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Gabryelczyk B, Sammalisto FE, Gandier JA, Feng J, Beaune G, Timonen JV, Linder MB. Recombinant protein condensation inside E. coli enables the development of building blocks for bioinspired materials engineering – Biomimetic spider silk protein as a case study. Mater Today Bio 2022; 17:100492. [DOI: 10.1016/j.mtbio.2022.100492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/05/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022] Open
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2
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Yang M, Wenner N, Dykes GF, Li Y, Zhu X, Sun Y, Huang F, Hinton JCD, Liu LN. Biogenesis of a bacterial metabolosome for propanediol utilization. Nat Commun 2022; 13:2920. [PMID: 35614058 PMCID: PMC9132943 DOI: 10.1038/s41467-022-30608-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 04/22/2022] [Indexed: 12/24/2022] Open
Abstract
Bacterial metabolosomes are a family of protein organelles in bacteria. Elucidating how thousands of proteins self-assemble to form functional metabolosomes is essential for understanding their significance in cellular metabolism and pathogenesis. Here we investigate the de novo biogenesis of propanediol-utilization (Pdu) metabolosomes and characterize the roles of the key constituents in generation and intracellular positioning of functional metabolosomes. Our results demonstrate that the Pdu metabolosome undertakes both "Shell first" and "Cargo first" assembly pathways, unlike the β-carboxysome structural analog which only involves the "Cargo first" strategy. Shell and cargo assemblies occur independently at the cell poles. The internal cargo core is formed through the ordered assembly of multiple enzyme complexes, and exhibits liquid-like properties within the metabolosome architecture. Our findings provide mechanistic insight into the molecular principles driving bacterial metabolosome assembly and expand our understanding of liquid-like organelle biogenesis.
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Affiliation(s)
- Mengru Yang
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Nicolas Wenner
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Gregory F Dykes
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Yan Li
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Xiaojun Zhu
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Yaqi Sun
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Fang Huang
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Jay C D Hinton
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Crown Street, Liverpool, L69 7ZB, United Kingdom
| | - Lu-Ning Liu
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown Street, Liverpool, L69 7ZB, United Kingdom.
- College of Marine Life Sciences, and Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, 266003, China.
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Meng W, Qiao K, Zhang W, Liu F, Gao X, Hu X, Zhu J. Development and Application of a New Arabinose-Inducible Vector in High-Attachment Strain Stenotrophomonas AGS-1 from Aerobic Granular Sludge. ACS Synth Biol 2022; 11:69-76. [PMID: 34989221 DOI: 10.1021/acssynbio.1c00446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To explore the molecular structure of attachment genes, we constructed and characterized a new arabinose-inducible vector for the high-attachment strain Stenotrophomonas AGS-1 isolated from aerobic granular sludge (AGS). mCherry was used as a simple observation biomarker, and the araC-PBAD-inducible promoter was chosen to artificially regulate the expression of target genes. The system achieved little leaky basal expression and high maximal induced expression. The araC-PBAD-based inducible expression was modulated over a wide range of 0.0005 to 0.2% l-arabinose. Notably, a "lag expression" phenomenon was observed in which mCherry was expressed after bacterial growth in LB medium. Using the system and the strategy of fusion expression of target genes (rmlA and AsCas12a) plus mCherry, the recombinant AGS-1 strain achieved the effective induction of rmlA and AsCas12a-mCherry gene expression in the range of 0.0005 to 0.1% l-arabinose. These results demonstrate that the new arabinose-inducible vector could be used as an important molecular tool in the gene function and genome-editing research of strain AGS-1.
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Affiliation(s)
- Wei Meng
- School of Environment, Beijing Normal University, Beijing 100875, China
- R & D Centre of Aerobic Granule Technology, Beijing 100875, China
| | - Kai Qiao
- School of Environment, Beijing Normal University, Beijing 100875, China
- State Key Laboratory of Water Simulation, Beijing 100875, China
| | - Wei Zhang
- School of Environment, Beijing Normal University, Beijing 100875, China
- R & D Centre of Aerobic Granule Technology, Beijing 100875, China
| | - Fan Liu
- School of Environment, Beijing Normal University, Beijing 100875, China
| | - Xu Gao
- School of Environment, Beijing Normal University, Beijing 100875, China
| | - Xuan Hu
- School of Environment, Beijing Normal University, Beijing 100875, China
- State Key Laboratory of Water Simulation, Beijing 100875, China
| | - Jianrong Zhu
- School of Environment, Beijing Normal University, Beijing 100875, China
- R & D Centre of Aerobic Granule Technology, Beijing 100875, China
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Marghani D, Ma Z, Centone AJ, Huang W, Malik M, Bakshi CS. An AraC/XylS Family Transcriptional Regulator Modulates the Oxidative Stress Response of Francisella tularensis. J Bacteriol 2021; 203:e0018521. [PMID: 34543107 PMCID: PMC8570275 DOI: 10.1128/jb.00185-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 09/09/2021] [Indexed: 11/20/2022] Open
Abstract
Francisella tularensis is a Gram-negative bacterium that causes a fatal human disease known as tularemia. The Centers for Disease Control and Prevention have classified F. tularensis as a category A tier 1 select agent. The virulence mechanisms of Francisella are not entirely understood. Francisella possesses very few transcription regulators, and most of these regulate the expression of genes involved in intracellular survival and virulence. The F. tularensis genome sequence analysis reveals an AraC (FTL_0689) transcriptional regulator homologous to the AraC/XylS family of transcriptional regulators. In Gram-negative bacteria, AraC activates genes required for l-arabinose utilization and catabolism. The role of the FTL_0689 regulator in F. tularensis is not known. In this study, we characterized the role of FTL_0689 in the gene regulation of F. tularensis and investigated its contribution to intracellular survival and virulence. The results demonstrate that FTL_0689 in Francisella is not required for l-arabinose utilization. Instead, FTL_0689 specifically regulates the expression of the oxidative and global stress response, virulence, metabolism, and other key pathways genes required by Francisella when exposed to oxidative stress. The FTL_0689 mutant is attenuated for intramacrophage growth and virulence in mice. Based on the deletion mutant phenotype, FTL_0689 was termed osrR (oxidative stress response regulator). Altogether, this study elucidates the role of the osrR transcriptional regulator in tularemia pathogenesis. IMPORTANCE The virulence mechanisms of category A select agent Francisella tularensis, the causative agent of a fatal human disease known as tularemia, remain largely undefined. The present study investigated the role of a transcriptional regulator and its overall contribution to the oxidative stress resistance of F. tularensis. The results provide an insight into a novel gene regulatory mechanism, especially when Francisella is exposed to oxidative stress conditions. Understanding such Francisella- specific regulatory mechanisms will help identify potential targets for developing effective therapies and vaccines to prevent tularemia.
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Affiliation(s)
- Dina Marghani
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
| | - Zhuo Ma
- Department of Basic and Clinical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York, USA
| | - Anthony J. Centone
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
| | - Weihua Huang
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
| | - Meenakshi Malik
- Department of Basic and Clinical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York, USA
| | - Chandra Shekhar Bakshi
- Department of Pathology, Microbiology, and Immunology, New York Medical College, Valhalla, New York, USA
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L-arabinose induces the formation of viable non-proliferating spheroplasts in Vibrio cholerae. Appl Environ Microbiol 2021; 87:AEM.02305-20. [PMID: 33355111 PMCID: PMC8090878 DOI: 10.1128/aem.02305-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae, the agent of the deadly human disease cholera, propagates as a curved rod-shaped bacterium in warm waters. It is sensitive to cold, but persists in cold waters under the form of viable but non-dividing coccoidal shaped cells. Additionally, V. cholerae is able to form non-proliferating spherical cells in response to cell wall damage. It was recently reported that L-arabinose, a component of the hemicellulose and pectin of terrestrial plants, stops the growth of V. cholerae. Here, we show that L-arabinose induces the formation of spheroplasts that lose the ability to divide and stop growing in volume over time. However, they remain viable and upon removal of L-arabinose they start expanding in volume, form branched structures and give rise to cells with a normal morphology after a few divisions. We further show that WigKR, a histidine kinase/response regulator pair implicated in the induction of a high expression of cell wall synthetic genes, prevents the lysis of the spheroplasts during growth restart. Finally, we show that the physiological perturbations result from the import and catabolic processing of L-arabinose by the V. cholerae homolog of the E. coli galactose transport and catabolic system. Taken together, our results suggest that the formation of non-growing spherical cells is a common response of Vibrios exposed to detrimental conditions. They also permit to define conditions preventing any physiological perturbation of V. cholerae when using L-arabinose to induce gene expression from the tightly regulated promoter of the Escherichia coli araBAD operon.Importance Vibrios among other bacteria form transient cell wall deficient forms as a response to different stresses and revert to proliferating rods when permissive conditions have been restored. Such cellular forms have been associated to antimicrobial tolerance, chronic infections and environmental dispersion.The effect of L-Ara on V. cholerae could provide an easily tractable model to study the ability of Vibrios to form viable reversible spheroplasts. Indeed, the quick transition to spheroplasts and reversion to proliferating rods by addition or removal of L-Ara is ideal to understand the genetic program governing this physiological state and the spatial rearrangements of the cellular machineries during cell shape transitions.
