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Gustavsson M, Do TH, Lüthje P, Tran NT, Brauner A, Samuelson P, Truong NH, Larsson G. Improved cell surface display of Salmonella enterica serovar Enteritidis antigens in Escherichia coli. Microb Cell Fact 2015; 14:47. [PMID: 25889453 PMCID: PMC4415288 DOI: 10.1186/s12934-015-0227-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 03/12/2015] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Salmonella enterica serovar Enteritidis (SE) is one of the most potent pathogenic Salmonella serotypes causing food-borne diseases in humans. We have previously reported the use of the β-autotransporter AIDA-I to express the Salmonella flagellar protein H:gm and the SE serotype-specific fimbrial protein SefA at the surface of E. coli as live bacterial vaccine vehicles. While SefA was successfully displayed at the cell surface, virtually no full-length H:gm was exposed to the medium due to extensive proteolytic cleavage of the N-terminal region. In the present study, we addressed this issue by expressing a truncated H:gm variant (H:gmd) covering only the serotype-specific central region. This protein was also expressed in fusion to SefA (H:gmdSefA) to understand if the excellent translocation properties of SefA could be used to enhance the secretion and immunogenicity. RESULTS H:gmd and H:gmdSefA were both successfully translocated to the E. coli outer membrane as full-length proteins using the AIDA-I system. Whole-cell flow cytometric analysis confirmed that both antigens were displayed and accessible from the extracellular environment. In contrast to H:gm, the H:gmd protein was not only expressed as full-length protein, but it also seemed to promote the display of the protein fusion H:gmdSefA. Moreover, the epitopes appeared to be recognized by HT-29 intestinal cells, as measured by induction of the pro-inflammatory interleukin 8. CONCLUSIONS We believe this study to be an important step towards a live bacterial vaccine against Salmonella due to the central role of the flagellar antigen H:gm and SefA in Salmonella infections and the corresponding immune responses against Salmonella.
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Affiliation(s)
- Martin Gustavsson
- Royal Institute of Technology (KTH), Division of Industrial Biotechnology, AlbaNova University Center, SE 10691, Stockholm, Sweden.
| | - Thi-Huyen Do
- Institute of Biotechnology, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Cau Giay, Ha Noi, Vietnam.
| | - Petra Lüthje
- Department of Microbiology, Tumor and Cell Biology, Division of Clinical Microbiology, Karolinska Institute and Karolinska University Hospital, Stockholm, Sweden.
| | - Ngoc Tan Tran
- Institute of Biotechnology, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Cau Giay, Ha Noi, Vietnam.
| | - Annelie Brauner
- Department of Microbiology, Tumor and Cell Biology, Division of Clinical Microbiology, Karolinska Institute and Karolinska University Hospital, Stockholm, Sweden.
| | - Patrik Samuelson
- Royal Institute of Technology (KTH), Division of Industrial Biotechnology, AlbaNova University Center, SE 10691, Stockholm, Sweden.
| | - Nam Hai Truong
- Institute of Biotechnology, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Cau Giay, Ha Noi, Vietnam.
| | - Gen Larsson
- Royal Institute of Technology (KTH), Division of Industrial Biotechnology, AlbaNova University Center, SE 10691, Stockholm, Sweden.
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Sandersjöö L, Kostallas G, Löfblom J, Samuelson P. A protease substrate profiling method that links site-specific proteolysis with antibiotic resistance. Biotechnol J 2013; 9:155-62. [DOI: 10.1002/biot.201300234] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 10/15/2013] [Accepted: 10/21/2013] [Indexed: 11/09/2022]
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Jarmander J, Gustavsson M, Do TH, Samuelson P, Larsson G. A dual tag system for facilitated detection of surface expressed proteins in Escherichia coli. Microb Cell Fact 2012; 11:118. [PMID: 22943700 PMCID: PMC3511212 DOI: 10.1186/1475-2859-11-118] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 08/18/2012] [Indexed: 11/17/2022] Open
Abstract
Background The discovery of the autotransporter family has provided a mechanism for surface expression of proteins in laboratory strains of Escherichia coli. We have previously reported the use of the AIDA-I autotransport system to express the Salmonella enterica serovar Enteritidis proteins SefA and H:gm. The SefA protein was successfully exposed to the medium, but the orientation of H:gm in the outer membrane could not be determined due to proteolytic cleavage of the N-terminal detection-tag. The goal of the present work was therefore to construct a vector containing elements that facilitates analysis of surface expression, especially for proteins that are sensitive to proteolysis or otherwise difficult to express. Results The surface expression system pAIDA1 was created with two detection tags flanking the passenger protein. Successful expression of SefA and H:gm on the surface of E. coli was confirmed with fluorescently labeled antibodies specific for the N-terminal His6-tag and the C-terminal Myc-tag. While both tags were detected during SefA expression, only the Myc-tag could be detected for H:gm. The negative signal indicates a proteolytic cleavage of this protein that removes the His6-tag facing the medium. Conclusions Expression levels from pAIDA1 were comparable to or higher than those achieved with the formerly used vector. The presence of the Myc- but not of the His6-tag on the cell surface during H:gm expression allowed us to confirm the hypothesis that this fusion protein was present on the surface and oriented towards the cell exterior. Western blot analysis revealed degradation products of the same molecular weight for SefA and H:gm. The size of these fragments suggests that both fusion proteins have been cleaved at a specific site close to the C-terminal end of the passenger. This proteolysis was concluded to take place either in the outer membrane or in the periplasm. Since H:gm was cleaved to a much greater extent then the three times smaller SefA, it is proposed that the longer translocation time for the larger H:gm makes it more susceptible to proteolysis.
