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Perillo MA, Burgos I, Clop EM, Sanchez JM, Nolan V. The role of water in reactions catalysed by hydrolases under conditions of molecular crowding. Biophys Rev 2023; 15:639-660. [PMID: 37681097 PMCID: PMC10480385 DOI: 10.1007/s12551-023-01104-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 07/23/2023] [Indexed: 09/09/2023] Open
Abstract
Under macromolecular crowding (MC) conditions such as cellular, extracellular, food and other environments of biotechnological interest, the thermodynamic activity of the different macromolecules present in the system is several orders of magnitude higher than in dilute solutions. In this state, the diffusion rates are affected by the volume exclusion induced by the crowders. Immiscible liquid phases, which may arise in MC by liquid-liquid phase separation, may induce a dynamic confinement of reactants, products and/or enzymes, tuning reaction rates. In cellular environments and other crowding conditions, membranes and macromolecules provide, on the whole, large surfaces that can perturb the solvent, causing its immobilisation by adsorption in the short range and also affecting the solvent viscosity in the long range. The latter phenomenon can affect the conformation of a protein and/or the degree of association of its protomers and, consequently, its activity. Changes in the water structure can also alter the enzyme-substrate interaction, and, in the case of hydrolytic enzymes, where water is one of the substrates, it also affects the reaction mechanism. Here, we review the evidence for how macromolecular crowding affects the catalysis induced by hydrolytic enzymes, focusing on the structure and dynamics of water.
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Affiliation(s)
- Maria A. Perillo
- Facultad de Ciencias Exactas, Físicas y Naturales, ICTA and Departamento de Química, Cátedra de Química Biológica, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), Córdoba, Argentina
| | - Inés Burgos
- CONICET, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), Córdoba, Argentina
- Facultad de Ciencias Exactas, Físicas y Naturales, ICTA and Departamento de Química Industrial y Aplicada, Cátedra de Química Biológica, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, 5016 Córdoba, Argentina
| | - Eduardo M. Clop
- Facultad de Ciencias Exactas, Físicas y Naturales, ICTA and Departamento de Química, Cátedra de Química Biológica, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), Córdoba, Argentina
| | - Julieta M. Sanchez
- Facultad de Ciencias Exactas, Físicas y Naturales, ICTA and Departamento de Química, Cátedra de Química Biológica, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), Córdoba, Argentina
- Institut de Biotecnologia I de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
- Departament de Genètica I de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
- CIBER de Bioingeniería Biomateriales y Nanomedicina (CIBER-BBN), Bellaterra, 08193 Barcelona, Spain
| | - Verónica Nolan
- Facultad de Ciencias Exactas, Físicas y Naturales, ICTA and Departamento de Química, Cátedra de Química Biológica, Universidad Nacional de Córdoba, Av. Vélez Sársfield 1611, 5016 Córdoba, Argentina
- CONICET, Instituto de Investigaciones Biológicas y Tecnológicas (IIByT), Córdoba, Argentina
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Carratalá JV, Atienza-Garriga J, López-Laguna H, Vázquez E, Villaverde A, Sánchez JM, Ferrer-Miralles N. Enhanced recombinant protein capture, purity and yield from crude bacterial cell extracts by N-Lauroylsarcosine-assisted affinity chromatography. Microb Cell Fact 2023; 22:81. [PMID: 37098491 PMCID: PMC10131332 DOI: 10.1186/s12934-023-02081-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 04/04/2023] [Indexed: 04/27/2023] Open
Abstract
BACKGROUND Recombinant proteins cover a wide range of biomedical, biotechnological, and industrial needs. Although there are diverse available protocols for their purification from cell extracts or from culture media, many proteins of interest such as those containing cationic domains are difficult to purify, a fact that results in low yields of the final functional product. Unfortunately, this issue prevents the further development and industrial or clinical application of these otherwise interesting products. RESULTS Aiming at improving the purification of such difficult proteins, a novel procedure has been developed based on supplementing crude cell extracts with non-denaturing concentrations of the anionic detergent N-Lauroylsarcosine. The incorporation of this simple step in the downstream pipeline results in a substantial improvement of the protein capture by affinity chromatography, an increase of protein purity and an enhancement of the overall process yield, being the detergent not detectable in the final product. CONCLUSION By taking this approach, which represents a smart repurposing of N-Lauroylsarcosine applied to protein downstream, the biological activity of the protein is not affected. Being technologically simple, the N-Lauroylsarcosine-assisted protein purification might represent a critical improvement in recombinant protein production with wide applicability, thus smothering the incorporation of promising proteins into the protein market.
