RESUMO
Introduction: In human and experimentally induced asthma, a dysfunction of the intra-alveolar-surface active agent (surfactant) has been demonstrated. Type II alveolar epithelial cells (AEII) synthesize, secrete and recycle surfactant. Prior to secretion, intracellular surfactant is stored in specific secretory organelles of AEII. The lamellar bodies (Lb) represent its ultrastructural correlate. The aim of this study was to investigate whether disturbances of the intra-alveolar surfactant are accompanied by alterations in the intracellular surfactant.Material and Methods: Brown-Norway rats were sensitized twice with ovalbumin (OVA) and heat killed Bordetella pertussis bacilli. During airway challenge, an aerosol of 5% ovalbumin/saline solution (0.25 l/min) was nebulized. 24 h after airway challenge, lungs were fixed by vascular perfusion. AEII and their Lb were characterized stereologically by light and electron microscopy.Results: In both groups, AEII were structurally intact. The number of AEII per lung and their number-weighted mean volume did not differ (controls: 49 × 106, 393 µm3; asthmatics: 44 × 106, 390 µm3). A mean of 90 Lb in AEII of asthmatics and of 93 Lb in AEII of controls were evaluated. The Lb mean total volume was 59 µm in asthmatics and 68 µm in controls. Values of both parameters did not reach significance. Also, the size distribution and mean volume of Lb was not influenced by asthma induction, because the volume weighted mean volume of Lb (2.18 µm in asthmatics compared to 1.87 µm in controls) and the numerical weighted mean volume (0.96 µm in asthmatics and 0.75 µm in controls) were comparable in both groups.Conclusion: The obtained results suggest that asthma-induced surfactant dysfunction is not related to disturbances in the intracellular surfactant´s ultrastructural correlates.
Assuntos
Asma , Surfactantes Pulmonares , Humanos , Animais , Ratos , Tensoativos/farmacologia , Ovalbumina , Células Epiteliais Alveolares , Asma/induzido quimicamenteRESUMO
We have developed a system for producing a supramolecular scaffold that permeates the entire Escherichia coli cytoplasm. This cytoscaffold is constructed from a three-component system comprising a bacterial microcompartment shell protein and two complementary de novo coiled-coil peptides. We show that other proteins can be targeted to this intracellular filamentous arrangement. Specifically, the enzymes pyruvate decarboxylase and alcohol dehydrogenase have been directed to the filaments, leading to enhanced ethanol production in these engineered bacterial cells compared to those that do not produce the scaffold. This is consistent with improved metabolic efficiency through enzyme colocation. Finally, the shell-protein scaffold can be directed to the inner membrane of the cell, demonstrating how synthetic cellular organization can be coupled with spatial optimization through in-cell protein design. The cytoscaffold has potential in the development of next-generation cell factories, wherein it could be used to organize enzyme pathways and metabolite transporters to enhance metabolic flux.
Assuntos
Proteínas de Bactérias/metabolismo , Escherichia coli/metabolismo , Engenharia Metabólica/métodos , Álcool Desidrogenase/metabolismo , Bacillus/metabolismo , Proteínas de Bactérias/genética , Citoplasma/metabolismo , Escherichia coli/genética , Proteínas Luminescentes/metabolismo , Microscopia Confocal , Domínios Proteicos , Piruvato Descarboxilase/metabolismoRESUMO
Bacterial microcompartments (BMCs) are protein-bound prokaryotic organelles, discovered in cyanobacteria more than 60 years ago. Functionally similar to eukaryotic cellular organelles, BMCs compartment metabolic activities in the cytoplasm, foremost to increase local enzyme concentration and prevent toxic intermediates from damaging the cytosolic content. Advanced knowledge of the functional and structural properties of multiple types of BMCs, particularly over the last 10 years, have highlighted design principles of microcompartments. This has prompted new research into their potential to function as programmable synthetic nano-bioreactors and novel bio-materials with biotechnological and medical applications. Moreover, due to the involvement of microcompartments in bacterial pathogenesis and human health, BMCs have begun to gain attention as potential novel drug targets. This mini-review gives an overview of important synthetic biology developments in the bioengineering of BMCs and a perspective on future directions in the field.
