1
|
Production of Lysostaphin by Nonproprietary Method Utilizing a Promoter from Toxin–Antitoxin System. Mol Biotechnol 2019; 61:774-782. [DOI: 10.1007/s12033-019-00203-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
2
|
Fukushima K, Kamimura T, Takimoto-Kamimura M. Structure basis 1/2SLPI and porcine pancreas trypsin interaction. JOURNAL OF SYNCHROTRON RADIATION 2013; 20:943-7. [PMID: 24121345 PMCID: PMC3795561 DOI: 10.1107/s090904951302133x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/31/2013] [Indexed: 06/02/2023]
Abstract
SLPI (secretory leukocyte protease inhibitor) is a 107-residue protease inhibitor which inhibits various serine proteases, including elastase, cathepsin G, chymotrypsin and trypsin. SLPI is obtained as a multiple inhibitor in lung defense and in chronic airway infection. X-ray crystal structures have so far reported that they are full-length SLPIs with bovine α-chymotrypsin and 1/2SLPI (recombinant C-terminal domain of SLPI; Arg58-Ala107) with HNE (human neutrophil elastase). To understand the role of this multiple inhibitory mechanism, the crystal structure of 1/2SLPI with porcine pancreas trypsin was solved and the binding modes of two other complexes compared. The Leu residue surprisingly interacts with the S1 site of trypsin, as with chymotrypsin and elastase. The inhibitory mechanism of 1/2SLPI using the wide primary binding site contacts (from P2' to P5) with various serine proteases is discussed. These inhibitory mechanisms have been acquired in the evolution of the protection system for acute inflammatory diseases.
Collapse
Affiliation(s)
- Kei Fukushima
- Medicinal Chemistry Technology Department, Teijin Institute for Bio-Medical Research, 4-3-2 Asahigaoka, Hino-shi, Tokyo 191-8512, Japan
| | - Takashi Kamimura
- Medicinal Chemistry Technology Department, Teijin Institute for Bio-Medical Research, 4-3-2 Asahigaoka, Hino-shi, Tokyo 191-8512, Japan
| | - Midori Takimoto-Kamimura
- Medicinal Chemistry Technology Department, Teijin Institute for Bio-Medical Research, 4-3-2 Asahigaoka, Hino-shi, Tokyo 191-8512, Japan
| |
Collapse
|
3
|
Sahdev S, Khattar SK, Saini KS. Production of active eukaryotic proteins through bacterial expression systems: a review of the existing biotechnology strategies. Mol Cell Biochem 2007. [PMID: 17874175 DOI: 10.1007/s11010‐007‐9603‐6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Among the various expression systems employed for the over-production of proteins, bacteria still remains the favorite choice of a Protein Biochemist. However, even today, due to the lack of post-translational modification machinery in bacteria, recombinant eukaryotic protein production poses an immense challenge, which invariably leads to the production of biologically in-active protein in this host. A number of techniques are cited in the literature, which describe the conversion of inactive protein, expressed as an insoluble fraction, into a soluble and active form. Overall, we have divided these methods into three major groups: Group-I, where the factors influencing the formation of insoluble fraction are modified through a stringent control of the cellular milieu, thereby leading to the expression of recombinant protein as soluble moiety; Group-II, where protein is refolded from the inclusion bodies and thereby target protein modification is avoided; Group-III, where the target protein is engineered to achieve soluble expression through fusion protein technology. Even within the same family of proteins (e.g., tyrosine kinases), optimization of standard operating protocol (SOP) may still be required for each protein's over-production at a pilot-scale in Escherichia coli. However, once standardized, this procedure can be made amenable to the industrial production for that particular protein with minimum alterations.
