/cells10020322] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 01/26/2021] [Accepted: 01/29/2021] [Indexed: 01/21/2023] Open
Abstract
mRNA secondary structure influences translation. Proteins that modulate the mRNA secondary structure around the translation initiation region may regulate translation in plastids. To test this hypothesis, we exposed Arabidopsis thaliana to high light, which induces translation of psbA mRNA encoding the D1 subunit of photosystem II. We assayed translation by ribosome profiling and applied two complementary methods to analyze in vivo RNA secondary structure: DMS-MaPseq and SHAPE-seq. We detected increased accessibility of the translation initiation region of psbA after high light treatment, likely contributing to the observed increase in translation by facilitating translation initiation. Furthermore, we identified the footprint of a putative regulatory protein in the 5' UTR of psbA at a position where occlusion of the nucleotide sequence would cause the structure of the translation initiation region to open up, thereby facilitating ribosome access. Moreover, we show that other plastid genes with weak Shine-Dalgarno sequences (SD) are likely to exhibit psbA-like regulation, while those with strong SDs do not. This supports the idea that changes in mRNA secondary structure might represent a general mechanism for translational regulation of psbA and other plastid genes.
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Affiliation(s)
- Piotr Gawroński
- Department of Plant Genetics, Breeding and Biotechnology, Institute of Biology, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland; (P.G.); (S.K.)
| | - Christel Enroth
- Department of Biology, Section for Computational and RNA Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 København N, Denmark; (C.E.); (J.V.)
| | - Peter Kindgren
- Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark; (P.K.); (S.M.)
| | - Sebastian Marquardt
- Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark; (P.K.); (S.M.)
| | - Stanisław Karpiński
- Department of Plant Genetics, Breeding and Biotechnology, Institute of Biology, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland; (P.G.); (S.K.)
| | - Dario Leister
- Plant Molecular Biology, Department Biology I, Ludwig-Maximilians-University Munich, Großhadernerstr. 2-4, 82152 Planegg-Martinsried, Germany;
| | - Poul Erik Jensen
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark;
| | - Jeppe Vinther
- Department of Biology, Section for Computational and RNA Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 København N, Denmark; (C.E.); (J.V.)
| | - Lars B. Scharff
- Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark; (P.K.); (S.M.)
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17
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Abstract
One of the fundamental properties of engineered large-scale complex systems is modularity. In synthetic biology, genetic parts exhibit context-dependent behavior. Here, we describe and quantify a major source of such behavior: retroactivity. In particular, we provide a step-by-step guide for characterizing retroactivity to restore the modular description of genetic modules. Additionally, we also discuss how retroactivity can be leveraged to quantify and maximize robustness to perturbations due to interconnection of genetic modules.
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Affiliation(s)
- Andras Gyorgy
- New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.
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18
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Abstract
Expression of transgenes from the plastid genome offers a number of attractions to biotechnologists, with the potential to attain very high protein accumulation levels arguably being the most attractive one. High-level transgene expression is of particular importance in resistance engineering (e.g., for expression of insecticidal proteins) and molecular farming (e.g., for expression of pharmaceutical proteins and industrial enzymes). Over the past decades, the production of many commercially valuable proteins in chloroplast-transgenic (transplastomic) plants has been attempted, including pharmaceutical proteins (e.g., subunit vaccines and protein antibiotics) and industrial enzymes. Although in some cases, spectacularly high foreign protein accumulation levels have been obtained, expression levels were disappointingly poor in other cases. In this review, I summarize our current knowledge about the factors influencing the efficiency of plastid transgene expression, and highlight possible optimization strategies to alleviate problems with poor expression levels. I also discuss available techniques for inducible expression of chloroplast transgenes.
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19
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Zhang H, Hall I, Nissley AJ, Abdallah K, Keane SC. A Tale of Two Transitions: The Unfolding Mechanism of the prfA RNA Thermosensor. Biochemistry 2020; 59:4533-4545. [PMID: 33231432 DOI: 10.1021/acs.biochem.0c00588] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
RNA thermosensors (RNATs), found in the 5' untranslated region (UTR) of some bacterial messenger RNAs (mRNAs), control the translation of the downstream gene in a temperature-dependent manner. In Listeria monocytogenes, the expression of a key transcription factor, PrfA, is mediated by an RNAT in its 5' UTR. PrfA functions as a master regulator of virulence in L. monocytogenes, controlling the expression of many virulence factors. The temperature-regulated expression of PrfA by its RNAT element serves as a signal of successful host invasion for the bacteria. Structurally, the prfA RNAT bears little resemblance to known families of RNATs, and prior studies demonstrated that the prfA RNAT is highly responsive over a narrow temperature range. Herein, we have undertaken a comprehensive mutational and thermodynamic analysis to ascertain the molecular determinants of temperature sensitivity. We provide evidence to support the idea that the prfA RNAT unfolding is different from that of cssA, a well-characterized RNAT, suggesting that these RNATs function via distinct mechanisms. Our data show that the unfolding of the prfA RNAT occurs in two distinct events and that the internal loops play an important role in mediating the cooperativity of RNAT unfolding. We further demonstrated that regions distal to the ribosome binding site (RBS) not only contribute to RNAT structural stability but also impact translation of the downstream message. Our collective results provide insight connecting the thermal stability of the prfA RNAT structure, unfolding energetics, and translational control.
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Affiliation(s)
- Huaqun Zhang
- Biophysics Program, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Ian Hall
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Amos J Nissley
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kyrillos Abdallah
- Biophysics Program, University of Michigan, Ann Arbor, Michigan 48109, United States.,Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Sarah C Keane
- Biophysics Program, University of Michigan, Ann Arbor, Michigan 48109, United States.,Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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20
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Montagud-Martínez R, Ventura J, Ballesteros-Garrido R, Rosado A, Rodrigo G. Probing the operability regime of an engineered ribocomputing unit in terms of dynamic range maintenance with extracellular changes and time. J Biol Eng 2020; 14:12. [PMID: 32226483 PMCID: PMC7098154 DOI: 10.1186/s13036-020-00234-5] [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: 11/07/2019] [Accepted: 03/10/2020] [Indexed: 11/16/2022] Open
Abstract
Synthetic biology aims at engineering gene regulatory circuits to end with cells (re)programmed on purpose to implement novel functions or discover natural behaviors. However, one overlooked question is whether the resulting circuits perform as intended in variety of environments or with time. Here, we considered a recently engineered genetic system that allows programming the cell to work as a minimal computer (arithmetic logic unit) in order to analyze its operability regime. This system involves transcriptional and post-transcriptional regulations. In particular, we studied the analog behavior of the system, the effect of physicochemical changes in the environment, the impact on cell growth rate of the heterologous expression, and the ability to maintain the arithmetic functioning over time. Conclusively, our results suggest 1) that there are wide input concentration ranges that the system can correctly process, the resulting outputs being predictable with a simple mathematical model, 2) that the engineered circuitry is quite sensitive to temperature effects, 3) that the expression of heterologous small RNAs is costly for the cell, not only of heterologous proteins, and 4) that a proper genetic reorganization of the system to reduce the amount of heterologous DNA in the cell can improve its evolutionary stability.
