RESUMEN
Mass vaccination compaigns against viral diseases, both human and anim al, depend on the availability of cheap viral antigens. The eukaryote Dictyostelium discoideum has simple growth requirements and rapid growth rates and forms stable cell lines. These features, together with the possibility of secreting recombinant (glyco)proteins into a defined buffer, make the D. discoideum expression system an attractive option for producing economical recombinant subunit vaccines.
Asunto(s)
Antígenos Virales , Proteínas de la Cápside , Dictyostelium/genética , Vacunas Sintéticas/genética , Vacunas Virales/genética , Animales , Cápside/biosíntesis , Cápside/genética , Dictyostelium/crecimiento & desarrollo , Humanos , Rotavirus/genética , Vacunas Sintéticas/biosíntesis , Vacunas Virales/biosíntesisRESUMEN
Dictyostelium discoideum is a well known amoeboid organism, with unicellular and multicellular life-cycle stages, that is used for studying cell and developmental biology. With advances in gene-disruption technology and transformation of this organism, many homologous proteins have been expressed either to complement defective proteins or to study basic cell biology. Now, D. discoideum is being used to express heterologous proteins that are difficult to study in other systems, and its unique cell biology is being exploited to facilitate a wide range of protein modifications. In the past year, substantial progress has been made in expressing correctly folded forms of malarial circumsporozoite antigen and rotavirus surface glycoprotein VP7. Exciting developments have also been made in expressing human muscarinic receptors.
Asunto(s)
Dictyostelium/metabolismo , Glicoproteínas/biosíntesis , Proteínas Recombinantes/biosíntesis , Animales , Ingeniería GenéticaRESUMEN
A mouse monoclonal antibody (H318) with specificity for an antigenic determinant in the C gamma 2 domain of human IgG, which was produced following immunisation with purified syncytiotrophoblast plasma membranes, has been shown to stain strongly human syncytiotrophoblast in immunofluorescence on cryostat section of term placental villous tissue. The staining was more pronounced with this antibody than with other monoclonal antibodies to the C gamma 2 domain of human IgG produced following the same immunisation or immunisation with isolated IgG. It appears that the H318 antibody may recognise an antigenic determinant which is enhanced on IgG that is associated with syncytiotrophoblast, possibly resultant from its interaction with IgG-binding structures.
Asunto(s)
Trabajo de Parto , Placenta/inmunología , Trofoblastos/inmunología , Animales , Anticuerpos Monoclonales/inmunología , Especificidad de Anticuerpos , Sitios de Unión de Anticuerpos , Precipitación Química , Epítopos , Femenino , Técnica del Anticuerpo Fluorescente , Humanos , Ratones , Ratones Endogámicos , EmbarazoRESUMEN
Dictyostelium discoideum is a newly developed eukaryotic expression system which is an alternative to tissue cultures for the production of recombinant proteins requiring eukaryotic folding and post-translational modifications. The homologous glycoprotein PsA (prespore specific antigen) is a glycosyl phosphatidylinositol (GPI) anchored membrane protein from D. discoideum. A truncated form of PsA has been expressed in D. discoideum and secreted into a peptone based broth at levels of 10 mg per 1 growth medium. A simple purification protocol for recombinant PsA (rPsA) involved three steps: the concentration of the culture supernatant by ammonium sulfate precipitation, Mono Q anion-exchange chromatography, followed by size exclusion chromatography on Superdex 75. 20 mg of rPsA was purified to 98% purity from 37.1 culture supernatant. Purified rPsA was characterised. The molecular mass of the purified rPsA is 15.6 kDa, which suggests that the molecule is secreted as a monomer and contains 12% (w/w) carbohydrate. The protein sequence of rPsA proved identical to that of the predicted DNA construct. Although the recombinant form of PsA is expressed at a different developmental stage from the native molecule, the same Thr residues that are O-glycosylated in the authentic molecule are glycosylated in the recombinant protein.