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A modular chromosomally integrated toolkit for ectopic gene expression in Vibrio cholerae. Sci Rep 2020; 10:15398. [PMID: 32958839 PMCID: PMC7505983 DOI: 10.1038/s41598-020-72387-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/27/2020] [Indexed: 12/16/2022] Open
Abstract
The ability to express genes ectopically in bacteria is essential for diverse academic and industrial applications. Two major considerations when utilizing regulated promoter systems for ectopic gene expression are (1) the ability to titrate gene expression by addition of an exogenous inducer and (2) the leakiness of the promoter element in the absence of the inducer. Here, we describe a modular chromosomally integrated platform for ectopic gene expression in Vibrio cholerae. We compare the broadly used promoter elements Ptac and PBAD to versions that have an additional theophylline-responsive riboswitch (Ptac-riboswitch and PBAD-riboswitch). These constructs all exhibited unimodal titratable induction of gene expression, however, max induction varied with Ptac > PBAD > PBAD-riboswitch > Ptac-riboswitch. We also developed a sensitive reporter system to quantify promoter leakiness and show that leakiness for Ptac > Ptac-riboswitch > PBAD; while the newly developed PBAD-riboswitch exhibited no detectable leakiness. We demonstrate the utility of the tightly inducible PBAD-riboswitch construct using the dynamic activity of type IV competence pili in V. cholerae as a model system. The modular chromosomally integrated toolkit for ectopic gene expression described here should be valuable for the genetic study of V. cholerae and could be adapted for use in other species.
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Liu Y, Guérard F, Hodges M, Jossier M. Phosphomimetic T335D Mutation of Hydroxypyruvate Reductase 1 Modifies Cofactor Specificity and Impacts Arabidopsis Growth in Air. PLANT PHYSIOLOGY 2020; 183:194-205. [PMID: 32156771 PMCID: PMC7210656 DOI: 10.1104/pp.19.01225] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 02/26/2020] [Indexed: 05/13/2023]
Abstract
Photorespiration is an essential process in oxygenic photosynthetic organisms triggered by the oxygenase activity of Rubisco. In peroxisomes, photorespiratory HYDROXYPYRUVATE REDUCTASE1 (HPR1) catalyzes the conversion of hydroxypyruvate to glycerate together with the oxidation of a pyridine nucleotide cofactor. HPR1 regulation remains poorly understood; however, HPR1 phosphorylation at T335 has been reported. By comparing the kinetic properties of phosphomimetic (T335D), nonphosphorylatable (T335A), and wild-type recombinant Arabidopsis (Arabidopsis thaliana) HPR1, it was found that HPR1-T335D exhibits reduced NADH-dependent hydroxypyruvate reductase activity while showing improved NADPH-dependent activity. Complementation of the Arabidopsis hpr1-1 mutant by either wild-type HPR1 or HPR1-T335A fully complemented the photorespiratory growth phenotype of hpr1-1 in ambient air, whereas HPR1-T335D-containing hpr1-1 plants remained smaller and had lower photosynthetic CO2 assimilation rates. Metabolite analyses indicated that these phenotypes were associated with subtle perturbations in the photorespiratory cycle of HPR1-T335D-complemented hpr1-1 rosettes compared to all other HPR1-containing lines. Therefore, T335 phosphorylation may play a role in the regulation of HPR1 activity in planta, although it was not required for growth under ambient air controlled conditions. Furthermore, improved NADP-dependent HPR1 activities in peroxisomes could not compensate for the reduced NADH-dependent HPR1 activity.
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Affiliation(s)
- Yanpei Liu
- Institute of Plant Sciences Paris-Saclay, CNRS, Université Paris-Sud, Institut National de la Recherche Agronomique, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Florence Guérard
- Institute of Plant Sciences Paris-Saclay, CNRS, Université Paris-Sud, Institut National de la Recherche Agronomique, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Michael Hodges
- Institute of Plant Sciences Paris-Saclay, CNRS, Université Paris-Sud, Institut National de la Recherche Agronomique, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Mathieu Jossier
- Institute of Plant Sciences Paris-Saclay, CNRS, Université Paris-Sud, Institut National de la Recherche Agronomique, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, 91405 Orsay Cedex, France
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8
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Abstract
Escherichia coli BL21-AI is a commercially available strain possessing a phage T7-based protein-expression system. A combination of tight regulation and high yield makes it widely used for high-level expression of toxic recombinant proteins. Here, we present the complete genome sequence of BL21-AI and provide insights on its genome.
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9
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Freihat LA, Wheeler JI, Wong A, Turek I, Manallack DT, Irving HR. IRAK3 modulates downstream innate immune signalling through its guanylate cyclase activity. Sci Rep 2019; 9:15468. [PMID: 31664109 PMCID: PMC6820782 DOI: 10.1038/s41598-019-51913-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 10/09/2019] [Indexed: 01/03/2023] Open
Abstract
Interleukin-1 receptor associated kinase 3 (IRAK3) is a cytoplasmic homeostatic mediator of inflammatory responses and is potentially useful as a prognostic marker in inflammation. IRAK3 inhibits signalling cascades downstream of myddosome complexes associated with toll like receptors. IRAK3 contains a death domain that interacts with other IRAK family members, a pseudokinase domain and a C-terminus domain involved with tumour necrosis factor receptor associated factor 6 (TRAF6). Previous bioinformatic studies revealed that IRAK3 contained a guanylate cyclase centre in its pseudokinase domain but its role in IRAK3 action is unresolved. We demonstrate that wildtype IRAK3 is capable of producing cGMP. Furthermore, we show that a specific point mutation in the guanylate cyclase centre reduced cGMP production. Cells containing toll like receptor 4 and a nuclear factor kappa-light-chain-enhancer of activated B cells (NFĸB) reporter system were transfected with IRAK3 or mutant IRAK3 proteins. Cell-permeable cGMP treatment of untransfected control cells suppresses downstream signalling through modulation of the NFĸB in the presence of lipopolysaccharides. Cells transfected with wildtype IRAK3 also suppress lipopolysaccharide induced NFĸB activity in the absence of exogenous cGMP. Lipopolysaccharide induced NFĸB activity was not suppressed in cells transfected with the IRAK3 mutant with reduced cGMP-generating capacity. Whereas in the presence of exogenously applied cell-permeable cGMP the IRAK3 mutant was able to retain its function by suppressing lipopolysaccharide induced NFĸB activity. Furthermore, increasing the amount of membrane permeable cGMP did not affect IRAK3's ability to reduce NFĸB activity. These results suggest that cGMP generated by IRAK3 may be involved in regulatory function of the protein where the presence of cGMP may selectively affect downstream signalling pathway(s) by modulating binding and/or activity of nearby proteins that interact in the inflammatory signalling cascade.
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Affiliation(s)
- L A Freihat
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
- La Trobe Institute for Molecular Science, La Trobe University, Bendigo, VIC, 3552, Australia
| | - J I Wheeler
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
- AgriBio, La Trobe University, Bundoora, VIC, 3083, Australia
| | - A Wong
- Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
- Department of Biology, Wenzhou-Kean University, 88 Daxue Road, Ouhai, Wenzhou, Zhejiang Province, 325060, China
| | - I Turek
- La Trobe Institute for Molecular Science, La Trobe University, Bendigo, VIC, 3552, Australia
| | - D T Manallack
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - H R Irving
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
- La Trobe Institute for Molecular Science, La Trobe University, Bendigo, VIC, 3552, Australia.
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Kleine D, Chodorski J, Mitra S, Schlegel C, Huttenlochner K, Müller‐Renno C, Mukherjee J, Ziegler C, Ulber R. Monitoring of biofilms grown on differentially structured metallic surfaces using confocal laser scanning microscopy. Eng Life Sci 2019; 19:513-521. [PMID: 32625028 PMCID: PMC6999451 DOI: 10.1002/elsc.201800176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 02/12/2019] [Accepted: 05/09/2019] [Indexed: 12/29/2022] Open
Abstract
Imaging of biofilms on opaque surfaces is a challenge presented to researchers especially considering pathogenic bacteria, as those typically grow on living tissue, such as mucosa and bone. However, they can also grow on surfaces used in industrial applications such as food production, acting as a hindrance to the process. Thus, it is important to understand bacteria better in the environment they actually have relevance in. Stainless steel and titanium substrata were line structured and dotted surface topographies for titanium substrata were prepared to analyze their effects on biofilm formation of a constitutively green fluorescent protein (GFP)-expressing Escherichia coli strain. The strain was batch cultivated in a custom built flow cell initially for 18 h, followed by continuous cultivation for 6 h. Confocal laser scanning microscopy (CLSM) was used to determine the biofilm topography. Biofilm growth of E. coli GFPmut2 was not affected by the type of metal substrate used; rather, attachment and growth were influenced by variable shapes of the microstructured titanium surfaces. In this work, biofilm cultivation in flow cells was coupled with the most widely used biofilm analytical technique (CLSM) to study the time course of growth of a GFP-expressing biofilm on metallic surfaces without intermittent sampling or disturbing the natural development of the biofilm.
