Molecular Cloning, Expression and Peroxidase Conjugation of Staphylococcus aureus Protein A

BACKGROUND: Staphylococcal protein A (SPA) is a cell wall component of Staphylococcus aureus that binds to different IgG subclasses of human and several animal species. This bacterial protein can be used as an antibody detector in various immunological assays or as an isolation reagent for the purification of antibody molecules via immuno-chromatography procedures. OBJECTIVES: Molecular cloning and expression of SPA followed by the purification and conjugation of the recombinant protein to peroxidase enzyme. MATERIAL AND METHODS: Encoding DNA fragment of SPA was amplified and inserted into a prokaryotic plasmid vector for the expression of recombinant SPA fused to a maltose binding protein (MBP). The recombinant protein was purified using amylose resin column chromatography and conjugated to horseradish peroxidase (HRP) enzyme. Finally, the reactivity of the recombinant SPA was examined against human IgG molecules in ELISA. RESULTS: The results indicated that the recombinant peroxidase-conjugated SPA has a good recognition capacity for human IgG molecules and it was able to produce significant OD values after reacting with human IgG molecules at a concentration up to 0.06 μg.well(-1). CONCLUSIONS: This recombinant protein can be very useful in all research laboratories and may decrease some of the expenses, e.g. those for preparing conjugated anti-antibodies.