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Affiliation(s)
- Roser Montagud-Martínez
- 1Institute for Integrative Systems Biology (I2SysBio), CSIC - University of Valencia, 46980 Paterna, Valencia Spain
| | - Jordi Ventura
- 1Institute for Integrative Systems Biology (I2SysBio), CSIC - University of Valencia, 46980 Paterna, Valencia Spain
| | - Rafael Ballesteros-Garrido
- 1Institute for Integrative Systems Biology (I2SysBio), CSIC - University of Valencia, 46980 Paterna, Valencia Spain.,2Present address: Department of Organic Chemistry, University of Valencia, 46100 Burjassot, Valencia Spain
| | - Arantxa Rosado
- 1Institute for Integrative Systems Biology (I2SysBio), CSIC - University of Valencia, 46980 Paterna, Valencia Spain
| | - Guillermo Rodrigo
- 1Institute for Integrative Systems Biology (I2SysBio), CSIC - University of Valencia, 46980 Paterna, Valencia Spain
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21
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Schramm T, Lempp M, Beuter D, Sierra SG, Glatter T, Link H. High-throughput enrichment of temperature-sensitive argininosuccinate synthetase for two-stage citrulline production in E. coli. Metab Eng 2020; 60:14-24. [PMID: 32179161 PMCID: PMC7225747 DOI: 10.1016/j.ymben.2020.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 03/03/2020] [Accepted: 03/08/2020] [Indexed: 12/20/2022]
Abstract
Controlling metabolism of engineered microbes is important to modulate cell growth and production during a bioprocess. For example, external parameters such as light, chemical inducers, or temperature can act on metabolism of production strains by changing the abundance or activity of enzymes. Here, we created temperature-sensitive variants of an essential enzyme in arginine biosynthesis of Escherichia coli (argininosuccinate synthetase, ArgG) and used them to dynamically control citrulline overproduction and growth of E. coli. We show a method for high-throughput enrichment of temperature-sensitive ArgG variants with a fluorescent TIMER protein and flow cytometry. With 90 of the thus derived ArgG variants, we complemented an ArgG deletion strain showing that 90% of the strains exhibit temperature-sensitive growth and 69% of the strains are auxotrophic for arginine at 42 °C and prototrophic at 30 °C. The best temperature-sensitive ArgG variant enabled precise and tunable control of cell growth by temperature changes. Expressing this variant in a feedback-dysregulated E. coli strain allowed us to realize a two-stage bioprocess: a 33 °C growth-phase for biomass accumulation and a 39 °C stationary-phase for citrulline production. With this two-stage strategy, we produced 3 g/L citrulline during 45 h cultivation in a 1-L bioreactor. These results show that temperature-sensitive enzymes can be created en masse and that they may function as metabolic valves in engineered bacteria. Method to enrich temperature-sensitive enzymes en masse. Temperature-sensitive enzymes function as metabolic valve. Temperature controlled two-stage production of citrulline.
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Affiliation(s)
- Thorben Schramm
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Martin Lempp
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Dominik Beuter
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Silvia González Sierra
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Timo Glatter
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Hannes Link
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany.
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22
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Armarego-Marriott T. Ralph Bock. THE PLANT CELL 2020; 32:4-6. [PMID: 31748332 PMCID: PMC6961626 DOI: 10.1105/tpc.19.00894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
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23
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Noll P, Treinen C, Müller S, Senkalla S, Lilge L, Hausmann R, Henkel M. Evaluating temperature-induced regulation of a ROSE-like RNA-thermometer for heterologous rhamnolipid production in Pseudomonas putida KT2440. AMB Express 2019; 9:154. [PMID: 31555921 PMCID: PMC6761213 DOI: 10.1186/s13568-019-0883-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 09/17/2019] [Indexed: 11/24/2022] Open
Abstract
The microbial production of rhamnolipids has been in the focus of research for the last decades. Today, mainly heterologous production systems are targeted due to the advantage of non-pathogenic hosts as well as uncoupling from complex quorum sensing regulatory networks compared to their natural producer Pseudomonas aeruginosa. In the recent past, the presence and function of a ROSE-like RNA-thermometer located in the 5′UTR of the rhamnosyltransferase genes rhlAB has been reported in wild type P. aeruginosa. In this study, the temperature-induced regulation of this native RNA-thermometer for heterologous rhamnolipid production was evaluated and its potential application for process control is discussed. For this purpose, the non-pathogenic production host P. putida KT2440 containing the rhlAB genes with the native P. aeruginosa 5′-UTR region was used. The system was evaluated and characterized regarding the effect of temperature on growth and product formation, as represented by efficiency parameters and yields. Experimental data suggests a major effect of temperature on specific rhamnolipid production rates. With maximum values of 0.23 g/(g h) at 37 °C, this constitutes a more than 60% increase compared to the production rate of 0.14 g/(g h) at the growth optimum of 30 °C. Interestingly however, control experiments unveiled that besides the regulatory effect of the RNA-thermometer, multiple metabolic effects may contribute equally to the observed increase in production rate. As such, this work constitutes an important step towards the utilization of temperature-based process designs and enables the possibility for novel approaches for process control.
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24
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Verdú C, Sanchez E, Ortega C, Hidalgo A, Berenguer J, Mencía M. A Modular Vector Toolkit with a Tailored Set of Thermosensors To Regulate Gene Expression in Thermus thermophilus. ACS OMEGA 2019; 4:14626-14632. [PMID: 31528818 PMCID: PMC6740178 DOI: 10.1021/acsomega.9b02107] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 08/14/2019] [Indexed: 05/02/2023]
Abstract
Modular plasmid architectures have shown to be a very useful resource to standardize, build, share, and compare biological parts and functional vectors, and are being applied in an increasing number of microorganisms. Here, we present a modular plasmid toolkit for Thermus thermophilus, a species considered as a workhorse for biotechnology and a model for high-temperature biology. Apart from integrating improved versions of already existing parts, we have characterized specific promoters and developed a thermosensor-based palette that restricts the expression to Thermus and, at the same time, controls protein expression in this organism in a temperature-dependent manner.
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Affiliation(s)
| | | | | | | | - José Berenguer
- E-mail: . Tel.: +34 911964498. Fax: +34 911964420 (J.B.)
| | - Mario Mencía
- E-mail: . Tel.: +34 911964664.
Fax: +34 911964420 (M.M.)
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25
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Johansson J, Freitag NE. Regulation of Listeria monocytogenes Virulence. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0064-2019. [PMID: 31441398 PMCID: PMC10957223 DOI: 10.1128/microbiolspec.gpp3-0064-2019] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Indexed: 02/07/2023] Open
Abstract
Whereas obligate human and animal bacterial pathogens may be able to depend upon the warmth and relative stability of their chosen replication niche, environmental bacteria such as Listeria monocytogenes that harbor the ability to replicate both within animal cells and in the outside environment must maintain the capability to manage life under a variety of disparate conditions. Bacterial life in the outside environment requires adaptation to wide ranges of temperature, available nutrients, and physical stresses such as changes in pH and osmolarity as well as desiccation. Following ingestion by a susceptible animal host, the bacterium must adapt to similar changes during transit through the gastrointestinal tract and overcome a variety of barriers associated with host innate immune responses. Rapid alteration of patterns of gene expression and protein synthesis represent one strategy for quickly adapting to a dynamic host landscape. Here, we provide an overview of the impressive variety of strategies employed by the soil-dwelling, foodborne, mammalian pathogen L. monocytogenes to straddle diverse environments and optimize bacterial fitness both inside and outside host cells.
