Controlled self-assembly of re-engineered insulin by Fe(II)

Area of Science:

• Biochemistry
• Protein Engineering
• Biophysical Chemistry

Background:

• Protein self-assembly is vital in biology, often regulated by metal ions.
• Controlling protein oligomeric states is key for understanding biological functions and developing new therapeutics.
• Insulin's hexameric form, stabilized by zinc(II), is crucial for its storage and formulation.

Purpose of the Study:

• To engineer an insulin variant for controlled self-assembly using an abiotic metal ion ligand.
• To achieve chemoselective binding of a metal ion to the engineered ligand over native protein sites.
• To develop a visually trackable method for monitoring protein self-assembly.

Main Methods:

• Re-engineering insulin by covalently attaching 2,2'-bipyridine.
• Utilizing iron(II) ions for selective metal-ligand binding.
• Spectrophotometric monitoring of the iron(II) complex for visual tracking of self-assembly.

Main Results:

• The engineered insulin variant selectively bound iron(II) via the bipyridine ligand.
• Formation of a well-defined insulin homotrimer was achieved in a reversible manner.
• The self-assembly process was visually trackable due to the distinct color of the iron(II) complex.

Conclusions:

• Chemoselective metal ion binding can control protein self-assembly.
• The engineered insulin variant provides the first visually trackable system for insulin trimer formation.
• This approach offers novel strategies for controlling protein oligomeric states and developing protein-based therapeutics.