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Affiliation(s)
- Johan Jarmander
- School of Biotechnology, Division of Bioprocess Technology, Royal Institute of Technology, KTH, Stockholm, SE, 106 91, Sweden
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Kostallas G, Löfdahl PÅ, Samuelson P. Substrate profiling of tobacco etch virus protease using a novel fluorescence-assisted whole-cell assay. PLoS One 2011; 6:e16136. [PMID: 21267463 PMCID: PMC3022733 DOI: 10.1371/journal.pone.0016136] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 12/14/2010] [Indexed: 11/18/2022] Open
Abstract
Site-specific proteolysis of proteins plays an important role in many cellular functions and is often key to the virulence of infectious organisms. Efficient methods for characterization of proteases and their substrates will therefore help us understand these fundamental processes and thereby hopefully point towards new therapeutic strategies. Here, a novel whole-cell in vivo method was used to investigate the substrate preference of the sequence specific tobacco etch virus protease (TEVp). The assay, which utilizes protease-mediated intracellular rescue of genetically encoded short-lived fluorescent substrate reporters to enhance the fluorescence of the entire cell, allowed subtle differences in the processing efficiency of closely related substrate peptides to be detected. Quantitative screening of large combinatorial substrate libraries, through flow cytometry analysis and cell sorting, enabled identification of optimal substrates for TEVp. The peptide, ENLYFQG, identical to the protease's natural substrate peptide, emerged as a strong consensus cleavage sequence, and position P3 (tyrosine, Y) and P1 (glutamine, Q) within the substrate peptide were confirmed as being the most important specificity determinants. In position P1′, glycine (G), serine (S), cysteine (C), alanine (A) and arginine (R) were among the most prevalent residues observed, all known to generate functional TEVp substrates and largely in line with other published studies stating that there is a strong preference for short aliphatic residues in this position. Interestingly, given the complex hydrogen-bonding network that the P6 glutamate (E) is engaged in within the substrate-enzyme complex, an unexpectedly relaxed residue preference was revealed for this position, which has not been reported earlier. Thus, in the light of our results, we believe that our assay, besides enabling protease substrate profiling, also may serve as a highly competitive platform for directed evolution of proteases and their substrates.
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Affiliation(s)
- George Kostallas
- Department of Molecular Biotechnology, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Per-Åke Löfdahl
- Department of Molecular Biotechnology, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Patrik Samuelson
- Department of Molecular Biotechnology, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
- * E-mail:
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5
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Abstract
Efficient enrichment of staphylococcal cells displaying specific heterologous affinity ligands on their cell surfaces was demonstrated by using fluorescence-activated cell sorting. Using bacterial surface display of peptide or protein libraries for the purpose of combinatorial protein engineering has previously been investigated by using gram-negative bacteria. Here, the potential for using a gram-positive bacterium was evaluated by employing the well-established surface expression system for Staphylococcus carnosus. Staphylococcus aureus protein A domains with binding specificity to immunoglobulin G or engineered specificity for the G protein of human respiratory syncytial virus were expressed as surface display on S. carnosus cells. The surface accessibility and retained binding specificity of expressed proteins were demonstrated in whole-cell enzyme and flow cytometry assays. Also, affibody-expressing target cells could be sorted essentially quantitatively from a moderate excess of background cells in a single step by using a high-stringency sorting mode. Furthermore, in a simulated library selection experiment, a more-than-25,000-fold enrichment of target cells could be achieved through only two rounds of cell sorting and regrowth. The results obtained indicate that staphylococcal surface display of affibody libraries combined with fluoresence-activated cell sorting might indeed constitute an attractive alternative to existing technology platforms for affinity-based selections.
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Affiliation(s)
- Henrik Wernérus
- Department of Biotechnology, AlbaNova University Center, Royal Institute of Technology (KTH), SE-106 91 Stockholm, Sweden
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Abstract
The twin arginine translocation (Tat) pathway of bacteria and plant chloroplasts mediates translocation of essentially folded proteins across the cytoplasmic membrane. The detailed understanding of the mechanism of protein targeting to the Tat pathway has been hampered by the lack of screening or selection systems suitable for genetic analysis. We report here the development of a highly quantitative protein reporter for genetic analysis of Tat-specific export. Specifically, export via the Tat pathway rescues green fluorescent protein (GFP) fused to an SsrA peptide from degradation by the cytoplasmic proteolytic ClpXP machinery. As a result, cellular fluorescence is determined by the amount of GFP in the periplasmic space. We used the GFP-SsrA reporter to isolate gain-of-function mutants of a Tat-specific leader peptide and for the genetic analysis of the "invariant" signature RR dipeptide motif. Flow cytometric screening of trimethylamine N-oxide reductase (TorA) leader peptide libraries resulted in isolation of six gain-of function mutants that conferred significantly higher steady-state levels of export relative to the wild-type TorA leader. All the gain-of-function mutations occurred within or near the (S/T)RRXFLK consensus motif, highlighting the significance of this region in interactions with the Tat export machinery. Randomization of the consensus RR dipeptide in the TorA leader revealed that a basic side chain (R/K) is required at the first position whereas the second position can also accept Gln and Asn in addition to basic amino acids. This result indicates that twin arginine translocation does not require the presence of an arginine dipeptide within the conserved sequence motif.