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Affiliation(s)
- Jörgen Johansson
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS) and Umeå Centre for Microbial Research (UCMR), Umeå University, 90187 Umeå, Sweden
| | - Nancy E Freitag
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago IL
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26
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Evolving methods for rational de novo design of functional RNA molecules. Methods 2019; 161:54-63. [PMID: 31059832 DOI: 10.1016/j.ymeth.2019.04.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/26/2019] [Accepted: 04/29/2019] [Indexed: 12/16/2022] Open
Abstract
Artificial RNA molecules with novel functionality have many applications in synthetic biology, pharmacy and white biotechnology. The de novo design of such devices using computational methods and prediction tools is a resource-efficient alternative to experimental screening and selection pipelines. In this review, we describe methods common to many such computational approaches, thoroughly dissect these methods and highlight open questions for the individual steps. Initially, it is essential to investigate the biological target system, the regulatory mechanism that will be exploited, as well as the desired components in order to define design objectives. Subsequent computational design is needed to combine the selected components and to obtain novel functionality. This process can usually be split into constrained sequence sampling, the formulation of an optimization problem and an in silico analysis to narrow down the number of candidates with respect to secondary goals. Finally, experimental analysis is important to check whether the defined design objectives are indeed met in the target environment and detailed characterization experiments should be performed to improve the mechanistic models and detect missing design requirements.
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27
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Nshogozabahizi J, Aubrey K, Ross J, Thakor N. Applications and limitations of regulatory
RNA
elements in synthetic biology and biotechnology. J Appl Microbiol 2019; 127:968-984. [DOI: 10.1111/jam.14270] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 03/09/2019] [Accepted: 03/21/2019] [Indexed: 12/13/2022]
Affiliation(s)
- J.C. Nshogozabahizi
- Department of Chemistry and Biochemistry Alberta RNA Research and Training Institute (ARRTI) University of Lethbridge Lethbridge AB Canada
| | - K.L. Aubrey
- Department of Chemistry and Biochemistry Alberta RNA Research and Training Institute (ARRTI) University of Lethbridge Lethbridge AB Canada
| | - J.A. Ross
- Department of Chemistry and Biochemistry Alberta RNA Research and Training Institute (ARRTI) University of Lethbridge Lethbridge AB Canada
| | - N. Thakor
- Department of Chemistry and Biochemistry Alberta RNA Research and Training Institute (ARRTI) University of Lethbridge Lethbridge AB Canada
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Abstract
Fluctuating environments such as changes in ambient temperature represent a fundamental challenge to life. Cells must protect gene networks that protect them from such stresses, making it difficult to understand how temperature affects gene network function in general. Here, we focus on single genes and small synthetic network modules to reveal four key effects of nonoptimal temperatures at different biological scales: (i) a cell fate choice between arrest and resistance, (ii) slower growth rates, (iii) Arrhenius reaction rates, and (iv) protein structure changes. We develop a multiscale computational modeling framework that captures and predicts all of these effects. These findings promote our understanding of how temperature affects living systems and enables more robust cellular engineering for real-world applications. Most organisms must cope with temperature changes. This involves genes and gene networks both as subjects and agents of cellular protection, creating difficulties in understanding. Here, we study how heating and cooling affect expression of single genes and synthetic gene circuits in Saccharomyces cerevisiae. We discovered that nonoptimal temperatures induce a cell fate choice between stress resistance and growth arrest. This creates dramatic gene expression bimodality in isogenic cell populations, as arrest abolishes gene expression. Multiscale models incorporating population dynamics, temperature-dependent growth rates, and Arrhenius scaling of reaction rates captured the effects of cooling, but not those of heating in resistant cells. Molecular-dynamics simulations revealed how heating alters the conformational dynamics of the TetR repressor, fully explaining the experimental observations. Overall, nonoptimal temperatures induce a cell fate decision and corrupt gene and gene network function in computationally predictable ways, which may aid future applications of engineered microbes in nonstandard temperatures.
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Hammer S, Tschiatschek B, Flamm C, Hofacker IL, Findeiß S. RNAblueprint: flexible multiple target nucleic acid sequence design. Bioinformatics 2018; 33:2850-2858. [PMID: 28449031 PMCID: PMC5870862 DOI: 10.1093/bioinformatics/btx263] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 04/21/2017] [Indexed: 01/06/2023] Open
Abstract
Motivation Realizing the value of synthetic biology in biotechnology and medicine requires the design of molecules with specialized functions. Due to its close structure to function relationship, and the availability of good structure prediction methods and energy models, RNA is perfectly suited to be synthetically engineered with predefined properties. However, currently available RNA design tools cannot be easily adapted to accommodate new design specifications. Furthermore, complicated sampling and optimization methods are often developed to suit a specific RNA design goal, adding to their inflexibility. Results We developed a C ++ library implementing a graph coloring approach to stochastically sample sequences compatible with structural and sequence constraints from the typically very large solution space. The approach allows to specify and explore the solution space in a well defined way. Our library also guarantees uniform sampling, which makes optimization runs performant by not only avoiding re-evaluation of already found solutions, but also by raising the probability of finding better solutions for long optimization runs. We show that our software can be combined with any other software package to allow diverse RNA design applications. Scripting interfaces allow the easy adaption of existing code to accommodate new scenarios, making the whole design process very flexible. We implemented example design approaches written in Python to demonstrate these advantages. Availability and implementation RNAblueprint, Python implementations and benchmark datasets are available at github: https://github.com/ViennaRNA. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Stefan Hammer
- Faculty of Chemistry, Department of Theoretical Chemistry.,Faculty of Computer Science, Research Group Bioinformatics and Computational Biology
| | - Birgit Tschiatschek
- Faculty of Computer Science, Research Group Bioinformatics and Computational Biology
| | - Christoph Flamm
- Faculty of Chemistry, Department of Theoretical Chemistry.,Research Network Chemistry Meets Microbiology, University of Vienna, 1090 Vienna, Austria
| | - Ivo L Hofacker
- Faculty of Chemistry, Department of Theoretical Chemistry.,Faculty of Computer Science, Research Group Bioinformatics and Computational Biology.,Center for Non-Coding RNA in Technology and Health, University of Copenhagen, Copenhagen DK-1870, Denmark
| | - Sven Findeiß
- Faculty of Chemistry, Department of Theoretical Chemistry.,Faculty of Computer Science, Research Group Bioinformatics and Computational Biology
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Deepthi KG, Jayasudha R, Girish RN, Manikandan P, Ram R, Narendran V, Prabagaran SR. Polybacterial community analysis in human conjunctiva through 16S rRNA gene libraries. Exp Eye Res 2018; 174:1-12. [PMID: 29772229 DOI: 10.1016/j.exer.2018.05.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 04/18/2018] [Accepted: 05/10/2018] [Indexed: 10/16/2022]
Abstract
The conjunctival sac of healthy human harbours a variety of microorganisms. When the eye is compromised, an occasional inadvertent spread happens to the adjacent tissue, resulting in bacterial ocular infections. Microbiological investigation of the conjunctival swab is one of the broadly used modality to study the aetiological agent of conjunctiva. However, most of the time such methods yield unsatisfactory results. Hence, the present study intends to identify the bacterial community in human conjunctiva of pre-operative subjects through 16S rRNA gene libraries. Out of 45 samples collected from preoperative patients undergoing cataract surgery, 36 libraries were constructed with bacterial nested-PCR-positive samples. The representative clones with unique restriction pattern were generated through Amplified Ribosomal DNA Restriction Analysis (ARDRA) which were sequenced for phylogenetic affiliation. A total of 211 representative clones were obtained which were distributed in phyla Actinobacteria, Firmicutes, α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, Bacteroidetes, and Deinococcus-Thermus. Findings revealed the presence of polybacterial community, especially in some cases even though no bacterium or a single bacterium alone was identified through cultivable method. Remarkably, we identified 17 species which have never been reported in any ocular infections. The sequencing data reported 6 unidentified bacteria suggesting the possibility of novel organisms in the sample. Since, polybacterial community has been identified consisting of both gram positive and gram negative bacteria, a broad spectrum antibiotic therapy is advisable to the patients who are undergoing cataract surgery. Consolidated effort would significantly improve a clear understanding of the nature of microbial community in the human conjunctiva which will promote administration of appropriate antibiotic regimen and also help in the development of oligonucleotide probes to screen the predominant pathogens for early predisposition.
