1
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Kehrli J, Husser C, Ryckelynck M. Fluorogenic RNA-Based Biosensors of Small Molecules: Current Developments, Uses, and Perspectives. BIOSENSORS 2024; 14:376. [PMID: 39194605 DOI: 10.3390/bios14080376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Revised: 07/14/2024] [Accepted: 07/19/2024] [Indexed: 08/29/2024]
Abstract
Small molecules are highly relevant targets for detection and quantification. They are also used to diagnose and monitor the progression of disease and infectious processes and track the presence of contaminants. Fluorogenic RNA-based biosensors (FRBs) represent an appealing solution to the problem of detecting these targets. They combine the portability of molecular systems with the sensitivity and multiplexing capacity of fluorescence, as well as the exquisite ligand selectivity of RNA aptamers. In this review, we first present the different sensing and reporting aptamer modules currently available to design an FRB, together with the main methodologies used to discover modules with new specificities. We next introduce and discuss how both modules can be functionally connected prior to exploring the main applications for which FRB have been used. Finally, we conclude by discussing how using alternative nucleotide chemistries may improve FRB properties and further widen their application scope.
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Affiliation(s)
- Janine Kehrli
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, F-67000 Strasbourg, France
| | - Claire Husser
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, F-67000 Strasbourg, France
| | - Michael Ryckelynck
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, F-67000 Strasbourg, France
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2
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Mumbleau M, Chevance F, Hughes K, Hammond MC. Investigating the Effect of RNA Scaffolds on the Multicolor Fluorogenic Aptamer Pepper in Different Bacterial Species. ACS Synth Biol 2024; 13:1093-1099. [PMID: 38593047 PMCID: PMC11037261 DOI: 10.1021/acssynbio.4c00009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 04/11/2024]
Abstract
RNA synthetic biology tools have primarily been applied in E. coli; however, many other bacteria are of industrial and clinical significance. Thus, the multicolor fluorogenic aptamer Pepper was evaluated in both Gram-positive and Gram-negative bacteria. Suitable HBC-Pepper dye pairs were identified that give blue, green, or red fluorescence signals in the E. coli, Bacillus subtilis, and Salmonella enterica serovar Typhimurium (S. Typhimurium). Furthermore, we found that different RNA scaffolds have a drastic effect on in vivo fluorescence, which did not correlate with the in vitro folding efficiency. One such scaffold termed DF30-tRNA displays 199-fold greater fluorescence than the Pepper aptamer alone and permits simultaneous dual color imaging in live cells.
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Affiliation(s)
- Madeline
M. Mumbleau
- Department
of Chemistry and Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah 84112, United States
| | - Fabienne Chevance
- School
of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Kelly Hughes
- School
of Biological Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Ming C. Hammond
- Department
of Chemistry and Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah 84112, United States
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3
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Ji R, Wang L, Shang Y, Du S, Xiao Y, Dong W, Cui L, Gao R, Ren K. RNA Condensate as a Versatile Platform for Improving Fluorogenic RNA Aptamer Properties and Cell Imaging. J Am Chem Soc 2024; 146:4402-4411. [PMID: 38329936 DOI: 10.1021/jacs.3c09162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Fluorogenic RNA aptamers are valuable tools for cell imaging, but they still suffer from shortcomings such as easy degradation, limited photostability, and low fluorescence enhancement. Molecular crowding conditions enable the stabilization of the structure, promotion of folding, and improvement of activity of functional RNA. Based on artificial RNA condensates, here we present a versatile platform to improve fluorogenic RNA aptamer properties and develop sensors for target analyte imaging in living cells. Using the CUG repeat as a general tag to drive phase separation, various fluorogenic aptamer-based RNA condensates (FLARE) were prepared. We show that the molecular crowding of FLARE can improve the enzymatic resistance, thermostability, photostability, and binding affinity of fluorogenic RNA aptamers. Moreover, the FLARE systems can be modularly engineered into sensors (FLARES), which demonstrate enhanced brightness and sensitivity compared to free sensors dispersed in homogeneous solution. This scalable design principle provides new insights into RNA aptamer property regulation and cellular imaging.
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Affiliation(s)
- Ruoyang Ji
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Long Wang
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Yuzhe Shang
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Songyuan Du
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Yang Xiao
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Wei Dong
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Lin Cui
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, P.R. China
| | - Ruru Gao
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Kewei Ren
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
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4
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Wu Y, Zhu L, Zhang Y, Xu W. Multidimensional Applications and Challenges of Riboswitches in Biosensing and Biotherapy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2304852. [PMID: 37658499 DOI: 10.1002/smll.202304852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 08/15/2023] [Indexed: 09/03/2023]
Abstract
Riboswitches have received significant attention over the last two decades for their multiple functionalities and great potential for applications in various fields. This article highlights and reviews the recent advances in biosensing and biotherapy. These fields involve a wide range of applications, such as food safety detection, environmental monitoring, metabolic engineering, live cell imaging, wearable biosensors, antibacterial drug targets, and gene therapy. The discovery, origin, and optimization of riboswitches are summarized to help readers better understand their multidimensional applications. Finally, this review discusses the multidimensional challenges and development of riboswitches in order to further expand their potential for novel applications.
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Affiliation(s)
- Yifan Wu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Longjiao Zhu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Yangzi Zhang
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Wentao Xu
- Key Laboratory of Precision Nutrition and Food Quality, Beijing Laboratory for Food Quality and Safety, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
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5
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Aggarwal T, Wang L, Gutierrez B, Guven H, Erguven H, Izgu EC. A Small-Molecule Approach to Bypass In Vitro Selection of New Aptamers: Designer Pre-Ligands Turn Baby Spinach into Sensors for Reactive Inorganic Targets. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.29.551132. [PMID: 38168427 PMCID: PMC10760011 DOI: 10.1101/2023.07.29.551132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Fluorescent light-up aptamer (FLAP) systems are promising biosensing platforms that can be genetically encoded. Here, we describe how a single FLAP that works with specific organic ligands can detect multiple, structurally unique, non-fluorogenic, and reactive inorganic targets. We developed 4-O-functionalized benzylidene imidazolinones as pre-ligands with suppressed fluorescent binding interactions with the RNA aptamer Baby Spinach. Inorganic targets, hydrogen sulfide (H2S) or hydrogen peroxide (H2O2), can specifically convert these pre-ligands into the native benzylidene imidazolinones, and thus be detected with Baby Spinach. Adaptation of this approach to live cells opened a new opportunity for top-down construction of whole-cell sensors: Escherichia coli transformed with a Baby Spinach-encoding plasmid and incubated with pre-ligands generated fluorescence in response to exogenous H2S or H2O2. Our approach eliminates the requirement of in vitro selection of a new aptamer sequence for molecular target detection, allows for the detection of short-lived targets, thereby advancing FLAP systems beyond their current capabilities. Leveraging the functional group reactivity of small molecules can lead to cell-based sensors for inorganic molecular targets, exploiting a new synergism between synthetic organic chemistry and synthetic biology.
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Affiliation(s)
- Tushar Aggarwal
- Department of Chemistry and Chemical Biology, Rutgers University, New Brunswick, NJ 08854, USA
| | - Liming Wang
- Department of Chemistry and Chemical Biology, Rutgers University, New Brunswick, NJ 08854, USA
| | - Bryan Gutierrez
- Department of Chemistry and Chemical Biology, Rutgers University, New Brunswick, NJ 08854, USA
| | - Hakan Guven
- Department of Chemistry and Chemical Biology, Rutgers University, New Brunswick, NJ 08854, USA
| | - Huseyin Erguven
- Department of Chemistry and Chemical Biology, Rutgers University, New Brunswick, NJ 08854, USA
| | - Enver Cagri Izgu
- Department of Chemistry and Chemical Biology, Rutgers University, New Brunswick, NJ 08854, USA
- Cancer Institute of New Jersey, Rutgers University, New Brunswick, NJ 08901, USA
- Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901, USA
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6
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Xu J, Hou J, Ding M, Wang Z, Chen T. Riboswitches, from cognition to transformation. Synth Syst Biotechnol 2023; 8:357-370. [PMID: 37325181 PMCID: PMC10265488 DOI: 10.1016/j.synbio.2023.05.008] [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: 03/01/2023] [Revised: 05/20/2023] [Accepted: 05/25/2023] [Indexed: 06/17/2023] Open
Abstract
Riboswitches are functional RNA elements that regulate gene expression by directly detecting metabolites. Twenty years have passed since it was first discovered, researches on riboswitches are becoming increasingly standardized and refined, which could significantly promote people's cognition of RNA function as well. Here, we focus on some representative orphan riboswitches, enumerate the structural and functional transformation and artificial design of riboswitches including the coupling with ribozymes, hoping to attain a comprehensive understanding of riboswitch research.