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Affiliation(s)
- Jose Vicente Carratalá
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, 08193, Cerdanyola del Vallès, Barcelona, Spain
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
| | - Jan Atienza-Garriga
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, 08193, Cerdanyola del Vallès, Barcelona, Spain
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
| | - Hèctor López-Laguna
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, 08193, Cerdanyola del Vallès, Barcelona, Spain
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
| | - Esther Vázquez
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, 08193, Cerdanyola del Vallès, Barcelona, Spain
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
| | - Antonio Villaverde
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain.
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, 08193, Cerdanyola del Vallès, Barcelona, Spain.
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain.
| | - Julieta M Sánchez
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain.
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, 08193, Cerdanyola del Vallès, Barcelona, Spain.
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain.
- Instituto de Investigaciones Biológicas y Tecnológicas (IIBYT) (CONICET-Universidad Nacional de Córdoba), ICTA, FCEFyN, UNC., Av. Velez Sarsfield 1611, X 5016GCA, Córdoba, Argentina.
| | - Neus Ferrer-Miralles
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain.
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, 08193, Cerdanyola del Vallès, Barcelona, Spain.
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain.
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Mital S, Christie G, Dikicioglu D. Recombinant expression of insoluble enzymes in Escherichia coli: a systematic review of experimental design and its manufacturing implications. Microb Cell Fact 2021; 20:208. [PMID: 34717620 PMCID: PMC8557517 DOI: 10.1186/s12934-021-01698-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 10/22/2021] [Indexed: 02/06/2023] Open
Abstract
Recombinant enzyme expression in Escherichia coli is one of the most popular methods to produce bulk concentrations of protein product. However, this method is often limited by the inadvertent formation of inclusion bodies. Our analysis systematically reviews literature from 2010 to 2021 and details the methods and strategies researchers have utilized for expression of difficult to express (DtE), industrially relevant recombinant enzymes in E. coli expression strains. Our review identifies an absence of a coherent strategy with disparate practices being used to promote solubility. We discuss the potential to approach recombinant expression systematically, with the aid of modern bioinformatics, modelling, and ‘omics’ based systems-level analysis techniques to provide a structured, holistic approach. Our analysis also identifies potential gaps in the methods used to report metadata in publications and the impact on the reproducibility and growth of the research in this field.
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Affiliation(s)
- Suraj Mital
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Duygu Dikicioglu
- Department of Biochemical Engineering, University College London, London, WC1E 6BT, UK.
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4
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Vassen V, Valotteau C, Feuillie C, Formosa-Dague C, Dufrêne YF, De Bolle X. Localized incorporation of outer membrane components in the pathogen Brucella abortus. EMBO J 2019; 38:e100323. [PMID: 30635335 PMCID: PMC6396147 DOI: 10.15252/embj.2018100323] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 11/29/2018] [Accepted: 12/04/2018] [Indexed: 12/21/2022] Open
Abstract
The zoonotic pathogen Brucella abortus is part of the Rhizobiales, which are alpha-proteobacteria displaying unipolar growth. Here, we show that this bacterium exhibits heterogeneity in its outer membrane composition, with clusters of rough lipopolysaccharide co-localizing with the essential outer membrane porin Omp2b, which is proposed to allow facilitated diffusion of solutes through the porin. We also show that the major outer membrane protein Omp25 and peptidoglycan are incorporated at the new pole and the division site, the expected growth sites. Interestingly, lipopolysaccharide is also inserted at the same growth sites. The absence of long-range diffusion of main components of the outer membrane could explain the apparent immobility of the Omp2b clusters, as well as unipolar and mid-cell localizations of newly incorporated outer membrane proteins and lipopolysaccharide. Unipolar growth and limited mobility of surface structures also suggest that new surface variants could arise in a few generations without the need of diluting pre-existing surface antigens.