Collapse
Affiliation(s)
- Sudhir Sahdev
- Department of Biotechnology & Bioinformatics, New Drug Discovery Research, Ranbaxy Research Laboratories-R&D-3, 20-Sector 18 Udyog Vihar, Gurgaon, India.
| | | | | |
Collapse
|
4
|
Sahdev S, Khattar SK, Saini KS. Production of active eukaryotic proteins through bacterial expression systems: a review of the existing biotechnology strategies. Mol Cell Biochem 2007; 307:249-64. [PMID: 17874175 DOI: 10.1007/s11010-007-9603-6] [Citation(s) in RCA: 254] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 08/27/2007] [Indexed: 12/13/2022]
Abstract
Among the various expression systems employed for the over-production of proteins, bacteria still remains the favorite choice of a Protein Biochemist. However, even today, due to the lack of post-translational modification machinery in bacteria, recombinant eukaryotic protein production poses an immense challenge, which invariably leads to the production of biologically in-active protein in this host. A number of techniques are cited in the literature, which describe the conversion of inactive protein, expressed as an insoluble fraction, into a soluble and active form. Overall, we have divided these methods into three major groups: Group-I, where the factors influencing the formation of insoluble fraction are modified through a stringent control of the cellular milieu, thereby leading to the expression of recombinant protein as soluble moiety; Group-II, where protein is refolded from the inclusion bodies and thereby target protein modification is avoided; Group-III, where the target protein is engineered to achieve soluble expression through fusion protein technology. Even within the same family of proteins (e.g., tyrosine kinases), optimization of standard operating protocol (SOP) may still be required for each protein's over-production at a pilot-scale in Escherichia coli. However, once standardized, this procedure can be made amenable to the industrial production for that particular protein with minimum alterations.
Collapse
Affiliation(s)
- Sudhir Sahdev
- Department of Biotechnology & Bioinformatics, New Drug Discovery Research, Ranbaxy Research Laboratories-R&D-3, 20-Sector 18 Udyog Vihar, Gurgaon, India.
| | | | | |
Collapse
|
5
|
Furuya M, Tsushima Y, Tani S, Kamimura T. Development of affinity chromatography using a bioactive peptide as a ligand. Bioorg Med Chem 2006; 14:5093-8. [PMID: 16650997 DOI: 10.1016/j.bmc.2006.04.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Revised: 04/03/2006] [Accepted: 04/04/2006] [Indexed: 11/19/2022]
Abstract
By repeatedly introducing hydrophilic polyethylene glycol (PEG) spacer (2) onto affinity resin bearing a bioactive peptide (1/2 secretory leukocyte protease inhibitor, 1/2SLPI) as a ligand, the adsorption of nonspecific binding proteins was effectively reduced and the purification efficacy of elastase, which is one of the target molecules for 1/2SLPI, from a protein mixture was improved. Moreover, using this resin, we also successfully detected L-plastin, as an endogenous target molecule for SLPI, from HL-60 cell lysate.
Collapse
Affiliation(s)
- Minoru Furuya
- Pharmaceutical Discovery Research Laboratories, Teijin Institute for Bio-medical Research, Teijin Pharma Ltd, 4-3-2 Asahigaoka, Hino, Tokyo 191-8512, Japan.
| | | | | | | |
Collapse
|
6
|
Miksch G, Bettenworth F, Friehs K, Flaschel E, Saalbach A, Twellmann T, Nattkemper TW. Libraries of synthetic stationary-phase and stress promoters as a tool for fine-tuning of expression of recombinant proteins in Escherichia coli. J Biotechnol 2005; 120:25-37. [PMID: 16019099 DOI: 10.1016/j.jbiotec.2005.04.027] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2004] [Revised: 03/31/2005] [Accepted: 04/12/2005] [Indexed: 11/23/2022]
Abstract
Due to their induction characteristics stationary-phase promoters have a great potential in biotechnological processes for the production of heterologous proteins on a large-scale. In order to broaden the utility of stationary-phase promoters in bacterial expression systems and to create novel promoters induced by metabolic conditions, a library of synthetic stationary-phase/stress promoters for Escherichia coli was constructed. For designing the promoters the known -10 consensus sequence as well as the extended -10 region and an A/T-rich region downstream of the -10 region were kept constant, while sequences from -37 to -14 were partially or completely randomized. For detection and selection of stationary-phase promoters GFP with enhanced fluorescence was used. The expression pattern of the GFP reporter system was compared with that of the LacZ reporter system. To screen and characterize colonies containing stationary-phase/stress promoters a bioinformatic approach was developed. In total, 33 promoters were selected which cover a broad range of promoter activities and induction times indicating that the strength of promoters can be modulated by partially randomizing the sequence upstream of the -10 region. The induction ratio of synthetic promoters at the transition from exponential to stationary-phase was from 4 to over 6000 and the induction time relative to the entrance into stationary-phase from -1.4 to 2.7 h. Ninety-one percentage of the promoters had no or only low background activity during exponential growth. The broad variability of the promoters offers good possibilities for fine-tuning of gene expression and for applications in industrial bioprocesses.