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Affiliation(s)
- Jingdong Xu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China
- Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300350, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300350, China
| | - Junyuan Hou
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China
- Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300350, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300350, China
| | - Mengnan Ding
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China
- Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300350, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300350, China
| | - Zhiwen Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China
- Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300350, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300350, China
| | - Tao Chen
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China
- Frontier Science Center for Synthetic Biology, Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300350, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300350, China
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7
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Ortega AD. Real-Time Assessment of Intracellular Metabolites in Single Cells through RNA-Based Sensors. Biomolecules 2023; 13:biom13050765. [PMID: 37238635 DOI: 10.3390/biom13050765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/24/2023] [Accepted: 04/26/2023] [Indexed: 05/28/2023] Open
Abstract
Quantification of the concentration of particular cellular metabolites reports on the actual utilization of metabolic pathways in physiological and pathological conditions. Metabolite concentration also constitutes the readout for screening cell factories in metabolic engineering. However, there are no direct approaches that allow for real-time assessment of the levels of intracellular metabolites in single cells. In recent years, the modular architecture of natural bacterial RNA riboswitches has inspired the design of genetically encoded synthetic RNA devices that convert the intracellular concentration of a metabolite into a quantitative fluorescent signal. These so-called RNA-based sensors are composed of a metabolite-binding RNA aptamer as the sensor domain, connected through an actuator segment to a signal-generating reporter domain. However, at present, the variety of available RNA-based sensors for intracellular metabolites is still very limited. Here, we go through natural mechanisms for metabolite sensing and regulation in cells across all kingdoms, focusing on those mediated by riboswitches. We review the design principles underlying currently developed RNA-based sensors and discuss the challenges that hindered the development of novel sensors and recent strategies to address them. We finish by introducing the current and potential applicability of synthetic RNA-based sensors for intracellular metabolites.
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Affiliation(s)
- Alvaro Darío Ortega
- Department of Cell Biology, Faculty of Biological Sciences, Complutense University of Madrid, 28040 Madrid, Spain
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8
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Wu Y, Zhu L, Li S, Chu H, Wang X, Xu W. High content design of riboswitch biosensors: All-around rational module-by-module design. Biosens Bioelectron 2022; 220:114887. [DOI: 10.1016/j.bios.2022.114887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/27/2022] [Accepted: 11/03/2022] [Indexed: 11/11/2022]
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9
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Pavlova N, Penchovsky R. Bioinformatics and Genomic Analyses of the Suitability of Eight Riboswitches for Antibacterial Drug Targets. Antibiotics (Basel) 2022; 11:antibiotics11091177. [PMID: 36139956 PMCID: PMC9495176 DOI: 10.3390/antibiotics11091177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 11/23/2022] Open
Abstract
Antibiotic resistance (AR) is an acute problem that results in prolonged and debilitating illnesses. AR mortality worldwide is growing and causes a pressing need to research novel mechanisms of action and untested target molecules. This article presents in silico analyses of eight bacterial riboswitches for their suitability for antibacterial drug targets. Most bacterial riboswitches are located in the 5′-untranslated region of messenger RNAs, act as allosteric cis-acting gene control elements, and have not been found in humans before. Sensing metabolites, the riboswitches regulate the synthesis of vital cellular metabolites in various pathogenic bacteria. The analyses performed in this article represent a complete and informative genome-wide bioinformatics analysis of the adequacy of eight riboswitches as antibacterial drug targets in different pathogenic bacteria based on four criteria. Due to the ability of the riboswitch to control biosynthetic pathways and transport proteins of essential metabolites and the presence/absence of alternative biosynthetic pathways, we classified them into four groups based on their suitability for use as antibacterial drug targets guided by our in silico analyses. We concluded that some of them are promising targets for antibacterial drug discovery, such as the PreQ1, MoCo RNA, cyclic-di-GMP I, and cyclic-di-GMP II riboswitches.
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10
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Xu J, Cotruvo JA. Reconsidering the czcD (NiCo) Riboswitch as an Iron Riboswitch. ACS BIO & MED CHEM AU 2022; 2:376-385. [PMID: 35996475 PMCID: PMC9389577 DOI: 10.1021/acsbiomedchemau.1c00069] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
![]()
Recent work has proposed
a new mechanism of bacterial iron regulation:
riboswitches that undergo a conformational change in response to FeII. The czcD (NiCo) riboswitch was initially
proposed to be specific for NiII and CoII, but
we recently showed via a czcD-based fluorescent sensor
that FeII is also a plausible physiological ligand for
this riboswitch class. Here, we provide direct evidence that this
riboswitch class responds to FeII. Isothermal titration
calorimetry studies of the native czcD riboswitches
from three organisms show no response to MnII, a weak response
to ZnII, and similar dissociation constants (∼1
μM) and conformational responses for FeII, CoII, and NiII. Only the iron response is in the physiological
concentration regime; the riboswitches’ responses to CoII, NiII, and ZnII require 103-, 105-, and 106-fold higher “free”
metal ion concentrations, respectively, than the typical availability
of those metal ions in cells. By contrast, the “Sensei”
RNA, recently claimed to be an iron-specific riboswitch, exhibits
no response to FeII. Our results demonstrate that iron
responsiveness is a conserved property of czcD riboswitches
and clarify that this is the only family of iron-responsive riboswitch
identified to date, setting the stage for characterization of their
physiological function.
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Affiliation(s)
- Jiansong Xu
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Joseph A. Cotruvo
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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11
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Mumbleau MM, Meyer MR, Hammond MC. Determination of In Vitro and Cellular Turn-on Kinetics for Fluorogenic RNA Aptamers. J Vis Exp 2022:10.3791/64367. [PMID: 36036622 PMCID: PMC9701086 DOI: 10.3791/64367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2023] Open
Abstract
Fluorogenic RNA aptamers have been applied in live cells to tag and visualize RNAs, report on gene expression, and activate fluorescent biosensors that detect levels of metabolites and signaling molecules. In order to study dynamic changes in each of these systems, it is desirable to obtain real-time measurements, but the accuracy of the measurements depends on the kinetics of the fluorogenic reaction being faster than the sampling frequency. Here, we describe methods to determine the in vitro and cellular turn-on kinetics for fluorogenic RNA aptamers using a plate reader equipped with a sample injector and a flow cytometer, respectively. We show that the in vitro kinetics for the fluorescence activation of the Spinach2 and Broccoli aptamers can be modeled as two-phase association reactions and have differing fast phase rate constants of 0.56 s-1 and 0.35 s-1, respectively. In addition, we show that the cellular kinetics for the fluorescence activation of Spinach2 in Escherichia coli, which is further limited by dye diffusion into the Gram-negative bacteria, is still sufficiently rapid to enable accurate sampling frequency on the minute timescale. These methods to analyze fluorescence activation kinetics are applicable to other fluorogenic RNA aptamers that have been developed.
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Affiliation(s)
- Madeline M Mumbleau
- Department of Chemistry and Henry Eyring Center for Cell & Genome Science, University of Utah
| | - Madeline R Meyer
- Department of Chemistry and Henry Eyring Center for Cell & Genome Science, University of Utah
| | - Ming C Hammond
- Department of Chemistry and Henry Eyring Center for Cell & Genome Science, University of Utah;
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12
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Geraci I, Autour A, Pietruschka G, Shiian A, Borisova M, Mayer C, Ryckelynck M, Mayer G. Fluorogenic RNA-Based Biosensor to Sense the Glycolytic Flux in Mammalian Cells. ACS Chem Biol 2022; 17:1164-1173. [PMID: 35427113 DOI: 10.1021/acschembio.2c00100] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The visualization of metabolic flux in real time requires sensor molecules that transduce variations of metabolite concentrations into an appropriate output signal. In this regard, fluorogenic RNA-based biosensors are promising molecular tools as they fluoresce only upon binding to another molecule. However, to date no such sensor is available that enables the direct observation of key metabolites in mammalian cells. Toward this direction, we selected and characterized an RNA light-up sensor designed to respond to fructose 1,6-bisphosphate and applied it to probe glycolytic flux variation in mammal cells.
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Affiliation(s)
- Ignazio Geraci
- Life and Medical Sciences Institute (LIMES), University of Bonn, Gerhard-Domagk-Str.1, 53121 Bonn, Germany
| | - Alexis Autour
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR 9002, 67084 Strasbourg, France
| | - Georg Pietruschka
- Life and Medical Sciences Institute (LIMES), University of Bonn, Gerhard-Domagk-Str.1, 53121 Bonn, Germany
| | - Aleksandra Shiian
- Life and Medical Sciences Institute (LIMES), University of Bonn, Gerhard-Domagk-Str.1, 53121 Bonn, Germany
| | - Marina Borisova
- Interfaculty Institute of Microbiology and Infection Medicine, Organismic Interactions/Glycobiology, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany
| | - Christoph Mayer
- Interfaculty Institute of Microbiology and Infection Medicine, Organismic Interactions/Glycobiology, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany
| | - Michael Ryckelynck
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR 9002, 67084 Strasbourg, France
| | - Günter Mayer
- Life and Medical Sciences Institute (LIMES), University of Bonn, Gerhard-Domagk-Str.1, 53121 Bonn, Germany
- Center of Aptamer Research & Development, University of Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
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13
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Abstract
Microbial biofilms have caused serious concerns in healthcare, medical, and food industries because of their intrinsic resistance against conventional antibiotics and cleaning procedures and their capability to firmly adhere on surfaces for persistent contamination. These global issues strongly motivate researchers to develop novel methodologies to investigate the kinetics underlying biofilm formation, to understand the response of the biofilm with different chemical and physical treatments, and to identify biofilm-specific drugs with high-throughput screenings. Meanwhile microbial biofilms can also be utilized positively as sensing elements in cell-based sensors due to their strong adhesion on surfaces. In this perspective, we provide an overview on the connections between sensing and microbial biofilms, focusing on tools used to investigate biofilm properties, kinetics, and their response to chemicals or physical agents, and biofilm-based sensors, a type of biosensor using the bacterial biofilm as a biorecognition element to capture the presence of the target of interest by measuring the metabolic activity of the immobilized microbial cells. Finally we discuss possible new research directions for the development of robust and rapid biofilm related sensors with high temporal and spatial resolutions, pertinent to a wide range of applications.