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Affiliation(s)
- Victoria Vassen
- Research Unit in Biology of Microorganisms (URBM), Narilis University of Namur (UNamur), Namur, Belgium
| | - Claire Valotteau
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Cécile Feuillie
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Cécile Formosa-Dague
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Yves F Dufrêne
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Wavre, Belgium
| | - Xavier De Bolle
- Research Unit in Biology of Microorganisms (URBM), Narilis University of Namur (UNamur), Namur, Belgium
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Meister SW, Hendrikse NM, Löfblom J. Directed evolution of the 3C protease from coxsackievirus using a novel fluorescence-assisted intracellular method. Biol Chem 2019; 400:405-415. [PMID: 30521472 DOI: 10.1515/hsz-2018-0362] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/21/2018] [Indexed: 01/08/2023]
Abstract
Proteases are crucial for regulating biological processes in organisms through hydrolysis of peptide bonds. Recombinant proteases have moreover become important tools in biotechnological, and biomedical research and as therapeutics. We have developed a label-free high-throughput method for quantitative assessment of proteolytic activity in Escherichia coli. The screening method is based on co-expression of a protease of interest and a reporter complex. This reporter consists of an aggregation-prone peptide fused to a fluorescent protein via a linker that contains the corresponding substrate sequence. Cleavage of the substrate rescues the fluorescent protein from aggregation, resulting in increased fluorescence that correlates to proteolytic activity, which can be monitored using flow cytometry. In one round of flow-cytometric cell sorting, we isolated an efficiently cleaved tobacco etch virus (TEV) substrate from a 1:100 000 background of non-cleavable sequences, with around 6000-fold enrichment. We then engineered the 3C protease from coxsackievirus B3 (CVB3 3Cpro) towards improved proteolytic activity on the substrate LEVLFQ↓GP. We isolated highly proteolytic active variants from a randomly mutated CVB3 3Cpro library with up to 4-fold increase in activity. The method enables simultaneous measurement of proteolytic activity and protease expression levels and can therefore be applied for protease substrate profiling, as well as directed evolution of proteases.
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Affiliation(s)
- Sebastian W Meister
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Natalie M Hendrikse
- Department of Fibre and Polymer Technology, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
| | - John Löfblom
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-106 91 Stockholm, Sweden
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6
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de Marco A, Ferrer-Miralles N, Garcia-Fruitós E, Mitraki A, Peternel S, Rinas U, Trujillo-Roldán MA, Valdez-Cruz NA, Vázquez E, Villaverde A. Bacterial inclusion bodies are industrially exploitable amyloids. FEMS Microbiol Rev 2019; 43:53-72. [PMID: 30357330 DOI: 10.1093/femsre/fuy038] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 10/23/2018] [Indexed: 12/13/2022] Open
Abstract
Understanding the structure, functionalities and biology of functional amyloids is an issue of emerging interest. Inclusion bodies, namely protein clusters formed in recombinant bacteria during protein production processes, have emerged as unanticipated, highly tunable models for the scrutiny of the physiology and architecture of functional amyloids. Based on an amyloidal skeleton combined with varying amounts of native or native-like protein forms, bacterial inclusion bodies exhibit an unusual arrangement that confers mechanical stability, biological activity and conditional protein release, being thus exploitable as versatile biomaterials. The applicability of inclusion bodies in biotechnology as enriched sources of protein and reusable catalysts, and in biomedicine as biocompatible topographies, nanopills or mimetics of endocrine secretory granules has been largely validated. Beyond these uses, the dissection of how recombinant bacteria manage the aggregation of functional protein species into structures of highly variable complexity offers insights about unsuspected connections between protein quality (conformational status compatible with functionality) and cell physiology.