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Affiliation(s)
- Matthew P DeLisa
- Department of Chemical Engineering and the Institute for Cell and Molecular Biology, University of Texas, Austin, Texas 78712, USA
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Abstract
Display of heterologous proteins on the surface of microorganisms, enabled by means of recombinant DNA technology, has become an increasingly used strategy in various applications in microbiology, biotechnology and vaccinology. Gram-negative, Gram-positive bacteria, viruses and phages are all being investigated in such applications. This review will focus on the bacterial display systems and applications. Live bacterial vaccine delivery vehicles are being developed through the surface display of foreign antigens on the bacterial surfaces. In this field, 'second generation' vaccine delivery vehicles are at present being generated by the addition of mucosal targeting signals, through co-display of adhesins, in order to achieve targeting of the live bacteria to immunoreactive sites to thereby increase immune responses. Engineered bacteria are further being evaluated as novel microbial biocatalysts with heterologous enzymes immobilized as surface exposed on the bacterial cell surface. A discussion has started whether bacteria can find use as new types of whole-cell diagnostic devices since single-chain antibodies and other type of tailor-made binding proteins can be displayed on bacteria. Bacteria with increased binding capacity for certain metal ions can be created and potential environmental or biosensor applications for such recombinant bacteria as biosorbents are being discussed. Certain bacteria have also been employed for display of various poly-peptide libraries for use as devices in in vitro selection applications. Through various selection principles, individual clones with desired properties can be selected from such libraries. This article explains the basic principles of the different bacterial display systems, and discusses current uses and possible future trends of these emerging technologies.
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Affiliation(s)
- Patrik Samuelson
- Division of Molecular Biotechnology, Department of Biotechnology, SCFAB, Royal Institute of Technology (KTH), Roslagstullsbacken 21, SE-10691 Stockholm, Sweden
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8
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Abstract
Novel surface proteins can be introduced onto bacterial cell surfaces by recombinant means. Here, we describe various applications of two such display systems for the food-grade bacteria Staphylococcus carnosus and Staphylococcus xylosus, respectively. The achievements in the use of such staphylococci as live bacterial vaccine delivery vehicles will be described. Co-display of proteins and peptides with adhesive properties to enable targeting of the bacteria, have significantly improved the vaccine delivery potential. Recently, protective immunity to respiratory syncytial virus (RSV) could be evoked in mice by intranasal immunization using such 'second generation' vaccine delivery systems. Furthermore, antibody fragments and other 'affinity proteins' with capacity to specifically bind a certain protein, e.g. Staphylococcus aureus protein A-based affibodies, have been surface-displayed on staphylococci as initial efforts to create whole-cell diagnostic devices. Surface display of metal-binding peptides, or protein domains into which metal binding properties has been engineered by combinatorial protein engineering, have been exploited to create staphylococcal bioadsorbents for potential environmental or biosensor applications. The use of these staphylococcal surface display systems as alternatives for display of large protein libraries and subsequent affinity selection of relevant binding proteins by fluorescence-activated cell sorting (FACS) will be discussed.
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Affiliation(s)
- Henrik Wernérus
- Department of Biotechnology, SCFAB, Royal Institute of Technology (KTH), S-106 91, Stockholm, Sweden.
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Hansson M, Samuelson P, Nguyen TN, Ståhl S. General expression vectors for Staphylococcus carnosus enabled efficient production of the outer membrane protein A of Klebsiella pneumoniae. FEMS Microbiol Lett 2002; 210:263-70. [PMID: 12044685 DOI: 10.1111/j.1574-6968.2002.tb11191.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
General expression vectors, designed for intracellular expression or secretion of recombinant proteins in the non-pathogenic Staphylococcus carnosus, were constructed. Both vector systems encode two different affinity tags, an upstream albumin binding protein and a downstream hexahistidyl peptide, and are furnished with cleavage sites for two site-specific proteases for optional affinity tag removal. To evaluate the novel vectors, the gene encoding the outer membrane protein A (OmpA) of Klebsiella pneumoniae was introduced into the vectors. Efficient production was demonstrated in both systems, although, as expected for OmpA fusions, somewhat better intracellularly, and the fusion proteins could be recovered as full-length products by affinity chromatography.
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Affiliation(s)
- Marianne Hansson
- Department of Biotechnology, SCFAB, Royal Institute of Technology (KTH), SE-10691, Stockholm, Sweden
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10
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Olsson T, Edenius C, Ferm M, Samuelson P, Torrång A, Wallström E, Khademi M, Andersson M, Arfors L. Depletion of Vbeta5.2/5.3 T cells with a humanized antibody in patients with multiple sclerosis. Eur J Neurol 2002; 9:153-64. [PMID: 11882056 DOI: 10.1046/j.1468-1331.2002.00370.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A potentially pathogenic expansion of T cells expressing T cell receptor (TCR) Vbeta5.2/5.3 has been demonstrated in patients with multiple sclerosis (MS). A humanized antibody (ATM-027) directed against these T cells has been developed to further investigate the role of this subpopulation of T cells in MS. The pharmacokinetics/dynamics and safety of ATM-027 (0.3-300 mg intravenously over 30 min) were investigated in 14 patients with MS. The effect of treatment on cytokine expression and autoreactivity to peptides of myelin basic protein (MBP) was also studied. ATM-027 was well tolerated and raised no safety concerns. Clearance of the antibody was low and elimination half-life was approximately 3 weeks. The majority of the target Vbeta5.2/5.3 expressing T cells were depleted for at least 18 months. The small remaining fraction of target cells showed a marked decrease in their TCR expression, which was recovered within 8 months. The numbers of peripheral blood mononuclear cells (PBMCs) with spontaneous expression of IFN-gamma was decreased at 72 h and 8 weeks after treatment, whilst no clear effects on TNF-alpha, IL-4, IL-10, TGF-beta expression were observed. There was also a significant decrease in the number of PBMCs producing IFN-gamma in response to MBP peptide 80-102. We conclude that long-term depletion of T cells expressing defined Vbeta subgroups in MS patients is feasible using selective immunotherapy. The selective depletion of Vbeta5.2/5.3 expressing T cells in this study resulted in a decrease in potentially disease promoting anti-MBP reactivity and pro-inflammatory cytokine production.