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Affiliation(s)
- Riccardo Funari
- Dipartimento di Fisica “M. Merlin”, Università degli Studi di Bari Aldo Moro, Via Amendola, 173, Bari 70125, Italy
- CNR, Istituto di Fotonica e Nanotecnologie, Via Amendola, 173, 70125 Bari, Italy
| | - Amy Q. Shen
- Micro/Bio/Nanofluidics Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
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14
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Signaling events that occur when cells of Escherichia coli encounter a glass surface. Proc Natl Acad Sci U S A 2022; 119:2116830119. [PMID: 35131853 PMCID: PMC8833168 DOI: 10.1073/pnas.2116830119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2021] [Indexed: 12/02/2022] Open
Abstract
Microbial cells organized on solid surfaces are the most ancient form of biological communities. Yet how single cells interact with surfaces and integrate a variety of signals to establish a sessile lifestyle is poorly understood. We developed and used sensitive biosensors to determine the kinetics of second messengers’ responses to surface attachment. This allowed us to examine cell-by-cell variability of the initial signaling events and establish that some of these events depend on flagellar motor function while others do not. Environmentally determined factors, like the energetic status of the cell, can modulate all signaling events. The complex interplay between the surface interaction inputs and external conditions can now be studied using our system. Bacterial cells interact with solid surfaces and change their lifestyle from single free-swimming cells to sessile communal structures (biofilms). Cyclic di-guanosine monophosphate (c-di-GMP) is central to this process, yet we lack tools for direct dynamic visualization of c-di-GMP in single cells. Here, we developed a fluorescent protein–based c-di-GMP–sensing system for Escherichia coli that allowed us to visualize initial signaling events and assess the role played by the flagellar motor. The sensor was pH sensitive, and the events that appeared on a seconds’ timescale were alkaline spikes in the intracellular pH. These spikes were not apparent when signals from different cells were averaged. Instead, a signal appeared on a minutes’ timescale that proved to be due to an increase in intracellular c-di-GMP. This increase, but not the alkaline spikes, depended upon a functional flagellar motor. The kinetics and the amplitude of both the pH and c-di-GMP responses displayed cell-to-cell variability indicative of the distinct ways the cells approached and interacted with the surface. The energetic status of a cell can modulate these events. In particular, the alkaline spikes displayed an oscillatory behavior and the c-di-GMP increase was modest in the presence of glucose.
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15
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Gao Y, Xu Y, Li Y, Chen K, Wu X, Liu Y, Feng X, Kong D, Ning X. The First FRET-Based RNA Aptamer NanoKit for Sensitively and Specifically Detecting c-di-GMP. NANO LETTERS 2022; 22:716-725. [PMID: 34994567 DOI: 10.1021/acs.nanolett.1c03970] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
An effective method to identify c-di-GMP may significantly facilitate the exploration of its signaling pathways and bacterial pathogenesis. Herein, we have developed the first conjugated polymer-amplified RNA aptamer NanoKit with a unique core-shell-shell architecture, which combines the advantages of high selectivity of RNA aptamers and high sensitivity of strong fluorescence resonance energy transfer (FRET) effect, for precisely detecting c-di-GMP. We identified that NanoKit could selectively detect c-di-GMP with a low detection limit of 50 pM. Importantly, NanoKit could identify bacterial species and physiological states, such as planktonic, biofilm, and even antibiotic-resistance, on the basis of their different c-di-GMP expression patterns. Particularly, NanoKit could distinguish bacterial infection and inflammation and identify Pseudomonas aeruginosa associated pneumonia and sepsis, thereby guiding treatment choice and monitoring antibiotic effects. Therefore, NanoKit provides a promising strategy to rapidly identify c-di-GMP and its associated diseases and may benefit for pathophoresis management.
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Affiliation(s)
- Ya Gao
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Chemistry and Biomedicine Innovation Center, College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210093, China
| | - Yurui Xu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Chemistry and Biomedicine Innovation Center, College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210093, China
| | - Yanyan Li
- College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing 210093, China
| | - Kerong Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Chemistry and Biomedicine Innovation Center, College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210093, China
| | - Xiaotong Wu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Chemistry and Biomedicine Innovation Center, College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210093, China
| | - Yuhang Liu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Chemistry and Biomedicine Innovation Center, College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210093, China
| | - Xuli Feng
- School of Pharmaceutical Sciences and Innovative Drug Research Center, Chongqing University, Chongqing 401331, China
| | - Desheng Kong
- College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing 210093, China
| | - Xinghai Ning
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Chemistry and Biomedicine Innovation Center, College of Engineering and Applied Sciences, Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210093, China
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16
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Mantovanelli L, Gaastra BF, Poolman B. Fluorescence-based sensing of the bioenergetic and physicochemical status of the cell. CURRENT TOPICS IN MEMBRANES 2021; 88:1-54. [PMID: 34862023 DOI: 10.1016/bs.ctm.2021.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fluorescence-based sensors play a fundamental role in biological research. These sensors can be based on fluorescent proteins, fluorescent probes or they can be hybrid systems. The availability of a very large dataset of fluorescent molecules, both genetically encoded and synthetically produced, together with the structural insights on many sensing domains, allowed to rationally design a high variety of sensors, capable of monitoring both molecular and global changes in living cells or in in vitro systems. The advancements in the fluorescence-imaging field helped researchers to obtain a deeper understanding of how and where specific changes occur in a cell or in vitro by combining the readout of the fluorescent sensors with the spatial information provided by fluorescent microscopy techniques. In this review we give an overview of the state of the art in the field of fluorescent biosensors and fluorescence imaging techniques, and eventually guide the reader through the choice of the best combination of fluorescent tools and techniques to answer specific biological questions. We particularly focus on sensors for probing the bioenergetics and physicochemical status of the cell.
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Affiliation(s)
- Luca Mantovanelli
- Department of Biochemistry, University of Groningen, Groningen, the Netherlands
| | - Bauke F Gaastra
- Department of Biochemistry, University of Groningen, Groningen, the Netherlands
| | - Bert Poolman
- Department of Biochemistry, University of Groningen, Groningen, the Netherlands.
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17
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Ficaretta ED, Wrobel CJJ, Roy SJS, Erickson SB, Italia JS, Chatterjee A. A Robust Platform for Unnatural Amino Acid Mutagenesis in E. coli Using the Bacterial Tryptophanyl-tRNA synthetase/tRNA pair. J Mol Biol 2021; 434:167304. [PMID: 34655653 PMCID: PMC9005579 DOI: 10.1016/j.jmb.2021.167304] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 10/04/2021] [Accepted: 10/06/2021] [Indexed: 01/13/2023]
Abstract
We report the development of a robust user-friendly Escherichia coli (E. coli) expression system, derived from the BL21(DE3) strain, for site-specifically incorporating unnatural amino acids (UAAs) into proteins using engineered E. coli tryptophanyl-tRNA synthetase (EcTrpRS)-tRNATrp pairs. This was made possible by functionally replacing the endogenous EcTrpRS-tRNATrp pair in BL21(DE3) E. coli with an orthogonal counterpart from Saccharomyces cerevisiae, and reintroducing it into the resulting altered translational machinery tryptophanyl (ATMW-BL21) E. coli strain as an orthogonal nonsense suppressor. The resulting expression system benefits from the favorable characteristics of BL21(DE3) as an expression host, and is compatible with the broadly used T7-driven recombinant expression system. Furthermore, the vector expressing the nonsense-suppressing engineered EcTrpRS-tRNATrp pair was systematically optimized to significantly enhance the incorporation efficiency of various tryptophan analogs. Together, the improved strain and the optimized suppressor plasmids enable efficient UAA incorporation (up to 65% of wild-type levels) into several different proteins. This robust and user-friendly platform will significantly expand the scope of the genetically encoded tryptophan-derived UAAs.
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Affiliation(s)
- Elise D Ficaretta
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Chester J J Wrobel
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Soumya J S Roy
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Sarah B Erickson
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - James S Italia
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Abhishek Chatterjee
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA.
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18
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Abstract
Technologies for RNA imaging in live cells play an important role in understanding the function and regulatory process of RNAs. One approach for genetically encoded fluorescent RNA imaging involves fluorescent light-up aptamers (FLAPs), which are short RNA sequences that can bind cognate fluorogens and activate their fluorescence greatly. Over the past few years, FLAPs have emerged as genetically encoded RNA-based fluorescent biosensors for the cellular imaging and detection of various targets of interest. In this review, we first give a brief overview of the development of the current FLAPs based on various fluorogens. Then we further discuss on the photocycles of the reversibly photoswitching properties in FLAPs and their photostability. Finally, we focus on the applications of FLAPs as genetically encoded RNA-based fluorescent biosensors in biosensing and bioimaging, including RNA, non-nucleic acid molecules, metal ions imaging and quantitative imaging. Their design strategies and recent cellular applications are emphasized and summarized in detail.
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Affiliation(s)
- Huangmei Zhou
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China
| | - Sanjun Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, China.,NYU-ECNU Institute of Physics at NYU Shanghai, Shanghai, China
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19
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Manna S, Truong J, Hammond MC. Guanidine Biosensors Enable Comparison of Cellular Turn-on Kinetics of Riboswitch-Based Biosensor and Reporter. ACS Synth Biol 2021; 10:566-578. [PMID: 33646758 PMCID: PMC7985839 DOI: 10.1021/acssynbio.0c00583] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Indexed: 12/30/2022]
Abstract
Cell-based sensors are useful for many synthetic biology applications, including regulatory circuits, metabolic engineering, and diagnostics. While considerable research efforts have been made toward recognizing new target ligands and increasing sensitivity, the analysis and optimization of turn-on kinetics is often neglected. For example, to our knowledge there has been no systematic study that compared the performance of a riboswitch-based biosensor versus reporter for the same ligand. In this study, we show the development of RNA-based fluorescent (RBF) biosensors for guanidine, a common chaotropic agent that is a precursor to both fertilizer and explosive compounds. Guanidine is cell permeable and nontoxic to E. coli at millimolar concentrations, which in contrast to prior studies enabled direct activation of the riboswitch-based biosensor and corresponding reporter with ligand addition to cells. Our results reveal that the biosensors activate fluorescence in the cell within 4 min of guanidine treatment, which is at least 15 times faster than a reporter derived from the same riboswitch, and this rapid sensing activity is maintained for up to 1.6 weeks. Together, this study describes the design of two new biosensor topologies and showcases the advantages of RBF biosensors for monitoring dynamic processes in cell biology, biotechnology, and synthetic biology.