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Affiliation(s)
- Ario de Marco
- Laboratory for Environmental and Life Sciences, University of Nova Gorica, Vipavska Cesta 13, 5000 Nova Gorica, Slovenia
| | - Neus Ferrer-Miralles
- Institut de Biotecnologia i de Biomedicina (IBB), Carrer de la Vall Moronta s/n, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain.,Departament de Genètica i de Microbiologia, Carrer de la Vall Moronta s/n, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain.,CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Carrer de la Vall Moronta s/n, 08193 Cerdanyola del Vallès, Spain
| | - Elena Garcia-Fruitós
- Department of Ruminant Production, Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Torre Marimon, 08140 Caldes de Montbui, Barcelona, Spain
| | - Anna Mitraki
- Department of Materials Science and Technology, University of Crete, Vassilika Vouton, 70013 Heraklion, Crete, Greece.,Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology Hellas (FORTH), N. Plastira 100, Vassilika Vouton, 70013 Heraklion, Crete, Greece
| | | | - Ursula Rinas
- Leibniz University of Hannover, Technical Chemistry and Life Science, 30167 Hannover, Germany.,Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Mauricio A Trujillo-Roldán
- Programa de Investigación de Producción de Biomoléculas, Unidad de Bioprocesos, Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510 Ciudad de México, México
| | - Norma A Valdez-Cruz
- Programa de Investigación de Producción de Biomoléculas, Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510 Ciudad de México, México
| | - Esther Vázquez
- Institut de Biotecnologia i de Biomedicina (IBB), Carrer de la Vall Moronta s/n, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain.,Departament de Genètica i de Microbiologia, Carrer de la Vall Moronta s/n, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain.,CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Carrer de la Vall Moronta s/n, 08193 Cerdanyola del Vallès, Spain
| | - Antonio Villaverde
- Institut de Biotecnologia i de Biomedicina (IBB), Carrer de la Vall Moronta s/n, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain.,Departament de Genètica i de Microbiologia, Carrer de la Vall Moronta s/n, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain.,CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Carrer de la Vall Moronta s/n, 08193 Cerdanyola del Vallès, Spain
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7
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A Spatial Control for Correct Timing of Gene Expression during the Escherichia coli Cell Cycle. Genes (Basel) 2016; 8:genes8010001. [PMID: 28025549 PMCID: PMC5294996 DOI: 10.3390/genes8010001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 12/09/2016] [Accepted: 12/15/2016] [Indexed: 01/14/2023] Open
Abstract
Temporal transcriptions of genes are achieved by different mechanisms such as dynamic interaction of activator and repressor proteins with promoters, and accumulation and/or degradation of key regulators as a function of cell cycle. We find that the TorR protein localizes to the old poles of the Escherichia coli cells, forming a functional focus. The TorR focus co-localizes with the nucleoid in a cell-cycle-dependent manner, and consequently regulates transcription of a number of genes. Formation of one TorR focus at the old poles of cells requires interaction with the MreB and DnaK proteins, and ATP, suggesting that TorR delivery requires cytoskeleton organization and ATP. Further, absence of the protein–protein interactions and ATP leads to loss in function of TorR as a transcription factor. We propose a mechanism for timing of cell-cycle-dependent gene transcription, where a transcription factor interacts with its target genes during a specific period of the cell cycle by limiting its own spatial distribution.
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Li G, Young KD. A new suite of tnaA mutants suggests that Escherichia coli tryptophanase is regulated by intracellular sequestration and by occlusion of its active site. BMC Microbiol 2015; 15:14. [PMID: 25650045 PMCID: PMC4323232 DOI: 10.1186/s12866-015-0346-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 01/13/2015] [Indexed: 11/17/2022] Open
Abstract
Background The Escherichia coli enzyme tryptophanase (TnaA) converts tryptophan to indole, which triggers physiological changes and regulates interactions between bacteria and their mammalian hosts. Tryptophanase production is induced by external tryptophan, but the activity of TnaA is also regulated by other, more poorly understood mechanisms. For example, the enzyme accumulates as a spherical inclusion (focus) at midcell or at one pole, but how or why this localization occurs is unknown. Results TnaA activity is low when the protein forms foci during mid-logarithmic growth but its activity increases as the protein becomes more diffuse, suggesting that foci may represent clusters of inactive (or less active) enzyme. To determine what protein characteristics might mediate these localization effects, we constructed 42 TnaA variants: 6 truncated forms and 36 missense mutants in which different combinations of 83 surface-exposed residues were converted to alanine. A truncated TnaA protein containing only domains D1 and D3 (D1D3) localized to the pole. Mutations affecting the D1D3-to-D1D3 interface did not affect polar localization of D1D3 but did delay assembly of wild type TnaA foci. In contrast, alterations to the D1D3-to-D2 domain interface produced diffuse localization of the D1D3 variant but did not affect the wild type protein. Altering several surface-exposed residues decreased TnaA activity, implying that tetramer assembly may depend on interactions involving these sites. Interestingly, changing any of three amino acids at the base of a loop near the catalytic pocket decreased TnaA activity and caused it to form elongated ovoid foci in vivo, indicating that the alterations affect focus formation and may regulate how frequently tryptophan reaches the active site. Conclusions The results suggest that TnaA activity is regulated by subcellular localization and by a loop-associated occlusion of its active site. Equally important, these new TnaA variants are immediately available to the research community and should be useful for investigating how tryptophanase is localized and assembled, how substrate accesses its active site, the functional role of acetylation, and other structural and functional questions. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0346-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gang Li
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205-7199, USA.
| | - Kevin D Young
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205-7199, USA.