Assuntos
Bactérias/metabolismo , Bioengenharia , Organelas/metabolismo , Redes e Vias MetabólicasRESUMO
Bacterial microcompartments enclose a biochemical pathway and reactive intermediate within a protein envelope formed by the shell proteins. Herein, the orientation of the propanediol-utilization (Pdu) microcompartment shell protein PduA in bacterial microcompartments and in synthetic nanotubes, and the orientation of PduB in synthetic nanotubes are revealed. When produced individually, PduA hexamers and PduB trimers, tessellate to form flat sheets in the crystal, or they can self-assemble to form synthetic protein nanotubes in solution. Modelling the orientation of PduA in the 20 nm nanotube so as to preserve the shape complementarity and key interactions seen in the crystal structure suggests that the concave surface of the PduA hexamer faces out. This orientation is confirmed experimentally in synthetic nanotubes and in the bacterial microcompartment produced in vivo. The PduB nanotubes described here have a larger diameter, 63 nm, with the concave surface of the trimer again facing out. The conserved concave surface out characteristic of these nano-structures reveals a generic assembly process that causes the interface between adjacent subunits to bend in a common direction that optimizes shape complementarity and minimizes steric clashes. This understanding underpins engineering strategies for the biotechnological application of protein nanotubes.
Assuntos
Proteínas de Bactérias/química , Nanotubos/química , Escherichia coli/metabolismo , Modelos Moleculares , Nanotubos/ultraestruturaRESUMO
Compartmentalization is an important process, since it allows the segregation of metabolic activities and, in the era of synthetic biology, represents an important tool by which defined microenvironments can be created for specific metabolic functions. Indeed, some bacteria make specialized proteinaceous metabolic compartments called bacterial microcompartments (BMCs) or metabolosomes. Here we demonstrate that the shell of the metabolosome (representing an empty BMC) can be produced within E. coli cells by the coordinated expression of genes encoding structural proteins. A plethora of diverse structures can be generated by changing the expression profile of these genes, including the formation of large axial filaments that interfere with septation. Fusing GFP to PduC, PduD, or PduV, none of which are shell proteins, allows regiospecific targeting of the reporter group to the empty BMC. Live cell imaging provides unexpected evidence of filament-associated BMC movement within the cell in the presence of PduV.
Assuntos
Bactérias/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Organelas/química , Organelas/metabolismo , Bactérias/genética , Bactérias/ultraestrutura , Proteínas de Bactérias/genética , Clonagem Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Escherichia coli/ultraestrutura , Genes Bacterianos , Organelas/genéticaRESUMO
Gammaproteobacteria are important gut microbes but only persist at low levels in the healthy gut. The ecology of Gammaproteobacteria in the gut environment is poorly understood. Here, we demonstrate that choline is an important growth substrate for representatives of Gammaproteobacteria. Using Proteus mirabilis as a model, we investigate the role of choline metabolism and demonstrate that the cutC gene, encoding a choline-trimethylamine lyase, is essential for choline degradation to trimethylamine by targeted mutagenesis of cutC and subsequent complementation experiments. Proteus mirabilis can rapidly utilize choline to enhance growth rate and cell yield in broth culture. Importantly, choline also enhances swarming-associated colony expansion of P. mirabilis under anaerobic conditions on a solid surface. Comparative transcriptomics demonstrated that choline not only induces choline-trimethylamine lyase but also genes encoding shell proteins for the formation of bacterial microcompartments. Subsequent analyses by transmission electron microscopy confirmed the presence of such novel microcompartments in cells cultivated in liquid broth and hyper-flagellated swarmer cells from solid medium. Together, our study reveals choline metabolism as an adaptation strategy for P. mirabilis and contributes to better understand the ecology of this bacterium in health and disease.
Assuntos
Colina/metabolismo , Proteus mirabilis/metabolismo , Anaerobiose , Liases/genética , Mutagênese , Proteus mirabilis/genética , Proteus mirabilis/crescimento & desenvolvimento , Proteus mirabilis/ultraestruturaRESUMO
Bacterial microcompartments (BMCs) enhance the breakdown of metabolites such as 1,2-propanediol (1,2-PD) to propionic acid. The encapsulation of proteins within the BMC is mediated by the presence of targeting sequences. In an attempt to redesign the Pdu BMC into a 1,2-PD synthesising factory using glycerol as the starting material we added N-terminal targeting peptides to glycerol dehydrogenase, dihydroxyacetone kinase, methylglyoxal synthase and 1,2-propanediol oxidoreductase to allow their inclusion into an empty BMC. 1,2-PD producing strains containing the fused enzymes exhibit a 245% increase in product formation in comparison to un-tagged enzymes, irrespective of the presence of BMCs. Tagging of enzymes with targeting peptides results in the formation of dense protein aggregates within the cell that are shown by immuno-labelling to contain the vast majority of tagged proteins. It can therefore be concluded that these protein inclusions are metabolically active and facilitate the significant increase in product formation.
