Bottom-up design of calcium channels from defined selectivity filter geometry

Area of Science:

• Biophysics
• Structural Biology
• Computational Biology

Background:

• Native ion channels are vital in biology and engineered channels serve as tools.
• Designing ion selectivity, a key channel feature, is challenging due to precision limitations in residue placement.

Purpose of the Study:

• To develop a method for designing ion channels with controlled Ca2+ selectivity.
• To create symmetric oligomeric channels with specific Ca2+ selectivity filter geometries.

Main Methods:

• Utilized a bottom-up RFdiffusion-based computational approach.
• Designed Ca2+ channels with varying coordination numbers and geometries.
• Assembled designed proteins into homogenous particles.
• Performed patch-clamp experiments and cryo-electron microscopy.

Main Results:

• Designed tetrameric and hexameric channels demonstrated higher Ca2+ conductance than other ions.
• Cryo-electron microscopy confirmed high accuracy, with structures closely matching design models.
• The designed channels assembled into homogenous, pore-containing particles.

Conclusions:

• The bottom-up design approach enables precise construction of selective ion channels.
• This method facilitates testing structure-selectivity relationships.
• Provides a pathway for creating custom ion channels for diverse applications.