Molecular Recognition at Septin Interfaces: The Switches Hold the Key

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Septin filaments are crucial for cellular processes, requiring precise assembly of homologous monomers.
• Understanding the molecular basis of septin interactions is key to deciphering their function.

Purpose of the Study:

• To elucidate the structural basis of selective septin filament assembly.
• To characterize the distinct G-interfaces within septin complexes.

Main Methods:

• X-ray crystallography of heterodimeric septin complexes.
• Analysis of G-interface structures and conserved residues.

Main Results:

• Presented four crystal structures of heterodimeric septin complexes.
• Detailed the two distinct G-interfaces (SEPT2/SEPT6 and SEPT7/SEPT3) essential for filament formation.
• Demonstrated the role of switch I in discriminating between G-interfaces and subgroup-specific residues in ensuring correct assembly.

Conclusions:

• The structural insights explain the molecular recognition mechanisms governing septin filament assembly.
• Switch regions, particularly switch I, are repurposed for molecular recognition in septins.
• Subgroup-specific residues are critical for forming correct septin interfaces and ensuring functional filament assembly.