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Affiliation(s)
- Tomas Olsson
- Neuroimmunology Unit, Centre for Molecular Medicine L8:04, Karolinska Hospital, S-171 76 Stockholm, Sweden.
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Abstract
Scientists who study encryption or computer security or otherwise reverse engineer technical measures, who make tools enabling them to do this work, and who report the results of their research face new risks of legal liability because of recently adopted rules prohibiting the circumvention of technical measures and manufacture or distribution of circumvention tools. Because all data in digital form can be technically protected, the impact of these rules goes far beyond encryption and computer security research. The scientific community must recognize the harms these rules pose and provide guidance about how to improve the anticircumvention rules.
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Abstract
Heterologous surface display on Gram-positive bacteria was first described almost a decade ago and has since then developed into an active research area. Gram-positive bacterial surface display has today found a range of applications, in immunology, microbiology and biotechnology. Live bacterial vaccine delivery vehicles are being developed through the surface display of selected foreign antigens on the bacterial surfaces. In this field, "second generation" vaccine delivery vehicles are at present being generated by the addition of mucosal targeting signals through co-display of adhesins, in order to achieve targeting of the live bacteria to immunoreactive sites to thereby increase immune responses. Engineered Gram-positive bacteria are further being evaluated as novel microbial biocatalysts with heterologous enzymes immobilized as surface exposed on the bacterial cell surface. A discussion has started whether bacteria can find use as new types of whole-cell diagnostic devices since single-chain antibodies and other variants of tailor-made binding proteins can be displayed on bacteria. Bacteria with increased binding capacity for certain metal ions can be created and potential environmental or biosensor applications for such recombinant bacteria as biosorbents are being discussed. This article explains the basis of Gram-positive bacterial surface display, and discusses current uses and possible future trends of this emerging technology.
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Affiliation(s)
- M Hansson
- Department of Biotechnology, Royal Institute of Technology (KTH), Stockholm, S-100 44, Sweden
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13
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Lehtiö J, Wernérus H, Samuelson P, Teeri TT, Ståhl S. Directed immobilization of recombinant staphylococci on cotton fibers by functional display of a fungal cellulose-binding domain. FEMS Microbiol Lett 2001; 195:197-204. [PMID: 11179652 DOI: 10.1111/j.1574-6968.2001.tb10521.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The immobilization of recombinant staphylococci onto cellulose fibers through surface display of a fungal cellulose-binding domain (CBD) was investigated. Chimeric proteins containing the CBD from Trichoderma reesei cellulase Cel6A were found to be correctly targeted to the cell wall of Staphylococcus carnosus cells, since full-length proteins could be extracted and affinity-purified. Furthermore, surface accessibility of the CBD was verified using a monoclonal antibody and functionality in terms of cellulose-binding was demonstrated in two different assays in which recombinant staphylococci were found to efficiently bind to cotton fibers. The implications of this strategy of directed immobilization for the generation of whole-cell microbial tools for different applications will be discussed.
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Affiliation(s)
- J Lehtiö
- Department of Biotechnology, Royal Institute of Technology (KTH), SE-100 44 Stockholm, Sweden
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14
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Ståhl S, Robert A, Gunneriusson E, Wernérus H, Cano F, Liljeqvist S, Hansson M, Nguyen TN, Samuelson P. Staphylococcal surface display and its applications. Int J Med Microbiol 2000; 290:571-7. [PMID: 11200538 DOI: 10.1016/s1438-4221(00)80002-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022] Open
Abstract
Novel surface proteins can be introduced onto the bacterial cell surface by recombinant means. Here, we describe the development of such display systems for two food-grade bacteria, Staphylococcus carnosus and Staphylococcus xylosus, and present how such engineered bacteria can be used in different applications. A study will be described in which such staphylococci were employed as vaccine delivery vehicles to elicit protective antibody responses to respiratory syncytial virus (RSV). The use of surface-engineered staphylococci as novel microbial biocatalysts, as a new type of whole-cell diagnostic devices or for adsorption of metal ions with potential environmental or biosensor applications, will also be discussed.
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Affiliation(s)
- S Ståhl
- Department of Biotechnology, Kungliga Tekniska Högskolan, Stockholm, Sweden.
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15
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Samuelson P. Cancer screening rates. J Am Board Fam Pract 2000; 13:468-9. [PMID: 11117349 DOI: 10.3122/15572625-13-6-468b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Cano F, Plotnicky-Gilquin H, Nguyen TN, Liljeqvist S, Samuelson P, Bonnefoy J, Stâhl S, Robert A. Partial protection to respiratory syncytial virus (RSV) elicited in mice by intranasal immunization using live staphylococci with surface-displayed RSV-peptides. Vaccine 2000; 18:2743-52. [PMID: 10781862 DOI: 10.1016/s0264-410x(00)00063-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A live bacterial vaccine-delivery system based on the food-grade bacterium Staphylococcus carnosus was used for delivery of peptides from the G glycoprotein of human respiratory syncytial virus, subtype A (RSV-A). Three peptides, corresponding to the G protein amino acids, 144-159 (denoted G5), 190-203 (G9) and 171-188 (G4 S), the latter with four cysteine residues substituted for serines, were expressed by recombinant means as surface-exposed on three different bacteria, and their surface accessibility on the bacteria was verified by fluorescence-activated cell sorting (FACS). Intranasal immunization of mice with the live recombinant staphylococci elicited significant anti-peptide as well as anti-virus serum IgG responses of balanced IgG1/IgG2a isotype profiles, and upon viral challenge with 10(5) tissue culture infectious doses(50) (TCID(50)), lung protection was demonstrated for approximately half of the mice in the G9 and G4 S immunization groups. To our knowledge, this is the first study in which protective immunity to a viral pathogen has been evoked using food-grade bacteria as vaccine-delivery vehicles.
