Protein encapsulation within the internal cavity of a bacterioferritin

Abstract

The controlled, reversible dissociation of bacterioferritin allows the trapping of guest molecules such as proteins within the internal cavity.

Molecular Engineering of E. coli Bacterioferritin: A Versatile Nanodimensional Protein Cage

“…Motivation for this work was driven by two factors: an ever-expanding need to produce novel materials with diverse functionalities from self-assembling biomolecules, and the need to further understand how to incorporate additional sophistication into biological architectures. The goal was to design several structural features into the Bfr scaffold to provide additional versatility to the ferritin class of protein cages, a focus of great current interest [ 7 , 58 , 59 , 60 ]. The implementation of engineered non-native affinity linkers in the interior of Bfr and the presence of chemically modifiable heme cofactors has demonstrated that the interior surface can be controllably modified to encapsulate a diverse set of molecular guests all the while employing the same scaffold .…”

“…Substantial efforts are being made to utilize multimeric, self-assembling protein complexes in bionanotechnological applications [ 1 , 2 , 3 , 4 , 5 ]. Nanodimensional cage-proteins such as ferritins [ 6 , 7 ], cavity-containing enzymes [ 8 ], chaperonins [ 9 ], virus capsids [ 10 , 11 , 12 ], vault proteins [ 13 , 14 ], microbial microcompartments [ 15 , 16 , 17 ], and encapsulins [ 18 ] can be engineered with some precision to accommodate guest molecules within their hollow interior cavities. The strategic design of protein cages has resulted in the creation of biomolecular platforms capable of encapsulating a diverse set of guest molecules ranging from drugs [ 8 , 19 ], metal nanoparticles [ 20 , 21 ], enzymes [ 22 , 23 ], polymers [ 24 , 25 ], and oligonucleotides [ 26 ].…”

“…An encapsulation strategy was devised ( Figure 1 b), which required declustering of the engineered Bfr under non-denaturing conditions, affinity-selective complex formation between guest and declustered Bfr, and subsequent protein reclustering. Although the declustering and reclustering of capsule proteins such as ferritins has been found to be a successful approach to encapsulate a range of guest molecules, the affinity approach described herein was expected to lend itself to a more controllable entrapment strategy [ 4 , 7 , 50 , 51 ]. The first guest that was explored by this approach was a small molecular weight NTA-linked fluorescent dye, Pro-Q ® Sapphire 365 [ 52 , 53 ].…”

Ferritin-based nanomedicine for disease treatment

“…[ 60 ] employed TmFtn to encapsulate positively supercharged green fluorescent protein (+36GFP) that four +36GFP molecules were loaded into one TmFtn nanocage. Bacterioferritin (Bfr), which contained a heme prosthetic group at the interface of each subunit dimer, showing similar salt-induced disassembly/reassembly behavior [ 75 , 61 ]. Bradley et al.…”

“…Bradley et al. [ 61 ] also utilized this loading strategy to encapsulated ferredoxin into Bfr nanocage. Although salt-induced drug loading method was gentler, it has not been widely used since these archaeobacterial ferritins may cause stronger immune reaction compared with human ferritin.…”