Asunto(s)
Antígenos de Protozoos , Antígenos de Superficie/biosíntesis , Dictyostelium/metabolismo , Proteínas Fúngicas/biosíntesis , Glicoproteínas de Membrana/biosíntesis , Proteínas Protozoarias , Proteínas Recombinantes/biosíntesis , Secuencia de Aminoácidos , Animales , Antígenos de Superficie/química , Antígenos de Superficie/aislamiento & purificación , Secuencia de Bases , Western Blotting , Cromatografía en Gel , Cromatografía por Intercambio Iónico , Clonación Molecular , Cartilla de ADN , Dictyostelium/genética , Electroforesis en Gel de Poliacrilamida , Proteínas Fúngicas/química , Proteínas Fúngicas/aislamiento & purificación , Vectores Genéticos , Glicosilfosfatidilinositoles/metabolismo , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/aislamiento & purificación , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , Fragmentos de Péptidos/aislamiento & purificación , Plásmidos , Reacción en Cadena de la Polimerasa , Pliegue de Proteína , Procesamiento Proteico-Postraduccional , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , Mapeo RestrictivoRESUMEN
Large-scale purification of a Dictyostelium discoideum cell surface glycoprotein, which is anchored in the membrane via a glycosylphosphatidylinositol (GPI) moiety, is described. The purification protocol involved four steps: separation of crude cell membranes by low-speed centrifugation, delipidization of these membranes using acetone, extraction of the membrane proteins using the detergent Octyl beta-D-thioglucopyranoside (OTP), and purification of a specific membrane protein by monoclonal antibody immunoaffinity chromatography. The protein purified, PsA (prespore-specific antigen), is a developmentally regulated membrane glycoprotein found on a subset of cells from the cellular slime mould, D. discoideum. The protocol provides an efficient, economical, and technically simple way to purify GPI proteins in sufficient quantities for structural and functional studies. PsA was recovered at a yield of about 60%; with a purity of 97%, the extraction of 1 x 10(10) cells (1.1 g dry weight) yielded about 0.5 mg PsA glycoprotein. Techniques are described for growing kilogram quantities of D. discoideum cells in stainless steel trays at little cost. D. discoideum has considerable potential as a novel expression system for the production of foreign membrane-associated proteins. The purification strategy provides a means of purifying other GPI proteins, including those produced by protein engineering techniques.
Asunto(s)
Dictyostelium/análisis , Proteínas Fúngicas/aislamiento & purificación , Glucolípidos/fisiología , Glicoproteínas de Membrana/aislamiento & purificación , Fosfatidilinositoles/fisiología , Anticuerpos Monoclonales , Fraccionamiento Celular , Membrana Celular/química , Cromatografía de Afinidad , Detergentes , Dictyostelium/crecimiento & desarrollo , Electroforesis en Gel de Poliacrilamida , Proteínas Fúngicas/química , Glicosilfosfatidilinositoles , Inmunoensayo , Glicoproteínas de Membrana/química , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/aislamiento & purificación , TioglucósidosRESUMEN
We have expressed useful amounts of three recombinant proteins in a new eukaryotic host/vector system. The cellular slime mold Dictyostelium discoideum efficiently secreted two recombinant products, a soluble form of the normally cell surface associated D. discoideum glycoprotein (PsA) and the heterologous protein glutathione-S-transferase (GST) from Schistosoma japonicum, while the enzyme beta-glucuronidase (GUS) from Escherichia coli was cell associated. Up to 20mg/l of recombinant PsA and 1mg/l of GST were obtained after purification from a standard, peptone based growth medium. The secretion signal peptide was correctly cleaved from the recombinant GST- and PsA-proteins and the expression of recombinant PsA was shown to be stable for at least one hundred generations in the absence of selection.
