Characterization of single-chain antibody (sFv)-toxin fusion proteins produced in vitro in rabbit reticulocyte lysate
| Autor: | S. M. Andrew, Richard J. Youle, Jef C. M. Raus, H. R. Hoogenboom, Virginia Gray Johnson, P. J. Nicholls |
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| Rok vydání: | 1993 |
| Předmět: |
chemistry.chemical_classification
Diphtheria toxin viruses Mutant Cell Biology biochemical phenomena metabolism and nutrition Biology Biochemistry Molecular biology Fusion protein Amino acid Cell-free system medicine.anatomical_structure chemistry Reticulocyte medicine Pseudomonas exotoxin Molecular Biology Binding domain |
| Zdroj: | Journal of Biological Chemistry. 268:5302-5308 |
| ISSN: | 0021-9258 |
| Popis: | Chimeric proteins consisting of a fusion between binding-deficient mutants of diphtheria toxin (DT) or Pseudomonas exotoxin A (PE) and a single-chain antibody (E6 sFv) against the human transferrin receptor (TfnR) were expressed in a rabbit reticulocyte lysate system. Molecules utilizing PE40 (the carboxyl terminus 40 kDa of PE, lacking the binding domain) exhibited significant E6 sFv-mediated, cell type-specific cytotoxicity (IC50 1 x 10(-10) M) against a human erythroleukemia-derived cell line, K562. In contrast, a fusion protein between the same sFv and a DT mutant, DTM1 (containing two amino acid substitutions in the binding domain [S(508)F, S(525)F]) was not significantly cytotoxic, despite being enzymatically active. A tripartite protein in the form NH2-DTM1-E6 sFv-PE40-COOH exhibited cytotoxicity comparable to that of the PE40-sFv fusion (IC50 1 x 10(-10) M), suggesting that the deficit in activity of DTM1-sFv is not a function of misfolding of the sFv moiety or of a reduced ability to bind TfnR. In contrast to DTM1-E6 sFv, a fusion protein between a second DT mutant, CRM 107 [S(525)F], and the E6 sFv was specifically cytotoxic (IC50 1 x 10(-9) M), and toxicity could be blocked by addition of excess E6 antibody. The cell-free in vitro expression system we describe is rapid and may be used to express functional toxin-sFv fusion proteins. No protein refolding procedures are required, and the technique may be used to express proteins which, due to restrictions imposed on manipulation of toxin-encoding genes in Escherichia coli, could not be produced by more conventional methods. |
| Databáze: | OpenAIRE |
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