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Affiliation(s)
- F Cano
- Centre d'Immunologie Pierre Fabre, F-74 164 Saint-Julien en Genevois, France
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17
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Abstract
Recombinant Staphylococcus xylosus and Staphylococcus carnosus strains were generated with surface-exposed chimeric proteins containing polyhistidyl peptides designed for binding to divalent metal ions. Surface accessibility of the chimeric surface proteins was demonstrated and the chimeric surface proteins were found to be functional in terms of metal binding, since the recombinant staphylococcal cells were shown to have gained Ni(2+)- and Cd(2+)-binding capacity, suggesting that such bacteria could find use in bioremediation of heavy metals. This is, to our knowledge, the first time that recombinant, surface-exposed metal-binding peptides have been expressed on gram-positive bacteria. Potential environmental or biosensor applications for such recombinant staphylococci as biosorbents are discussed.
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Affiliation(s)
- P Samuelson
- Department of Biotechnology, Kungliga Tekniska Högskolan, S-100 44 Stockholm, Sweden
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Samuelson P, Cano F, Robert A, Ståhl S. Engineering of a Staphylococcus carnosus surface display system by substitution or deletion of a Staphylococcus hyicus lipase propeptide. FEMS Microbiol Lett 1999; 179:131-9. [PMID: 10481097 DOI: 10.1111/j.1574-6968.1999.tb08718.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Surface display of recombinant proteins on bacteria and phages has become an important topic in bioscience. A system for the display of heterologous proteins on the surface of Staphylococcus carnosus employs the secretion signal and propeptide from a Staphylococcus hyicus lipase for translocation and since the propeptide is of considerable size (207 amino acids) and not processed in S. carnosus, we have investigated the possibility to delete or substitute the propeptide for smaller protein domains, to thereby improve the surface display system. A set of new vectors was constructed and the surface expression of model proteins was investigated by various methods, including fluorescence-activated cell sorting. The results suggest that the propeptide region indeed can be deleted when proteins which are easily secretable are displayed. In contrast, the propeptide seems to be advantageous for translocation of inefficiently secreted proteins. Moreover, our study also presents a rational strategy for how to monitor the engineering efforts for the optimization of a surface display system.
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Affiliation(s)
- P Samuelson
- Department of Biotechnology, Kungliga Tekniska Högskolan, S-100 44, Stockholm, Sweden
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Gunneriusson E, Samuelson P, Ringdahl J, Grönlund H, Nygren PA, Ståhl S. Staphylococcal surface display of immunoglobulin A (IgA)- and IgE-specific in vitro-selected binding proteins (affibodies) based on Staphylococcus aureus protein A. Appl Environ Microbiol 1999; 65:4134-40. [PMID: 10473426 PMCID: PMC99751 DOI: 10.1128/aem.65.9.4134-4140.1999] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An expression system designed for cell surface display of hybrid proteins on Staphylococcus carnosus has been evaluated for the display of Staphylococcus aureus protein A (SpA) domains, normally binding to immunoglobulin G (IgG) Fc but here engineered by combinatorial protein chemistry to yield SpA domains, denoted affibodies, with new binding specificities. Such affibodies, with human IgA or IgE binding activity, have previously been selected from a phage library, based on an SpA domain. In this study, these affibodies have been genetically introduced in monomeric or dimeric forms into chimeric proteins expressed on the surface of S. carnosus by using translocation signals from a Staphylococcus hyicus lipase construct together with surface-anchoring regions of SpA. The recombinant surface proteins, containing the IgA- or IgE-specific affibodies, were demonstrated to be expressed as full-length proteins, localized and properly exposed at the cell surface of S. carnosus. Furthermore, these chimeric receptors were found to be functional, since recombinant S. carnosus cells were shown to have gained IgA and IgE binding capacity, respectively. In addition, a positive effect in terms of IgA and IgE reactivity was observed when dimeric versions of the affibodies were present. Potential applications for recombinant bacteria with redirected binding specificity in their surface proteins are discussed.
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Affiliation(s)
- E Gunneriusson
- Department of Biotechnology, Royal Institute of Technology (KTH), S-100 44 Stockholm, Sweden
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Cano F, Liljeqvist S, Nguyen TN, Samuelson P, Bonnefoy JY, Ståhl S, Robert A. A surface-displayed cholera toxin B peptide improves antibody responses using food-grade staphylococci for mucosal subunit vaccine delivery. FEMS Immunol Med Microbiol 1999; 25:289-98. [PMID: 10459584 DOI: 10.1111/j.1574-695x.1999.tb01354.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The possibility of improving the antibody responses to a model streptococcal antigen, administered by intranasal immunization as surface-displayed on the food-grade bacterium Staphylococcus carnosus, by co-exposure of a peptide (CTBp) comprising amino acids 50-75 of the cholera toxin B subunit, was investigated. It was found that the introduction of the CTBp into the chimeric surface proteins, containing a serum albumin binding protein (ABP) from streptococcal protein G as model antigen, significantly increased serum IgG responses upon intranasal immunization. Similarly, elicited local IgA responses were also found to be improved. Furthermore, it was demonstrated that live delivery of the staphylococci was required to obtain this effect, since UV-irradiated or heat-killed bacteria exposing the same chimeric surface proteins did not show increased anti-ABP IgG responses.