Asunto(s)
Proteínas Bacterianas/biosíntesis , Clonación Molecular/métodos , Dictyostelium , Glutatión Transferasa/biosíntesis , Proteínas del Complejo del Centro de Reacción Fotosintética/biosíntesis , Complejo de Proteína del Fotosistema I , Proteínas Recombinantes/biosíntesis , Secuencia de Aminoácidos , Animales , Proteínas Bacterianas/genética , Proteínas Bacterianas/aislamiento & purificación , Secuencia de Bases , Western Blotting , Codón/genética , Cartilla de ADN , Vectores Genéticos , Glucuronidasa/biosíntesis , Glucuronidasa/genética , Glucuronidasa/aislamiento & purificación , Glutatión Transferasa/genética , Glutatión Transferasa/aislamiento & purificación , Datos de Secuencia Molecular , Proteínas del Complejo del Centro de Reacción Fotosintética/genética , Proteínas del Complejo del Centro de Reacción Fotosintética/aislamiento & purificación , Plásmidos , Reacción en Cadena de la Polimerasa , Señales de Clasificación de Proteína/biosíntesis , Señales de Clasificación de Proteína/metabolismo , Proteínas Recombinantes de Fusión/biosíntesis , Proteínas Recombinantes/aislamiento & purificación , Mapeo Restrictivo , Schistosoma japonicum/enzimología , Schistosoma japonicum/genética , Homología de Secuencia de AminoácidoAsunto(s)
Citocromos/aislamiento & purificación , Microsomas Hepáticos/enzimología , Animales , Anticuerpos Monoclonales/inmunología , Precipitación Química , Citocromo P-450 CYP1A2 , Sistema Enzimático del Citocromo P-450/aislamiento & purificación , Citocromos/inmunología , Masculino , Ratones , Ratones Endogámicos BALB C , ConejosAsunto(s)
Dictyostelium , Glicoproteínas/biosíntesis , Lectinas , Proteínas Protozoarias , Proteínas Recombinantes/biosíntesis , Actinas/biosíntesis , Actinas/genética , Animales , Antígenos de Superficie/biosíntesis , Discoidinas , Proteínas Fúngicas/biosíntesis , Proteínas Fúngicas/genética , Expresión Génica , Ingeniería Genética/métodos , Vectores Genéticos , Glicosilación , Humanos , Regiones Promotoras Genéticas , Receptor Muscarínico M2 , Receptores Muscarínicos/biosíntesisRESUMEN
Ddp2 is a 5.8-kb, high-copy-number, nuclear plasmid found in the eukaryote Dictyostelium discoideum. We have identified two functional domains, a large open reading frame (Rep gene) and a 626-bp fragment containing an origin of replication (ori). The ori, when cloned into a shuttle vector, confers stable extrachromosomal replication in D. discoideum, provided that the Rep gene, which acts in trans, is integrated into the host genome. Ddp2 carries a 501-bp imperfect inverted repeat, and part of the ori overlaps with one of these repeats. The ori sequence contains two direct repeats of 49 bp comprising two 10-bp "TGTCATGACA" palindromes separated by a poly(T.A) sequence. Deletion of either 49-bp repeat abolished extrachromosomal replication.
Asunto(s)
Núcleo Celular/fisiología , Replicación del ADN , Dictyostelium/genética , Plásmidos , Secuencia de Bases , Cromosomas Fúngicos , Clonación Molecular , ADN de Hongos/genética , ADN de Hongos/aislamiento & purificación , Vectores Genéticos , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Mapeo Restrictivo , Transformación GenéticaRESUMEN
The complete nucleotide sequence of the plasmid Ddp2 found in the nucleus of the simple eukaryote Dictyostelium discoideum is reported. This 5852-bp plasmid contains a 2661-bp open reading frame (ORF), named the "Rep gene," and 501-bp imperfect inverted repeats. A 1762-bp section of Ddp2, which includes one of the 501-bp repeat sequences, could be deleted without abolishing extrachromosomal replication. Deletion of the second 501-bp repeat, or interruption of the Rep gene, removed the ability to replicate extrachromosomally. We suggest that Ddp2 encodes a protein, "REP," that positively regulates replication initiation, a regulatory mechanism different from that of the yeast 2 mu plasmid which also possesses inverted repeat sequences. Ddp2 has a structure similar to that of plasmid pDG1, found in an unidentified isolate of Dictyostelium, with a similar sized ORF and inverted repeats. A common evolutionary origin is suggested by considerable sequence homology between the ORFs of pDG1 and Ddp2.
Asunto(s)
Núcleo Celular/fisiología , Dictyostelium/genética , Plásmidos , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , Replicación del ADN , Escherichia coli/genética , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Secuencias Repetitivas de Ácidos Nucleicos , Mapeo Restrictivo , Homología de Secuencia de Ácido Nucleico , Transformación GenéticaRESUMEN
Complex I, a key component of the mitochondrial electron transport system, is thought to have evolved from at least two separate enzyme systems prior to the evolution of mitochondria from a bacterial endosymbiont, but the genes for one of the enzyme systems are thought to have subsequently been transferred to the nuclear DNA. We demonstrated that the cellular slime mold Dictyostelium discoideum retains the ancestral characteristic of having mitochondria encoding at least one gene (80-kDa subunit) that is nuclear encoded in other eukaryotes. This is consistent with the cellular slime molds of the family Dictyosteliaceae having diverged from other eukaryotes at an early stage prior to the loss of the mitochondrial gene in the lineage giving rise to plants and animals. The D. discoideum mitochondrially encoded 80-kDa subunit of complex I exhibits a twofold-higher mutation rate compared with the homologous chromosomal gene in other eukaryotes, making it the most divergent eukaryotic form of this protein.