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Affiliation(s)
- Sudeshna Manna
- Department
of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
- Henry
Eyring Center for Cell & Genome Science, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Johnny Truong
- Department
of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
- Henry
Eyring Center for Cell & Genome Science, University of Utah, Salt Lake
City, Utah 84112, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Ming C. Hammond
- Department
of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
- Henry
Eyring Center for Cell & Genome Science, University of Utah, Salt Lake
City, Utah 84112, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
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20
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Kitto RZ, Christiansen KE, Hammond MC. RNA-based fluorescent biosensors for live cell detection of bacterial sRNA. Biopolymers 2021; 112:e23394. [PMID: 32786000 PMCID: PMC7856060 DOI: 10.1002/bip.23394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/11/2020] [Accepted: 07/13/2020] [Indexed: 01/21/2023]
Abstract
Bacteria contain a diverse set of RNAs to provide tight regulation of gene expression in response to environmental stimuli. Bacterial small RNAs (sRNAs) work in conjunction with protein cofactors to bind complementary mRNA sequences in the cell, leading to up- or downregulation of protein synthesis. In vivo imaging of sRNAs can aid in understanding their spatiotemporal dynamics in real time, which inspires new ways to manipulate these systems for a variety of applications including synthetic biology and therapeutics. Current methods for sRNA imaging are quite limited in vivo and do not provide real-time information about fluctuations in sRNA levels. Herein, we describe our efforts toward the development of an RNA-based fluorescent biosensor for bacterial sRNA both in vitro and in vivo. We validated these sensors for three different bacterial sRNAs in Escherichia coli and demonstrated that the designs provide a bright, sequence-specific signal output in response to exogenous and endogenous RNA targets.
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Affiliation(s)
- Rebekah Z Kitto
- Department of Chemistry, University of California, Berkeley, California, USA
- Department of Chemistry and Henry Eyring Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Kylee E Christiansen
- Department of Chemistry and Henry Eyring Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Ming C Hammond
- Department of Chemistry, University of California, Berkeley, California, USA
- Department of Chemistry and Henry Eyring Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah, USA
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21
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Live Cell Imaging Using Riboswitch-Spinach tRNA Fusions as Metabolite-Sensing Fluorescent Biosensors. Methods Mol Biol 2021; 2323:121-140. [PMID: 34086278 DOI: 10.1007/978-1-0716-1499-0_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The development of fluorescent biosensors is motivated by the desire to monitor cellular metabolite levels in real time. Most genetically encodable fluorescent biosensors are based on receptor proteins fused to fluorescent protein domains. More recently, small molecule-binding riboswitches have been adapted for use as fluorescent biosensors through fusion to the in vitro selected Spinach aptamer, which binds a profluorescent, cell-permeable small molecule mimic of the GFP chromophore, DFHBI. Here we describe methods to prepare and analyze riboswitch-Spinach tRNA fusions for ligand-dependent activation of fluorescence in vivo. Example procedures describe the use of the Vc2-Spinach tRNA biosensor to monitor perturbations in cellular levels of cyclic di-GMP using either fluorescence microscopy or flow cytometry. In this updated chapter, we have added procedures on using biosensors in flow cytometry to detect exogenously added compounds. The relative ease of cloning and imaging of these biosensors, as well as their modular nature, should make this method appealing to other researchers interested in utilizing riboswitch-based biosensors for metabolite sensing.
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22
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Ren K, Keshri P, Wu R, Sun Z, Yu Q, Tian Q, Zhao B, Bagheri Y, Xie Y, You M. A Genetically Encoded RNA Photosensitizer for Targeted Cell Regulation. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202010106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Kewei Ren
- Department of Chemistry University of Massachusetts Amherst MA 01003 USA
| | - Puspam Keshri
- Department of Chemistry University of Massachusetts Amherst MA 01003 USA
| | - Rigumula Wu
- Department of Chemistry University of Massachusetts Amherst MA 01003 USA
| | - Zhining Sun
- Department of Chemistry University of Massachusetts Amherst MA 01003 USA
| | - Qikun Yu
- Department of Chemistry University of Massachusetts Amherst MA 01003 USA
| | - Qian Tian
- Department of Chemistry University of Massachusetts Amherst MA 01003 USA
| | - Bin Zhao
- Department of Chemistry University of Massachusetts Amherst MA 01003 USA
| | - Yousef Bagheri
- Department of Chemistry University of Massachusetts Amherst MA 01003 USA
| | - Yiwen Xie
- Department of Chemistry University of Massachusetts Amherst MA 01003 USA
| | - Mingxu You
- Department of Chemistry University of Massachusetts Amherst MA 01003 USA
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23
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Ren K, Keshri P, Wu R, Sun Z, Yu Q, Tian Q, Zhao B, Bagheri Y, Xie Y, You M. A Genetically Encoded RNA Photosensitizer for Targeted Cell Regulation. Angew Chem Int Ed Engl 2020; 59:21986-21990. [PMID: 32797667 PMCID: PMC7747015 DOI: 10.1002/anie.202010106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/13/2020] [Indexed: 12/12/2022]
Abstract
Genetically encoded RNA devices have emerged for various cellular applications in imaging and biosensing, but their functions as precise regulators in living systems are still limited. Inspired by protein photosensitizers, we propose here a genetically encoded RNA aptamer based photosensitizer (GRAP). Upon illumination, the RNA photosensitizer can controllably generate reactive oxygen species for targeted cell regulation. The GRAP system can be selectively activated by endogenous stimuli and light of different wavelengths. Compared with their protein analogues, GRAP is highly programmable and exhibits reduced off-target effects. These results indicate that GRAP enables efficient noninvasive target cell ablation with high temporal and spatial precision. This new RNA regulator system will be widely used for optogenetics, targeted cell ablation, subcellular manipulation, and imaging.
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Affiliation(s)
- Kewei Ren
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
| | - Puspam Keshri
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
| | - Rigumula Wu
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
| | - Zhining Sun
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
| | - Qikun Yu
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
| | - Qian Tian
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
| | - Bin Zhao
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
| | - Yousef Bagheri
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
| | - Yiwen Xie
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
| | - Mingxu You
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
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24
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Cambré A, Aertsen A. Bacterial Vivisection: How Fluorescence-Based Imaging Techniques Shed a Light on the Inner Workings of Bacteria. Microbiol Mol Biol Rev 2020; 84:e00008-20. [PMID: 33115939 PMCID: PMC7599038 DOI: 10.1128/mmbr.00008-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The rise in fluorescence-based imaging techniques over the past 3 decades has improved the ability of researchers to scrutinize live cell biology at increased spatial and temporal resolution. In microbiology, these real-time vivisections structurally changed the view on the bacterial cell away from the "watery bag of enzymes" paradigm toward the perspective that these organisms are as complex as their eukaryotic counterparts. Capitalizing on the enormous potential of (time-lapse) fluorescence microscopy and the ever-extending pallet of corresponding probes, initial breakthroughs were made in unraveling the localization of proteins and monitoring real-time gene expression. However, later it became clear that the potential of this technique extends much further, paving the way for a focus-shift from observing single events within bacterial cells or populations to obtaining a more global picture at the intra- and intercellular level. In this review, we outline the current state of the art in fluorescence-based vivisection of bacteria and provide an overview of important case studies to exemplify how to use or combine different strategies to gain detailed information on the cell's physiology. The manuscript therefore consists of two separate (but interconnected) parts that can be read and consulted individually. The first part focuses on the fluorescent probe pallet and provides a perspective on modern methodologies for microscopy using these tools. The second section of the review takes the reader on a tour through the bacterial cell from cytoplasm to outer shell, describing strategies and methods to highlight architectural features and overall dynamics within cells.
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Affiliation(s)
- Alexander Cambré
- KU Leuven, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Leuven, Belgium
| | - Abram Aertsen
- KU Leuven, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Leuven, Belgium
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25
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Kong J, Wang Y, Qi W, Huang M, Su R, He Z. Green fluorescent protein inspired fluorophores. Adv Colloid Interface Sci 2020; 285:102286. [PMID: 33164780 DOI: 10.1016/j.cis.2020.102286] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 10/11/2020] [Accepted: 10/12/2020] [Indexed: 12/20/2022]
Abstract
Green fluorescence proteins (GFP) are appealing to a variety of biomedical and biotechnology applications, such as protein fusion, subcellular localizations, cell visualization, protein-protein interaction, and genetically encoded sensors. To mimic the fluorescence of GFP, various compounds, such as GFP chromophores analogs, hydrogen bond-rich proteins, and aromatic peptidyl nanostructures that preclude free rotation of the aryl-alkene bond, have been developed to adapt them for a fantastic range of applications. Herein, we firstly summarize the structure and luminescent mechanism of GFP. Based on this, the design strategy, fluorescent properties, and the advanced applications of GFP-inspired fluorophores are then carefully discussed. The diverse advantages of bioinspired fluorophores, such as biocompatibility, structural simplicity, and capacity to form a variety of functional nanostructures, endow them potential candidates as the next-generation bio-organic optical materials.