Collapse
Affiliation(s)
- Gerhard Miksch
- Lehrstuhl für Fermentationstechnik, Technische Fakultät, Universität Bielefeld, D-33594 Bielefeld, Germany.
| | | | | | | | | | | | | |
Collapse
|
7
|
|
8
|
Hollander C, Nyström M, Janciauskiene S, Westin U. Human mast cells decrease SLPI levels in type II - like alveolar cell model, in vitro. Cancer Cell Int 2003; 3:14. [PMID: 12952550 PMCID: PMC194615 DOI: 10.1186/1475-2867-3-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2003] [Accepted: 08/20/2003] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND: Mast cells are known to accumulate at sites of inflammation and upon activation to release their granule content, e.g. histamine, cytokines and proteases. The secretory leukocyte protease inhibitor (SLPI) is produced in the respiratory mucous and plays a role in regulating the activity of the proteases. RESULT: We have used the HMC-1 cell line as a model for human mast cells to investigate their effect on SLPI expression and its levels in cell co-culture experiments, in vitro. In comparison with controls, we found a significant reduction in SLPI levels (by 2.35-fold, p < 0.01) in a SLPI-producing, type II-like alveolar cell line, (A549) when co-cultured with HMC-1 cells, but not in an HMC-1-conditioned medium, for 96 hours. By contrast, increased SLPI mRNA expression (by 1.58-fold, p < 0.05) was found under the same experimental conditions. Immunohistochemical analysis revealed mast cell transmigration in co-culture with SLPI-producing A549 cells for 72 and 96 hours. CONCLUSION: These results indicate that SLPI-producing cells may assist mast cell migration and that the regulation of SLPI release and/or consumption by mast cells requires interaction between these cell types. Therefore, a "local relationship" between mast cells and airway epithelial cells might be an important step in the inflammatory response.
Collapse
Affiliation(s)
- Camilla Hollander
- Department of Otolaryngology and Head and Neck Surgery, University of Lund, SE-205 02 Malmö, Sweden
| | - Max Nyström
- Department of Surgical Pathophysiology, University of Lund, SE-205 02 Malmö, Sweden
- Department of Surgery, University of Lund, SE-205 02 Malmö, Sweden
| | | | - Ulla Westin
- Department of Otolaryngology and Head and Neck Surgery, University of Lund, SE-205 02 Malmö, Sweden
- Department of Surgical Pathophysiology, University of Lund, SE-205 02 Malmö, Sweden
| |
Collapse
|
9
|
Cunto-Amesty G, Luo P, Monzavi-Karbassi B, Kieber-Emmons T. Exploiting molecular mimicry: defining rules of the game. Int Rev Immunol 2002; 20:157-80. [PMID: 11878763 DOI: 10.3109/08830180109043032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Molecular mimicry has been touted as a mean to develop new generation of vaccines to target carbohydrate antigens on pathogens and on tumor cells. Structural and immunological rules governing molecular mimicry require definition for its successful exploitation. Of interest are the kinds of structures that peptides adopt as carbohydrate mimics, the extent to which topological or sequence similarities among peptide mimeotopes define serum cross-reactivity to carbohydrate antigens and the extent to which peptide mimeotopes affect T-cell responses. Rational design concepts can be applied to define how a peptide may mimic carbohydrate antigens, similarities in binding affinities of antibodies for carbohydrate and for peptides, how peptides can mimic core structures on otherwise dissimilar carbohydrate antigens, and how peptide mimeotopes can be used to manipulate cellular responses not achievable by carbohydrate antigens.
