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High-yield expression in Escherichia coli, biophysical characterization, and biological evaluation of plant toxin gelonin

Ding, Guo-Bin, Wu, Gengfeng, Li, Binchun, Yang, Peng, Li, Zhuoyu
3 Biotech 2019 v.9 no.1 pp. 19
Escherichia coli, antineoplastic activity, cell lines, circular dichroism spectroscopy, colorectal neoplasms, cytotoxicity, neoplasm cells, protein subunits, protein synthesis, ribosomal proteins, toxins
Gelonin is a plant toxin that exerts potent cytotoxic activity by inactivation of the 60S ribosomal subunit. The high-level expression of soluble gelonin still remains a great challenge and there was no detailed biophysical analysis of gelonin from Escherichia coli (E. coli) yet. In this study, the soluble and high-yield expression of recombinant gelonin (rGel) was achieved in E. coli BL21 (DE3) for the first time, with a yield of 6.03 mg/L medium. Circular dichroism (CD) analysis indicated that rGel consisted of 21.7% α-helix, 26.3% β-sheet, 18.5% β-turn, and 32.3% random coil, and it could maintain its secondary structure up to 60 °C. The antitumor activity of rGel was evaluated in two colon cancer cell lines—HCT116 and HCT-8, and it was clearly demonstrated that rGel exerted antiproliferative activity against these two cell lines by inhibiting cellular protein synthesis. These findings provide insights for researchers involved in the expression of similar biotoxins, and the biophysical characterizations of gelonin will favor its further therapeutic applications.