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9
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DNA transport across the outer and inner membranes of naturally transformable Vibrio cholerae is spatially but not temporally coupled. mBio 2014; 5:mBio.01409-14. [PMID: 25139903 PMCID: PMC4147865 DOI: 10.1128/mbio.01409-14] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The physiological state of natural competence for transformation allows certain bacteria to take up free DNA from the environment and to recombine such newly acquired DNA into their chromosomes. However, even though conserved components that are required to undergo natural transformation have been identified in several naturally competent bacteria, our knowledge of the underlying mechanisms of the DNA uptake process remains very limited. To better understand these mechanisms, we investigated the competence-mediated DNA transport in the naturally transformable pathogen Vibrio cholerae. Previously, we used a cell biology-based approach to experimentally address an existing hypothesis, which suggested the competence protein ComEA plays a role in the DNA uptake process across the outer membrane of Gram-negative bacteria. Here, we extended this knowledge by investigating the dynamics of DNA translocation across both membranes. More precisely, we indirectly visualized the transfer of the external DNA from outside the cell into the periplasm followed by the shuttling of the DNA into the cytoplasm. Based on these data, we conclude that for V. cholerae, the DNA translocation across the outer and inner membranes is spatially but not temporally coupled. As a mode of horizontal gene transfer, natural competence for transformation has contributed substantially to the plasticity of genomes and to bacterial evolution. Natural competence is often a tightly regulated process and is induced by diverse environmental cues. This is in contrast to the mechanistic aspects of the DNA translocation event, which are most likely conserved among naturally transformable bacteria. However, the DNA uptake process is still not well understood. We therefore investigated how external DNA reaches the cytosol of the naturally transformable bacterium V. cholerae. More specifically, we provide evidence that the DNA translocation across the membranes is spatially but not temporally coupled. We hypothesize that this model also applies to other competent Gram-negative bacteria and that our study contributes to the general understanding of this important biological process.
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Van der Henst C, de Barsy M, Zorreguieta A, Letesson JJ, De Bolle X. The Brucella pathogens are polarized bacteria. Microbes Infect 2013; 15:998-1004. [PMID: 24141086 DOI: 10.1016/j.micinf.2013.10.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 10/01/2013] [Accepted: 10/03/2013] [Indexed: 11/30/2022]
Abstract
Brucella pathogens are responsible for brucellosis, a worldwide zoonosis. They are facultative intracellular pathogens characterized by their asymmetric division and their unipolar growth. This growth modality generates poles with specialized functions (through polar recruitment of polar adhesins or of cell cycle regulators) and progeny cells with potentially different fates.
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Affiliation(s)
- Charles Van der Henst
- Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 19, 1015 Lausanne, Switzerland
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11
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The histidine kinase PdhS controls cell cycle progression of the pathogenic alphaproteobacterium Brucella abortus. J Bacteriol 2012; 194:5305-14. [PMID: 22843843 DOI: 10.1128/jb.00699-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial differentiation is often associated with the asymmetric localization of regulatory proteins, such as histidine kinases. PdhS is an essential and polarly localized histidine kinase in the pathogenic alphaproteobacterium Brucella abortus. After cell division, PdhS is asymmetrically segregated between the two sibling cells, highlighting a differentiation event. However, the function(s) of PdhS in the B. abortus cell cycle remains unknown. We used an original approach, the pentapeptide scanning mutagenesis method, to generate a thermosensitive allele of pdhS. We report that a B. abortus strain carrying this pdhS allele displays growth arrest and an altered DivK-yellow fluorescent protein (YFP) polar localization at the restrictive temperature. Moreover, the production of a nonphosphorylatable PdhS protein or truncated PdhS proteins leads to dominant-negative effects by generating morphological defects consistent with the inhibition of cell division. In addition, we have used a domain mapping approach combined with yeast two-hybrid and fluorescence microscopy methods to better characterize the unusual PdhS sensory domain. We have identified a fragment of the PdhS sensory domain required for protein-protein interaction (amino acids [aa] 210 to 434), a fragment sufficient for polar localization (aa 1 to 434), and a fragment (aa 527 to 661) whose production in B. abortus correlates with the generation of cell shape alterations. The data support a model in which PdhS acts as an essential regulator of cell cycle progression in B. abortus and contribute to a better understanding of the differentiation program inherited by the two sibling cells.
