Controlling Protein Nanocage Assembly with Hydrostatic Pressure

• Published in: Journal of the American Chemical Society 2020-12, Vol.142 (49), p.20640-20650
• Main Authors: Le Vay, Kristian, Carter, Ben M, Watkins, Daniel W, Dora Tang, T.-Y, Ting, Valeska P, Cölfen, Helmut, Rambo, Robert P, Smith, Andrew J, Ross Anderson, J. L, Perriman, Adam W
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Circular Dichroism; Cytochrome b Group - chemistry; Cytochrome b Group - metabolism; Dimerization; Escherichia coli - metabolism; Ferritins - chemistry; Ferritins - metabolism; Hydrostatic Pressure; Kinetics; Scattering, Small Angle; Thermodynamics; X-Ray Diffraction
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.0c07285

Controlling the assembly and disassembly of nanoscale protein cages for the capture and internalization of protein or non-proteinaceous components is fundamentally important to a diverse range of bionanotechnological applications. Here, we study the reversible, pressure-induced dissociation of a natural protein nanocage, E. coli bacterioferritin (Bfr), using synchrotron radiation small-angle X-ray scattering (SAXS) and circular dichroism (CD). We demonstrate that hydrostatic pressures of 450 MPa are sufficient to completely dissociate the Bfr 24-mer into protein dimers, and the reversibility and kinetics of the reassembly process can be controlled by selecting appropriate buffer conditions. We also demonstrate that the heme B prosthetic group present at the subunit dimer interface influences the stability and pressure lability of the cage, despite its location being discrete from the interdimer interface that is key to cage assembly. This indicates a major cage-stabilizing role for heme within this family of ferritins.