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Affiliation(s)
| | | | - Rameshan Nair Girish
- Department of Biotechnology, Bharathiar University, Coimbatore, Tamil Nadu, India
| | - Palanisamy Manikandan
- Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Coimbatore, Tamil Nadu, India
| | - Rammohan Ram
- Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Coimbatore, Tamil Nadu, India
| | - Venkatapathy Narendran
- Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Coimbatore, Tamil Nadu, India
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31
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Somero GN. RNA thermosensors: how might animals exploit their regulatory potential? J Exp Biol 2018; 221:221/4/jeb162842. [DOI: 10.1242/jeb.162842] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
ABSTRACT
The secondary and tertiary orders of RNA structure are crucial for a suite of RNA-related functions, including regulation of translation, gene expression and RNA turnover. The temperature sensitivity of RNA secondary and tertiary structures is exploited by bacteria to fabricate RNA thermosensing systems that allow a rapid adaptive response to temperature change. RNA thermometers (RNATs) present in non-coding regions of certain mRNAs of pathogenic bacteria enable rapid upregulation of translation of virulence proteins when the temperature of the bacterium rises after entering a mammalian host. Rapid upregulation of translation of bacterial heat-shock proteins likewise is governed in part by RNATs. Turnover of mRNA may be regulated by temperature-sensitive RNA structures. Whereas the roles of temperature-sensitive RNA structures similar to RNATs in Eukarya and Archaea are largely unknown, there would appear to be a potential for all taxa to adaptively regulate their thermal physiology through exploitation of RNA-based thermosensory responses akin to those of bacteria. In animals, these responses might include regulation of translation of stress-induced proteins, alternative splicing of messenger RNA precursors, differential expression of allelic proteins, modulation of activities of small non-coding RNAs, regulation of mRNA turnover and control of RNA editing. New methods for predicting, detecting and experimentally modifying RNA secondary structure offer promising windows into these fascinating aspects of RNA biochemistry. Elucidating whether animals too have exploited the types of RNA thermosensing tools that are used so effectively by bacteria seems likely to provide exciting new insights into the mechanisms of evolutionary adaptation and acclimatization to temperature.
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Affiliation(s)
- George N. Somero
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
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32
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Roßmanith J, Weskamp M, Narberhaus F. Design of a Temperature-Responsive Transcription Terminator. ACS Synth Biol 2018; 7:613-621. [PMID: 29191010 DOI: 10.1021/acssynbio.7b00356] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
RNA structures regulate various steps in gene expression. Transcription in bacteria is typically terminated by stable hairpin structures. Translation initiation can be modulated by metabolite- or temperature-sensitive RNA structures, called riboswitches or RNA thermometers (RNATs), respectively. RNATs control translation initiation by occlusion of the ribosome binding site at low temperatures. Increasing temperatures destabilize the RNA structure and facilitate ribosome access. In this study, we exploited temperature-responsive RNAT structures to design regulatory elements that control transcription termination instead of translation initiation in Escherichia coli. In order to mimic the structure of factor-independent intrinsic terminators, naturally occurring RNAT hairpins were genetically engineered to be followed by a U-stretch. Functional temperature-responsive terminators (thermoterms) prevented mRNA synthesis at low temperatures but resumed transcription after a temperature upshift. The successful design of temperature-controlled terminators highlights the potential of RNA structures as versatile gene expression control elements.
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Affiliation(s)
| | - Mareen Weskamp
- Microbial Biology, Ruhr University Bochum, 44780 Bochum, Germany
| | - Franz Narberhaus
- Microbial Biology, Ruhr University Bochum, 44780 Bochum, Germany
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Abstract
Cell-free synthetic biology approaches enable engineering of biomolecular systems exhibiting complex, cell-like behaviors in the absence of living entities. Often essential to these systems are user-controllable mechanisms to regulate gene expression. Here we describe synthetic RNA thermometers that enable temperature-dependent translation in the PURExpress in vitro protein synthesis system. Previously described cellular thermometers lie wholly in the 5' untranslated region and do not retain their intended function in PURExpress. By contrast, we designed hairpins between the Shine-Dalgarno sequence and complementary sequences within the gene of interest. The resulting thermometers enable high-yield, cell-free protein expression in an inducible temperature range compatible with in vitro translation systems (30-37 °C). Moreover, expression efficiency and switching behavior are tunable via small variations to the coding sequence. Our approach and resulting thermometers provide new tools for exploiting temperature as a rapid, external trigger for in vitro gene regulation.
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Affiliation(s)
- Fredrik W. Sadler
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455
| | - Igor Dodevski
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455
| | - Casim A. Sarkar
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455
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34
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Choi EK, Ulanowicz KA, Nguyen YAH, Frandsen JK, Mitton-Fry RM. SHAPE analysis of the htrA RNA thermometer from Salmonella enterica. RNA (NEW YORK, N.Y.) 2017; 23:1569-1581. [PMID: 28739676 PMCID: PMC5602114 DOI: 10.1261/rna.062299.117] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 07/18/2017] [Indexed: 06/07/2023]
Abstract
RNA thermometers regulate expression of some genes involved in virulence of pathogenic bacteria such as Yersinia, Neisseria, and Salmonella They often function through temperature-dependent conformational changes that alter accessibility of the ribosome-binding site. The 5'-untranslated region (UTR) of the htrA mRNA from Salmonella enterica contains a very short RNA thermometer. We have systematically characterized the structure and dynamics of this thermometer at single-nucleotide resolution using SHAPE (selective 2'-hydroxyl acylation analyzed by primer extension) assays. Our results confirm that the htrA thermometer adopts the predicted hairpin conformation at low temperatures, with conformational change occurring over a physiological temperature regime. Detailed SHAPE melting curves for individual nucleotides suggest that the thermometer unfolds in a cooperative fashion, with nucleotides from both upper and lower portions of the stem gaining flexibility at a common transition temperature. Intriguingly, analysis of an extended htrA 5' UTR sequence revealed not only the presence of the RNA thermometer, but also an additional, stable upstream structure. We generated and analyzed point mutants of the htrA thermometer, revealing elements that modulate its stability, allowing the hairpin to melt under the slightly elevated temperatures experienced during the infection of a warm-blooded host. This work sheds light on structure-function relationships in htrA and related thermometers, and it also illustrates the utility of SHAPE assays for detailed study of RNA thermometer systems.
