Recombinant expression and purification of a tumor-targeted toxin in Bacillus anthracis
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 (United States)
Highlights: Black-Right-Pointing-Pointer Non-infectious and protease-deficient Bacillus anthracis protein expression system. Black-Right-Pointing-Pointer Successful expression and purification of a tumor-targeted fusion protein drug. Black-Right-Pointing-Pointer Very low endotoxin contamination of purified protein. Black-Right-Pointing-Pointer Efficient protein secretion simplifies purification. Black-Right-Pointing-Pointer Functional anti-tumor fusion protein purified. -- Abstract: Many recombinant therapeutic proteins are purified from Escherichia coli. While expression in E. coli is easily achieved, some disadvantages such as protein aggregation, formation of inclusion bodies, and contamination of purified proteins with the lipopolysaccharides arise. Lipopolysaccharides have to be removed to prevent inflammatory responses in patients. Use of the Gram-positive Bacillus anthracis as an expression host offers a solution to circumvent these problems. Using the multiple protease-deficient strain BH460, we expressed a fusion of the N-terminal 254 amino acids of anthrax lethal factor (LFn), the N-terminal 389 amino acids of diphtheria toxin (DT389) and human transforming growth factor alpha (TGF{alpha}). The resulting fusion protein was constitutively expressed and successfully secreted by B. anthracis into the culture supernatant. Purification was achieved by anion exchange chromatography and proteolytic cleavage removed LFn from the desired fusion protein (DT389 fused to TGF{alpha}). The fusion protein showed the intended specific cytotoxicity to epidermal growth factor receptor-expressing human head and neck cancer cells. Final analyses showed low levels of lipopolysaccharides, originating most likely from contamination during the purification process. Thus, the fusion to LFn for protein secretion and expression in B. anthracis BH460 provides an elegant tool to obtain high levels of lipopolysaccharide-free recombinant protein.
- OSTI ID:
- 22210363
- Journal Information:
- Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 1 Vol. 430; ISSN 0006-291X; ISSN BBRCA9
- Country of Publication:
- United States
- Language:
- English
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