重组鹅 β-防御素4蛋白的原核表达及其生物学特性分析

In this paper a novel goose β-defensins 4 was isolated from goose by RT-PCR. Sequence analysis showed the gene fragment of goose AvBD4 consisted of 171 bp encoding 56 amino acids. In addition, phylogenetic relationships between the goose AvBD4 genes from other avian species, and some mammalian beta-defensin were analyzed. It was demonstrated that goose AvBD4 shared high amino acid homology 80.9% with chicken AvBD4.The cDNA of goose AvBD4 were cloned into EcoR I and Sal I sites of pProEX HTa vector,The recombinant expression plasmids were translated into Ecoli Rosseta and the bacteria were expression induced by IPTG.It was demonstrated by Tricine-SDS-PAGE that the recombinant protein was produced as insoluble bodies in the cells. Additionally, the goose AvBD4 recombinant protein was purified. Micrococcus tetragenus, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella pullorum were used to research the antibacterial activities of AvBD4 by colony counting method. The results indicated that the recombinant protein have different degrees of antibacterial activity. Furthermore, the effect of salt concentration on the antibacterial activity and hemolytic activity of the recombinant protein was investigated. The results indicated that in high salt ions conditions, antibacterial activity of recombinant protein was significantly decreased. The goose AvBD4 was not found significant hemolytic activity.