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26
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Li X, Mo L, Litke JL, Dey SK, Suter SR, Jaffrey SR. Imaging Intracellular S-Adenosyl Methionine Dynamics in Live Mammalian Cells with a Genetically Encoded Red Fluorescent RNA-Based Sensor. J Am Chem Soc 2020; 142:14117-14124. [PMID: 32698574 PMCID: PMC8158784 DOI: 10.1021/jacs.0c02931] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
To understand the role of intracellular metabolites in cellular processes, it is important to measure the dynamics and fluxes of small molecules in living cells. Although conventional metabolite sensors composed of fluorescent proteins have been made to detect some metabolites, an emerging approach is to use genetically encoded sensors composed of RNA. Because of the ability to rapidly generate metabolite-binding RNA aptamers, RNA-based sensors have the potential to be designed more readily than protein-based sensors. Numerous strategies have been developed to convert the green-fluorescent Spinach or Broccoli fluorogenic RNA aptamers into metabolite-regulated sensors. Nevertheless, red fluorescence is particularly desirable because of the low level of red background fluorescence in cells. However, the red fluorescent variant of the Broccoli aptamer, Red Broccoli, does not exhibit red fluorescence in cells when imaged with its cognate fluorophore. It is not known why Red Broccoli is fluorescent in vitro but not in live mammalian cells. Here, we develop a new fluorophore, OBI (3,5-difluoro-4-hydroxybenzylidene-imidazolinone-2-oxime-1-benzoimidazole), which binds Red Broccoli with high affinity and makes Red Broccoli resistant to thermal unfolding. We show that OBI enables Red Broccoli to be readily detected in live mammalian cells. Furthermore, we show that Red Broccoli can be fused to a S-adenosyl methionine (SAM)-binding aptamer to generate a red fluorescent RNA-based sensor that enables imaging of SAM in live mammalian cells. These results reveal a red fluorescent fluorogenic aptamer that functions in mammalian cells and that can be readily developed into red fluorescent RNA-based sensors.
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Affiliation(s)
- Xing Li
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, New York 10065, United States
| | - Liuting Mo
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, New York 10065, United States
| | - Jacob L Litke
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, New York 10065, United States
| | - Sourav Kumar Dey
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, New York 10065, United States
| | - Scott R Suter
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, New York 10065, United States
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, New York 10065, United States
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27
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Broch F, Gautier A. Illuminating Cellular Biochemistry: Fluorogenic Chemogenetic Biosensors for Biological Imaging. Chempluschem 2020; 85:1487-1497. [PMID: 32644262 DOI: 10.1002/cplu.202000413] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/18/2020] [Indexed: 12/19/2022]
Abstract
Cellular activity is defined by the precise spatiotemporal regulation of various components, such as ions, small molecules, or proteins. Studying cell physiology consequently requires the optical recording of these processes, notably by using fluorescent biosensors. The recent development of various fluorogenic systems greatly expanded the palette of reporters to be included in these sensors design. Fluorogenic reporters consist of a protein or RNA tag that can complex either an endogenous or a synthetic fluorogenic dye (so-called fluorogen). The intrinsic nature of these tags, along with the high tunability of their cognate chromophore provide interesting features such as far-red to near-infrared emission, oxygen independence, or unprecedented color versatility. These engineered photoreceptors, self-labelling proteins, or noncovalent aptamers and protein tags were rapidly identified as promising reporters to observe biological events. This Minireview focuses on the new perspectives they offer to design unique and innovative biosensors, thus pushing the boundaries of cellular imaging.
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Affiliation(s)
- Fanny Broch
- Sorbonne Université, École normale supérieure, PSL University, CNRS Laboratoire des biomolécules, LBM, 75005, Paris, France
| | - Arnaud Gautier
- Sorbonne Université, École normale supérieure, PSL University, CNRS Laboratoire des biomolécules, LBM, 75005, Paris, France.,Institut Universitaire de France, France
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28
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Petchiappan A, Naik SY, Chatterji D. Tracking the homeostasis of second messenger cyclic-di-GMP in bacteria. Biophys Rev 2020; 12:719-730. [PMID: 32060735 PMCID: PMC7311556 DOI: 10.1007/s12551-020-00636-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/05/2020] [Indexed: 01/09/2023] Open
Abstract
Cyclic-di-GMP (c-di-GMP) is an important second messenger in bacteria which regulates the bacterial transition from motile to sessile phase and also plays a major role in processes such as cell division, exopolysaccharide synthesis, and biofilm formation. Due to its crucial role in dictating the bacterial phenotype, the synthesis and hydrolysis of c-di-GMP is tightly regulated via multiple mechanisms. Perturbing the c-di-GMP homeostasis affects bacterial growth and survival, so it is necessary to understand the underlying mechanisms related to c-di-GMP metabolism. Most techniques used for estimating the c-di-GMP concentration lack single-cell resolution and do not provide information about any heterogeneous distribution of c-di-GMP inside cells. In this review, we briefly discuss how the activity of c-di-GMP metabolising enzymes, particularly bifunctional proteins, is modulated to maintain c-di-GMP homeostasis. We further highlight how fluorescence-based methods aid in understanding the spatiotemporal regulation of c-di-GMP signalling. Finally, we discuss the blind spots in our understanding of second messenger signalling and outline how they can be addressed in the future.
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Affiliation(s)
| | - Sujay Y Naik
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Dipankar Chatterji
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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29
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Anderson WA, Dippel AB, Maiden MM, Waters CM, Hammond MC. Chemiluminescent sensors for quantitation of the bacterial second messenger cyclic di-GMP. Methods Enzymol 2020; 640:83-104. [PMID: 32560807 PMCID: PMC8238376 DOI: 10.1016/bs.mie.2020.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Chemiluminescent biosensors have been developed and broadly applied to mammalian cell systems for studying intracellular signaling networks. For bacteria, biosensors have largely relied on fluorescence-based systems for quantitating signaling molecules, but these designs can encounter issues in complex environments due to their reliance on external illumination. In order to circumvent these issues, we designed the first ratiometric chemiluminescent biosensors for studying a key bacterial second messenger, cyclic di-GMP. We have shown recently that these biosensors function both in vitro and in vivo for detecting changes in cyclic di-GMP levels. In this chapter, we present a practical and broadly applicable method for high-throughput quantitation of cyclic di-GMP in bacterial cell extracts using the high affinity biosensor tVYN-TmΔ that could serve as the "Bradford assay" equivalent for this bacterial signaling molecule.
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Affiliation(s)
- Wyatt A Anderson
- Department of Chemistry and Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT, United States; Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Andrew B Dippel
- Department of Chemistry and Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT, United States; Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States
| | - Michael M Maiden
- Departments of Microbiology and Molecular Genetics and The BEACON Center for The Study of Evolution in Action, Michigan State University, East Lansing, MI, United States
| | - Christopher M Waters
- Departments of Microbiology and Molecular Genetics and The BEACON Center for The Study of Evolution in Action, Michigan State University, East Lansing, MI, United States
| | - Ming C Hammond
- Department of Chemistry and Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT, United States; Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States.
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30
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Hoang Trung Chau T, Hoang Anh Mai D, Ngoc Pham D, Thi Quynh Le H, Yeol Lee E. Developments of Riboswitches and Toehold Switches for Molecular Detection-Biosensing and Molecular Diagnostics. Int J Mol Sci 2020; 21:E3192. [PMID: 32366036 PMCID: PMC7247568 DOI: 10.3390/ijms21093192] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 12/20/2022] Open
Abstract
Riboswitches and toehold switches are considered to have potential for implementation in various fields, i.e., biosensing, metabolic engineering, and molecular diagnostics. The specific binding, programmability, and manipulability of these RNA-based molecules enable their intensive deployments in molecular detection as biosensors for regulating gene expressions, tracking metabolites, or detecting RNA sequences of pathogenic microorganisms. In this review, we will focus on the development of riboswitches and toehold switches in biosensing and molecular diagnostics. This review introduces the operating principles and the notable design features of riboswitches as well as toehold switches. Moreover, we will describe the advances and future directions of riboswitches and toehold switches in biosensing and molecular diagnostics.
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Affiliation(s)
| | | | | | | | - Eun Yeol Lee
- Department of Chemical Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Korea; (T.H.T.C.); (D.H.A.M.); (D.N.P.); (H.T.Q.L.)
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31
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Dippel AB, Anderson WA, Park JH, Yildiz FH, Hammond MC. Development of Ratiometric Bioluminescent Sensors for in Vivo Detection of Bacterial Signaling. ACS Chem Biol 2020; 15:904-914. [PMID: 32186367 DOI: 10.1021/acschembio.9b00800] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Second messenger signaling networks allow cells to sense and adapt to changing environmental conditions. In bacteria, the nearly ubiquitous second messenger molecule cyclic di-GMP coordinates diverse processes such as motility, biofilm formation, and virulence. In bacterial pathogens, these signaling networks allow the bacteria to survive changing environmental conditions that are experienced during infection of a mammalian host. While studies have examined the effects of cyclic di-GMP levels on virulence in these pathogens, it has not been possible to visualize cyclic di-GMP levels in real time during the stages of host infection. Toward this goal, we generate the first ratiometric, chemiluminescent biosensor scaffold that selectively responds to c-di-GMP. By engineering the biosensor scaffold, a suite of Venus-YcgR-NLuc (VYN) biosensors is generated that provide extremely high sensitivity (KD < 300 pM) and large changes in the bioluminescence resonance energy transfer (BRET) signal (up to 109%). As a proof-of-concept that VYN biosensors can image cyclic di-GMP in tissues, we show that the VYN biosensors function in the context of a tissue phantom model, with only ∼103-104 biosensor-expressing E. coli cells required for the measurement. Furthermore, we utilize the biosensor in vitro to assess changes in cyclic di-GMP in V. cholerae grown with different inputs found in the host environment. The VYN sensors developed here can serve as robust in vitro diagnostic tools for high throughput screening, as well as genetically encodable tools for monitoring the dynamics of c-di-GMP in live cells, and lay the groundwork for live cell imaging of c-di-GMP dynamics in bacteria within tissues and other complex environments.
