A target-specific chimeric toxin composed of epidermal growth factor and Pseudomonas exotoxin A with a deletion in its toxin-binding domain

C. W. Liao, T. H. Hseu, J. Hwang

Research output: Contribution to journalArticle

7 Citations (Scopus)


We have fused the epidermal growth factor (EGF) to the amino terminus of Pseudomonas exotoxin A (PE) to create a cytotoxic agent, designated EGF-PE, which preferentially kills EGF-receptor-bearing cells. In this study, we analyzed the effect of the Ia domain, the binding domain, of PE on the cytotoxicity of EGF-PE towards EGF-receptor-bearing cells and tried to develop a more potent EGF-receptor-targeting toxin. EGF-PE molecules with sequential deletions at the amino terminus of PE were constructed and expressed in E. coli strain BL21 (DE3). The cytotoxicity of these chimeric toxins was then examined. Our results show that the amino-terminal and carboxy-terminal regions of the Ia domain of PE are important for the cytotoxicity of a PE-based targeting toxin. To design a more potent PE-based EGF-receptor-targeting toxin, a chimeric toxin, named EGF-PE(Δ34–220), which had most of the Ia domain deleted but retained amino acid residues 1–33 and 221–252 of this domain, was constructed. EGF-PE(Δ34–220) has EGF-receptor-binding activity but does not show PE-receptor-binding activity and is mildly cytotoxic to EGF-receptor-deficient NR6 cells. As expected, EGF-PE(Δ34–220) is a more potent cytotoxic agent towards EGF-receptor-bearing cells than EGF-PE(Δ1–252), where the entire Ia domain of PE was deleted. In addition, EGF-PE(Δ34–220) was shown to be extremely cytotoxic to EGF-receptor-bearing cancer cells, such as A431, CE81T/VGH, and KB-3-1 cells. We also found that EGF-PE(Δ34–220) was highly expressed in BL21 (DE3) and could be easily purified by urea extraction. Thus, EGF-PE(Δ34–220) can be a useful cytotoxic agent towards EGF-receptor-bearing cells.

Original languageEnglish
Pages (from-to)498-507
Number of pages10
JournalApplied Microbiology and Biotechnology
Issue number3
Publication statusPublished - 1995
Externally publishedYes


ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology
  • Bioengineering
  • Microbiology

Cite this