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Affiliation(s)
- Daniel Kleine
- Institute of Bioprocess EngineeringTU KaiserslauternKaiserslauternGermany
| | - Jonas Chodorski
- Institute of Bioprocess EngineeringTU KaiserslauternKaiserslauternGermany
| | - Sayani Mitra
- School of Environmental StudiesJadavpur UniversityKolkataIndia
| | - Christin Schlegel
- Institute of Bioprocess EngineeringTU KaiserslauternKaiserslauternGermany
| | | | | | | | - Christiane Ziegler
- Department of Physics and Research Center OPTIMASTU KaiserslauternKaiserslauternGermany
| | - Roland Ulber
- Institute of Bioprocess EngineeringTU KaiserslauternKaiserslauternGermany
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Guo S, Murray RM. Construction of Incoherent Feedforward Loop Circuits in a Cell-Free System and in Cells. ACS Synth Biol 2019; 8:606-610. [PMID: 30790525 DOI: 10.1021/acssynbio.8b00493] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cells utilize transcriptional regulation networks to respond to environmental signals. Network motifs, such as feedforward loops, play essential roles in these regulatory networks. In this work, we construct two different functional and modular incoherent type 1 feedforward loop circuits in a cell-free transcription-translation system and in cells. With the help of mathematical modeling and the cell-free system, we can streamline the design-build-test cycles of the circuits, in which we characterize and optimize these circuits in vitro to confirm that they function as expected before implementing them in vivo. We show that the performance of these circuits from in vitro studies closely recapitulates those from in vivo experiments. We demonstrate that these feedforward loops show dynamic response and pulse-like behavior both in vitro and in vivo. These novel feedforward loop network motifs can be incorporated in more complicated biological circuits as detectors or responders.
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Affiliation(s)
- Shaobin Guo
- Department of Biochemistry and Molecular Biophysics, California Institute of Technology, Pasadena, California 91125, United States
| | - Richard M. Murray
- Department of Biochemistry and Molecular Biophysics, California Institute of Technology, Pasadena, California 91125, United States
- Department of Control and Dynamical Systems, California Institute of Technology, Pasadena, California 91125, United States
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12
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Faramarzi T, Mobasheri M, Yoosefy A, Valadkhani Z. Expression and purification of truncated recombinant B8/1 protein of Echinococcus granulosus for diagnosis of hydatid infection in human. Acta Trop 2019; 191:139-145. [PMID: 30599175 DOI: 10.1016/j.actatropica.2018.12.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 12/04/2018] [Accepted: 12/28/2018] [Indexed: 12/28/2022]
Abstract
Hydatidosis is one of the most important diseases common between animals and human beings. Caused by Echinococcus granulosus tapeworm, the disease has a global epidemic. The serological diagnostic tests that are now utilized to confirm the imaging approaches have some drawbacks such as low sensitivity and cross-reaction with the serum of the patients infected with other parasites. The application of recombinant and synthetic antigens has proven improvement in the functionality of serological diagnostic tests. The purpose of this study was to demonstrate the expression and purification of truncated recombinant B8/1 (trB8/1) antigen and its application in ELISA for diagnosis of hydatid infection in human. The tEgB8/1 was colonized in the expression vector pET28b (+) and expressed in different strains of E. coli. This protein was purified by Ni2+-NTA chromatography. The antigenicity of the protein was evaluated by Western blotting and ELISA. In the test, 50 positive serum samples from hydatid infected patients, 50 samples from healthy people, and 30 serum samples from patients with other parasitic diseases were used to determine the sensitivity and the specificity of this antigen. The measured sensitivity and specificity of this antigen were identified to be 75.75% and 96.38% respectively. The P value of <0.0001 by using ROC curve, confirmed that this antigen is able to differentiate between healthy and hydatid-infected individuals. Considering the excellent specificity of this antigen and in order to enhance the sensitivity, it is recommended to use a combination of this antigen with other antigens (e.g., EgB8/2-8/5).
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Affiliation(s)
- Tahereh Faramarzi
- Department of Biotechnology, Faculty of Advanced Sciences and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran; Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
| | - Meysam Mobasheri
- Department of Biotechnology, Faculty of Advanced Sciences and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Asiyeh Yoosefy
- Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
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13
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Choudhury D, Gayen K, Saini S. Dynamic control of arabinose and xylose utilization in E. coli. CAN J CHEM ENG 2018. [DOI: 10.1002/cjce.23197] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Debika Choudhury
- Department of Chemical Engineering; IIT Bombay; Mumbai Maharashtra 400076 India
| | - Kalyan Gayen
- Department of Chemical Engineering; NIT Agartala; Tripura 799055 India
| | - Supreet Saini
- Department of Chemical Engineering; IIT Bombay; Mumbai Maharashtra 400076 India
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14
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Ferreira EA, Pacheco CC, Pinto F, Pereira J, Lamosa P, Oliveira P, Kirov B, Jaramillo A, Tamagnini P. Expanding the toolbox for Synechocystis sp. PCC 6803: validation of replicative vectors and characterization of a novel set of promoters. Synth Biol (Oxf) 2018; 3:ysy014. [PMID: 32995522 PMCID: PMC7445879 DOI: 10.1093/synbio/ysy014] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 07/27/2018] [Accepted: 07/30/2018] [Indexed: 11/14/2022] Open
Abstract
Cyanobacteria are promising 'low-cost' cell factories since they have minimal nutritional requirements, high metabolic plasticity and can use sunlight and CO2 as energy and carbon sources. The unicellular Synechocystis sp. PCC 6803, already considered the 'green' Escherichia coli, is the best studied cyanobacterium but to be used as an efficient and robust photoautotrophic chassis it requires a customized and well-characterized toolbox. In this context, we evaluated the possibility of using three self-replicative vectors from the Standard European Vector Architecture (SEVA) repository to transform Synechocystis. Our results demonstrated that the presence of the plasmid does not lead to an evident phenotype or hindered Synechocystis growth, being the vast majority of the cells able to retain the replicative plasmid even in the absence of selective pressure. In addition, a set of heterologous and redesigned promoters were characterized exhibiting a wide range of activities compared to the reference P rnpB , three of which could be efficiently repressed. As a proof-of-concept, from the expanded toolbox, one promoter was selected and assembled with the ggpS gene [encoding one of the proteins involved in the synthesis of the native compatible solute glucosylglycerol (GG)] and the synthetic device was introduced into Synechocystis using one of the SEVA plasmids. The presence of this device restored the production of the GG in a ggpS deficient mutant validating the functionality of the tools/device developed in this study.
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Affiliation(s)
- Eunice A Ferreira
- i3S - Instituto de Investigação e Inovação em Saúde Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular Universidade do Porto, Porto, Portugal.,ICBAS - Instituto de Ciências Biomédicas Abel Salazar Universidade do Porto, Porto, Portugal
| | - Catarina C Pacheco
- i3S - Instituto de Investigação e Inovação em Saúde Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular Universidade do Porto, Porto, Portugal
| | - Filipe Pinto
- i3S - Instituto de Investigação e Inovação em Saúde Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular Universidade do Porto, Porto, Portugal.,School of Biological Sciences, University of Edinburgh, Edinburgh, UK.,Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh, UK
| | - José Pereira
- i3S - Instituto de Investigação e Inovação em Saúde Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular Universidade do Porto, Porto, Portugal
| | - Pedro Lamosa
- Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA, Oeiras, Portugal
| | - Paulo Oliveira
- i3S - Instituto de Investigação e Inovação em Saúde Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular Universidade do Porto, Porto, Portugal
| | - Boris Kirov
- CNRS-UMR8030 Laboratoire iSSB and Université Paris-Saclay and Université d'Évry and CEA DRF, IG, Genoscope, Évry, France.,ANP - Faculty of Automatics, TU - Sofia, Sofia, Bulgaria.,BioInfoTech Lab - RDIC, Sofia Tech Park, Sofia, Bulgaria
| | - Alfonso Jaramillo
- CNRS-UMR8030 Laboratoire iSSB and Université Paris-Saclay and Université d'Évry and CEA DRF, IG, Genoscope, Évry, France.,Warwick Integrative Synthetic Biology Centre and School of Life Sciences, University of Warwick, Coventry, UK.,Institute for Integrative Systems Biology (I2SysBio) University of Valencia-CSIC, Paterna, Spain
| | - Paula Tamagnini
- i3S - Instituto de Investigação e Inovação em Saúde Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular Universidade do Porto, Porto, Portugal.,Faculdade de Ciências, Departamento de Biologia, Universidade do Porto, Porto, Portugal
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15
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Alba-Martínez Z, Ramírez-Silva L, Hernández-Alcántara G. Exploring the differences between the three pyruvate kinase isozymes from Vibrio cholerae in a heterologous expression system. BMC Res Notes 2018; 11:527. [PMID: 30064476 PMCID: PMC6069732 DOI: 10.1186/s13104-018-3651-8] [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: 05/14/2018] [Accepted: 07/25/2018] [Indexed: 11/17/2022] Open
Abstract
Objective The genome of Vibrio cholerae has three paralog genes encoding for distinct pyruvate kinases. We were interested in elucidating whether they were expressed, and contributed to the pyruvate kinase activity of V. cholerae. VcIPK and VcIIPK were transformed and expressed in BL21-CodonPlus(DE3)-RIL strain, whereas VcIIIPK could not be transformed. Those studied did contribute to the pyruvate kinase activity of the bacteria. Therefore, our aim was to find an efficient transformation and commonly used over-expression heterologous system for VcIIIPK and develop its purification protocol. Results vcIpk, vcIIpk and vcIIIpk genes were transformed in six different BL21 expression strains. No transformants were obtained for the vcIIIpk gene using BL21(DE3), BL21(DE3)pLysS and BL21(DE3)CodonPlus-RIL strains. Reduced rates of cell growth were observed for BL21-Gold(DE3)pLysS and Origami B(DE3)pLysS. High efficiency of transformation was obtained for BL21-AI. Using this strain, VcIIIPK was purified but proved to be unstable during its purification and storage. Therefore, the transformation of vcIIIpk gene resulted in a toxic, mildly toxic or nontoxic product for these BL21 strains. Despite VcIIPK and VcIIIPK being phylogenetically related, the preservation of the proteins is drastically different; whereas one is preserved during purification and storage, the other is auto-proteolyzed completely in less than a week. Electronic supplementary material The online version of this article (10.1186/s13104-018-3651-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zoe Alba-Martínez
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510, Mexico City, Mexico
| | - Leticia Ramírez-Silva
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510, Mexico City, Mexico
| | - Gloria Hernández-Alcántara
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510, Mexico City, Mexico.