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Affiliation(s)
- Andrew B. Dippel
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
- Department of Chemistry and Henry Eyring Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Wyatt A. Anderson
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
- Department of Chemistry and Henry Eyring Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah 84112, United States
| | - Jin Hwan Park
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Fitnat H. Yildiz
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Ming C. Hammond
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
- Department of Chemistry and Henry Eyring Center for Cell and Genome Sciences, University of Utah, Salt Lake City, Utah 84112, United States
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32
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Wu R, Karunanayake Mudiyanselage AP, Ren K, Sun Z, Tian Q, Zhao B, Bagheri Y, Lutati D, Keshri P, You M. Ratiometric Fluorogenic RNA-Based Sensors for Imaging Live-Cell Dynamics of Small Molecules. ACS APPLIED BIO MATERIALS 2020; 3:2633-2642. [DOI: 10.1021/acsabm.9b01237] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Rigumula Wu
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | | | - Kewei Ren
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Zhining Sun
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Qian Tian
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Bin Zhao
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Yousef Bagheri
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - David Lutati
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Puspam Keshri
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Mingxu You
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
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33
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Ozbakir HF, Anderson NT, Fan KC, Mukherjee A. Beyond the Green Fluorescent Protein: Biomolecular Reporters for Anaerobic and Deep-Tissue Imaging. Bioconjug Chem 2020; 31:293-302. [PMID: 31794658 PMCID: PMC7033020 DOI: 10.1021/acs.bioconjchem.9b00688] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Fluorescence imaging represents cornerstone technology for studying biological function at the cellular and molecular levels. The technology's centerpiece is a prolific collection of genetic reporters based on the green fluorescent protein (GFP) and related analogs. More than two decades of protein engineering have endowed the GFP repertoire with an incredible assortment of fluorescent proteins, allowing scientists immense latitude in choosing reporters tailored to various cellular and environmental contexts. Nevertheless, GFP and derivative reporters have specific limitations that hinder their unrestricted use for molecular imaging. These challenges have inspired the development of new reporter proteins and imaging mechanisms. Here, we review how these developments are expanding the frontiers of reporter gene techniques to enable nondestructive studies of cell function in anaerobic environments and deep inside intact animals-two important biological contexts that are fundamentally incompatible with the use of GFP-based reporters.
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Affiliation(s)
- Harun F. Ozbakir
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Nolan T. Anderson
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Kang-Ching Fan
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Arnab Mukherjee
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department of Chemistry, University of California, Santa Barbara, California 93106, United States
- Neuroscience Research Institute, University of California, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California, Santa Barbara, California 93106, United States
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34
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RNA-based fluorescent biosensors for live cell imaging of small molecules and RNAs. Curr Opin Biotechnol 2020; 63:157-166. [PMID: 32086101 DOI: 10.1016/j.copbio.2020.01.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 12/23/2019] [Accepted: 01/03/2020] [Indexed: 12/23/2022]
Abstract
Genetically encodable fluorescent biosensors provide spatiotemporal information on their target analytes in a label-free manner, which has enabled the study of cell biology and signaling in living cells. Over the past three decades, fueled by the development of a wide palette of fluorescent proteins, protein-based fluorescent biosensors against a broad array of targets have been developed. Recently, with the development of fluorogenic RNA aptamer-dye pairs that function in live cells, RNA-based fluorescent (RBF) biosensors have emerged as a complementary class of biosensors. Here we review the current state-of-the-art for fluorogenic RNA aptamers and RBF biosensors for imaging small molecules and RNAs, and highlight some emerging opportunities.
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35
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Ren K, Wu R, Karunanayake Mudiyanselage APKK, Yu Q, Zhao B, Xie Y, Bagheri Y, Tian Q, You M. In Situ Genetically Cascaded Amplification for Imaging RNA Subcellular Locations. J Am Chem Soc 2020; 142:2968-2974. [PMID: 31968164 DOI: 10.1021/jacs.9b11748] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In situ amplification methods, such as hybridization chain reaction, are valuable tools for mapping the spatial distribution and subcellular location of target analytes. However, the live-cell applications of these methods are still limited due to challenges in the probe delivery, degradation, and cytotoxicity. Herein, we report a novel genetically encoded in situ amplification method to noninvasively image the subcellular location of RNA targets in living cells. In our system, a fluorogenic RNA reporter, Broccoli, was split into two nonfluorescent fragments and conjugated to the end of two RNA hairpin strands. The binding of one target RNA can then trigger a cascaded hybridization between these hairpin pairs and thus activate multiple Broccoli fluorescence signals. We have shown that such an in situ amplified strategy can be used for the sensitive detection and location imaging of various RNA targets in living bacterial and mammalian cells. This new design principle provides an effective and versatile platform for tracking various intracellular analytes.
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Affiliation(s)
- Kewei Ren
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Rigumula Wu
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | | | - Qikun Yu
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Bin Zhao
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Yiwen Xie
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Yousef Bagheri
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Qian Tian
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Mingxu You
- Department of Chemistry , University of Massachusetts , Amherst , Massachusetts 01003 , United States
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36
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Xuan TF, Liu J, Wang ZQ, Chen WM, Lin J. Fluorescent Detection of the Ubiquitous Bacterial Messenger 3',5' Cyclic Diguanylic Acid by Using a Small Aromatic Molecule. Front Microbiol 2020; 10:3163. [PMID: 31993044 PMCID: PMC6970945 DOI: 10.3389/fmicb.2019.03163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 12/31/2019] [Indexed: 12/28/2022] Open
Abstract
3′,5′ Cyclic diguanylic acid (c-di-GMP) has been shown to play a central role in the regulation of bacterial physiological processes such as biofilm formation and virulence production, and is regarded as a potential target for the development of anti-infective drugs. A method for the facile detection of the bacterial level of cellular c-di-GMP is required to explore the details of c-di-GMP signaling and design drugs on the basis of this pathway. Current methods of c-di-GMP detection have limited sensitivity or difficultly in probe preparation. Herein a new fluorescent probe is reported for the detection of c-di-GMP at concentrations as low as 500 nM. The probe was developed on the basis of the G-quadruplex formation of c-di-GMP induced by aromatic molecules. When used on crude bacterial cell lysates, it can effectively distinguish between the low c-di-GMP levels of bacteria in plankton and the high c-di-GMP levels in biofilm. The method described here is simple, inexpensive, sensitive, and suitable for practical applications involving the rapid detection of cellular c-di-GMP levels in vitro after simple bacterial lysis and filtration.
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Affiliation(s)
- Teng-Fei Xuan
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, Guangzhou, China
| | - Jun Liu
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, Guangzhou, China
| | - Zi-Qiang Wang
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, Guangzhou, China
| | - Wei-Min Chen
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, Guangzhou, China
| | - Jing Lin
- International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, Guangzhou, China
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37
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Wu R, Karunanayake Mudiyanselage APKK, Shafiei F, Zhao B, Bagheri Y, Yu Q, McAuliffe K, Ren K, You M. Genetically Encoded Ratiometric RNA‐Based Sensors for Quantitative Imaging of Small Molecules in Living Cells. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201911799] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Rigumula Wu
- University of Massachusetts Amherst MA 01003 USA
| | | | | | - Bin Zhao
- University of Massachusetts Amherst MA 01003 USA
| | | | - Qikun Yu
- University of Massachusetts Amherst MA 01003 USA
| | | | - Kewei Ren
- University of Massachusetts Amherst MA 01003 USA
| | - Mingxu You
- University of Massachusetts Amherst MA 01003 USA
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38
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Wright TA, Jiang L, Park JJ, Anderson WA, Chen G, Hallberg ZF, Nan B, Hammond MC. Second messengers and divergent HD-GYP phosphodiesterases regulate 3',3'-cGAMP signaling. Mol Microbiol 2019; 113:222-236. [PMID: 31665539 DOI: 10.1111/mmi.14412] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2019] [Indexed: 12/16/2022]
Abstract
3',3'-cyclic GMP-AMP (cGAMP) is the third cyclic dinucleotide (CDN) to be discovered in bacteria. No activators of cGAMP signaling have yet been identified, and the signaling pathways for cGAMP have been inferred to display a narrow distribution based upon the characterized synthases, DncV and Hypr GGDEFs. Here, we report that the ubiquitous second messenger cyclic AMP (cAMP) is an activator of the Hypr GGDEF enzyme GacB from Myxococcus xanthus. Furthermore, we show that GacB is inhibited directly by cyclic di-GMP, which provides evidence for cross-regulation between different CDN pathways. Finally, we reveal that the HD-GYP enzyme PmxA is a cGAMP-specific phosphodiesterase (GAP) that promotes resistance to osmotic stress in M. xanthus. A signature amino acid change in PmxA was found to reprogram substrate specificity and was applied to predict the presence of non-canonical HD-GYP phosphodiesterases in many bacterial species, including phyla previously not known to utilize cGAMP signaling.
