Design of Functional Ferritin-Like Proteins with Hydrophobic Cavities

Abstract

Ferritin four-helix bundle subunits self-assemble to create a stable multimer with a large central hydrophilic cavity where metal ions bind. To explore the versatility of this reaction vessel, computational design was used to generate cavities with increasingly apolar surface areas inside a dodecameric ferritin-like protein, Dps. Cavity mutants, in which as many as 120 surface accessible hydrophilic residues were replaced with hydrophobic amino acids, were shown to still assemble properly using size-exclusion chromatography and dynamic light scattering measurements. Wild-type Dps exhibited highly cooperative subunit folding and assembly, which was monitored by changes in Trp fluorescence and UV circular dichroism. The hydrophobic cavity mutants showed distinctly less cooperative unfolding behavior, with one mutant forming a partially assembled intermediate upon guanidine denaturation. Although the stability of Dps to such denaturation decreased with increasing apolar surface area, all proteins exhibited high melting temperatures, T(m) = 74-90 degrees C. Despite the large number of mutations, near-native ability to mineralize iron was maintained. This work illustrates the versatility of the ferritin scaffold for engineering large protein cavities with novel properties.

Characterization and cellular uptake of platinum anticancer drugs encapsulated in apoferritin

“…The CD spectra in the far-ultraviolet region were recorded to further ascertain any possible changes in the secondary structure of AFt after the encapsulation of platinum drugs [31]. Fig.…”

Rational disruption of the oligomerization of the mini‐ferritin E. coli DPS through protein‐protein interface mutation

“…Wildtype DPS protein formed solely 12-mer, consistent with the literature. 18,25,26 All the DPS single mutants assembled into 12-mers but four mutants also formed smaller oligomers. Mutation of W52 resulted in some unassembled monomer (6%) and the mutant Y16A formed a small amount (16%) of dimer along with 12-mer.…”

A Histidine Aspartate Ionic Lock Gates the Iron Passage in Miniferritins from Mycobacterium smegmatis

“…Dps is a member of the ferritin superfamily, which includes multisubunit cage-like proteins with a hollow interior. These nano-compartments can be exploited to encapsulate nanoparticles (62,63) or for building higher order assemblies (64,65). Also, the surface of these nano-vehicles can be modified to target tissue systems in vivo, forming suitable carriers for drug delivery (66).…”