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16
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Jia B, Jeon CO. High-throughput recombinant protein expression in Escherichia coli: current status and future perspectives. Open Biol 2017; 6:rsob.160196. [PMID: 27581654 PMCID: PMC5008019 DOI: 10.1098/rsob.160196] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 08/03/2016] [Indexed: 12/26/2022] Open
Abstract
The ease of genetic manipulation, low cost, rapid growth and number of previous studies have made Escherichia coli one of the most widely used microorganism species for producing recombinant proteins. In this post-genomic era, challenges remain to rapidly express and purify large numbers of proteins for academic and commercial purposes in a high-throughput manner. In this review, we describe several state-of-the-art approaches that are suitable for the cloning, expression and purification, conducted in parallel, of numerous molecules, and we discuss recent progress related to soluble protein expression, mRNA folding, fusion tags, post-translational modification and production of membrane proteins. Moreover, we address the ongoing efforts to overcome various challenges faced in protein expression in E. coli, which could lead to an improvement of the current system from trial and error to a predictable and rational design.
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Affiliation(s)
- Baolei Jia
- Department of Life Science, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Che Ok Jeon
- Department of Life Science, Chung-Ang University, Seoul 06974, Republic of Korea
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17
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Engstrom MD, Pfleger BF. Transcription control engineering and applications in synthetic biology. Synth Syst Biotechnol 2017; 2:176-191. [PMID: 29318198 PMCID: PMC5655343 DOI: 10.1016/j.synbio.2017.09.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/26/2017] [Accepted: 09/26/2017] [Indexed: 12/18/2022] Open
Abstract
In synthetic biology, researchers assemble biological components in new ways to produce systems with practical applications. One of these practical applications is control of the flow of genetic information (from nucleic acid to protein), a.k.a. gene regulation. Regulation is critical for optimizing protein (and therefore activity) levels and the subsequent levels of metabolites and other cellular properties. The central dogma of molecular biology posits that information flow commences with transcription, and accordingly, regulatory tools targeting transcription have received the most attention in synthetic biology. In this mini-review, we highlight many past successes and summarize the lessons learned in developing tools for controlling transcription. In particular, we focus on engineering studies where promoters and transcription terminators (cis-factors) were directly engineered and/or isolated from DNA libraries. We also review several well-characterized transcription regulators (trans-factors), giving examples of how cis- and trans-acting factors have been combined to create digital and analogue switches for regulating transcription in response to various signals. Last, we provide examples of how engineered transcription control systems have been used in metabolic engineering and more complicated genetic circuits. While most of our mini-review focuses on the well-characterized bacterium Escherichia coli, we also provide several examples of the use of transcription control engineering in non-model organisms. Similar approaches have been applied outside the bacterial kingdom indicating that the lessons learned from bacterial studies may be generalized for other organisms.
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Affiliation(s)
- Michael D. Engstrom
- Genetics-Biotechnology Center, University of Wisconsin-Madison School of Medicine and Public Health, USA
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison College of Engineering, USA
| | - Brian F. Pfleger
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison College of Engineering, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, USA
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18
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The Escherichia coli rhaSR-PrhaBAD Inducible Promoter System Allows Tightly Controlled Gene Expression over a Wide Range in Pseudomonas aeruginosa. Appl Environ Microbiol 2016; 82:6715-6727. [PMID: 27613678 DOI: 10.1128/aem.02041-16] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 09/01/2016] [Indexed: 12/31/2022] Open
Abstract
The araC-ParaBAD inducible promoter system is tightly controlled and allows gene expression to be modulated over a wide range in Escherichia coli, which has led to its widespread use in other bacteria. Although anecdotal evidence suggests that araC-ParaBAD is leaky in Pseudomonas aeruginosa, neither a thorough analysis of this inducible promoter system in P. aeruginosa nor a concerted effort to identify alternatives with improved functionality has been reported. Here, we evaluated the functionality of the araC-ParaBAD system in P. aeruginosa Using transcriptional fusions to a lacZ reporter gene, we determined that the noninduced expression from araC-ParaBAD is high and cannot be reduced by carbon catabolite repression as it can in E. coli Modulating translational initiation by altering ribosome-binding site strength reduced the noninduced activity but also decreased the maximal induced activity and narrowed the induction range. Integrating the inducible promoter system into the posttranscriptional regulatory network that controls catabolite repression in P. aeruginosa significantly decreased the noninduced activity and increased the induction range. In addition to these improvements in the functionality of the araC-ParaBAD system, we found that the lacIq-Ptac and rhaSR-PrhaBAD inducible promoter systems had significantly lower noninduced expression and were inducible over a broader range than araC-ParaBAD We demonstrated that noninduced expression from the araC-ParaBAD system supported the function of genes involved in antibiotic resistance and tryptophan biosynthesis in P. aeruginosa, problems that were avoided with rhaSR-PrhaBAD. rhaSR-PrhaBAD is tightly controlled, allows gene expression over a wide range, and represents a significant improvement over araC-ParaBAD in P. aeruginosa IMPORTANCE: We report the shortcomings of the commonly used Escherichia coli araC-ParaBAD inducible promoter system in Pseudomonas aeruginosa, successfully reengineered it to improve its functionality, and show that the E. coli rhaSR-PrhaBAD system is tightly controlled and allows inducible gene expression over a wide range in P. aeruginosa.
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19
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Skjoedt ML, Snoek T, Kildegaard KR, Arsovska D, Eichenberger M, Goedecke TJ, Rajkumar AS, Zhang J, Kristensen M, Lehka BJ, Siedler S, Borodina I, Jensen MK, Keasling JD. Engineering prokaryotic transcriptional activators as metabolite biosensors in yeast. Nat Chem Biol 2016; 12:951-958. [DOI: 10.1038/nchembio.2177] [Citation(s) in RCA: 154] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 06/30/2016] [Indexed: 01/30/2023]
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20
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Kamran M, Sinha S, Dubey P, Lynn AM, Dhar SK. Identification of putative Z-ring-associated proteins, involved in cell division in human pathogenic bacteria Helicobacter pylori. FEBS Lett 2016; 590:2158-71. [PMID: 27253179 DOI: 10.1002/1873-3468.12230] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 05/19/2016] [Accepted: 05/23/2016] [Indexed: 11/07/2022]
Abstract
Cell division in bacteria is initiated by FtsZ, which forms a Z ring at the middle of the cell, between the nucleoids. The Z ring is stabilized by Z ring-associated proteins (Zaps), which crosslink the FtsZ filaments and provide strength. The deletion of Zaps leads to the elongation phenotype with an abnormal Z ring. The components of cell division in Helicobacter pylori are similar to other gram negative bacteria except for the absence of few components including Zaps. Here, we used HHsearch to identify homologs of the missing cell division proteins and got potential hits for ZapA and ZapB, as well as for few other cell division proteins. We further validated the function of the putative ZapA homolog by genetic complementation, immuno-colocalization and biochemical analysis.
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Affiliation(s)
- Mohammad Kamran
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Swati Sinha
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Priyanka Dubey
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Andrew M Lynn
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Suman K Dhar
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
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21
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Prajapat MK, Jain K, Choudhury D, Raj N, Saini S. Revisiting demand rules for gene regulation. MOLECULAR BIOSYSTEMS 2016; 12:421-30. [DOI: 10.1039/c5mb00693g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Starting with Savageau's pioneering work regarding demand rules for gene regulation from the 1970s, here, we choose the simplest transcription network and ask: how does the cell choose a particular regulatory topology from all available possibilities?
