Converting histidine-induced 3D protein arrays in crystals into their 3D analogues in solution by metal coordination cross-linking

Abstract

Histidine (His) residues represent versatile motifs for designing protein-protein interactions because the protonation state of the imidazole group of His is the only moiety in protein to be significantly pH dependent under physiological conditions. Here we show that, by the designed His motifs nearby the C4 axes, ferritin nanocages arrange in crystals with a simple cubic stacking pattern. The X-ray crystal structures obtained at pH 4.0, 7.0, and 9.0 in conjunction with thermostability analyses reveal the strength of the π–π interactions between two adjacent protein nanocages can be fine-tuned by pH. By using the crystal structural information as a guide, we constructed 3D protein frameworks in solution by a combination of the relatively weak His–His interaction and Ni2+-participated metal coordination with Glu residues from two adjacent protein nanocages. These findings open up a new way of organizing protein building blocks into 3D protein crystalline frameworks.

Kinetics of Ferritin Self-Assembly by Laser Light Scattering: Impact of Subunit Concentration, pH, and Ionic Strength

“…Interestingly, His residues (especially at the C 4 interfaces) have also been exploited to mediate/modulate the self-assembly phenomena in recombinant human H chain ferritin and recombinant shrimp ferritin. 46,47 Under all sets of varying reaction conditions, the DLS size distribution profile at the beginning and end of the kinetic run indicated a shift in hydrodynamic radius, R h , that confirmed the reassembly of ferritin subunits into a 24-mer nanocage structure (Figure S6 and Table S1). However, recent investigations based on the pH dependent structural changes in horse spleen ferritin and horse liver ferritin using atomic force microscopy (AFM) have reported higher size values (14−24 nm) even at pH ≤ 7.0, possibly due to the conformational changes/cage swelling/deformation with disassembled fragments.…”

“…However, the solution-state investigation of the significance of these histidine residues on the intra- and inter-subunit interactions and ultimately on the process of BfMF self-assembly remains a future perspective of the current work. Interestingly, His residues (especially at the C 4 interfaces) have also been exploited to mediate/modulate the self-assembly phenomena in recombinant human H chain ferritin and recombinant shrimp ferritin. , …”

Spatiotemporal control over 3D protein nanocage superlattices for the hierarchical encapsulation and release of different cargo molecules

“…35,36 Recently, we made an MjFer mutant via single mutation, in which Thr158 was replaced by histidine ( T158H MjFer), that can self-assemble into 3D protein nanocage arrays in response to Ni 2+ . 37 Since the 3D protein assembly is mainly controlled by Ni 2+ coordination, it is hardly affected by pH changes in solution; by contrast, the pH has a considerable effect on the assembly of our other recently constructed 3D protein nanocage frameworks via hydrophobic or π–π stacking interactions. 18,19 In addition, the designed His158 in the mutant T158H MjFer is located on the outer surface nearby the C 4 channels, which is also involved in the above 3D protein assembly through π–π interactions.…”

“…18,19 In addition, the designed His158 in the mutant T158H MjFer is located on the outer surface nearby the C 4 channels, which is also involved in the above 3D protein assembly through p-p interactions. 37 To simplify the design challenge, we used T158H MjFer as the starting material for further design.…”

Directed Compartmentalization of Mg2+ and Carbonic Anhydrase by Designed Three-Dimensional Protein Crystalline Frameworks for Efficient Conversion of CO2 into Nanoparticles

“…Protein-based nanomaterials by the rational design hold great promise to their applications. − In this study, by using dimeric ferritin as building blocks, we designed and constructed 3D protein crystalline frameworks which consist of two compartments, namely, the small inner cavity of ferritin nanocage and the large interglobular space, as shown in Scheme . With the three-dimensional (3D) frameworks as nanocarriers, directed compartmentalization of Mg 2+ and carbonic anhydrase (CA) can be realized using a one-pot method by taking advantage of both the great difference between these two molecular cargos in size and the specific binding of Mg 2+ on the inner surface of the ferritin nanocage.…”