Assuntos
Vias Biossintéticas/fisiologia , Compartimento Celular/fisiologia , Escherichia coli/fisiologia , Melhoramento Genético/métodos , Engenharia Metabólica/métodos , Complexos Multienzimáticos/genética , Células Artificiais/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Redes e Vias Metabólicas/fisiologia , Complexos Multienzimáticos/metabolismo , Propilenoglicol/isolamento & purificação , Propilenoglicol/metabolismo , Proteínas/genética , Proteínas/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismoRESUMO
It has been known for the past 20 years that two pathways exist in nature for the de novo biosynthesis of the coenzyme form of vitamin B12, adenosylcobalamin, representing aerobic and anaerobic routes. In contrast to the aerobic pathway, the anaerobic route has remained enigmatic because many of its intermediates have proven technically challenging to isolate, because of their inherent instability. However, by studying the anaerobic cobalamin biosynthetic pathway in Bacillus megaterium and using homologously overproduced enzymes, it has been possible to isolate all of the intermediates between uroporphyrinogen III and cobyrinic acid. Consequently, it has been possible to detail the activities of purified cobinamide biosynthesis (Cbi) proteins CbiF, CbiG, CbiD, CbiJ, CbiET, and CbiC, as well as show the direct in vitro conversion of 5-aminolevulinic acid into cobyrinic acid using a mixture of 14 purified enzymes. This approach has resulted in the isolation of the long sought intermediates, cobalt-precorrin-6A and -6B and cobalt-precorrin-8. EPR, in particular, has proven an effective technique in following these transformations with the cobalt(II) paramagnetic electron in the dyz orbital, rather than the typical dz2. This result has allowed us to speculate that the metal ion plays an unexpected role in assisting the interconversion of pathway intermediates. By determining a function for all of the pathway enzymes, we complete the tool set for cobalamin biosynthesis and pave the way for not only enhancing cobalamin production, but also design of cobalamin derivatives through their combinatorial use and modification.
Assuntos
Vitamina B 12/biossíntese , Anaerobiose , Bacillus megaterium/genética , Bacillus megaterium/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Vias Biossintéticas , Corrinoides/química , Corrinoides/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Modelos Químicos , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Vitamina B 12/análogos & derivados , Vitamina B 12/químicaRESUMO
B12 is unique among the vitamins as it is biosynthesized only by certain prokaryotes. The complexity of its synthesis relates to its distinctive cobalt corrin structure, which is essential for B12 biochemistry and renders coenzymeâ B12 (AdoCbl) so intriguingly suitable for enzymatic radical reactions. However, why is cobalt so fit for its role in B12 -dependent enzymes? To address this question, we considered the substitution of cobalt in AdoCbl with rhodium to generate the rhodium analogue 5'-deoxy-5'-adenosylrhodibalamin (AdoRbl). AdoRbl was prepared by deâ novo total synthesis involving both biological and chemical steps. AdoRbl was found to be inactive inâ vivo in microbial bioassays for methionine synthase and acted as an inâ vitro inhibitor of an AdoCbl-dependent diol dehydratase. Solution NMR studies of AdoRbl revealed a structure similar to that of AdoCbl. However, the crystal structure of AdoRbl revealed a conspicuously better fit of the corrin ligand for Rh(III) than for Co(III) , challenging the current views concerning the evolution of corrins.
