One-step protein purification: Use of a novel epitope tag for highly efficient detection and purification of recombinant proteins

We used the interaction between an epitope of the Tobacco mosaic virus 54K replicase (tag54) and its corresponding monoclonal antibody 54 (mAb54) for the design of a new epitope-tagging system. We fused the DNA sequence of tag54 and two elongated derivates thereof to the C-terminus of the chloramphenicol acetyltransferase (CAT) gene and produced the tagged proteins in tobacco. Immunoblot and ELISA analysis demonstrated that the tagged proteins were detected with high sensitivity in plant extracts. Moreover, the tag54 system enabled the full recovery of the recombinant CAT with excellent purity through immunoaffinity chromatography. We consider this novel epitope-tag system to be a valuable tool for both the detection and purification of recombinant proteins.