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Affiliation(s)
- Edric K Choi
- Department of Chemistry and Biochemistry, Denison University, Granville, Ohio 43023, USA
| | - Kelsey A Ulanowicz
- Department of Chemistry and Biochemistry, Denison University, Granville, Ohio 43023, USA
| | - Yen Anh H Nguyen
- Department of Chemistry and Biochemistry, Denison University, Granville, Ohio 43023, USA
| | - Jane K Frandsen
- Department of Chemistry and Biochemistry, Denison University, Granville, Ohio 43023, USA
| | - Rachel M Mitton-Fry
- Department of Chemistry and Biochemistry, Denison University, Granville, Ohio 43023, USA
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35
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Engineering a riboswitch-based genetic platform for the self-directed evolution of acid-tolerant phenotypes. Nat Commun 2017; 8:411. [PMID: 28871084 PMCID: PMC5583362 DOI: 10.1038/s41467-017-00511-w] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 07/05/2017] [Indexed: 12/12/2022] Open
Abstract
Environmental pH is a fundamental signal continuously directing the metabolism and behavior of living cells. Programming the precise cellular response toward environmental pH is, therefore, crucial for engineering cells for increasingly sophisticated functions. Herein, we engineer a set of riboswitch-based pH-sensing genetic devices to enable the control of gene expression according to differential environmental pH. We next develop a digital pH-sensing system to utilize the analogue-sensing behavior of these devices for high-resolution recording of host cell exposure to discrete external pH levels. The application of this digital pH-sensing system is demonstrated in a genetic program that autonomously regulated the evolutionary engineering of host cells for improved tolerance to a broad spectrum of organic acids, a valuable phenotype for metabolic engineering and bioremediation applications. Cells are exposed to shifts in environmental pH, which direct their metabolism and behavior. Here the authors design pH-sensing riboswitches to create a gene expression program, digitalize the system to respond to a narrow pH range and apply it to evolve host cells with improved tolerance to a variety of organic acids.
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36
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Abstract
Biomolecular temperature sensors can be used for efficient control of large-volume bioreactors, for spatiotemporal imaging and control of gene expression, and to engineer robustness to temperature in biomolecular circuit design. Although RNA-based sensors, called "thermometers", have been investigated in both natural and synthetic contexts, an important challenge is to design diverse responses to temperature differing in sensitivity and threshold. We address this issue by constructing a library of RNA thermometers based on thermodynamic computations and experimentally measuring their activities in cell-free biomolecular "breadboards". Using free energies of the minimum free energy structures as well as melt profile computations, we estimated that a diverse set of temperature responses were possible. We experimentally found a wide range of responses to temperature in the range 29-37 °C with fold-changes varying over 3-fold around the starting thermometer. The sensitivities of these responses ranged over 10-fold around the starting thermometer. We correlated these measurements with computational expectations, finding that although there was no strong correlation for the individual thermometers, overall trends of diversity, fold-changes, and sensitivities were similar. These results present a toolbox of RNA-based circuit elements with diverse temperature responses.
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Affiliation(s)
- Shaunak Sen
- Department
of Electrical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Divyansh Apurva
- Department
of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Rohit Satija
- Department
of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
- Institute
for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, United States
| | - Dan Siegal
- Division
of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
- Schafer Corporation, Arlington, Virginia 22203, United States
| | - Richard M. Murray
- Division
of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
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37
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Tunable thermal bioswitches for in vivo control of microbial therapeutics. Nat Chem Biol 2016; 13:75-80. [PMID: 27842069 DOI: 10.1038/nchembio.2233] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 09/16/2016] [Indexed: 01/06/2023]
Abstract
Temperature is a unique input signal that could be used by engineered microbial therapeutics to sense and respond to host conditions or spatially targeted external triggers such as focused ultrasound. To enable these possibilities, we present two families of tunable, orthogonal, temperature-dependent transcriptional repressors providing switch-like control of bacterial gene expression at thresholds spanning the biomedically relevant range of 32-46 °C. We integrate these molecular bioswitches into thermal logic circuits and demonstrate their utility in three in vivo microbial therapy scenarios, including spatially precise activation using focused ultrasound, modulation of activity in response to a host fever, and self-destruction after fecal elimination to prevent environmental escape. This technology provides a critical capability for coupling endogenous or applied thermal signals to cellular function in basic research, biomedical and industrial applications.
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38
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Saberi F, Kamali M, Najafi A, Yazdanparast A, Moghaddam MM. Natural antisense RNAs as mRNA regulatory elements in bacteria: a review on function and applications. Cell Mol Biol Lett 2016; 21:6. [PMID: 28536609 PMCID: PMC5415839 DOI: 10.1186/s11658-016-0007-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 12/23/2015] [Indexed: 12/20/2022] Open
Abstract
Naturally occurring antisense RNAs are small, diffusible, untranslated transcripts that pair to target RNAs at specific regions of complementarity to control their biological function by regulating gene expression at the post-transcriptional level. This review focuses on known cases of antisense RNA control in prokaryotes and provides an overview of some natural RNA-based mechanisms that bacteria use to modulate gene expression, such as mRNA sensors, riboswitches and antisense RNAs. We also highlight recent advances in RNA-based technology. The review shows that studies on both natural and synthetic systems are reciprocally beneficial.
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Affiliation(s)
- Fatemeh Saberi
- Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Mehdi Kamali
- Nanobiotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Ali Najafi
- Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Alavieh Yazdanparast
- Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
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39
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Gareau D, Desrosiers A, Vallée-Bélisle A. Programmable Quantitative DNA Nanothermometers. NANO LETTERS 2016; 16:3976-3981. [PMID: 27058370 DOI: 10.1021/acs.nanolett.6b00156] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Developing molecules, switches, probes or nanomaterials that are able to respond to specific temperature changes should prove of utility for several applications in nanotechnology. Here, we describe bioinspired strategies to design DNA thermoswitches with programmable linear response ranges that can provide either a precise ultrasensitive response over a desired, small temperature interval (±0.05 °C) or an extended linear response over a wide temperature range (e.g., from 25 to 90 °C). Using structural modifications or inexpensive DNA stabilizers, we show that we can tune the transition midpoints of DNA thermometers from 30 to 85 °C. Using multimeric switch architectures, we are able to create ultrasensitive thermometers that display large quantitative fluorescence gains within small temperature variation (e.g., > 700% over 10 °C). Using a combination of thermoswitches of different stabilities or a mix of stabilizers of various strengths, we can create extended thermometers that respond linearly up to 50 °C in temperature range. Here, we demonstrate the reversibility, robustness, and efficiency of these programmable DNA thermometers by monitoring temperature change inside individual wells during polymerase chain reactions. We discuss the potential applications of these programmable DNA thermoswitches in various nanotechnology fields including cell imaging, nanofluidics, nanomedecine, nanoelectronics, nanomaterial, and synthetic biology.