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Affiliation(s)
- F Cano
- Centre d'Immunologie Pierre Fabre, Saint-Julien en Genevois, France
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21
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Nguyen TN, Samuelson P, Sterky F, Merle-Poitte C, Robert A, Baussant T, Haeuw JF, Uhlén M, Binz H, Stâhl S. Chromosomal sequencing using a PCR-based biotin-capture method allowed isolation of the complete gene for the outer membrane protein A of Klebsiella pneumoniae. Gene 1998; 210:93-101. [PMID: 9524233 DOI: 10.1016/s0378-1119(98)00060-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
By employing a novel biotin- and PCR-assisted capture method, which allows determination of unknown sequences on chromosomal DNA, the gene for the outer membrane protein A (OmpA) of Klebsiella pneumoniae has been isolated and sequenced to completion. The method involves linear amplification of DNA from a biotinylated primer annealing to a region with known sequence. After capture of the amplified single-stranded DNA on to paramagnetic beads, unspecifically annealing primers, i.e. arbitrary primers, were used to generate sequences with only partly determined nt sequences. The homology of the sequenced gene to ompA of related bacteria is discussed, and the gene fragment was assembled for intracellular expression in Escherichia coli, and two different fusion proteins were produced and recovered with good yields. The importance of the novel chromosomal sequencing method for gene isolation in general and the potential use of the OmpA fusion proteins are discussed.
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Affiliation(s)
- T N Nguyen
- Centre d'Immunologie Pierre Fabre, F-74 164, Saint-Julien en Genevois, France
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22
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Andréoni C, Goetsch L, Libon C, Samuelson P, Nguyen TN, Robert A, Uhlén M, Binz H, Ståhl S. Flow cytometric quantification of surface-displayed recombinant receptors on staphylococci. Biotechniques 1997; 23:696-702, 704. [PMID: 9343695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Surface display of recombinant proteins on bacteria and phages has become an important tool in bioscience. To evaluate the various host systems, a great need exists for quantitative methods to determine the densities of displayed proteins and peptides on the bacteria and phage surfaces. Here we describe how a method previously applied for quantification of surface proteins on mammalian cells has been adapted for quantification of chimeric receptors surface-displayed on bacteria; in this study, the bacteria being recombinant staphylococci. The presented method takes advantage of fluorescence-activated cell sorting (FACS) technology and a new type of nonfluorescent plastic beads, similar in size (2 microns in diameter) to bacterial cells, and thus suitable for generation of calibration curves from which the number of chimeric receptors can be obtained. The method was used to estimate the number of antigenic sites on two types of recombinant staphylococci, both carrying heterologous chimeric receptors, and it was found that the recombinant Staphylococcus carnosus cells carried approximately 10(4) surface-displayed antigenic sites, while recombinant Staphylococcus xylosus exposed approximately 3 x 10(3) sites per cell. The use of the deviced method for different applications is discussed.
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Affiliation(s)
- C Andréoni
- Centre d'Immunologie Pierre Fabre, Saint Julien en Genevois, France
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23
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Liljeqvist S, Samuelson P, Hansson M, Nguyen TN, Binz H, Ståhl S. Surface display of the cholera toxin B subunit on Staphylococcus xylosus and Staphylococcus carnosus. Appl Environ Microbiol 1997; 63:2481-8. [PMID: 9212399 PMCID: PMC168546 DOI: 10.1128/aem.63.7.2481-2488.1997] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The heterologous surface expression of the cholera toxin B subunit (CTB) from Vibro cholerae in two staphylococcal species, Staphylococcus xylosus and Staphylococcus carnosus, has been investigated. The gene encoding native CTB (103 amino acids) was introduced into gene constructs encoding chimeric receptors designed to be translocated and anchored on the outer cell surface of the staphylococci. Since functionality of CTB is correlated with its ability to form pentamers and the capacity of the pentameric CTB to bind the GM1 ganglioside, both the surface accessibility and the functionality of the surface-displayed CTB receptors were evaluated. It could be concluded that the chimeric receptors were targeted to the cell wall of the staphylococci, since they could be released by lysostaphin treatment and, after subsequent affinity purification, identified as full-length products by immunoblotting. Surface accessibility of the chimeric receptors was demonstrated by a colorimetric assay and by immunofluorescence staining with a CTB-reactive rabbit antiserum. Pentamerization was investigated by using a monoclonal antibody described to be specific for pentameric CTB, and the functionality of the receptors was tested in a binding assay with digoxigenin-labelled GM1. It was concluded that functional CTB was present on both types of staphylococci, and for S. carnosus, the reactivity to the pentamer-specific monoclonal antibody and in the GM1 binding assay was indeed significant. The implications of the results for the design of live bacterial vaccine delivery systems intended for administration by the mucosal route are discussed.
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Affiliation(s)
- S Liljeqvist
- Department of Biochemistry and Biotechnology, Royal Institute of Technology, Stockholm, Sweden
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24
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Abstract
Two different host-vector expression systems, designed for cell surface display of heterologous receptors on Staphylococcus xylosus and Staphylococcus carnosus, respectively, were compared for the surface display of four variants of a 101 amino acid region derived from the G glycoprotein of human respiratory syncytial virus (RSV). Surface localization of the different chimeric receptors was evaluated by a colorimetric assay and by fluorescence-activated cell sorting. It was concluded that the S. carnosus system was better both in the ability to translocate inefficiently secreted peptides and in the number of exposed hybrid receptors. The potential use of the described staphylococci as live bacterial vaccine vehicles or alternatives to filamentous phages for surface display of protein libraries is discussed.