Asunto(s)
ADN Mitocondrial/genética , Dictyostelium/genética , NADH NADPH Oxidorreductasas/genética , Animales , Secuencia de Bases , Evolución Biológica , Dictyostelium/enzimología , Complejo I de Transporte de Electrón , Datos de Secuencia Molecular , Paracoccus denitrificans/enzimología , Paracoccus denitrificans/genética , Filogenia , Alineación de SecuenciaRESUMEN
AIMS: Pseudomonas spp. are considered the most important milk spoilage organisms. Here we describe development of a fluorescence in situ hybridization (FISH) probe specific for detection and enumeration of Pseudomonas spp. in milk. METHODS AND RESULTS: 16S rRNA sequences were analysed to develop specific oligonucleotide probe for the genus Pseudomonas. Twenty different Pseudomonas spp. and 23 bacterial species from genera other than Pseudomonas (as negative controls) were tested. All tested Pseudomonas spp. yielded a positive FISH reaction, whereas negative controls showed no FISH reaction except for Burkholderia cepacia that showed a relatively weak FISH reaction. The FISH assay specifically stains Pseudomonas in milk when the milk contains a mixture of other bacterial species. The FISH assay takes 2 h and compares favourably with current culturing methods, which take a minimum of 48 h. Specificity of the probe was validated using polymerase chain reaction to selectively amplifying the Pseudomonas rDNA gene and sequencing the gene products. CONCLUSIONS: The method presented in this study allows simultaneously detection, identification and enumeration of Pseudomonas spp. in milk. SIGNIFICANCE AND IMPACT OF THE STUDY: Rapid and accurate enumeration of Pseudomonas facilitates the identification of specific contamination sources in dairy plants, the accurate validation of pasteurization treatments and the prediction of shelf life of processed milk.
Asunto(s)
Microbiología de Alimentos , Leche/microbiología , Pseudomonas/aislamiento & purificación , Animales , Técnicas Bacteriológicas/métodos , ADN Bacteriano/genética , Citometría de Flujo/métodos , Hibridación Fluorescente in Situ/métodos , Reacción en Cadena de la Polimerasa/métodos , Pseudomonas/genética , Sondas ARN , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Sensibilidad y EspecificidadRESUMEN
We have identified S60, a new Cryptosporidium parvum sporozoite surface glycoprotein. S60 was cleaved into two subunits, S16 and S45, approximately 16-18 and 45-47 kDa respectively, with cleavage occurring at an SRSRR motif likely to be sensitive to trypsin in vivo. Analysis by surface biotinylation, lectins and monoclonal antibodies suggests S60 is an abundant sporozoite surface glycoprotein that is shed by migrating sporozoites. The major glycosylation on S60 was identified as single O-linked N-acetylgalactosamine sugars on threonine and serine residues. The gene encoding the S60 protein was identified and revealed a C-terminal consensus sequence for the addition of a glycosylphosphatidyl inositol anchor. Antisera raised against recombinant S60 produced in Escherichia coli reacted with the surface of sporozoites and the inner wall of excysted oocysts.
Asunto(s)
Anticuerpos Monoclonales/inmunología , Antígenos de Protozoos/genética , Cryptosporidium parvum/inmunología , Glicoproteínas de Membrana/genética , Proteínas Protozoarias/genética , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Animales , Antígenos de Protozoos/química , Antígenos de Protozoos/inmunología , Secuencia de Bases , Biotinilación , Western Blotting , Secuencia de Consenso , Glicosilación , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/inmunología , Microscopía Fluorescente , Datos de Secuencia Molecular , Proteínas Protozoarias/química , Proteínas Protozoarias/inmunología , Proteínas Recombinantes/química , Proteínas Recombinantes/inmunología , Análisis de Secuencia de Proteína , Serina/química , Esporas/química , Esporas/inmunología , Treonina/químicaRESUMEN
Cellulose-binding modules (CBMs) of two extracellular matrix proteins, St15 and ShD, from the slime mold Dictyostelium discoideum were expressed in Escherichia coli. The expressed proteins were purified to > 98% purity by extracting inclusion bodies at pH 11.5 and refolding proteins at pH 7.5. The two refolded CBMs bound tightly to amorphous phosphoric acid swollen cellulose (PASC), but had a low affinity toward xylan. Neither protein exhibited cellulase activity. St15, the stalk-specific protein, had fourfold higher binding affinity toward microcrystalline cellulose (Avicel) than the sheath-specific ShD CBM. St15 is unusual in that it consists of a solitary CBM homologous to family IIa CBMs. Sequence analysis of ShD reveals three putative domains containing: (a) a C-terminal CBM homologous to family IIb CBMs; (b) a Pro/Thr-rich linker domain; and (c) a N-terminal Cys-rich domain. The biological functions and potential role of St15 and ShD in building extracellular matrices during D. discoideum development are discussed.
