BACTERIAL EXPRESSION AND PURIFICATION OF RECOMBINANT PLASMODIUM-YOELII CIRCUMSPOROZOITE PROTEIN

We report the expression and purification of recombinant rodent malari al Plasmodium yoelii circumsporozoite surface protein (PyCSP) in Esche richia coli. To facilitate purification of the recombinant protein, th e PyCSP was expressed as an amino-terminal fusion protein to glutathio ne S-transferase and as a carboxyterminal fusion protein to a hexahist idyl tag. The expression of the fusion protein was controlled by the i nducible tac promoter. Under optimal conditions the immunoreactive PyC SP represented approximately 0.04% of the total cell lysate. Western b lot analysis probing with an anti-PyCSP antibody revealed a wide array of immunoreactive bands. Material isolated by affinity purification o n glutathione-Sepharose 4B resin also contained multiple bands indicat ive of premature termination or carboxyl-terminal degradation. Analysi s of protein retained on a nickel nitrilotriacetic acid resin revealed evidence of amino-terminal deleted material. Combining the two mild a ffinity purifications resulted in isolation of a single immunoreactive protein of approximate molecular weight of 96 kDa. We anticipate that the approach described in this study will facilitate the production o f highly purified recombinant proteins. (C) 1997 Academic Press.