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Affiliation(s)
| | - Kirti Jain
- Department of Chemical Engineering
- Indian Institute of Technology Bombay
- Mumbai - 400076
- India
| | - Debika Choudhury
- Department of Chemical Engineering
- Indian Institute of Technology Bombay
- Mumbai - 400076
- India
| | - Nikhil Raj
- Department of Chemical Engineering
- Indian Institute of Technology Bombay
- Mumbai - 400076
- India
| | - Supreet Saini
- Department of Chemical Engineering
- Indian Institute of Technology Bombay
- Mumbai - 400076
- India
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22
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Hong H, Lim D, Kim GJ, Park SH, Sik Kim H, Hong Y, Choy HE, Min JJ. Targeted deletion of the ara operon of Salmonella typhimurium enhances L-arabinose accumulation and drives PBAD-promoted expression of anti-cancer toxins and imaging agents. Cell Cycle 2015; 13:3112-20. [PMID: 25486570 DOI: 10.4161/15384101.2014.949527] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Tumor-specific expression of antitumor drugs can be achieved using attenuated Salmonella typhimurium harboring the PBAD promoter, which is induced by L-arabinose. However, L-arabinose does not accumulate because it is metabolized to D-xylulose-5-P by enzymes encoded by the ara operon in Salmonellae. To address this problem, we developed an engineered strain of S. typhimurium in which the ara operon is deleted. Linear DNA transformation was performed using λ red recombinase to exchange the ara operon with linear DNA carrying an antibiotic-resistance gene with homology to regions adjacent to the ara operon. The ara operon-deleted strain and its parental strain were transformed with a plasmid encoding Renilla luciferase variant 8 (RLuc8) or cytolysin A (clyA) under the control of the PBAD promoter. Luciferase assays demonstrated that RLuc8 expression was 49-fold higher in the ara operon-deleted S. typhimurium than in the parental strain after the addition of L-arabinose. In vivo bioluminescence imaging showed that the tumor tissue targeted by the ara operon-deleted Salmonella had a stronger imaging signal (~30-fold) than that targeted by the parental strain. Mice with murine colon cancer (CT26) that had been injected with the ara operon-deleted S. typhimurium expressing clyA showed significant tumor suppression. The present report demonstrates that deletion of the ara operon of S. typhimurium enhances L-arabinose accumulation and thereby drives PBAD-promoted expression of cytotoxic agents and imaging agents. This is a promising approach for tumor therapy and imaging.
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Affiliation(s)
- Hyun Hong
- a Department of Nuclear Medicine ; Chonnam National University Medical School and Hwasun Hospital ; Jeonnam , Republic of Korea
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23
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Holder IT, Hartig JS. A matter of location: influence of G-quadruplexes on Escherichia coli gene expression. ACTA ACUST UNITED AC 2015; 21:1511-21. [PMID: 25459072 DOI: 10.1016/j.chembiol.2014.09.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 08/13/2014] [Accepted: 09/17/2014] [Indexed: 01/01/2023]
Abstract
We provide important insights into secondary-structure-mediated regulation of gene expression in Escherichia coli. In a comprehensive survey, we show that the strand orientation and the exact position of a G-quadruplex sequence strongly influence its effect on transcription and translation. We generated a series of reporter gene constructs that contained systematically varied positions of quadruplexes and respective control sequences inserted into several positions within the promoter, 50-UTR, and 30-UTR regions. G-rich sequences at specific locations in the promoter and also in proximity to the ribosome-binding site (RBS) showed pronounced inhibitory effects. Additionally, we rationally designed a system where quadruplex formation showed a gene-activating behavior. Moreover, we characterized quadruplexes in proximity to the RBS that occur naturally in E. coli genes, demonstrating that some of these quadruplexes exert significant modulation of gene expression. Taken together, our data show strong position-dependent effects of quadruplex secondary structures on bacterial gene expression.
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Abstract
Based on his work with the Escherichia coli l-arabinose operon, Ellis Englesberg proposed in 1965 that the regulatory gene araC was an "activator gene" required for positive control of the ara operon. This challenged the widely held belief in a universal mechanism of negative regulation proposed earlier by Jacob and Monod. For years, Englesberg's model was met with deep skepticism. Despite much frustration with complex ad hoc explanations used to challenge his model, Englesberg persisted until the evidence for positive control in ara and other systems became overwhelming. Englesberg's pioneering work enriched the original operon model and had a lasting impact in opening new and exciting ways of thinking about transcriptional regulation.
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25
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Genome-scale analyses of Escherichia coli and Salmonella enterica AraC reveal noncanonical targets and an expanded core regulon. J Bacteriol 2013; 196:660-71. [PMID: 24272778 DOI: 10.1128/jb.01007-13] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli AraC is a well-described transcription activator of genes involved in arabinose metabolism. Using complementary genomic approaches, chromatin immunoprecipitation (ChIP)-chip, and transcription profiling, we identify direct regulatory targets of AraC, including five novel target genes: ytfQ, ydeN, ydeM, ygeA, and polB. Strikingly, only ytfQ has an established connection to arabinose metabolism, suggesting that AraC has a broader function than previously described. We demonstrate arabinose-dependent repression of ydeNM by AraC, in contrast to the well-described arabinose-dependent activation of other target genes. We also demonstrate unexpected read-through of transcription at the Rho-independent terminators downstream of araD and araE, leading to significant increases in the expression of polB and ygeA, respectively. AraC is highly conserved in the related species Salmonella enterica. We use ChIP sequencing (ChIP-seq) and RNA sequencing (RNA-seq) to map the AraC regulon in S. enterica. A comparison of the E. coli and S. enterica AraC regulons, coupled with a bioinformatic analysis of other related species, reveals a conserved regulatory network across the family Enterobacteriaceae comprised of 10 genes associated with arabinose transport and metabolism.
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26
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Rodrigues AL, Trachtmann N, Becker J, Lohanatha AF, Blotenberg J, Bolten CJ, Korneli C, de Souza Lima AO, Porto LM, Sprenger GA, Wittmann C. Systems metabolic engineering of Escherichia coli for production of the antitumor drugs violacein and deoxyviolacein. Metab Eng 2013; 20:29-41. [PMID: 23994489 DOI: 10.1016/j.ymben.2013.08.004] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/01/2013] [Accepted: 08/21/2013] [Indexed: 12/25/2022]
Abstract
Violacein and deoxyviolacein are interesting therapeutics against pathogenic bacteria and viruses as well as tumor cells. In the present work, systems-wide metabolic engineering was applied to target Escherichia coli, a widely accepted recombinant host in pharmaceutical biotechnology, for production of these high-value products. The basic producer, E. coli dVio-1, that expressed the vioABCE cluster from Chromobacterium violaceum under control of the inducible araC system, accumulated 180 mg L(-1) of deoxyviolacein. Targeted intracellular metabolite analysis then identified bottlenecks in tryptophan supporting pathways, the major product building block. This was used for comprehensive engineering of serine, chorismate and tryptophan biosynthesis and the non-oxidative pentose-phosphate pathway. The final strain, E. coli dVio-6, accumulated 320 mg L(-1) deoxyviolacein in shake flask cultures. The created chassis of a high-flux tryptophan pathway was complemented by genomic integration of the vioD gene of Janthinobacterium lividum, which enabled exclusive production of violacein. In a fed-batch process, the resulting producer E. coli Vio-4 accumulated 710 mg L(-1) of the desired product. With straightforward broth extraction and subsequent crystallization, violacein could be obtained with 99.8% purity. This demonstrates the potential of E. coli as a platform for production of tryptophan based therapeutics.
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Affiliation(s)
- André L Rodrigues
- Institute of Biochemical Engineering, Technische Universität Braunschweig, Germany
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27
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Baruah K, Norouzitallab P, Shihao L, Sorgeloos P, Bossier P. Feeding truncated heat shock protein 70s protect Artemia franciscana against virulent Vibrio campbellii challenge. FISH & SHELLFISH IMMUNOLOGY 2013; 34:183-191. [PMID: 23092733 DOI: 10.1016/j.fsi.2012.10.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/01/2012] [Accepted: 10/14/2012] [Indexed: 06/01/2023]
Abstract
The 70 kDa heat shock proteins (Hsp70s) are highly conserved in evolution, leading to striking similarities in structure and composition between eukaryotic Hsp70s and their homologs in prokaryotes. The eukaryotic Hsp70 like the DnaK (Escherichia coli equivalent Hsp70) protein, consist of three functionally distinct domains: an N-terminal 44-kDa ATPase portion, an 18-kDa peptide-binding domain and a C-terminal 10-kDa fragment. Previously, the amino acid sequence of eukaryotic (the brine shrimp Artemia franciscana) Hsp70 and DnaK proteins were shown to share a high degree of homology, particularly in the peptide-binding domain (59.6%, the putative innate immunity-activating portion) compared to the N-terminal ATPase (48.8%) and the C-terminal lid domains (19.4%). Next to this remarkable conservation, these proteins have been shown to generate protective immunity in Artemia against pathogenic Vibrio campbellii. This study, aimed to unravel the Vibrio-protective domain of Hsp70s in vivo, demonstrated that gnotobiotically cultured Artemia fed with recombinant C-terminal fragment (containing the conserved peptide binding domain) of Artemia Hsp70 or DnaK protein were well protected against subsequent Vibrio challenge. In addition, the prophenoloxidase (proPO) system, at both mRNA and protein activity levels, was also markedly induced by these truncated proteins, suggesting epitope(s) responsible for priming the proPO system and presumably other immune-related genes, consequently boosting Artemia survival upon challenge with V. campbellii, might be located within this conserved region of the peptide binding domain.
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Affiliation(s)
- Kartik Baruah
- Laboratory of Aquaculture & Artemia Reference Center, Faculty of Bioscience Engineering, Ghent University, Gent 9000, Belgium.