Assuntos
Cobamidas/farmacologia , Corrinoides/síntese química , Corrinoides/farmacologia , Desidrogenase do Álcool de Açúcar/antagonistas & inibidores , Citrobacter freundii/enzimologia , Cobamidas/química , Corrinoides/química , Cinética , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Conformação Molecular , Relação Estrutura-Atividade , Desidrogenase do Álcool de Açúcar/metabolismoRESUMO
Bacterial microcompartments are large proteinaceous assemblies that are found in the cytoplasm of some bacteria. These structures consist of proteins constituting a shell that houses a number of enzymes involved in specific metabolic processes. The 1,2-propanediol-utilizing microcompartment is assembled from seven different types of shell proteins, one of which is PduA. It is one of the more abundant components of the shell and intriguingly can form nanotubule-like structures when expressed on its own in the cytoplasm of Escherichia coli. We propose a model that accounts for the size and appearance of these PduA structures and underpin our model using a combinatorial approach. Making strategic mutations at Lys-26, Val-51, and Arg-79, we targeted residues predicted to be important for PduA assembly. We present the effect of the amino acid residue substitution on the phenotype of the PduA higher order assemblies (transmission electron microscopy) and the crystal structure of the K26D mutant with one glycerol molecule bound to the central pore. Our results support the view that the hexamer-hexamer interactions seen in PduA crystals persist in the cytoplasmic structures and reveal the profound influence of the two key amino acids, Lys-26 and Arg-79, on tiling, not only in the crystal lattice but also in the bacterial cytoplasm. Understanding and controlling PduA assemblies is valuable in order to inform manipulation for synthetic biology and biotechnological applications.
Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Citrobacter freundii/genética , Citrobacter freundii/metabolismo , Cristalografia por Raios X , Escherichia coli/genética , Escherichia coli/metabolismo , Escherichia coli/ultraestrutura , Corpos de Inclusão/química , Corpos de Inclusão/ultraestrutura , Microscopia Eletrônica de Transmissão , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Domínios e Motivos de Interação entre Proteínas , Multimerização Proteica , Estrutura Quaternária de Proteína , Subunidades Proteicas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , Eletricidade EstáticaRESUMO
Recombinant adeno-associated viruses (rAAVs) have emerged as important tools for gene therapy and, more recently, vaccine development. Nonetheless, manufacturing can be costly and time-consuming, emphasizing the importance of alternative production platforms. We investigate the potential of E. coli-based cell-free protein synthesis (CFPS) to produce recombinant AAV5 virus-like particles (VLPs). AAV5 virus protein 3 (VP3) constructs, both with and without Strep-tag II, were expressed with CFPS. Lower reaction temperatures resulted in increased solubility, with the untagged variant containing nearly 90% more soluble VLP VP3 protein at 18 °C than at 37 °C. Affinity chromatography of N-terminally Strep(II)-tagged VP3 enabled successful isolation with minimal processing. DLS and TEM confirmed the presence of â¼20 nm particles. Furthermore, the N-terminally tagged AAV5 VP3 VLPs were biologically active, successfully internalizing into HeLa cells. This study describes an innovative approach to AAV VLP production using E. coli-based CFPS, demonstrating its potential for rapid and biologically active AAV VLP synthesis.
RESUMO
Protein compartments offer definitive structures with a large potential design space that are of particular interest for green chemistry and therapeutic applications. One family of protein compartments, encapsulins, are simple prokaryotic nanocompartments that self-assemble from a single monomer into selectively permeable cages of between 18 and 42 nm. Over the past decade, encapsulins have been developed for a diverse application portfolio utilizing their defined cargo loading mechanisms and repetitive surface display. Although it has been demonstrated that encapsulation of non-native cargo proteins provides protection from protease activity, the thermal effects arising from enclosing cargo within encapsulins remain poorly understood. This study aimed to establish a methodology for loading a reporter protein into thermostable encapsulins to determine the resulting stability change of the cargo. Building on previous in vitro reassembly studies, we first investigated the effectiveness of in vitro reassembly and cargo-loading of two size classes of encapsulins Thermotoga maritima T = 1 and Myxococcus xanthus T = 3, using superfolder Green Fluorescent Protein. We show that the empty T. maritima capsid reassembles with higher yield than the M. xanthus capsid and that in vitro loading promotes the formation of the M. xanthus T = 3 capsid form over the T = 1 form, while overloading with cargo results in malformed T. maritima T = 1 encapsulins. For the stability study, a Förster resonance energy transfer (FRET)-probed industrially relevant enzyme cargo, transketolase, was then loaded into the T. maritima encapsulin. Our results show that site-specific orthogonal FRET labels can reveal changes in thermal unfolding of encapsulated cargo, suggesting that in vitro loading of transketolase into the T. maritima T = 1 encapsulin shell increases the thermal stability of the enzyme. This work supports the move toward fully harnessing structural, spatial, and functional control of in vitro assembled encapsulins with applications in cargo stabilization.