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Affiliation(s)
- A Robert
- Centre d'Immunologie Pierre Fabre, Saint-Julien en Genevois, France
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25
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Dahlstedt L, Samuelson P, Dalén N. Cryotherapy after cruciate knee surgery. Skin, subcutaneous and articular temperatures in 8 patients. Acta Orthop Scand 1996; 67:255-7. [PMID: 8686463 DOI: 10.3109/17453679608994683] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We recorded temperature changes on the skin surface, subcutaneously and intra-articularly during cryotherapy after knee surgery by using Cryo-cuff compression dressings. Subcutaneous recordings on the contralateral knee were used as reference. 8 patients were examined. There was a reproducible decrease in skin temperature and subcutaneous temperature. Skin temperature had to be lowered to about 20 degrees C to obtain demonstrable intraarticular temperature changes.
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Affiliation(s)
- L Dahlstedt
- Department of Orthopedics, Karolinska Institute, Danderyd Hospital, Sweden
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26
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Abstract
Two different host-vector expression systems designed for cell surface display of chimeric receptors on Staphylococcus xylosus and Staphylococcus carnosus have been evaluated for surface display of a mouse immunoglobulin G1(kappa) [IgG1(kappa)] anti-human IgE single-chain Fv (scFv) antibody fragment. To achieve surface anchoring of the chimeric receptors containing the scFv, the cell surface attachment regions from Staphylococcus aureus protein A were used in both expression systems. The different chimeric receptors could be recovered from cell wall extracts of both S. xylosus and S. carnosus, and surface localization was demonstrated by taking advantage of a serum albumin-binding reporter region present within the two types of receptors. In addition, the two different recombinant staphylococci carrying hybrid receptors containing the scFv were demonstrated to react with the antigen, which was human IgE, in whole-cell enzyme-linked immunosorbent assays. This is the first report of an antibody fragment expressed in a functional form anchored to the surface of gram-positive bacteria. The potential use of recombinant gram-positive bacteria as whole-cell diagnostic devices or alternatives to filamentous phages for surface display of scFv libraries is discussed.
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Affiliation(s)
- E Gunneriusson
- Department of Biochemistry and Biotechnology, Royal Institute of Technology, Stockholm, Sweden
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27
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Nguyen TN, Gourdon MH, Hansson M, Robert A, Samuelson P, Libon C, Andréoni C, Nygren PA, Binz H, Uhlén M. Hydrophobicity engineering to facilitate surface display of heterologous gene products on Staphylococcus xylosus. J Biotechnol 1995; 42:207-19. [PMID: 7576540 DOI: 10.1016/0168-1656(95)00081-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Protein engineering has been employed to investigate the effect of specific amino acid changes on the targeting of heterologous proteins to the outer cell surface of the Gram-positive bacterium Staphylococcus xylosus. Three different variants, corresponding to a 101 amino acid region of the major glycoprotein (G protein) of human respiratory syncytial virus (RSV), were generated in which multiple hydrophobic phenylalanine residues were either substituted or deleted. The different G protein fragments were expressed as one part of recombinant receptors designed for surface display on S. xylosus cells. The engineered variants of the RSV G protein hybrid receptors were, in contrast to a non-engineered fragment, efficiently targeted to the outer cell surface of recombinant S. xylosus cells as determined by different methods, including fluorescence-activated cell sorting. In addition, immunization of mice with live recombinant S. xylosus demonstrated that surface exposure was required to generate receptor-specific antibodies. The present strategy of hydrophobic engineering should be of general interest in surface-display applications and for secretion of proteins otherwise difficult to translocate through host cell membranes.
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Affiliation(s)
- T N Nguyen
- Centre d'Immunologie Pierre Fabre, Saint-Julien en Genevois, France
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28
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Samuelson P, Hansson M, Ahlborg N, Andréoni C, Götz F, Bächi T, Nguyen TN, Binz H, Uhlén M, Ståhl S. Cell surface display of recombinant proteins on Staphylococcus carnosus. J Bacteriol 1995; 177:1470-6. [PMID: 7883702 PMCID: PMC176761 DOI: 10.1128/jb.177.6.1470-1476.1995] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
A novel expression system for surface display of heterologous proteins on Staphylococcus carnosus cells has been developed. Taking advantage of the promoter and secretion signals, including a propeptide region, from the lipase gene of Staphylococcus hyicus and the cell wall-spanning and membrane-binding region of protein A from Staphylococcus aureus, efficient surface display of an 80-amino-acid peptide from a malaria blood stage antigen could be achieved. A serum albumin binding protein from streptococcal protein G was used both as a general reporter molecule and to increase the accessibility of the surface-displayed proteins. Immunoblotting, immunogold staining, and immunofluorescence on intact recombinant S. carnosus cells verified the presence of the propeptide, the malaria antigen, and the albumin-binding reporter protein on the bacterial surface. For the first time, fluorescence-activated cell sorting was used to analyze the presence of surface-displayed hybrid receptors on gram-positive bacteria.
