Efficient expression of recombinant human heavy chain ferritin (FTH1) with modified peptides

•Fusion of PfTrx greatly improved the solubility of His-tagged FTH1.•FTH1-PfTrx-His could be applied for presenting different polypeptides.•FTH1-PfTrx-His is an ideal platform to present functional peptides for drug delivery and molecular imaging.

Human heavy chain ferritin (FTH1) can self-assemble into a diameter of 12-nm spherical cage with an interior cavity of 8 nm in diameter. FTH1 has great potential as a nanocage in molecular imaging and drug delivery. Different peptides have been fused with FTH1 for targeting delivery; however, the expression of FTH1 modified with peptides in soluble form is not equivalent to natural FTH1. As shown in recent study, a novel scaffold protein --thioredoxin from the archaebacterium Pyrococcus furiosus (PfTrx)--exhibits a superior solubilization capacity and thermal stability [19]. Here we report a new construct (FTH1-PfTrx-His) that can be easily expressed and purified in Escherichia coli. Of note, different peptides inserted into FTH1-PfTrx-His did not influence the expression of proteins. Finally, the doxorubicin packaging ability of FTH1-PfTrx-His is comparable to natural FTH1. Our results showed that FTH1-PfTrx-His had a potential role as a novel peptide-modified ferritin carrier for drugs or imaging probes.