MISO: microfluidic protein isolation enables single-particle cryo-EM structure determination from a single cell...

Area of Science:

• Structural biology
• Biochemistry
• Microfluidics

Background:

• Single-particle cryogenic electron microscopy (cryo-EM) provides atomic-resolution 3D protein structures.
• Current cryo-EM methods require large amounts of purified protein, limiting structural studies.
• Picogram quantities of protein are theoretically sufficient for cryo-EM, but practical limitations exist.

Purpose of the Study:

• To develop a method for high-resolution cryo-EM structural determination using significantly reduced protein quantities.
• To overcome the limitations of current cryo-EM sample preparation protocols.
• To enable structural characterization of proteins previously inaccessible due to low abundance.

Main Methods:

• Development of the micro isolation (MISO) method, integrating microfluidics for protein purification and automated cryo-EM grid preparation.
• Application of MISO to soluble bacterial and eukaryotic membrane proteins.
• Optimization of sample processing from cells to cryo-EM grids within hours.

Main Results:

• Successful determination of cryo-EM structures from less than 1 µg of target protein.
• Reduction of starting biological material by hundreds to thousands of times compared to conventional methods.
• Demonstration of rapid sample-to-grid preparation (within hours) using the MISO technique.

Conclusions:

• The MISO method dramatically lowers the protein input requirement for cryo-EM.
• This technique expands the scope of proteins amenable to high-resolution structural analysis.
• MISO offers a sensitive and efficient approach for structural biology research.