Collapse
Affiliation(s)
- G Cunto-Amesty
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia 19104, USA
| | | | | | | |
Collapse
|
10
|
Monzavi-Karbassi B, Cunto-Amesty G, Luo P, Kieber-Emmons T. Use of surrogate antigens as vaccines against cancer. HYBRIDOMA AND HYBRIDOMICS 2002; 21:103-9. [PMID: 12031099 DOI: 10.1089/153685902317401690] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Tumor cells may evade immune surveillance by possessing polysaccharides or carbohydrates on their surface. This evasive strategy is effective because glycans are poorly immunogenic and fail to elicit immunological memory responses due to an absence of T-cell processing. Induction of an immune response to cell surface carbohydrate antigens is considered as an important strategy to fight cancer. As carbohydrates per se are poor immunogens, alternative approaches are being evaluated to induce functional cross-reactive responses. We are focusing on the use of peptide mimotopes of tumor-associated carbohydrate antigens to challenge cancer, as we would manipulate the immune system to establish protective immunity based on carbohydrate cross-reactive humoral and cellular responses.
Collapse
|
11
|
Kikuchi T, Abe T, Yaekashiwa M, Tominaga Y, Mitsuhashi H, Satoh K, Nakamura T, Nukiwa T. Secretory leukoprotease inhibitor augments hepatocyte growth factor production in human lung fibroblasts. Am J Respir Cell Mol Biol 2000; 23:364-70. [PMID: 10970828 DOI: 10.1165/ajrcmb.23.3.3942] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Secretory leukoprotease inhibitor (SLPI), an 11.7-kD nonglycosylated serine protease inhibitor, is produced and released into the fluids of mucosal surfaces including human lung. It comprises two domains with homologous amino acid sequences: the N-terminal domain possessing antibacterial activity, and the C-terminal domain with antiprotease activity. Here we report the positive regulation of hepatocyte growth factor (HGF) production in human lung fibroblasts exerted by SLPI or its C-terminal domain under physiologic concentrations (1 to 10 microM). This HGF production by SLPI was unaffected by the addition of interleukin (IL)-1 receptor antagonist. In contrast, human skin fibroblasts exerted no SLPI-stimulated increase in HGF production, despite the fact that IL-1beta increased HGF production with an intensity similar to that of human lung fibroblasts. Both the time-course and dose-response studies in human lung fibroblasts revealed that the induction of HGF messenger RNA (mRNA) and protein occurred in parallel, indicating that the mechanism existed at the steady-state mRNA level. A synthetic elastase inhibitor failed to induce HGF, but alpha(1)-antitrypsin also stimulated HGF production in lung fibroblasts. Inactivation of the antiprotease activity of SLPI or its C-terminal domain by an oxidizing agent (N-chlorosuccinimide) abolished their stimulatory effect on HGF production. These findings demonstrate that SLPI exerts a novel HGF induction and functions as an anti-inflammatory and regenerative factor in addition to its role in protease inhibition.