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28
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Simplifying protein expression with ligation-free, traceless and tag-switching plasmids. Protein Expr Purif 2012; 85:9-17. [DOI: 10.1016/j.pep.2012.06.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Revised: 06/01/2012] [Accepted: 06/08/2012] [Indexed: 01/30/2023]
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29
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Segato F, Damásio ARL, Gonçalves TA, de Lucas RC, Squina FM, Decker SR, Prade RA. High-yield secretion of multiple client proteins in Aspergillus. Enzyme Microb Technol 2012; 51:100-6. [PMID: 22664194 DOI: 10.1016/j.enzmictec.2012.04.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 03/27/2012] [Accepted: 04/24/2012] [Indexed: 10/28/2022]
Abstract
Production of pure and high-yield client proteins is an important technology that addresses the need for industrial applications of enzymes as well as scientific experiments in protein chemistry and crystallization. Fungi are utilized in industrial protein production because of their ability to secrete large quantities of proteins. In this study, we engineered a high-expression-secretion vector, pEXPYR that directs proteins towards the extracellular medium in two Aspergillii host strains, examine the effect of maltose-induced over-expression and protein secretion as well as time and pH-dependent protein stability in the medium. We describe five client proteins representing a core set of hemicellulose degrading enzymes that accumulated up to 50-100 mg/L of protein. Using a recyclable genetic marker that allows serial insertion of multiple genes, simultaneous hyper-secretion of three client proteins in a single host strain was accomplished.
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Affiliation(s)
- Fernando Segato
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
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30
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Kim SW, Kang HY, Hur J, Gal SW, Bang WY, Cho KK, Kim CW, Bahk JD, Lee JH. Construction of a conditional lethal Salmonella mutant via genetic recombination using the ara system and asd gene. J Microbiol Methods 2011; 87:202-7. [PMID: 21871930 DOI: 10.1016/j.mimet.2011.08.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 08/11/2011] [Accepted: 08/11/2011] [Indexed: 10/17/2022]
Abstract
In order to construct a conditional lethal Salmonella mutant, an arabinose-regulated recombinant genetic system was used. The Salmonella aspartate semialdehyde dehydrogenase (asd) gene was localized under the control of araC P(araBAD) in a plasmid to create the araC P(araBAD)::asd cassette. The cassette was cloned into a plasmid carrying a p15A replication origin to create the recombinant plasmid pMMP55. The growth of Salmonella MMP10 harboring pMMP55 was dependent on the presence of arabinose. In the presence of arabinose, the Asd deficiency due to chromosomal deletion of asd in the Salmonella host was complemented by the asd gene transcribed and translated under the P(araBAD) promoter and araBAD Shine-Dalgarno (SD) sequence in pMMP55. Growth inhibition of the strain was demonstrated by arabinose depletion in M9 minimal medium, indicating that the strain were unable to grow in an arabinose-limited environment. In addition, the analysis of a 50% lethal dose (LD50) using mice revealed that the strain MMP10 exhibited attenuation by approximately 100-fold relative to that of the unmodified strain. In conclusion, these data suggest that the araC P(araBAD)::asd system developed in this study can be used to construct conditional lethal Salmonella mutants for application as safe, live-attenuated Salmonella vaccines.
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Affiliation(s)
- Sam Woong Kim
- Swine Science & Technology Center, Gyeongnam National University of Science and Technology, 150 Chilam-dong, Jinju, Gyeongnam, 660-758, South Korea
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Francis DM, Page R. Strategies to optimize protein expression in E. coli. CURRENT PROTOCOLS IN PROTEIN SCIENCE 2010; Chapter 5:5.24.1-5.24.29. [PMID: 20814932 PMCID: PMC7162232 DOI: 10.1002/0471140864.ps0524s61] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Recombinant protein expression in Escherichia coli (E. coli) is simple, fast, inexpensive, and robust, with the expressed protein comprising up to 50 percent of the total cellular protein. However, it also has disadvantages. For example, the rapidity of bacterial protein expression often results in unfolded/misfolded proteins, especially for heterologous proteins that require longer times and/or molecular chaperones to fold correctly. In addition, the highly reductive environment of the bacterial cytosol and the inability of E. coli to perform several eukaryotic post-translational modifications results in the insoluble expression of proteins that require these modifications for folding and activity. Fortunately, multiple, novel reagents and techniques have been developed that allow for the efficient, soluble production of a diverse range of heterologous proteins in E. coli. This overview describes variables at each stage of a protein expression experiment that can influence solubility and offers a summary of strategies used to optimize soluble expression in E. coli.
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Baek KH, Skinner DZ. Molecular Cloning and Expression of Sequence Variants of Manganese Superoxide Dismutase Genes from Wheat. ACTA ACUST UNITED AC 2010. [DOI: 10.5338/kjea.2010.29.1.077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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33
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Heterologous expression of the msp2 gene from Marasmius scorodonius. Arch Microbiol 2009; 191:397-402. [DOI: 10.1007/s00203-009-0462-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 01/22/2009] [Accepted: 02/02/2009] [Indexed: 10/21/2022]
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34
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PBAD-based shuttle vectors for functional analysis of toxic and highly regulated genes in Pseudomonas and Burkholderia spp. and other bacteria. Appl Environ Microbiol 2008; 74:7422-6. [PMID: 18849445 DOI: 10.1128/aem.01369-08] [Citation(s) in RCA: 195] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the construction of a series of Escherichia-Pseudomonas broad-host-range expression vectors utilizing the P(BAD) promoter and the araC regulator for routine cloning, conditional expression, and analysis of tightly controlled and/or toxic genes in pseudomonads.
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35
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Construction and characterization of a recombinant whole-cell biocatalyst of Escherichia coli expressing styrene monooxygenase under the control of arabinose promoter. BIOTECHNOL BIOPROC E 2008. [DOI: 10.1007/s12257-007-0172-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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36
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Semprini S, Troup T, Kotelevtseva N, King K, Davis J, Mullins L, Chapman K, Dunbar D, Mullins J. Cryptic loxP sites in mammalian genomes: genome-wide distribution and relevance for the efficiency of BAC/PAC recombineering techniques. Nucleic Acids Res 2007; 35:1402-10. [PMID: 17284462 PMCID: PMC1865043 DOI: 10.1093/nar/gkl1108] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cre is widely used for DNA tailoring and, in combination with recombineering techniques, to modify BAC/PAC sequences for generating transgenic animals. However, mammalian genomes contain recombinase recognition sites (cryptic loxP sites) that can promote illegitimate DNA recombination and damage when cells express the Cre recombinase gene. We have created a new bioinformatic tool, FuzznucComparator, which searches for cryptic loxP sites and we have applied it to the analysis of the whole mouse genome. We found that cryptic loxP sites occur frequently and are homogeneously distributed in the genome. Given the mammalian nature of BAC/PAC genomic inserts, we hypothesised that the presence of cryptic loxP sites may affect the ability to grow and modify BAC and PAC clones in E. coli expressing Cre recombinase. We have observed a defect in bacterial growth when some BACs and PACs were transformed into EL350, a DH10B-derived bacterial strain that expresses Cre recombinase under the control of an arabinose-inducible promoter. In this study, we have demonstrated that Cre recombinase expression is leaky in un-induced EL350 cells and that some BAC/PAC sequences contain cryptic loxP sites, which are active and mediate the introduction of single-strand nicks in BAC/PAC genomic inserts.
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Affiliation(s)
- S. Semprini
- Molecular Physiology Group, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK, Current address: Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 9DU, UK, Endocrine Science Research Group, University of Manchester M13 9PT, UK and Endocrinology Unit, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK
| | - T.J. Troup
- Molecular Physiology Group, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK, Current address: Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 9DU, UK, Endocrine Science Research Group, University of Manchester M13 9PT, UK and Endocrinology Unit, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK
| | - N. Kotelevtseva
- Molecular Physiology Group, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK, Current address: Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 9DU, UK, Endocrine Science Research Group, University of Manchester M13 9PT, UK and Endocrinology Unit, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK
| | - K. King
- Molecular Physiology Group, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK, Current address: Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 9DU, UK, Endocrine Science Research Group, University of Manchester M13 9PT, UK and Endocrinology Unit, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK
| | - J.R.E. Davis
- Molecular Physiology Group, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK, Current address: Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 9DU, UK, Endocrine Science Research Group, University of Manchester M13 9PT, UK and Endocrinology Unit, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK
| | - L.J. Mullins
- Molecular Physiology Group, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK, Current address: Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 9DU, UK, Endocrine Science Research Group, University of Manchester M13 9PT, UK and Endocrinology Unit, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK
| | - K.E. Chapman
- Molecular Physiology Group, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK, Current address: Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 9DU, UK, Endocrine Science Research Group, University of Manchester M13 9PT, UK and Endocrinology Unit, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK
| | - D.R. Dunbar
- Molecular Physiology Group, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK, Current address: Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 9DU, UK, Endocrine Science Research Group, University of Manchester M13 9PT, UK and Endocrinology Unit, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK
| | - J.J. Mullins
- Molecular Physiology Group, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK, Current address: Department of Cardiovascular Medicine, University of Oxford, Oxford OX3 9DU, UK, Endocrine Science Research Group, University of Manchester M13 9PT, UK and Endocrinology Unit, University of Edinburgh Medical School, Edinburgh EH16 4TJ, UK
- *To whom correspondence should be addressed. +44-131-242-6722+44-131-242-6782
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Hoelzle LE, Hoelzle K, Wittenbrink MM. Expression of the Major Outer Membrane Protein (MOMP) of Chlamydophila abortus, Chlamydophila pecorum, and Chlamydia suis in Escherichia coli using an Arabinose-inducible Plasmid Vector. ACTA ACUST UNITED AC 2003; 50:383-9. [PMID: 14633208 DOI: 10.1046/j.1439-0450.2003.00685.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ompA genes encoding the 40 kDa major outer membrane protein (MOMP) of Chlamydophila (Ch.) abortus, Ch. pecorum, and Chlamydia (C.) suis were cloned into the arabinose-inducible plasmid vector pBADMycHis, and recombinant MOMPs (rMOMP) from the three chlamydial species were expressed at high levels in Escherichia (E.) coli. The proteins lacking the 22 aa N-terminal signal peptide were expressed as insoluble cytoplasmic inclusion bodies which were readily purified using immobilized metal-affinity chromatography. The rMOMPs including the N-terminal signal peptide were expressed and translocated as a surface-exposed immunoaccessible protein into the outer membrane of E. coli. Transformants expressing this full-length rMOMP were significantly reduced in viability. Purified native elementary bodies (EB) and rMOMPs of the three chlamydial species purified from the E. coli cytoplasm were used for immunization of rabbits. The resulting sera were analysed for their ability to recognize homologous and heterologous rMOMP and native EB. When testing rMOMP antisera against rMOMP and EB antigens, marked cross-reactivities were detected between the three species. Using EB antisera and rMOMPs as antigens, a significant species-specific reactivity was measured.