Assuntos
Estabilidade Enzimática , Tamanho da Partícula , Thermotoga maritima , Transcetolase , Transcetolase/metabolismo , Transcetolase/química , Thermotoga maritima/enzimologia , Teste de Materiais , Materiais Biocompatíveis/químicaRESUMO
Porcine circovirus type 2d (PCV2d) is becoming the predominant PCV genotype and considerably affects the global pig industry. Nevertheless, currently, no commercial PCV2d vaccine is available. Preventing and controlling the disease caused by PCV2d is therefore based on other genotype-based vaccines. However, their production platforms are laborious, limited in expression level, and relatively expensive for veterinary applications. To address these challenges, we have developed a simple and cost-efficient platform for a novel PCV2d vaccine production process, using fed-batch E. coli fermentation followed by cell disruption and filtration, and a single purification step via cation exchange chromatography. The process was developed at bench scale and then pilot scale, where the PCV2d subunit protein yield was approximately 0.93 g/L fermentation volume in a short production time. Moreover, we have successfully implemented this production process at two different sites, in Southeast Asia and Europe. This demonstrates transferability and the high potential for successful industrial production.
RESUMO
Cyanobacteria offer great potential as alternative biotechnological hosts due to their photoautotrophic capacities. However, in comparison to established heterotrophic hosts, several key aspects, such as product titers, are still lagging behind. Nanobiotechnology is an emerging field with great potential to improve existing hosts, but so far, it has barely been explored in microbial photosynthetic systems. Here, we report the establishment of large proteinaceous nanofilaments in the unicellular model cyanobacterium Synechocystis sp. PCC 6803 and the fast-growing cyanobacterial strain Synechococcus elongatus UTEX 2973. Transmission electron microscopy and electron tomography demonstrated that expression of pduA*, encoding a modified bacterial microcompartment shell protein, led to the generation of bundles of longitudinally aligned nanofilaments in S. elongatus UTEX 2973 and shorter filamentous structures in Synechocystis sp. PCC 6803. Comparative proteomics showed that PduA* was at least 50 times more abundant than the second most abundant protein in the cell and that nanofilament assembly had only a minor impact on cellular metabolism. Finally, as a proof-of-concept for co-localization with the filaments, we targeted a fluorescent reporter protein, mCitrine, to PduA* by fusion with an encapsulation peptide that natively interacts with PduA. The establishment of nanofilaments in cyanobacterial cells is an important step toward cellular organization of heterologous pathways and the establishment of cyanobacteria as next-generation hosts.
Assuntos
Synechocystis , Synechocystis/metabolismo , Fotossíntese , Transporte Proteico , Proteínas de Bactérias/metabolismoRESUMO
Perinatal exposure to alcohol (PEA) induces general developmental and specific neuropsychiatric disturbances accompanied by disturbed synaptic plasticity. Here we studied the long-term behavioral consequences of PEA and investigated glutamate transmission-related genes in a longitudinal fashion. After delivery, female Wistar rats and their pups were exposed to ethanol until postnatal day (PD)8 in vapor chambers. At the age of 5 months, the animals were behaviorally characterized. At both PD8 and after the behavioral testing we examined the expression of the vesicular glutamate transporter 1 and excitatory amino acid transporter (EAAT)1-4, as well as the N-methyl-D-aspartate receptor subunits (NR)1 and 2A-D, and in parallel receptor binding using (3) H-dizocilpine maleate receptor autoradiography. We found highly significant reductions of body weight and length following PEA in pups at PD8. These alterations disappeared in adulthood, when no changes of motor activity and only subtle differences of anxiety-related behavior were observed. It also did not affect T-maze learning, but had a pronounced effect on hippocampus-dependent spatial learning (Morris water maze testing). This specific learning deficit was accompanied by a dysregulation in hippocampal gene expression (significant induction of vesicular glutamate transporter 1, EAAT1, EAAT3, NR2A, 2B, 2C and 2D). Most of the examined genes turned out to be dysregulated to a higher degree at the age of 5 months. We therefore conclude that perinatal ethanol toxicity alters the plasticity of neurodevelopment and the regulation of glutamatergic gene expression, which may result in specific hippocampus-dependent learning deficits in adulthood.
