Helical crystallization of soluble and membrane binding proteins

Area of Science:

• Structural biology
• Biophysics
• Cryo-electron microscopy

Background:

• Helical protein arrays provide unique views for 3D structure determination via cryo-electron microscopy (cryo-EM).
• Proteins like actin and microtubules naturally form helical arrays, aiding decades of research.
• Most proteins do not spontaneously form helical arrays, limiting cryo-EM applications.

Purpose of the Study:

• To describe a method for forming helical protein arrays using functionalized lipid substrates.
• To enable the study of proteins that do not naturally assemble into helical structures.

Main Methods:

• Utilizing functionalized lipid nanotubes and liposomes as scaffolds.
• Binding soluble and membrane-associated proteins to these lipid structures.
• Employing cryo-electron microscopy (cryo-EM) for structure determination of the formed arrays.

Main Results:

• Demonstrated successful formation of helical arrays from non-native proteins.
• Enabled high-resolution 3D structure determination of previously difficult-to-study proteins.
• Improved signal-to-noise ratio through averaging of unit cells from multiple helical tubes.

Conclusions:

• Functionalized lipid nanotubes and liposomes are effective substrates for creating helical protein arrays.
• This approach expands the applicability of cryo-EM for structural studies of a wider range of proteins.
• Facilitates detailed structural insights into protein interactions and functions within helical assemblies.