Abstract: Rdrlec is a novel RNase gene form Rana dybowskii (GenBank accession No.EU384704) and its biological function has not been identified. In order to explore the biological activity of its encoded protein, the Rdrlec gene was adjusted according to Escherichia coli codon bias without changing its amino acids. The synthetic gene was inserted to the pET-28a (+) expression vector through the EcoR I and Hind III site, and the resulting recombination expression plasmid was named pET28-Rdrlec and transferred into Escherichia coli BL21 (DE3) strains. After induced with 0.5 mmol/L IPTG at 34℃ for 6 h, the fusion protein was found expressed mainly in inclusion body form. After a series of steps including refolding, enterokinase cutting and Ni-NTA affinity chromatographic purification, the wild type Rdrlec recombinant protein was obtained, and it showed a single band on SDS-PAGE. It showed enzymatic activity to degrade RNA intonucleotides, which suggests that this molecule has formed the correct spatial structure. The recombinant Rdrlec shows significant antibacterial activity against Escherichia coli and Staphylococcus aureus.

Key words: Rana dybowskii, Ribonuclease, Rdrlec, Prokaryotic expression, Antimicrobial activity