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Kumar A, Tiwari S, Thavaselvam D, Sathyaseelan K, Prakash A, Barua A, Arora S, Kameswara Rao M. Optimization and efficient purification of recombinant Omp28 protein of Brucella melitensis using Triton X-100 and β-mercaptoethanol. Protein Expr Purif 2012; 83:226-32. [PMID: 22542588 DOI: 10.1016/j.pep.2012.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 03/30/2012] [Accepted: 04/02/2012] [Indexed: 10/28/2022]
Abstract
The high level expression of recombinant proteins in Escherichia coli often leads to the formation of inclusion bodies that contain most of the expressed protein held together by non-covalent forces. The inclusion bodies are usually solubilized using strong denaturing agents like urea and guanidium hydrochloride. In this study recombinant Omp28 (rOmp28) protein of Brucella melitensis was expressed in two different vector systems and further efficient purification of the protein was done by modification in buffers to improve the yield and purity. Different concentrations of Triton X-100 and β-mercaptoethanol were optimized for the solubilization of inclusion bodies. The lysis buffer with 8M urea alone was not sufficient to solubilize the inclusion bodies. It was found that the use of 1% Triton X-100 and 20mM β-mercaptoethanol in lysis and wash buffers used at different purification steps under denaturing conditions increased the yield of purified rOmp28 protein. The final yield of purified protein obtained with modified purification protocol under denaturing conditions was 151 and 90mg/l of the culture or 11.8 and 9.37mg/g of wet weight of cells in pQE30UA and pET28a(+) vector respectively. Thus modified purification protocol yielded more than threefold increase of protein in pQE30UA as compared with purification by conventional methods.
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Affiliation(s)
- Ashu Kumar
- Microbiology Division, Defence Research and Development Establishment, Jhansi Road, Gwalior 474002, India
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Li G, Young KD. Isolation and identification of new inner membrane-associated proteins that localize to cell poles inEscherichia coli. Mol Microbiol 2012; 84:276-95. [DOI: 10.1111/j.1365-2958.2012.08021.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Dotreppe D, Mullier C, Letesson JJ, De Bolle X. The alkylation response protein AidB is localized at the new poles and constriction sites in Brucella abortus. BMC Microbiol 2011; 11:257. [PMID: 22111948 PMCID: PMC3236019 DOI: 10.1186/1471-2180-11-257] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 11/23/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Brucella abortus is the etiological agent of a worldwide zoonosis called brucellosis. This alpha-proteobacterium is dividing asymmetrically, and PdhS, an essential histidine kinase, was reported to be an old pole marker. RESULTS We were interested to identify functions that could be recruited to bacterial poles. The Brucella ORFeome, a collection of cloned predicted coding sequences, was placed in fusion with yellow fluorescent protein (YFP) coding sequence and screened for polar localizations in B. abortus. We report that AidB-YFP was systematically localized to the new poles and at constrictions sites in B. abortus, either in culture or inside infected HeLa cells or RAW264.7 macrophages. AidB is an acyl-CoA dehydrogenase (ACAD) homolog, similar to E. coli AidB, an enzyme putatively involved in destroying alkylating agents. Accordingly, a B. abortus aidB mutant is more sensitive than the wild-type strain to the lethality induced by methanesulphonic acid ethyl ester (EMS). The exposure to EMS led to a very low frequency of constriction events, suggesting that cell cycle is blocked during alkylation damage. The localization of AidB-YFP at the new poles and at constriction sites seems to be specific for this ACAD homolog since two other ACAD homologs fused to YFP did not show specific localization. The overexpression of aidB, but not the two other ACAD coding sequences, leads to multiple morphological defects. CONCLUSIONS Data reported here suggest that AidB is a marker of new poles and constriction sites, that could be considered as sites of preparation of new poles in the sibling cells originating from cell division. The possible role of AidB in the generation or the function of new poles needs further investigation.
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Affiliation(s)
- Delphine Dotreppe
- URBM, University of Namur (FUNDP), 61 rue de Bruxelles, Namur, 5000, Belgium
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