Codon optimization,prokaryotic expression and affinity determination of B domain of staphylococcal protein A

For efficient expression of recombinant protein BB-SPA which could specifically combined with immunoglobulins(Igs) of human,cattle,goat,rabbit,guinea pig and chicken and so on, B-SPA gene encoding Ig combination domain(B domain) of staphylococcal protein A(SPA) was designed and split to four oligonucleotide fragments. The B-SPA gene was amplified by using overlap extension PCR. Recombinant expression vector pET30a-BB-SPA was constructed and transformed into Escherichia coli Rosetta(DE3) pLysS. Recombinant protein BB-SPA with molecular weight about 14ku was expressed,and its relative expression load was 56%. Western-blot and ELISA results confirmed that BB-SPA had good biological activity.This study provided material support for purification and detection of a variety of animal immunoglobulins and development of diagnosis reagent.