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Affiliation(s)
- P Samuelson
- Department of Biochemistry and Biotechnology, Royal Institute of Technology, Stockholm, Sweden
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30
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Abstract
We have studied the interaction of the A:T specific minor-groove binding ligand 4',6-diamidino-2-phenylindole (DAPI) with synthetic DNA oligomers containing specific binding sites in order to investigate possible long-range interactions between bound ligands. We find that DAPI binds cooperatively to the oligomers. The degree of cooperativity increases with increasing number of binding sites and decreases with the separation between them. This dependence is paralleled by changes in the induced circular dichroism spectrum of DAPI, which decreases in intensity at 335 nm and increases at 365 nm. These results are consistent with an allosteric interaction of DAPI with DNA, where bound ligands cooperatively alter the structure of the DNA molecule. This structural change seems possible to induce under various conditions, including physiological. One consequence of allosteric binding is that ligands bound at a distance from each other sense each other's presence and influence each others' properties. If some regulatory proteins induce the same conformational change as DAPI, novel mechanisms for controlling gene expression can be anticipated.
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Affiliation(s)
- P Samuelson
- Department of Biochemistry and Biophysics, Chalmers University of Technology, Gothenburg, Sweden
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31
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Seideman P, Samuelson P, Neander G. Naproxen and paracetamol compared with naproxen only in coxarthrosis. Increased effect of the combination in 18 patients. Acta Orthop Scand 1993; 64:285-8. [PMID: 8322582 DOI: 10.3109/17453679308993626] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In a double-blind study of 18 patients with coxarthrosis the effect of 3 naproxen doses (0.5, 1.0, and 1.5 g daily) and 2 naproxen doses combined with paracetamol (0.5 g + 4 g daily and 1.0 g + 4 g daily) was investigated. Plasma levels of naproxen and paracetamol were measured (HPLC), and clinical assessment of pain, joint movement, activity of daily life and side-effects were performed at the end of the 5 treatment periods. A relationship was found between the 3 naproxen doses, naproxen plasma levels, pain at rest, and pain during movement. The combined treatment was more effective than treatment with the same naproxen dose alone. The effect of naproxen (0.5 g daily) combined with paracetamol (4 g daily) did not differ from that obtained during treatment with higher naproxen doses only. Furthermore, the effect of the highest naproxen dose was not better than the effect of the lower naproxen dose (1.0 g daily) combined with paracetamol. The main finding was that treatment with naproxen and paracetamol is more effective than treatment with higher naproxen doses alone.
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Affiliation(s)
- P Seideman
- Karolinska Institute, Department of Internal Medicine, Danderyd, Sweden
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32
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Lell W, Johnson P, Plagenhoef J, Samuelson P, Athanasuleas C, Hughes W, McEachern M. The effect of prophylactic nitroglycerin infusion on the incidence of regional wall-motion abnormalities and ST segment changes in patients undergoing coronary artery bypass surgery. J Card Surg 1993; 8:228-31. [PMID: 8461508 DOI: 10.1111/j.1540-8191.1993.tb01312.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effects of nitroglycerin (NTG) on regional wall-motion abnormalities, ST segment changes, and the incidence of myocardial infarction (MI), cardiac failure, and mortality were studied in 30 patients undergoing coronary artery bypass. Patients received continuous infusions of either normal saline or NTG (1 microgram/kg per min [low dose] or 2 micrograms/kg per min [high dose]) beginning at anesthesia and continuing for 4 hours postoperatively. The occurrence of wall-motion abnormalities as detected by transesophageal echocardiography was 38 events in the normal saline group (N = 10). Significantly fewer events (p < 0.05) were recorded in the low dose and high dose NTG groups (20 events and 15 events, respectively) compared to controls. There were no significant differences between the control and NTG groups with regard to the incidence of Holter ST segment events or the incidence of MI, cardiac failure, or cardiac death. NTG reduced the incidence of echocardiographic wall-motion abnormalities in a dose dependent manner while having no significant effect on other parameters examined.
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Affiliation(s)
- W Lell
- Division of Cardiothoracic Anesthesia and Surgery, Carraway Methodist Hospital, Birmingham, Alabama
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33
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Samuelson P. CONTU revisited: the case against copyright protection for computer programs in machine-readable form. Duke Law J 1984:663-769. [PMID: 10268940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Professor Samuelson casts a critical eye on the Final Report of the National Commission on New Technological Uses of Copyrighted Works (CONTU) which recommended that copyright protection be extended to machine-readable versions of computer programs. CONTU appears to have misunderstood computer technology and misinterpreted copyright tradition in two significant respects. The Commission failed to take into account the historical importance of disclosure of the contents of protected works as a fundamental goal of both the copyright and patent laws. It also erroneously opined that the utilitarian character of a work was no bar to its copyrightability when both the statute and the case law make clear that utilitarian works are not copyrightable. Since computer programs in machine-readable forms do not disclose their contents and are inherently utilitarian, copyright protection for them is inappropriate. Congress acted on CONTU's recommendation without understanding the significance of these conceptual flaws. Professor Samuelson recommends the creation of a new form of intellectual property law specifically designed for machine-readable programs.
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Yarnall SR, Samuelson P, Wakefield JS. Clinical evaluation of an automated screening history. Northwest Med 1972; 71:186-91. [PMID: 5011576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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36
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Moss AJ, Minken SL, Samuelson P, Angell C. Effects of exogenous and endogenous norepinephrine on the oxygen availability of intact muscular arteries. J Atheroscler Res 1969; 10:11-8. [PMID: 5380898 DOI: 10.1016/s0368-1319(69)80077-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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37
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Moss AJ, Samuelson P, Angell C, Minken SL. Polarographic evaluation of transmural oxygen availabitlity in intact muscular arteries. J Atheroscler Res 1968; 8:803-10. [PMID: 5688376 DOI: 10.1016/s0368-1319(68)80042-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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