Collapse
Affiliation(s)
- T Kikuchi
- Department of Respiratory Oncology and Molecular Medicine, Division of Cancer Control, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Sano C, Shimizu T, Sato K, Kawauchi H, Tomioka H. Effects of secretory leucocyte protease inhibitor on the production of the anti-inflammatory cytokines, IL-10 and transforming growth factor-beta (TGF-beta), by lipopolysaccharide-stimulated macrophages. Clin Exp Immunol 2000; 121:77-85. [PMID: 10886242 PMCID: PMC1905674 DOI: 10.1046/j.1365-2249.2000.01269.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We studied the effects of secretory leucocyte protease inhibitor (SLPI) on the production of the anti-inflammatory cytokines, IL-10 and TGF-beta, by lipopolysaccharide (LPS)-stimulated macrophages, using half-sized SLPI (1/2 SLPI) containing the C-terminal domain (Arg58-Ala107). ELISA testing of macrophage culture fluids showed a temporary production of IL-10 by the macrophages in the early phase (24 h) after LPS stimulation at low (1 ng/ml) or high (10 microg/ml) concentrations. On the other hand, TGF-beta production was initiated after day 3 and progressively increased. 1/2 SLPI significantly increased IL-10 and TGF-beta production by macrophages in response to a low dose as well as a high dose of LPS. Reverse transcription-polymerase chain reaction analysis showed that 1/2 SLPI caused a significant increase in the expression of both IL-10 and TGF-beta mRNAs by LPS-stimulated macrophages. Thus, although the profile of macrophage TGF-beta production by LPS-stimulated macrophages is markedly different from that of their IL-10 production, SLPI causes an up-regulation of the production of these anti-inflammatory cytokines by LPS-stimulated macrophages.
Collapse
Affiliation(s)
- C Sano
- Department of Microbiology and Immunology and Department of Otorhinolaryngology, Shimane Medical University, Izumo, Shimane, Japan
| | | | | | | | | |
Collapse
|
13
|
Qiu J, Luo P, Wasmund K, Steplewski Z, Kieber-Emmons T. Towards the development of peptide mimotopes of carbohydrate antigens as cancer vaccines. Hybridoma (Larchmt) 1999; 18:103-12. [PMID: 10211797 DOI: 10.1089/hyb.1999.18.103] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Tumor-associated carbohydrate antigens are considered important targets in efforts to develop cancer vaccines. To further enhance vaccine efforts, we are developing peptide mimotopes of tumor-associated carbohydrate antigens that can elicit functional immune responses. Mapping peptide epitopes with anticarbohydrate antibodies can lend to defining structural relationships that can go undetected by screening of carbohydrate antigens alone. Here we contrast reactivity patterns for peptides using monoclonal antibodies (MAbs) directed to the neolactoseries related Lewis Y (LeY) and sialyl-Lewis X (sLeX) antigen and the GD3/GD2 ganglioside antigen. We observe that representative MAbs cross-react with a WRY-containing peptide and that this motif type is isolated by the respective monoclonal in peptide phage display screening. Primary immunization with multiple antigen peptide preparations with QS-21 adjuvant efficiently elicited cytotoxic IgM antibodies for a murine Meth A fibrosarcoma line expressing sLeX. The cytotoxicity of IgG polyclonal response was found to be as effective as IgM in mediating complement-dependent cytotoxicity against the Meth A line. These experiments suggest that peptide mimotopes of the LeY and sLeX tumor-associated carbohydrate antigen and QS-21 adjuvant could be considered as an immunogenic therapeutic vaccine in carcinoma and melanoma patients in the minimal residual disease setting.