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Affiliation(s)
- Todd A Wright
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA.,Department of Chemistry and Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT, 84112, USA
| | - Lucy Jiang
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - James J Park
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - Wyatt A Anderson
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA.,Department of Chemistry and Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT, 84112, USA
| | - Ge Chen
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Zachary F Hallberg
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - Beiyan Nan
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Ming C Hammond
- Department of Chemistry and Henry Eyring Center for Cell and Genome Science, University of Utah, Salt Lake City, UT, 84112, USA
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39
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Wu R, Karunanayake Mudiyanselage APKK, Shafiei F, Zhao B, Bagheri Y, Yu Q, McAuliffe K, Ren K, You M. Genetically Encoded Ratiometric RNA-Based Sensors for Quantitative Imaging of Small Molecules in Living Cells. Angew Chem Int Ed Engl 2019; 58:18271-18275. [PMID: 31591798 DOI: 10.1002/anie.201911799] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Indexed: 12/20/2022]
Abstract
Precisely determining the intracellular concentrations of metabolites and signaling molecules is critical in studying cell biology. Fluorogenic RNA-based sensors have emerged to detect various targets in living cells. However, it is still challenging to apply these genetically encoded sensors to quantify the cellular concentrations and distributions of targets. Herein, using a pair of orthogonal fluorogenic RNA aptamers, DNB and Broccoli, we engineered a modular sensor system to apply the DNB-to-Broccoli fluorescence ratio to quantify the cell-to-cell variations of target concentrations. These ratiometric sensors can be broadly applied for live-cell imaging and quantification of metabolites, signaling molecules, and other synthetic compounds.
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Affiliation(s)
- Rigumula Wu
- University of Massachusetts, Amherst, MA, 01003, USA
| | | | | | - Bin Zhao
- University of Massachusetts, Amherst, MA, 01003, USA
| | | | - Qikun Yu
- University of Massachusetts, Amherst, MA, 01003, USA
| | | | - Kewei Ren
- University of Massachusetts, Amherst, MA, 01003, USA
| | - Mingxu You
- University of Massachusetts, Amherst, MA, 01003, USA
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40
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Abstract
Prokaryotic organisms occupy the most diverse set of environments and conditions on our planet. Their ability to sense and respond to a broad range of external cues remain key research areas in modern microbiology, central to behaviors that underlie beneficial and pathogenic interactions of bacteria with multicellular organisms and within complex ecosystems. Advances in our understanding of the one- and two-component signal transduction systems that underlie these sensing pathways have been driven by advances in imaging the behavior of many individual bacterial cells, as well as visualizing individual proteins and protein arrays within living cells. Cryo-electron tomography continues to provide new insights into the structure and function of chemosensory receptors and flagellar motors, while advances in protein labeling and tracking are applied to understand information flow between receptor and motor. Sophisticated microfluidics allow simultaneous analysis of the behavior of thousands of individual cells, increasing our understanding of how variance between individuals is generated, regulated and employed to maximize fitness of a population. In vitro experiments have been complemented by the study of signal transduction and motility in complex in vivo models, allowing investigators to directly address the contribution of motility, chemotaxis and aggregation/adhesion on virulence during infection. Finally, systems biology approaches have demonstrated previously uncharted areas of protein space in which novel two-component signal transduction pathways can be designed and constructed de novo These exciting experimental advances were just some of the many novel findings presented at the 15th Bacterial Locomotion and Signal Transduction conference (BLAST XV) in January 2019.
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41
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Wu MJ, Andreasson JOL, Kladwang W, Greenleaf W, Das R. Automated Design of Diverse Stand-Alone Riboswitches. ACS Synth Biol 2019; 8:1838-1846. [PMID: 31298841 PMCID: PMC6703183 DOI: 10.1021/acssynbio.9b00142] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
![]()
Riboswitches that couple binding
of ligands to conformational changes
offer sensors and control elements for RNA synthetic biology and medical
biotechnology. However, design of these riboswitches has required
expert intuition or software specialized to transcription or translation
outputs; design has been particularly challenging for applications
in which the riboswitch output cannot be amplified by other molecular
machinery. We present a fully automated design method called RiboLogic
for such “stand-alone” riboswitches and test it via high-throughput experiments on 2875 molecules using
RNA-MaP (RNA on a massively parallel array) technology. These molecules
consistently modulate their affinity to the MS2 bacteriophage coat
protein upon binding of flavin mononucleotide, tryptophan, theophylline,
and microRNA miR-208a, achieving activation ratios of up to 20 and
significantly better performance than control designs. By encompassing
a wide diversity of stand-alone switches and highly quantitative data,
the resulting ribologic-solves experimental data
set provides a rich resource for further improvement of riboswitch
models and design methods.
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42
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Karunanayake Mudiyanselage APKK, Wu R, Leon-Duque MA, Ren K, You M. "Second-generation" fluorogenic RNA-based sensors. Methods 2019; 161:24-34. [PMID: 30660865 PMCID: PMC6589113 DOI: 10.1016/j.ymeth.2019.01.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/11/2019] [Accepted: 01/13/2019] [Indexed: 02/07/2023] Open
Abstract
A fluorogenic aptamer can specifically interact with a fluorophore to activate its fluorescence. These nucleic acid-based fluorogenic modules have been dramatically developed over the past decade, and have been used as versatile reporters in the sensor development and for intracellular imaging. In this review, we summarize the design principles, applications, and challenges of the first-generation fluorogenic RNA-based sensors. Moreover, we discuss some strategies to develop next-generation biosensors with improved sensitivity, selectivity, quantification property, and eukaryotic robustness. Using genetically encoded catalytic hairpin assembly strategy as an example, we further introduce a standard protocol to design, characterize, and apply these fluorogenic RNA-based sensors for in vitro detection and cellular imaging of target biomolecules. By incorporating natural RNA machineries, nucleic acid nanotechnology, and systematic evolution approaches, next-generation fluorogenic RNA-based devices can be potentially engineered to be widely applied in cell biology and biomedicine.
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Affiliation(s)
| | - Rigumula Wu
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | - Mark A Leon-Duque
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | - Kewei Ren
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | - Mingxu You
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA.
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43
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Hallberg ZF, Chan CH, Wright TA, Kranzusch PJ, Doxzen KW, Park JJ, Bond DR, Hammond MC. Structure and mechanism of a Hypr GGDEF enzyme that activates cGAMP signaling to control extracellular metal respiration. eLife 2019; 8:43959. [PMID: 30964001 PMCID: PMC6456294 DOI: 10.7554/elife.43959] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/12/2019] [Indexed: 12/16/2022] Open
Abstract
A newfound signaling pathway employs a GGDEF enzyme with unique activity compared to the majority of homologs associated with bacterial cyclic di-GMP signaling. This system provides a rare opportunity to study how signaling proteins natively gain distinct function. Using genetic knockouts, riboswitch reporters, and RNA-Seq, we show that GacA, the Hypr GGDEF in Geobacter sulfurreducens, specifically regulates cyclic GMP-AMP (3′,3′-cGAMP) levels in vivo to stimulate gene expression associated with metal reduction separate from electricity production. To reconcile these in vivo findings with prior in vitro results that showed GacA was promiscuous, we developed a full kinetic model combining experimental data and mathematical modeling to reveal mechanisms that contribute to in vivo specificity. A 1.4 Å-resolution crystal structure of the Geobacter Hypr GGDEF domain was determined to understand the molecular basis for those mechanisms, including key cross-dimer interactions. Together these results demonstrate that specific signaling can result from a promiscuous enzyme. Microscopic organisms known as bacteria are found in virtually every environment on the planet. One reason bacteria are so successful is that they are able to form communities known as biofilms on surfaces in animals and other living things, as well as on rocks and other features in the environment. These biofilms protect the bacteria from fluctuations in the environment and toxins. For over 30 years, a class of enzymes called the GGDEF enzymes were thought to make a single signal known as cyclic di-GMP that regulates the formation of biofilms. However, in 2016, a team of researchers reported that some GGDEF enzymes, including one from a bacterium called Geobacter sulfurreducens, were also able to produce two other signals known as cGAMP and cyclic di-AMP. The experiments involved making the enzymes and testing their activity outside the cell. Therefore, it remained unclear whether these enzymes (dubbed ‘Hypr’ GGDEF enzymes) actually produce all three signals inside cells and play a role in forming bacterial biofilms. G. sulfurreducens is unusual because it is able to grow on metallic minerals or electrodes to generate electrical energy. As part of a community of microorganisms, they help break down pollutants in contaminated areas and can generate electricity from wastewater. Now, Hallberg, Chan et al. – including many of the researchers involved in the 2016 work – combined several experimental and mathematical approaches to study the Hypr GGDEF enzymes in G. sulfurreducens. The experiments show that the Hypr GGDEF enzymes produced cGAMP, but not the other two signals, inside the cells. This cGAMP regulated the ability of G. sulfurreducens to grow by extracting electrical energy from the metallic minerals, which appears to be a new, biofilm-less lifestyle. Further experiments revealed how Hypr GGDEF enzymes have evolved to preferentially make cGAMP over the other two signals. Together, these findings demonstrate that enzymes with the ability to make several different signals, are capable of generating specific responses in bacterial cells. By understanding how bacteria make decisions, it may be possible to change their behaviors. The findings of Hallberg, Chan et al. help to identify the signaling pathways involved in this decision-making and provide new tools to study them in the future.
