Controlling Protein Nanocage Assembly with Hydrostatic Pressure.

Area of Science:

• Biochemistry
• Nanotechnology
• Structural Biology

Background:

• Controlling protein cage assembly/disassembly is crucial for bionanotechnology.
• E. coli bacterioferritin (Bfr) is a natural protein nanocage with potential applications.

Purpose of the Study:

• To investigate the reversible, pressure-induced dissociation and reassembly of E. coli bacterioferritin (Bfr).
• To understand the role of the heme B prosthetic group in Bfr stability and pressure lability.

Main Methods:

• Synchrotron radiation small-angle X-ray scattering (SAXS) to study structural changes.
• Circular dichroism (CD) spectroscopy to assess protein conformation.
• Controlled application of hydrostatic pressure (up to 450 MPa).

Main Results:

• Complete dissociation of the Bfr 24-mer into dimers was achieved at 450 MPa.
• Reassembly kinetics and reversibility were controllable via buffer conditions.
• Heme B influences Bfr stability and pressure-induced dissociation, despite its location.

Conclusions:

• Hydrostatic pressure is an effective tool for controlling Bfr disassembly and reassembly.
• Heme B plays a significant cage-stabilizing role in ferritins.
• Findings advance understanding of protein nanocage dynamics for bionanotechnological applications.