Assuntos
Etanol/farmacologia , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Ácido Glutâmico/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/fisiologia , Aprendizagem em Labirinto/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Animais , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Etanol/sangue , Transportador 1 de Aminoácido Excitatório/genética , Transportador 1 de Aminoácido Excitatório/metabolismo , Transportador 3 de Aminoácido Excitatório/genética , Transportador 3 de Aminoácido Excitatório/metabolismo , Feminino , Humanos , Deficiências da Aprendizagem/induzido quimicamente , Masculino , Aprendizagem em Labirinto/fisiologia , Testes Neuropsicológicos , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , Ratos , Ratos Wistar , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismo , Transmissão Sináptica/fisiologia , Proteína Vesicular 1 de Transporte de Glutamato/genética , Proteína Vesicular 1 de Transporte de Glutamato/metabolismoRESUMO
Tandem-core hepatitis B core antigen (HBcAg) virus-like particles (VLPs), in which two HBcAg monomers are joined together by a peptide linker, can be used to display two different antigens on the VLP surface. We produced universal influenza vaccine candidates that use this scaffold in an Escherichia coli-based cell-free protein synthesis (CFPS) platform. We then used the CFPS system to rapidly test modifications to the arginine-rich region typically found in wild-type HBcAg, the peptide linkers around the influenza antigen inserts, and the plasmid vector backbone to improve titer and quality. Using a minimal plasmid vector backbone designed for CFPS improved titers by at least 1.4-fold over the original constructs. When the linker lengths for the influenza inserts were more consistent in length and a greater variety of codons for glycine and serine were utilized, titers were further increased to over 70 µg/mL (4.0-fold greater than the original construct) and the presence of lower molecular weight product-related impurities was significantly reduced, although improvements in particle assembly were not seen. Furthermore, any constructs with the C-terminal arginine-rich region removed resulted in asymmetric particles of poor quality. This demonstrates the potential for CFPS as a screening platform for VLPs.
RESUMO
Cell-free protein synthesis (CFPS) is an established method for rapid recombinant protein production. Advantages like short synthesis times and an open reaction environment make CFPS a desirable platform for new and difficult-to-express products. Most recently, interest has grown in using the technology to make larger amounts of material. This has been driven through a variety of reasons from making site specific antibody drug conjugates, to emergency response, to the safe manufacture of toxic biological products. We therefore need robust methods to determine the appropriate reaction conditions for product expression in CFPS. Here we propose a process development strategy for Escherichia coli lysate-based CFPS reactions that can be completed in as little as 48 hr. We observed the most dramatic increases in titer were due to the E. coli strain for the cell extract. Therefore, we recommend identifying a high-producing cell extract for the product of interest as a first step. Next, we manipulated the plasmid concentration, amount of extract, temperature, concentrated reaction mix pH levels, and length of reaction. The influence of these process parameters on titer was evaluated through multivariate data analysis. The process parameters with the highest impact on titer were subsequently included in a design of experiments to determine the conditions that increased titer the most in the design space. This proposed process development strategy resulted in superfolder green fluorescent protein titers of 0.686 g/L, a 38% improvement on the standard operating conditions, and hepatitis B core antigen titers of 0.386 g/L, a 190% improvement.
