OPTIMIZATION OF RECOMBINANT PROTEIN EXPRESSION FOR CELL-PENETRATING PEPTIDE FUSIONS TO PROTEIN CARGO

Abstract

Recombinant production of cell-penetrating peptides (CPPs) as fusions to protein “cargo” leads to low yields for some CPP-cargo fusions; thus, ways to enhance the recombinant expression of peptide-cargo fusions need to be identified. We optimized expression conditions for fusions of five CPPs (NPFSD, pVEC, SynB, histatin-5 and MPG) to the cargo proteins biotin carboxyl carrier protein (BCCP), maltose binding protein (MBP) and green fluorescent protein GFP. Glutathione-S-transferase was incorporated as a fusion partner to improve expression. In general, expression at 37 oC for 6 h and 10 h led

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to the highest levels of expression for the different CPP-cargo constructs. The fusion of histatin-5 to GFP was purified, and its translocation into the fungal pathogen Candida albicans was studied. The purified protein translocated into the nearly 3% of C. albicans cells. These results provide the foundation for future studies to improve translocation of varied CPP-cargo fusions into C. albicans cells.