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Affiliation(s)
- David Gareau
- Laboratory of Biosensors and Nanomachines, Département de Chimie and ‡Département de Biochimie et Médecine Moléculaire, Université de Montréal , C.P. 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada
| | - Arnaud Desrosiers
- Laboratory of Biosensors and Nanomachines, Département de Chimie and ‡Département de Biochimie et Médecine Moléculaire, Université de Montréal , C.P. 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada
| | - Alexis Vallée-Bélisle
- Laboratory of Biosensors and Nanomachines, Département de Chimie and ‡Département de Biochimie et Médecine Moléculaire, Université de Montréal , C.P. 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada
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Garcia-Martin JA, Dotu I, Fernandez-Chamorro J, Lozano G, Ramajo J, Martinez-Salas E, Clote P. RNAiFold2T: Constraint Programming design of thermo-IRES switches. Bioinformatics 2016; 32:i360-i368. [PMID: 27307638 PMCID: PMC4908349 DOI: 10.1093/bioinformatics/btw265] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
MOTIVATION RNA thermometers (RNATs) are cis-regulatory elements that change secondary structure upon temperature shift. Often involved in the regulation of heat shock, cold shock and virulence genes, RNATs constitute an interesting potential resource in synthetic biology, where engineered RNATs could prove to be useful tools in biosensors and conditional gene regulation. RESULTS Solving the 2-temperature inverse folding problem is critical for RNAT engineering. Here we introduce RNAiFold2T, the first Constraint Programming (CP) and Large Neighborhood Search (LNS) algorithms to solve this problem. Benchmarking tests of RNAiFold2T against existent programs (adaptive walk and genetic algorithm) inverse folding show that our software generates two orders of magnitude more solutions, thus allowing ample exploration of the space of solutions. Subsequently, solutions can be prioritized by computing various measures, including probability of target structure in the ensemble, melting temperature, etc. Using this strategy, we rationally designed two thermosensor internal ribosome entry site (thermo-IRES) elements, whose normalized cap-independent translation efficiency is approximately 50% greater at 42 °C than 30 °C, when tested in reticulocyte lysates. Translation efficiency is lower than that of the wild-type IRES element, which on the other hand is fully resistant to temperature shift-up. This appears to be the first purely computational design of functional RNA thermoswitches, and certainly the first purely computational design of functional thermo-IRES elements. AVAILABILITY RNAiFold2T is publicly available as part of the new release RNAiFold3.0 at https://github.com/clotelab/RNAiFold and http://bioinformatics.bc.edu/clotelab/RNAiFold, which latter has a web server as well. The software is written in C ++ and uses OR-Tools CP search engine. CONTACT clote@bc.edu SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
| | - Ivan Dotu
- Department of Experimental and Health Sciences, Research Programme on Biomedical Informatics (GRIB), Universitat Pompeu Fabra. Dr. Aiguader 88, Barcelona, Spain
| | - Javier Fernandez-Chamorro
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Gloria Lozano
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Jorge Ramajo
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Encarnacion Martinez-Salas
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Peter Clote
- Biology Department, Boston College, Chestnut Hill, MA 02467, USA
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Jia H, Sun X, Sun H, Li C, Wang Y, Feng X, Li C. Intelligent Microbial Heat-Regulating Engine (IMHeRE) for Improved Thermo-Robustness and Efficiency of Bioconversion. ACS Synth Biol 2016; 5:312-20. [PMID: 26793993 DOI: 10.1021/acssynbio.5b00158] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The growth and production of microorganisms in bioconversion are often hampered by heat stress. In this study, an intelligent microbial heat-regulating engine (IMHeRE) was developed and customized to improve the thermo-robustness of Escherichia coli via the integration of a thermotolerant system and a quorum-regulating system. At the cell level, the thermotolerant system composed of different heat shock proteins and RNA thermometers hierarchically expands the optimum temperature by sensing heat changes. At the community level, the quorum-regulating system dynamically programs the altruistic sacrifice of individuals to reduce metabolic heat release by sensing the temperature and cell density. Using this hierarchical, dynamical, and multilevel regulation, the IMHeRE is able to significantly improve cell growth and production. In a real application, the production of lysine was increased 5-fold at 40 °C using the IMHeRE. Our work provides new potential for the development of bioconversion by conserving energy and increasing productivity.
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Affiliation(s)
- Haiyang Jia
- Department
of Biological Engineering, School of Life Science, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Xiangying Sun
- Department
of Biological Engineering, School of Life Science, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Huan Sun
- Department
of Biological Engineering, School of Life Science, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Chenyi Li
- Department
of Biological Engineering, School of Life Science, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Yunqian Wang
- Department
of Biological Engineering, School of Life Science, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Xudong Feng
- Department
of Biological Engineering, School of Life Science, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Chun Li
- Department
of Biological Engineering, School of Life Science, Beijing Institute of Technology, Beijing 100081, P. R. China
- State
Key Laboratory of System Bioengineering of the Ministry of Education, Tianjin University, Tianjin 300072, P. R. China
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42
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Roßmanith J, Narberhaus F. Exploring the modular nature of riboswitches and RNA thermometers. Nucleic Acids Res 2016; 44:5410-23. [PMID: 27060146 PMCID: PMC4914106 DOI: 10.1093/nar/gkw232] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/28/2016] [Indexed: 01/20/2023] Open
Abstract
Natural regulatory RNAs like riboswitches and RNA thermometers (RNAT) have considerable potential in synthetic biology. They are located in the 5′ untranslated region (UTR) of bacterial mRNAs and sense small molecules or changes in temperature, respectively. While riboswitches act on the level of transcription, translation or mRNA stability, all currently known RNATs regulate translation initiation. In this study, we explored the modularity of riboswitches and RNATs and obtained regulatory devices with novel functionalities. In a first approach, we established three riboswitch-RNAT systems conferring dual regulation of transcription and translation depending on the two triggers ligand binding and temperature sensing. These consecutive fusions control gene expression in vivo and can even orchestrate complex cellular behavior. In another approach, we designed two temperature-controlled riboswitches by the integration of an RNAT into a riboswitch aptamer domain. These ‘thermoswitches’ respond to the cognate ligand at low temperatures and are turned into a continuous on-state by a temperature upshift. They represent the first RNATs taking control of transcription. Overall, this study demonstrates that riboswitches and RNATs are ideal for engineering synthetic RNA regulators due to their modular behavior.