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Affiliation(s)
- Zachary F Hallberg
- Department of Chemistry, University of California, Berkeley, Berkeley, United States
| | - Chi Ho Chan
- Department of Plant and Microbial Biology and BioTechnology Institute, University of Minnesota, Minnesota, United States
| | - Todd A Wright
- Department of Chemistry, University of California, Berkeley, Berkeley, United States
| | - Philip J Kranzusch
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States.,Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, United States.,Parker Institute for Cancer Immunotherapy at Dana-Farber Cancer Institute, Boston, United States
| | - Kevin W Doxzen
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, United States
| | - James J Park
- Department of Chemistry, University of California, Berkeley, Berkeley, United States
| | - Daniel R Bond
- Department of Plant and Microbial Biology and BioTechnology Institute, University of Minnesota, Minnesota, United States
| | - Ming C Hammond
- Department of Chemistry, University of California, Berkeley, Berkeley, United States.,Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, United States.,Department of Chemistry, University of Utah, Salt Lake City, United States
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44
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Autour A, Bouhedda F, Cubi R, Ryckelynck M. Optimization of fluorogenic RNA-based biosensors using droplet-based microfluidic ultrahigh-throughput screening. Methods 2019; 161:46-53. [PMID: 30902664 DOI: 10.1016/j.ymeth.2019.03.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 03/17/2019] [Accepted: 03/18/2019] [Indexed: 12/19/2022] Open
Abstract
Biosensors are biological molecules able to detect and report the presence of a target molecule by the emission of a signal. Nucleic acids are particularly appealing for the design of such molecule since their great structural plasticity makes them able to specifically interact with a wide range of ligands and their structure can rearrange upon recognition to trigger a reporting event. A biosensor is typically made of three main domains: a sensing domain that is connected to a reporting domain via a communication module in charge of transmitting the sensing event through the molecule. The communication module is therefore an instrumental element of the sensor. This module is usually empirically developed through a trial-and-error strategy with the testing of only a few combinations judged relevant by the experimenter. In this work, we introduce a novel method combining the use of droplet-based microfluidics and next generation sequencing. This method allows to functionally characterize up to a million of different sequences in a single set of experiments and, by doing so, to exhaustively test every possible sequence permutations of the communication module. Here, we demonstrate the efficiency of the approach by isolating a set of optimized RNA biosensors able to sense theophylline and to convert this recognition into fluorescence emission.
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Affiliation(s)
- Alexis Autour
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, F-67000 Strasbourg, France
| | - Farah Bouhedda
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, F-67000 Strasbourg, France
| | - Roger Cubi
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, F-67000 Strasbourg, France
| | - Michael Ryckelynck
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, F-67000 Strasbourg, France.
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You M, Litke JL, Wu R, Jaffrey SR. Detection of Low-Abundance Metabolites in Live Cells Using an RNA Integrator. Cell Chem Biol 2019; 26:471-481.e3. [PMID: 30773480 DOI: 10.1016/j.chembiol.2019.01.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 12/05/2018] [Accepted: 01/10/2019] [Indexed: 01/05/2023]
Abstract
Genetically encoded biosensors are useful tools for detecting the presence and levels of diverse biomolecules in living cells. However, low-abundance targets are difficult to detect because they are often unable to bind and activate enough biosensors to detect using standard microscopic imaging approaches. Here we describe a type of RNA-based biosensor, an RNA integrator, which enables detection of low-abundance targets in vitro and in living cells. The RNA integrator is an RNA sequence comprising a ribozyme and an unfolded form of the fluorogenic aptamer Broccoli. Upon binding its target, the ribozyme undergoes cleavage and releases Broccoli, which subsequently folds and becomes fluorescent. Importantly, each target molecule can bind and induce cleavage of multiple copies of the integrator sensor, resulting in an amplified signal. We show that this approach can be generalized to numerous different ribozyme types for the detection of various small molecules.
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Affiliation(s)
- Mingxu You
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA; Department of Pharmacology, Weill Medical College, Weill Cornell Medicine, New York, NY 10065, USA.
| | - Jacob L Litke
- Department of Pharmacology, Weill Medical College, Weill Cornell Medicine, New York, NY 10065, USA
| | - Rigumula Wu
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Medical College, Weill Cornell Medicine, New York, NY 10065, USA.
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Intracellular Imaging with Genetically Encoded RNA-based Molecular Sensors. NANOMATERIALS 2019; 9:nano9020233. [PMID: 30744040 PMCID: PMC6410142 DOI: 10.3390/nano9020233] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 02/05/2019] [Accepted: 02/05/2019] [Indexed: 01/10/2023]
Abstract
Genetically encodable sensors have been widely used in the detection of intracellular molecules ranging from metal ions and metabolites to nucleic acids and proteins. These biosensors are capable of monitoring in real-time the cellular levels, locations, and cell-to-cell variations of the target compounds in living systems. Traditionally, the majority of these sensors have been developed based on fluorescent proteins. As an exciting alternative, genetically encoded RNA-based molecular sensors (GERMS) have emerged over the past few years for the intracellular imaging and detection of various biological targets. In view of their ability for the general detection of a wide range of target analytes, and the modular and simple design principle, GERMS are becoming a popular choice for intracellular analysis. In this review, we summarize different design principles of GERMS based on various RNA recognition modules, transducer modules, and reporting systems. Some recent advances in the application of GERMS for intracellular imaging are also discussed. With further improvement in biostability, sensitivity, and robustness, GERMS can potentially be widely used in cell biology and biotechnology.
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48
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Galizi R, Jaramillo A. Engineering CRISPR guide RNA riboswitches for in vivo applications. Curr Opin Biotechnol 2019; 55:103-113. [PMID: 30265865 DOI: 10.1016/j.copbio.2018.08.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/13/2018] [Accepted: 08/16/2018] [Indexed: 02/07/2023]
Abstract
CRISPR-based genome editing provides a simple and scalable toolbox for a variety of therapeutic and biotechnology applications. Whilst the fundamental properties of CRISPR proved easily transferable from the native prokaryotic hosts to eukaryotic and multicellular organisms, the tight control of the CRISPR-editing activity remains a major challenge. Here we summarise recent developments of CRISPR and riboswitch technologies and recommend novel functionalised synthetic-gRNA (sgRNA) designs to achieve inducible and spatiotemporal regulation of CRISPR-based genetic editors in response to cellular or extracellular stimuli. We believe that future advances of these tools will have major implications for both basic and applied research, spanning from fundamental genetic studies and synthetic biology to genetic editing and gene therapy.
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Affiliation(s)
- Roberto Galizi
- Department of Life Sciences, Imperial College London, London, United Kingdom.
| | - Alfonso Jaramillo
- Warwick Integrative Synthetic Biology Centre (WISB) and School of Life Sciences, University of Warwick, CV4 7AL Coventry, United Kingdom; ISSB, CNRS, Univ Evry, CEA, Université Paris-Saclay, 91025 Evry, France; Institute for Integrative Systems Biology (I2SysBio), University of Valencia-CSIC, 46980 Paterna, Spain.
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Abstract
In bacteria and archaea, small RNAs (sRNAs) regulate complex networks through antisense interactions with target mRNAs in trans, and riboswitches regulate gene expression in cis based on the ability to bind small-molecule ligands. Although our understanding and characterization of these two important regulatory RNA classes is far from complete, these RNA-based mechanisms have proven useful for a wide variety of synthetic biology applications. Besides classic and contemporary applications in the realm of metabolic engineering and orthogonal gene control, this review also covers newer applications of regulatory RNAs as biosensors, logic gates, and tools to determine RNA-RNA interactions. A separate section focuses on critical insights gained and challenges posed by fundamental studies of sRNAs and riboswitches that should aid future development of synthetic regulatory RNAs.
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Dippel AB, Anderson WA, Evans RS, Deutsch S, Hammond MC. Chemiluminescent Biosensors for Detection of Second Messenger Cyclic di-GMP. ACS Chem Biol 2018; 13:1872-1879. [PMID: 29466657 DOI: 10.1021/acschembio.7b01019] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bacteria colonize highly diverse and complex environments, from gastrointestinal tracts to soil and plant surfaces. This colonization process is controlled in part by the intracellular signal cyclic di-GMP, which regulates bacterial motility and biofilm formation. To interrogate cyclic di-GMP signaling networks, a variety of fluorescent biosensors for live cell imaging of cyclic di-GMP have been developed. However, the need for external illumination precludes the use of these tools for imaging bacteria in their natural environments, including in deep tissues of whole organisms and in samples that are highly autofluorescent or photosensitive. The need for genetic encoding also complicates the analysis of clinical isolates and environmental samples. Toward expanding the study of bacterial signaling to these systems, we have developed the first chemiluminescent biosensors for cyclic di-GMP. The biosensor design combines the complementation of split luciferase (CSL) and bioluminescence resonance energy transfer (BRET) approaches. Furthermore, we developed a lysate-based assay for biosensor activity that enabled reliable high-throughput screening of a phylogenetic library of 92 biosensor variants. The screen identified biosensors with very large signal changes (∼40- and 90-fold) as well as biosensors with high affinities for cyclic di-GMP ( KD < 50 nM). These chemiluminescent biosensors then were applied to measure cyclic di-GMP levels in E. coli. The cellular experiments revealed an unexpected challenge for chemiluminescent imaging in Gram negative bacteria but showed promising application in lysates. Taken together, this work establishes the first chemiluminescent biosensors for studying cyclic di-GMP signaling and provides a foundation for using these biosensors in more complex systems.
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Affiliation(s)
- Andrew B. Dippel
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Wyatt A. Anderson
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Robert S. Evans
- DOE Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, California 94598, United States
| | - Samuel Deutsch
- DOE Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, California 94598, United States
| | - Ming C. Hammond
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, United States
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