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Affiliation(s)
- L E Hoelzle
- Institute of Veterinary Bacteriology, University of Zurich, Winterthurerstrasse 270, CH-8057 Zurich, Switzerland.
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38
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Tay ST, Rohani MY, Ho TM, Devi S. Expression of recombinant proteins of Orientia tsutsugamushi and their applications in the serodiagnosis of scrub typhus. Diagn Microbiol Infect Dis 2002; 44:137-42. [PMID: 12458119 DOI: 10.1016/s0732-8893(02)00434-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In this study, recombinant proteins that encompassed the AD I-AD III regions of 56 kDa immunodominant gene of 2 Orientia tsutsugamushi (OT) serotypes; Gilliam and TA763 were expressed in Escherichia coli. Both recombinant proteins exhibited serologic cross-reactivity with the rabbit antisera against various OT serotypes, as evaluated by enzyme-linked immunosorbent assay (ELISA), but not against other rickettsial species, including Rickettsia typhi, R. prowazekii and TT118 SFG rickettsiae. The feasibility of using the recombinant proteins as a diagnostic reagent was further evaluated by ELISA using sera from blood donors and scrub typhus patients. The results suggested a higher affinity of the antihuman IgM than IgG with both recombinant proteins. The IgM ELISA findings were agreeable with the results of indirect immunoperoxidase (IIP) assay especially with sera of high antibody (1:1600). However, more than one antigen are probably needed for development of an effective assay for serodiagnosis of scrub typhus in endemic areas.
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Affiliation(s)
- S T Tay
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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39
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Laikova ON, Mironov AA, Gelfand MS. Computational analysis of the transcriptional regulation of pentose utilization systems in the gamma subdivision of Proteobacteria. FEMS Microbiol Lett 2001; 205:315-22. [PMID: 11750821 DOI: 10.1111/j.1574-6968.2001.tb10966.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The comparative approach to the recognition of transcription regulatory sites is based on the assumption that as long as a regulator is conserved in several genomes, one can expect that sets of co-regulated genes (regulons) and regulatory sites for the regulator in these genomes are conserved as well. We used this approach to analyze the ribose (RbsR), arabinose (AraC), and xylose (XylR) regulons of gamma Proteobacteria for which (almost) completely sequenced genomes were available. Candidate binding sites for RbsR and AraC were detected. The improved XylR site consensus was proposed. Potential new members of the xylose regulons were found in the Escherichia coli, Salmonella typhi, and Klebsiella pneumoniae genomes. The function of these new xylose-regulated operons is likely to be the utilization of oligosaccharides containing xylose. Finally, candidate cAMP receptor-protein sites were identified in the regulatory regions of the majority of RbsR-, AraC-, and XylR-regulated operons.
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Affiliation(s)
- O N Laikova
- State Scientific Center GosNIIGenetika, Moscow, Russia.
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40
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Grant AJ, Haigh R, Williams P, O'Connor CD. An in vitro transposon system for highly regulated gene expression: construction of Escherichia coli strains with arabinose-dependent growth at low temperatures. Gene 2001; 280:145-51. [PMID: 11738827 DOI: 10.1016/s0378-1119(01)00769-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Placing a gene of interest under the control of an inducible promoter greatly aids the purification, localization and functional analysis of proteins but usually requires the sub-cloning of the gene of interest into an appropriate expression vector. Here, we describe an alternative approach employing in vitro transposition of Tn Omega P(BAD) to place the highly regulable, arabinose inducible P(BAD) promoter upstream of the gene to be expressed. The method is rapid, simple and facilitates the optimization of expression by producing constructs with variable distances between the P(BAD) promoter and the gene. To illustrate the use of this approach, we describe the construction of a strain of Escherichia coli in which growth at low temperatures on solid media is dependent on threshold levels of arabinose. Other uses of the transposable promoter are also discussed.
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Affiliation(s)
- A J Grant
- Division of Biochemistry and Molecular Biology, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton S016 7PX, UK
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41
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Carlson SA, Frana TS, Griffith RW. Antibiotic resistance in Salmonella enterica serovar Typhimurium exposed to microcin-producing Escherichia coli. Appl Environ Microbiol 2001; 67:3763-6. [PMID: 11472964 PMCID: PMC93088 DOI: 10.1128/aem.67.8.3763-3766.2001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microcin 24 is an antimicrobial peptide secreted by uropathogenic Escherichia coli. Secretion of microcin 24 provides an antibacterial defense mechanism for E. coli. In a plasmid-based system using transformed Salmonella enterica, we found that resistance to microcin 24 could be seen in concert with a multiple-antibiotic resistance phenotype. This multidrug-resistant phenotype appeared when Salmonella was exposed to an E. coli strain expressing microcin 24. Therefore, it appears that multidrug-resistant Salmonella can arise as a result of an insult from other pathogenic bacteria.
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Affiliation(s)
- S A Carlson
- Preharvest Food Safety and Enteric Disease Research Unit, National Animal Disease Center, U.S. Department of Agriculture Agricultural Research Service, Ames, Iowa 50010, USA.
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42
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Abstract
Constitutive mutations were sought and found in the N-terminal arm of the Escherichia coli regulatory protein of the arabinose operon, AraC protein. A new mutation, N16D, was of particular interest. Asn-16 is not seen in the crystal structure of the AraC dimerization domain determined in the absence of arabinose, because the N-terminal arm 18 residues are disordered, but in the presence of arabinose, residues 7-18 fold over the arabinose and make many interactions with it. In this state Asn-16 lies near two positively charged amino acids, Lys-43 and Arg-99. We propose that the introduction of the negatively charged aspartic residue at position 16 creates a charge-charge interaction network among Asp-16, Lys-43, and Arg-99 that holds the arm to the dimerization domain even in the absence of arabinose. This frees the DNA-binding domains and allows them to bind cis to I(1)-I(2) half-sites and activate transcription. Mutating the two positively charged residues to alanines individually and collectively decreased or eliminated the constitutivity created by the N16D mutation.
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Affiliation(s)
- M Wu
- Biology Department, Johns Hopkins University, Baltimore, Maryland 21218, USA
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43
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Harmer T, Wu M, Schleif R. The role of rigidity in DNA looping-unlooping by AraC. Proc Natl Acad Sci U S A 2001; 98:427-31. [PMID: 11209047 PMCID: PMC14602 DOI: 10.1073/pnas.98.2.427] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We applied two experiments useful in the study of ligand-regulated DNA binding proteins to AraC, the dimeric regulator of the Escherichia coli l-arabinose operon. In the absence of arabinose, AraC prefers to loop DNA by binding to two half-sites that are separated by 210 base pairs, and in the presence of arabinose it prefers to bind to adjacently located half-sites. The basis for this ligand-regulated shift in binding appears to result from a shift in the rigidity of the system, where rigidity both in AraC protein in the absence of arabinose, and in the DNA are required to generate the free energy differences that produce the binding preferences. Eliminating the dimerization domains and connecting the two DNA binding domains of AraC by a flexible peptide linker should provide a protein whose behavior mimics that of AraC when there is no interaction between its dimerization and DNA binding domains. The resulting protein bound to adjacent half-sites on the DNA, like AraC protein in the presence of arabinose. When the two double-stranded DNA half-sites were connected by 24 bases of single-stranded, flexible DNA, wild-type AraC protein bound to the DNA in the presence and absence of arabinose with equal affinity, showing that AraC modulates its DNA binding affinity in response to arabinose by shifting the relative positions of its DNA binding domains. These results are consistent with the light switch mechanism for the action of AraC, refine the model, and extend the range of experimental tests to which it has been subjected.