Assuntos
Sistema Livre de Células/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Plasmídeos/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Proteínas de Escherichia coli/genética , Plasmídeos/genética , Biossíntese de Proteínas , Proteínas Recombinantes de Fusão/genéticaRESUMO
The development of Drug Delivery Systems (DDS) has led to increasingly efficient therapies for the treatment and detection of various diseases. DDS use a range of nanoscale delivery platforms produced from polymeric of inorganic materials, such as micelles, and metal and polymeric nanoparticles, but their variant chemical composition make alterations to their size, shape, or structures inherently complex. Genetically encoded protein nanocages are highly promising DDS candidates because of their modular composition, ease of recombinant production in a range of hosts, control over assembly and loading of cargo molecules and biodegradability. One example of naturally occurring nanocompartments are encapsulins, recently discovered bacterial organelles that have been shown to be reprogrammable as nanobioreactors and vaccine candidates. Here we report the design and application of a targeted DDS platform based on the Thermotoga maritima encapsulin reprogrammed to display an antibody mimic protein called Designed Ankyrin repeat protein (DARPin) on the outer surface and to encapsulate a cytotoxic payload. The DARPin9.29 chosen in this study specifically binds to human epidermal growth factor receptor 2 (HER2) on breast cancer cells, as demonstrated in an in vitro cell culture model. The encapsulin-based DDS is assembled in one step in vivo by co-expressing the encapsulin-DARPin9.29 fusion protein with an engineered flavin-binding protein mini-singlet oxygen generator (MiniSOG), from a single plasmid in Escherichia coli. Purified encapsulin-DARPin_miniSOG nanocompartments bind specifically to HER2 positive breast cancer cells and trigger apoptosis, indicating that the system is functional and specific. The DDS is modular and has the potential to form the basis of a multi-receptor targeted system by utilising the DARPin screening libraries, allowing use of new DARPins of known specificities, and through the proven flexibility of the encapsulin cargo loading mechanism, allowing selection of cargo proteins of choice.
RESUMO
Protein aggregation is a major pathological hallmark of many neurodegenerative disorders including polyglutamine diseases. Aggregation of the mutated form of the disease protein ataxin-3 into neuronal nuclear inclusions is well described in the polyglutamine disorder spinocerebellar ataxia type 3 (SCA3 or Machado-Joseph disease), although these inclusions are not thought to be directly pathogenic. Neuropil aggregates have not yet been described in SCA3. We performed a systematic immunohistochemical study of serial thick sections through brains of seven clinically diagnosed and genetically confirmed SCA3 patients. Using antibodies against ataxin-3, p62, ubiquitin, the polyglutamine marker 1C2 as well as TDP-43, we analyzed neuronal localization, composition and distribution of aggregates within SCA3 brains. The analysis revealed widespread axonal aggregates in fiber tracts known to undergo neurodegeneration in SCA3. Similar to neuronal nuclear inclusions, the axonal aggregates were ubiquitinated and immunopositive for the proteasome and autophagy associated shuttle protein p62, indicating involvement of neuronal protein quality control mechanisms. Rare TDP-43 positive axonal inclusions were also observed. Based on the correlation between affected fiber tracts and degenerating neuronal nuclei, we hypothesize that these novel axonal inclusions may be detrimental to axonal transport mechanisms and thereby contribute to degeneration of nerve cells in SCA3.
Assuntos
Axônios/ultraestrutura , Encéfalo/patologia , Corpos de Inclusão Intranuclear/metabolismo , Corpos de Inclusão Intranuclear/patologia , Doença de Machado-Joseph/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Axônios/patologia , Encéfalo/metabolismo , Feminino , Humanos , Doença de Machado-Joseph/genética , Masculino , Pessoa de Meia-Idade , Proteínas do Tecido Nervoso/metabolismo , Peptídeos/genética , Triptofano Hidroxilase/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Proteínas tau/metabolismoRESUMO
It has been suggested that ethanol metabolism in the strict anaerobe Clostridium kluyveri occurs within a metabolosome, a subcellular proteinaceous bacterial microcompartment. Two bacterial microcompartment shell proteins [EtuA (ethanol utilization shell protein A) and EtuB] are found encoded on the genome clustered with the genes for ethanol utilization. The function of the bacterial microcompartment is to facilitate fermentation by sequestering the enzymes, substrates and intermediates. Recent structural studies of bacterial microcompartment proteins have revealed both hexamers and pentamers that assemble to generate the pseudo-icosahedral bacterial microcompartment shell. Some of these shell proteins have pores on their symmetry axes. Here we report the structure of the trimeric bacterial microcompartment protein EtuB, which has a tandem structural repeat within the subunit and pseudo-hexagonal symmetry. The pores in the EtuB trimer are within the subunits rather than between symmetry related subunits. We suggest that the evolutionary advantage of this is that it releases the pore from the rotational symmetry constraint allowing more precise control of the fluxes of asymmetric molecules, such as ethanol, across the pore. We also model EtuA and demonstrate that the two proteins have the potential to interact to generate the casing for a metabolosome.