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Affiliation(s)
| | - Franz Narberhaus
- Microbial Biology, Ruhr University Bochum, 44780 Bochum, Germany
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Emadpour M, Karcher D, Bock R. Boosting riboswitch efficiency by RNA amplification. Nucleic Acids Res 2015; 43:e66. [PMID: 25824954 PMCID: PMC4446413 DOI: 10.1093/nar/gkv165] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 02/17/2015] [Accepted: 02/19/2015] [Indexed: 01/17/2023] Open
Abstract
Riboswitches are RNA sensors that regulate gene expression in response to binding of small molecules. Although they conceptually represent simple on/off switches and, therefore, hold great promise for biotechnology and future synthetic biology applications, the induction of gene expression by natural riboswitches after ligand addition or removal is often only moderate and, consequently, the achievable expression levels are not very high. Here, we have designed an RNA amplification-based system that strongly improves the efficiency of riboswitches. We have successfully implemented the method in a biological system for which currently no efficient endogenous tools for inducible (trans)gene expression are available: the chloroplasts of higher plants. We further show that an HIV antigen whose constitutive expression from the chloroplast genome is deleterious to the plant can be inducibly expressed under the control of the RNA amplification-enhanced riboswitch (RAmpER) without causing a mutant phenotype, demonstrating the potential of the method for the production of proteins and metabolites that are toxic to the host cell.
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Affiliation(s)
- Masoumeh Emadpour
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Daniel Karcher
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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Hoynes-O'Connor A, Hinman K, Kirchner L, Moon TS. De novo design of heat-repressible RNA thermosensors in E. coli. Nucleic Acids Res 2015; 43:6166-79. [PMID: 25979263 PMCID: PMC4499127 DOI: 10.1093/nar/gkv499] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 05/04/2015] [Indexed: 11/15/2022] Open
Abstract
RNA-based temperature sensing is common in bacteria that live in fluctuating environments. Most naturally-occurring RNA thermosensors are heat-inducible, have long sequences, and function by sequestering the ribosome binding site in a hairpin structure at lower temperatures. Here, we demonstrate the de novo design of short, heat-repressible RNA thermosensors. These thermosensors contain a cleavage site for RNase E, an enzyme native to Escherichia coli and many other organisms, in the 5′ untranslated region of the target gene. At low temperatures, the cleavage site is sequestered in a stem–loop, and gene expression is unobstructed. At high temperatures, the stem–loop unfolds, allowing for mRNA degradation and turning off expression. We demonstrated that these thermosensors respond specifically to temperature and provided experimental support for the central role of RNase E in the mechanism. We also demonstrated the modularity of these RNA thermosensors by constructing a three-input composite circuit that utilizes transcriptional, post-transcriptional, and post-translational regulation. A thorough analysis of the 24 thermosensors allowed for the development of design guidelines for systematic construction of similar thermosensors in future applications. These short, modular RNA thermosensors can be applied to the construction of complex genetic circuits, facilitating rational reprogramming of cellular processes for synthetic biology applications.
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Affiliation(s)
- Allison Hoynes-O'Connor
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Kristina Hinman
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Lukas Kirchner
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Tae Seok Moon
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
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Abstract
In this chapter, we review both computational and experimental aspects of de novo RNA sequence design. We give an overview of currently available design software and their limitations, and discuss the necessary setup to experimentally validate proper function in vitro and in vivo. We focus on transcription-regulating riboswitches, a task that has just recently lead to first successful designs of such RNA elements.
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Affiliation(s)
- Sven Findeiß
- Research Group Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Vienna, Austria; Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria
| | - Manja Wachsmuth
- Institute for Biochemistry, University of Leipzig, Leipzig, Germany
| | - Mario Mörl
- Institute for Biochemistry, University of Leipzig, Leipzig, Germany.
| | - Peter F Stadler
- Institute for Theoretical Chemistry, University of Vienna, Vienna, Austria; Bioinformatics Group, Department of Computer Science and the Interdisciplinary Center for Bioinformatic, University of Leipzig, Leipzig, Germany; Center for RNA in Technology and Health, University of Copenhagen, Frederiksberg, Denmark; Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany; Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany; Santa Fe Institute, Santa Fe, New Mexico, USA
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46
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Delvillani F, Sciandrone B, Peano C, Petiti L, Berens C, Georgi C, Ferrara S, Bertoni G, Pasini ME, Dehò G, Briani F. Tet-Trap, a genetic approach to the identification of bacterial RNA thermometers: application to Pseudomonas aeruginosa. RNA (NEW YORK, N.Y.) 2014; 20:1963-1976. [PMID: 25336583 PMCID: PMC4238360 DOI: 10.1261/rna.044354.114] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 09/10/2014] [Indexed: 06/04/2023]
Abstract
Modulation of mRNA translatability either by trans-acting factors (proteins or sRNAs) or by in cis-acting riboregulators is widespread in bacteria and controls relevant phenotypic traits. Unfortunately, global identification of post-transcriptionally regulated genes is complicated by poor structural and functional conservation of regulatory elements and by the limitations of proteomic approaches in protein quantification. We devised a genetic system for the identification of post-transcriptionally regulated genes and we applied this system to search for Pseudomonas aeruginosa RNA thermometers, a class of regulatory RNA that modulates gene translation in response to temperature changes. As P. aeruginosa is able to thrive in a broad range of environmental conditions, genes differentially expressed at 37 °C versus lower temperatures may be involved in infection and survival in the human host. We prepared a plasmid vector library with translational fusions of P. aeruginosa DNA fragments (PaDNA) inserted upstream of TIP2, a short peptide able to inactivate the Tet repressor (TetR) upon expression. The library was assayed in a streptomycin-resistant merodiploid rpsL(+)/rpsL31 Escherichia coli strain in which the dominant rpsL(+) allele, which confers streptomycin sensitivity, was repressed by TetR. PaDNA fragments conferring thermosensitive streptomycin resistance (i.e., expressing PaDNA-TIP2 fusions at 37°C, but not at 28°C) were sequenced. We identified four new putative thermosensors. Two of them were validated with conventional reporter systems in E. coli and P. aeruginosa. Interestingly, one regulates the expression of ptxS, a gene implicated in P. aeruginosa pathogenesis.
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Affiliation(s)
- Francesco Delvillani
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Barbara Sciandrone
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Clelia Peano
- Istituto di Tecnologie Biomediche, CNR, 20090 Segrate, Italy
| | - Luca Petiti
- Istituto di Tecnologie Biomediche, CNR, 20090 Segrate, Italy Doctoral Program of Molecular and Translational Medicine, Università degli Studi di Milano, 20133 Milano, Italy
| | - Christian Berens
- Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91052 Erlangen, Germany
| | - Christiane Georgi
- Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91052 Erlangen, Germany
| | - Silvia Ferrara
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Giovanni Bertoni
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Maria Enrica Pasini
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Gianni Dehò
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
| | - Federica Briani
- Dipartimento di Bioscienze, Università degli Studi di Milano, 20133 Milano, Italy
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Hollinshead W, He L, Tang YJ. Biofuel production: an odyssey from metabolic engineering to fermentation scale-up. Front Microbiol 2014; 5:344. [PMID: 25071754 PMCID: PMC4088188 DOI: 10.3389/fmicb.2014.00344] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 06/20/2014] [Indexed: 12/21/2022] Open
Abstract
Metabolic engineering has developed microbial cell factories that can convert renewable carbon sources into biofuels. Current molecular biology tools can efficiently alter enzyme levels to redirect carbon fluxes toward biofuel production, but low product yield and titer in large bioreactors prevent the fulfillment of cheap biofuels. There are three major roadblocks preventing economical biofuel production. First, carbon fluxes from the substrate dissipate into a complex metabolic network. Besides the desired product, microbial hosts direct carbon flux to synthesize biomass, overflow metabolites, and heterologous enzymes. Second, microbial hosts need to oxidize a large portion of the substrate to generate both ATP and NAD(P)H to power biofuel synthesis. High cell maintenance, triggered by the metabolic burdens from genetic modifications, can significantly affect the ATP supply. Thereby, fermentation of advanced biofuels (such as biodiesel and hydrocarbons) often requires aerobic respiration to resolve the ATP shortage. Third, mass transfer limitations in large bioreactors create heterogeneous growth conditions and micro-environmental fluctuations (such as suboptimal O2 level and pH) that induce metabolic stresses and genetic instability. To overcome these limitations, fermentation engineering should merge with systems metabolic engineering. Modern fermentation engineers need to adopt new metabolic flux analysis tools that integrate kinetics, hydrodynamics, and 13C-proteomics, to reveal the dynamic physiologies of the microbial host under large bioreactor conditions. Based on metabolic analyses, fermentation engineers may employ rational pathway modifications, synthetic biology circuits, and bioreactor control algorithms to optimize large-scale biofuel production.