Asunto(s)
Celulosa/química , Dictyostelium/química , Matriz Extracelular/química , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Sitios de Unión , Western Blotting , Celulasa/metabolismo , Clonación Molecular , Colorantes/farmacología , ADN Complementario/metabolismo , Electroforesis en Gel de Poliacrilamida , Escherichia coli/enzimología , Escherichia coli/metabolismo , Concentración de Iones de Hidrógeno , Cinética , Modelos Biológicos , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Unión Proteica , Pliegue de Proteína , Estructura Terciaria de Proteína , Proteínas Proto-Oncogénicas/química , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Protozoarias/química , Proteínas Protozoarias/metabolismo , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes/química , Colorantes de Rosanilina/farmacología , Sales (Química)/farmacología , Análisis de Secuencia de Proteína , Homología de Secuencia de AminoácidoRESUMEN
The cellular reactivity of six monoclonal antibodies (McAbs) produced to isolated human placental syncytiotrophoblast microvillous plasma membranes has been examined using a variety of normal and malignant cell types. Two McAbs reacted with antigenic determinants common to most normal human cells. Two other McAbs (H310 and H316) reacted predominantly with normal placental trophoblast and with lymphocytic cells, as well as with most transformed or neoplastic cultured cell lines. Two further McAbs (H315 and H317) identified foetal differentiation antigens expressed only on the membranes of normal placental trophoblast and of certain tumor cell lines. H317 has been shown to be specific for the heat-stable L-phenylalanine-inhibitable placental-type alkaline phosphatase isoenzyme. These latter McAbs (H315 and H317) may prove useful in monitoring of some human cancers.
Asunto(s)
Fosfatasa Alcalina/inmunología , Anticuerpos Monoclonales/inmunología , Antígenos/análisis , Placenta/inmunología , Trofoblastos/inmunología , Neoplasias de la Mama , Membrana Celular/inmunología , Células Cultivadas , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , EmbarazoRESUMEN
Growth factors and their binding proteins are important proteins regulating mammalian cell proliferation and differentiation so there is considerable interest in producing them as recombinant proteins, especially in hosts that do not already produce a complex mixture of growth factors. Many growth factors require post-translational modifications making them unsuitable for production in Escherichia coli or other prokaryotes. Since several expression vector systems have been recently developed for foreign protein production in the cellular slime mould, Dictyostelium discoideum, we attempted to use two of these systems to express human insulin-like growth factor binding protein 6 (hIGFBP6) and bovine beta-cellulin (bBTC) as secreted proteins. Although both proteins were successfully produced in stably transformed amoebae, no secretion was detected in spite of several attempts to facilitate this occurring.
Asunto(s)
Dictyostelium/metabolismo , Sustancias de Crecimiento/genética , Proteína 6 de Unión a Factor de Crecimiento Similar a la Insulina/genética , Péptidos y Proteínas de Señalización Intercelular , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Betacelulina , Biotecnología/métodos , Bovinos , Dictyostelium/crecimiento & desarrollo , Escherichia coli , Vectores Genéticos , Sustancias de Crecimiento/biosíntesis , Sustancias de Crecimiento/química , Humanos , Proteína 6 de Unión a Factor de Crecimiento Similar a la Insulina/química , Datos de Secuencia Molecular , Señales de Clasificación de Proteína , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Mapeo RestrictivoRESUMEN
To identify and analyze acceptor sequences for O-glycosylation, we have developed an in vivo system expressing short peptides as glutathione S-transferase fusion proteins in the eukaryotic host Dictyostelium discoideum. Using this approach, we show that a short peptide motif (PTVTPT), present in the D. discoideum cell-surface glycoprotein PsA, is sufficient as a signal for O-glycosylation, even when fused to a heterologous protein. Monosaccharide analysis and solid-phase protein sequencing showed that the modification is a single N-acetylglucosamine attached to threonine residues. This was further confirmed by electrospray-mass spectrometry. The O-linked glycosylation of both this peptide and authentic PsA presents the modB-dependent carbohydrate-specific epitope identified by the monoclonal antibody MUD50. Substitution of threonine by serine residues in this peptide also yields a glycosylated fusion protein which is modified with single N-acetylglucosamine residues, but not all of the serines are glycosylated.
