mem-iLID, a fast and economic protein purification method

Area of Science:

• Biochemistry
• Molecular Biology
• Biotechnology

Background:

• Protein purification is essential for studying protein function, structure, and interactions.
• Conventional methods like affinity chromatography often require harsh conditions (e.g., extreme pH, high salt, imidazole) that can compromise protein integrity.
• There is a need for mild, efficient, and scalable protein purification techniques.

Purpose of the Study:

• To establish an easy, fast, and mild protein purification method using light-induced dimerization.
• To demonstrate the flexibility and scalability of the developed method.
• To engineer a novel SspB mutant for improved protein release and reduced interference.

Main Methods:

• Utilized the improved light-induced dimer (iLID) system for light-regulated protein binding and release.
• Targeted the AsLOV2-SsrA component of iLID to the plasma membrane in Xenopus laevis oocytes and Escherichia coli.
• Fused the SspB component of iLID to the protein of interest (POI) for cytosolic expression.
• Captured SspB-POI to the membrane via light-induced dimerization and released it in the dark after centrifugation and washing.

Main Results:

• Successfully purified soluble proteins under mild conditions using the mem-iLID system.
• Demonstrated the purification of two functional enzymes: DNA polymerase and a light-activated adenylyl cyclase.
• Showcased the method's flexibility in scale and economic efficiency.
• Designed a new SspB mutant with enhanced dissociation properties.

Conclusions:

• The mem-iLID method provides a rapid, mild, and scalable approach for protein purification.
• This light-activated system simplifies protein isolation and preserves protein function.
• The developed SspB mutant holds potential for advancing optogenetic applications involving protein-protein interactions.