Abstract: Plant bifunctional nuclease 1 enzymes are responsible for plant growth and developmental processes, including senescence, and they also have anti-tumor effects in vitro. Based on the unigene sequences of the Sophora flavescens transcriptome data, the open reading frame (ORF) of bifunctional nuclease 1 gene (SfBFN1) from Sophora flavescens was cloned, and the physicochemical properties and structural characteristics of the encoded protein were analyzed. SfBFN1 was amplified by RT-PCR and further ligated into pET22b (+) vector, the recombinant plasmids were then transformed into BL21 competent cells. Optimization of the expression conditions for the SfBFN1 gene was performed at different temperatures and IPTG concentrations. The ORF fragment of SfBFN1 was 984 bp encoding SfBFN1 with 327 amino acids, which molecular weight was about 36.2 ku. SfBFN1 and the bifunctional nuclease 1 from Lupinus angustifolius showed the smallest genetic distance by the evolutionary analysis. The tertiary structure of SfBFN1 was predicted by PHYRE2 online software. The structure is rich in α helix and β fold, with five α helices wrapping seven β folds, forming the frame of the third dimension structure of the protein. The physicochemical properties and structural characteristics of SfBFN1 protein may lay the foundation for further studies on the protein as a potential anti-cancer drug.

Key words: Sophora flavescens Ait., bifunctional nuclease 1, gene clone, bioinformatics analysis