Collapse
Affiliation(s)
- J Qiu
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia 19104, USA
| | | | | | | | | |
Collapse
|
14
|
Luo P, Agadjanyan M, Qiu J, Westerink MA, Steplewski Z, Kieber-Emmons T. Antigenic and immunological mimicry of peptide mimotopes of Lewis carbohydrate antigens. Mol Immunol 1998; 35:865-79. [PMID: 9839555 DOI: 10.1016/s0161-5890(98)00067-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Peptides may substitute for carbohydrates in reactions with carbohydrate-specific molecules. Recently, we found that peptides containing aromatic residues mimic mucin and histo-blood group related carbohydrate epitopes, eliciting polyclonal responses cross-reactive with bacterial and viral antigens that express these carbohydrate forms. These results demonstrate that peptides can function in in vivo and in vitro models as carbohydrate surrogate antigens. To further explore the nature of the antigenic and immunogenic properties of such mimotopes, synthetic peptides with aromatic amino acids were tested to delineate reactivity patterns with several anti-neolactoseries monoclonal antibodies (MAbs). These MAbs recognize biologically important conformations of the histo-blood group related Lewis antigens expressed on the surface of a variety of human cancers. Results by ELISA demonstrate that the MAbs can distinguish particular peptide motifs that include the sequences GGIYYPYDIYYPYDIYYPYD, GGIYWRYDIYWRYDIYWRYD and GGIYYRYDIYYRYDIYYRYD. Substitution of Arg by Pro diminished the reactivity of the anti-Lewis Y (LeY) MAb BR55-2. Binding of LeY to BR55-2 was inhibitable by the Arg containing peptides. Serum against all three peptides displayed reactivity with synthetic histo-blood group related antigen probes. Immunologic presentation of the peptides as multiple antigen peptides (MAPs) improved peptide ability to induce LeY specific immune responses. Serum bound to human tumor cells that preferentially expressed neolactoseries antigens, but not to normal tissues. Immunoprecipitation of human breast tumor cell lysates before and after treatment with tunicamycin confirmed serum carbohydrate binding. The anti-peptide sera mediated tumor cell killing by complement mediated cytotoxicity. These results indicate that mapping peptide epitopes with anti-carbohydrate antibodies can lend to defining antibody fine specificities that can go undetected by screening of carbohydrate antigens alone. In addition, these results confirm that peptides and carbohydrates can bind to the same antibody binding site and that peptides can structurally mimic salient features of carbohydrate epitopes.
Collapse
Affiliation(s)
- P Luo
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | | | | | | | | |
Collapse
|
15
|
Abstract
Carbohydrate structures have been identified as significant antigens for bacterial, viral, and fungal pathogens as well as targets on human tumor cells. Many of these antigens are poorly immunogenic in humans, requiring extensive adjuvant sublimation. Although conjugate carbohydrate vaccines appear promising, there are limitations of using carbohydrate formulations. An alternative approach is to use surrogate antigens for some carbohydrates. We are developing peptides that mimic carbohydrates which might be further manipulated to induce responses that target biologically important carbohydrates expressed on pathogens and on tumor cells. We have shown that peptide mimotopes of carbohydrates induce immune responses to carbohydrate structures with in vivo and vitro functionality. Model systems include the Neisseria group C meningococcal polysaccharide; the histo-blood group-related antigens expressed on tumor cells; and mannose, sialyl, and histo-blood group-related carbohydrate epitopes expressed on human immunodeficiency virus.
Collapse
Affiliation(s)
- T Kieber-Emmons
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia 19104, USA.
| |
Collapse
|
16
|
Abstract
Progress in our understanding of several biological processes promises to broaden the usefulness of Escherichia coli as a tool for gene expression. There is an expanding choice of tightly regulated prokaryotic promoters suitable for achieving high-level gene expression. New host strains facilitate the formation of disulfide bonds in the reducing environment of the cytoplasm and offer higher protein yields by minimizing proteolytic degradation. Insights into the process of protein translocation across the bacterial membranes may eventually make it possible to achieve robust secretion of specific proteins into the culture medium. Studies involving molecular chaperones have shown that in specific cases, chaperones can be very effective for improved protein folding, solubility, and membrane transport. Negative results derived from such studies are also instructive in formulating different strategies. The remarkable increase in the availability of fusion partners offers a wide range of tools for improved protein folding, solubility, protection from proteases, yield, and secretion into the culture medium, as well as for detection and purification of recombinant proteins. Codon usage is known to present a potential impediment to high-level gene expression in E. coli. Although we still do not understand all the rules governing this phenomenon, it is apparent that "rare" codons, depending on their frequency and context, can have an adverse effect on protein levels. Usually, this problem can be alleviated by modification of the relevant codons or by coexpression of the cognate tRNA genes. Finally, the elucidation of specific determinants of protein degradation, a plethora of protease-deficient host strains, and methods to stabilize proteins afford new strategies to minimize proteolytic susceptibility of recombinant proteins in E. coli.
Collapse
Affiliation(s)
- S C Makrides
- Department of Molecular Biology, T Cell Sciences, Inc., Needham, Massachusetts 02194, USA
| |
Collapse
|