Bioinformatics classification of the MgtE Mg2+ channel and de novo protein design for the stabilization of its novel subclass

• Identified a novel 'mini-N type' subclass of MgtE channels lacking canonical N and CBS domains, expanding the known diversity of the MgtE family. • Demonstrated that de novo-designed protein fusions can stabilize and purify otherwise unstable membrane proteins, enabling structural studies. • Determined crystal structures of de novo-designed proteins and achieved preliminary cryo-EM imaging of a mini-N-type MgtE fusion. • Provides a promising strategy for structural and functional analysis of challenging membrane proteins, with potential implications for drug development and understanding Mg2+ homeostasis.