Asunto(s)
Acetilglucosamina/metabolismo , Dictyostelium/metabolismo , Glicosiltransferasas/metabolismo , Péptidos/metabolismo , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales/inmunología , Western Blotting , Electroforesis en Gel de Poliacrilamida , Factor Xa/metabolismo , Regulación de la Expresión Génica , Glicosilación , Espectrometría de Masas , Datos de Secuencia Molecular , Monosacáridos/análisis , Péptidos/química , Péptidos/genética , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Análisis de SecuenciaRESUMEN
The outer capsid protein of rotavirus, VP7, is a major neutralization antigen and is considered a necessary component of any subunit vaccine developed against rotavirus infection. For this reason, significant effort has been directed towards producing recombinant VP7 that maintains the antigenic characteristics of the native molecule. Using a relatively new expression system, the simple eukaryote Dictyostelium discoideum, we have cloned the portion of simian rotavirus SA11 genome segment 9, encoding the mature VP7 protein, downstream of a native D. discoideum secretion signal sequence in a high-copy-number extrachromosomal vector. The majority of the recombinant VP7 expressed by transformants was intracellular and was detected by Western immunoblot following gel electrophoresis as two or three bands with an apparent molecular mass of 35.5 to 37.5 kDa. A small amount of VP7 having an apparent molecular mass of 37.5 kDa was secreted. Both the intracellular VP7 and the secreted VP7 were N glycosylated and sensitive to endoglycosidase H digestion. Under nonreducing electrophoresis conditions, over half the intracellular VP7 migrated as a monomer while the remainder migrated with an apparent molecular mass approximately twice that of the monomeric form. In an enzyme-linked immunosorbent assay, intracellular VP7 reacted with both nonneutralizing and neutralizing antibodies. The monoclonal antibody recognition pattern paralleled that found with VP7 expressed in either vaccinia virus or herpes simplex virus type 1 and confirms that D. discoideum-expressed VP7 is able to form the major neutralization domains present on viral VP7. Because D. discoideum cells are easy and cheap to grow, this expression system provides a valuable alternative for the large-scale production of recombinant VP7 protein.
Asunto(s)
Proteínas de la Cápside , Cápside/biosíntesis , Clonación Molecular/métodos , Dictyostelium/genética , Animales , Anticuerpos Monoclonales , Anticuerpos Antivirales/inmunología , Antígenos Virales/genética , Antígenos Virales/inmunología , Secuencia de Bases , Cápside/inmunología , Cartilla de ADN/química , Vectores Genéticos , Glicosilación , Datos de Secuencia Molecular , Proteínas Recombinantes , Vacunas SintéticasRESUMEN
The advantages of the organism Dictyostelium discoideum as an expression host for recombinant glycoproteins have been exploited for the production of an isotopically labeled cell surface protein for NMR structure studies. Growth medium containing [(15)N]NH(4)Cl and [(13)C]glycerol was used to generate isotopically labeled Escherichia coli, which was subsequently introduced to D. discoideum cells in simple Mes buffer. A variety of growth conditions were screened to establish minimal amounts of nitrogen and carbon metabolites for a cost-effective protocol. Following single-step purification by anion-exchange chromatography, 8 mg of uniformly (13)C,(15)N-labeled protein secreted by approximately 10(10) D. discoideum cells was isolated from 3.3 liters of supernatant. Mass spectrometry showed the recombinant protein of 16 kDa to have incorporated greater than 99.9% isotopic label. The two-dimensional (1)H-(13)C HSQC spectrum confirms (13)C labeling of both glycan and amino acid residues of the glycoprotein. All heteronuclear NMR spectra showed a good dispersion of cross-peaks essential for high-quality structure determination.