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Affiliation(s)
- Whitney Hollinshead
- Department of Energy, Environmental and Chemical Engineering, Washington University St. Louis, MO, USA
| | - Lian He
- Department of Energy, Environmental and Chemical Engineering, Washington University St. Louis, MO, USA
| | - Yinjie J Tang
- Department of Energy, Environmental and Chemical Engineering, Washington University St. Louis, MO, USA
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Krajewski SS, Narberhaus F. Temperature-driven differential gene expression by RNA thermosensors. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:978-988. [PMID: 24657524 DOI: 10.1016/j.bbagrm.2014.03.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 02/28/2014] [Accepted: 03/14/2014] [Indexed: 12/20/2022]
Abstract
Many prokaryotic genes are organized in operons. Genes organized in such transcription units are co-transcribed into a polycistronic mRNA. Despite being clustered in a single mRNA, individual genes can be subjected to differential regulation, which is mainly achieved at the level of translation depending on initiation and elongation. Efficiency of translation initiation is primarily determined by the structural accessibility of the ribosome binding site (RBS). Structured cis-regulatory elements like RNA thermometers (RNATs) can contribute to differential regulation of individual genes within a polycistronic mRNA. RNATs are riboregulators that mediate temperature-responsive regulation of a downstream gene by modulating the accessibility of its RBS. At low temperature, the RBS is trapped by intra-molecular base pairing prohibiting translation initiation. The secondary structure melts with increasing temperature thus liberating the RBS. Here, we present an overview of different RNAT types and specifically highlight recently discovered RNATs. The main focus of this review is on RNAT-based differential control of polycistronic operons. Finally, we discuss the influence of temperature on other riboregulators and the potential of RNATs in synthetic RNA biology. This article is part of a Special Issue entitled: Riboswitches.
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Identification of polybacterial communities in patients with postoperative, posttraumatic, and endogenous endophthalmitis through 16S rRNA gene libraries. J Clin Microbiol 2014; 52:1459-66. [PMID: 24574297 DOI: 10.1128/jcm.02093-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Endophthalmitis is a potential vision-threatening complication following surgical procedures (postoperative endophthalmitis [POE]), trauma (posttraumatic endophthalmitis [PTE]), and bacteremic seeding of the eye from a distant infection site (endogenous endophthalmitis [EE]). Several studies have revealed the polybacterial characteristics of endophthalmitis, which make the administration of antibiotics to treat the disease challenging. However, until now, the polybacterial communities of POE, PTE, and EE have not been precisely studied. Hence, the present study was designed to identify the bacterial community of endophthalmitis through 16S rRNA gene libraries. Of the 40 intraocular samples tested, 30 libraries were constructed with bacterial nested-PCR-positive samples. The obtained recombinant clones were screened through amplified rRNA gene restriction analysis (ARDRA) to identify unique clones. The multiple types of ARDRA patterns (P=0.345) and diverse bacterial sequences (P=0.277) within the libraries revealed the polybacterial nature of infection in POE, PTE, and EE. Moreover, to the best of our knowledge, this is the first report on polybacterial infection in EE. Gram-positive bacteria, including Bacillus spp. (n=19), Streptococcus spp. (n=18), Staphylococcus spp. (n=6), Exiguobacterium spp. (n=3), Gemella spp. (n=2), Enterococcus spp. (n=2), a Lysinibacillus sp. (n=1), a Clostridium sp. (n=1), and a Nocardia sp. (n=1), and Gram-negative bacteria, including Serratia spp. (n=18), Pseudomonas spp. (n=10), Enterobacter spp. (n=8), Acinetobacter spp. (n=3), Pantoea spp. (n=3), a Haemophilus sp. (n=1), and a Massilia sp. (n=1), were identified. Interestingly, among them, 10 bacterial species were not previously reported to be associated with endophthalmitis or other ocular infections. Besides, the presence of 4 unidentifiable clones suggests the possibility of novel organisms that might cause eye infections. Therefore, it is recommended that, in addition to the polybacterial nature of POE, PTE, and EE infections, the spectrum of the pathogenic bacterial community identified in this work should be considered while administering antibiotic therapy in suspected endophthalmitis cases.
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50
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Kang MS, Han SS, Kim MY, Kim BY, Huh JP, Kim HS, Lee JH. High-level expression in Corynebacterium glutamicum of nitrile hydratase from Rhodococcus rhodochrous for acrylamide production. Appl Microbiol Biotechnol 2014; 98:4379-87. [PMID: 24493572 DOI: 10.1007/s00253-014-5544-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 01/12/2014] [Accepted: 01/13/2014] [Indexed: 10/25/2022]
Abstract
The nhhBAG gene of Rhodococcus rhodochrous M33 that encodes nitrile hydratase (NHase), converting acrylonitrile into acrylamide, was cloned and expressed in Corynebacterium glutamicum under the control of an ilvC promoter. The specific enzyme activity in recombinant C. glutamicum cells was about 13.6 μmol/min/mg dry cell weight (DCW). To overexpress the NHase, five types of plasmid variants were constructed by introducing mutations into 80 nucleotides near the translational initiation region (TIR) of nhhB. Of them, pNBM4 with seven mutations showed the highest NHase activity, exhibiting higher expression levels of NhhB and NhhA than wild-type pNBW33, mainly owing to decreased secondary-structure stability and an introduction of a conserved Shine-Dalgarno sequence in the translational initiation region. In a fed-batch culture of recombinant Corynebacterium cells harboring pNBM4, the cell density reached 53.4 g DCW/L within 18 h, and the specific and total enzyme activities were estimated to be 37.3 μmol/min/mg DCW and 1,992 μmol/min/mL, respectively. The use of recombinant Corynebacterium cells for the production of acrylamide from acrylonitrile resulted in a conversion yield of 93 % and a final acrylamide concentration of 42.5 % within 6 h when the total amount of fed acrylonitrile was 456 g.
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Affiliation(s)
- Mi-Suk Kang
- Department of Food Science & Biotechnology, Kyungsung University, 309, Suyeong-ro, Nam-gu, Busan, 608-736, South Korea
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