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Affiliation(s)
- T Harmer
- Biology Department, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
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44
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Thapar N, Clarke S. Expression, purification, and characterization of the protein repair l-isoaspartyl methyltransferase from Arabidopsis thaliana. Protein Expr Purif 2000; 20:237-51. [PMID: 11049748 DOI: 10.1006/prep.2000.1311] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Protein l-isoaspartate (d-aspartate) O-methyltransferase (EC 2.1.1. 77) is a repair enzyme that methylates abnormal l-isoaspartate residues in proteins which arise spontaneously as a result of aging. This enzyme initiates their conversion back into the normal l-aspartate form by a methyl esterification reaction. Previously, partial cDNAs of this enzyme were isolated from the higher plant Arabidopsis thaliana. In this study, we report the cloning and expression of a full-length cDNA of l-isoaspartyl methyltransferase from A. thaliana into Escherichia coli under the P(BAD) promoter, which offers a high level of expression under a tight regulatory control. The enzyme is found largely in the soluble fraction. We purified this recombinant enzyme to homogeneity using a series of steps involving DEAE-cellulose, gel filtration, and hydrophobic interaction chromatographies. The homogeneous enzyme was found to have maximum activity at 45 degrees C and a pH optimum from 7 to 8. The enzyme was found to have a wide range of affinities for l-isoaspartate-containing peptides and displayed relatively poor reactivity toward protein substrates. The best methyl-accepting substrates were KASA-l-isoAsp-LAKY (K(m) = 80 microM) and VYP-l-isoAsp-HA (K(m) = 310 microM). We also expressed the full-length form and a truncated version of this enzyme (lacking the N-terminal 26 amino acid residues) in E. coli under the T7 promoter. Both the full-length and the truncated forms were active, though overexpression of the truncated enzyme led to a complete loss of activity.
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Affiliation(s)
- N Thapar
- Department of Chemistry and Biochemistry, Molecular Biology Institute, Los Angeles, California 90095, USA
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45
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Dhiman A, Schleif R. Recognition of overlapping nucleotides by AraC and the sigma subunit of RNA polymerase. J Bacteriol 2000; 182:5076-81. [PMID: 10960090 PMCID: PMC94654 DOI: 10.1128/jb.182.18.5076-5081.2000] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/1999] [Accepted: 06/14/2000] [Indexed: 11/20/2022] Open
Abstract
The Escherichia coli promoter p(BAD), under the control of the AraC protein, drives the expression of mRNA encoding the AraB, AraA, and AraD gene products of the arabinose operon. The binding site of AraC at p(BAD) overlaps the RNA polymerase -35 recognition region by 4 bases, leaving 2 bases of the region not contacted by AraC. This overlap raises the question of whether AraC substitutes for the sigma subunit of RNA polymerase in recognition of the -35 region or whether both AraC and sigma make important contacts with the DNA in the -35 region. If sigma does not contact DNA near the -35 region, p(BAD) activity should be independent of the identity of the bases in the hexamer region that are not contacted by AraC. We have examined this issue in the p(BAD) promoter and in a second promoter where the AraC binding site overlaps the -35 region by only 2 bases. In both cases promoter activity is sensitive to changes in bases not contacted by AraC, showing that despite the overlap, sigma does read DNA in the -35 region. Since sigma and AraC are thus closely positioned at p(BAD), it is possible that AraC and sigma contact one another during transcription initiation. DNA migration retardation assays, however, showed that there exists only a slight degree of DNA binding cooperativity between AraC and sigma, thus suggesting either that the normal interactions between AraC and sigma are weak or that the presence of the entire RNA polymerase is necessary for significant interaction.
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Affiliation(s)
- A Dhiman
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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46
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Clarke BR, Esumeh F, Roberts IS. Cloning, expression, and purification of the K5 capsular polysaccharide lyase (KflA) from coliphage K5A: evidence for two distinct K5 lyase enzymes. J Bacteriol 2000; 182:3761-6. [PMID: 10850992 PMCID: PMC94548 DOI: 10.1128/jb.182.13.3761-3766.2000] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Escherichia coli K5 capsular polysaccharide [-4)-betaGlcA-(1, 4)-alphaGlcNAc-(1-] is a receptor for the capsule-specific bacteriophage K5A. Associated with the structure of bacteriophage K5A is a polysaccharide lyase which degrades the K5 capsule to expose the underlying bacterial cell surface. The bacteriophage K5A lyase gene (kflA) was cloned and sequenced. The kflA gene encodes a polypeptide with a predicted molecular mass of 66.9 kDa and which exhibits amino acid homology with ElmA, a K5 polysaccharide lyase encoded on the chromosome of E. coli SEBR 3282. There was only limited nucleotide homology between the kflA and elmA genes, suggesting that these two genes are distinct and either have been derived from separate progenitors or have diverged from a common progenitor for a considerable length of time. Southern blot analysis revealed that kflA was not present on the chromosome of the E. coli strains examined. In contrast, elmA was present in a subset of E. coli strains. Homology was observed between DNA flanking the kflA gene of bacteriophage K5A and DNA flanking a small open reading frame (ORF(L)) located 5' of the endosialidase gene of the E. coli K1 capsule-specific bacteriophage K1E. The DNA homology between these noncoding sequences indicated that bacteriophages K5A and K1E were related. The deduced polypeptide sequence of ORF(L) in bacteriophage K1E exhibited homology to the N terminus of KflA from bacteriophage K5A, suggesting that ORF(L) is a truncated remnant of KflA. The presence of this truncated kflA gene implies that bacteriophage K1E has evolved from bacteriophage K5A by acquisition of the endosialidase gene and subsequent loss of functional kflA. A (His)(6)-KflA fusion protein was overexpressed in E. coli and purified to homogeneity with a yield of 4.8 mg per liter of bacterial culture. The recombinant enzyme was active over a broad pH range and NaCl concentration and was capable of degrading K5 polysaccharide into a low-molecular-weight product.
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Affiliation(s)
- B R Clarke
- School of Biological Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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47
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Abstract
We have isolated mutations in AraC protein that specifically block either induction or repression at the ara pBAD promoter. These hemiplegic mutations identify amino acid residues that, correspondingly, are involved only in the induction or only in the repression activities of the protein. Residues key only for induction are 13, 15, and 18, which are located in the N-terminal arm of AraC, and residues 80 and 82 which lie in the arabinose-binding pocket of the protein's sugar-binding and dimerization domain. Alteration of residues 157, 244 and 257 can leave the protein able to activate transcription but not able to repress transcription. The behavior of the mutant proteins is consistent with the light switch mechanism for AraC action in which the presence of arabinose pulls the N-terminal arms of the protein off the DNA-binding domains, thereby freeing them to assume a direct-repeat orientation, bind to adjacent direct-repeat DNA half-sites, and activate transcription.
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Affiliation(s)
- W L Reed
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
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48
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Abstract
Bacterial genes are often differentially expressed in response to specific environmental conditions. We have devised a method to identify regulated bacterial promoters, such that transient promoter expression leads to a permanent and selectable change in bacterial phenotype. This system consists of a promoterless derivative of cre, the phage P1 recombinase, carried on a plasmid, and two chromosomal loxP sites, the targets of the Cre recombinase. The loxP sites flank npt, conferring kanamycin resistance, and sacB, which confers sensitivity to sucrose, allowing positive selection for both the presence and absence of this chromosomal cassette. Fusion of active promoters to cre induces recombination of the loxP sites and deletion of intervening DNA, allowing selection on media containing sucrose, while inactive promoters fail to induce recombination and so remain resistant to kanamycin. We tested the system in Salmonella typhimurium using a known regulated promoter, that from the araBAD operon, and found it to be a sensitive indicator of gene expression over a wide range of promoter induction. We then used this system to identify S. typhimurium genes that are specifically expressed when bacteria interact with cultured epithelial cells and identified a novel DNA fragment, not found in E. coli, which might represent part of a new pathogenicity island.
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Affiliation(s)
- C Altier
- Department of Microbiology, North Carolina State University College of Veterinary Medicine, 4700 Hillsborough St., Raleigh, NC, USA.
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49
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Bustamante VH, Calva E, Puente JL. Analysis of cis-acting elements required for bfpA expression in enteropathogenic Escherichia coli. J Bacteriol 1998; 180:3013-6. [PMID: 9603898 PMCID: PMC107275 DOI: 10.1128/jb.180.11.3013-3016.1998] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/1997] [Accepted: 03/25/1998] [Indexed: 02/07/2023] Open
Abstract
bfpA expression in enteropathogenic Escherichia coli is regulated by growth medium, temperature, and ammonium concentration and requires the BfpT protein (also called PerA), a member of the AraC family of transcriptional activators. Site-directed and PCR random mutagenesis, as well as deletion analysis of the bfpA upstream regulatory region, supported assignment of the promoter elements and demonstrated that the cis-acting elements that mediate BfpT-dependent regulation of bfpA are located between positions -85 and -46. Interestingly, this region shares 73% identity with a 40-bp-long AT-rich tract located upstream of the bfpT gene, which is essential for bfpT autoregulation.
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Affiliation(s)
- V H Bustamante
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62250, Mexico
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50
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Abstract
In the absence of arabinose and interactions with other proteins, AraC, the activator-repressor that regulates the araBAD operon in Escherichia coli, was found to prefer participating in DNA looping interactions between the two well-separated DNA half-sites, araI1 and araO2 at their normal separation of 211 base-pairs rather than binding to these same two half-sites when they are adjacent to one another. On the addition of arabinose, AraC preferred to bind to the adjacently located half-sites. Inverting the distally located araO2 half-site eliminated the looping preference. These results demonstrate that apo-AraC possesses an intrinsic looping preference that is eliminated by the presence of arabinose. We developed a method for the accurate determination of the relative affinities of AraC for the DNA half-sites araI1, araI2, and araO2 and non-specific DNA. These affinities allowed accurate calculation of basal level and induced levels of expression from pBAD under a wide variety of natural and mutant conditions. The calculations independently predicted the looping preference of apo-AraC.
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Affiliation(s)
- R R Seabold
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
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