Fusion Protein-Assisted Crystallization of Human SUMO1

Area of Science:

• Structural Biology
• Biochemistry
• Molecular Biology

Background:

• Human SUMO1 is a crucial protein modifier involved in various cellular processes.
• SUMO1 interacts with SUMO-interacting motifs (SIMs) and is essential for substrate modification.
• Previous attempts to crystallize SUMO1 in isolation were unsuccessful.

Purpose of the Study:

• To develop a novel method for crystallizing human SUMO1 in isolation.
• To obtain a high-resolution crystal structure of apo SUMO1.
• To assess the utility of the developed construct for studying SUMO1-SIM interactions and SUMOylation.

Main Methods:

• Employing a fusion protein strategy, fusing the TELSAM domain to human SUMO1 (residues 18-97).
• Utilizing a simple purification protocol to obtain the fusion protein.
• Determining the crystal structure of the TELSAM-SUMO1 fusion protein at 2.05 Å resolution.

Main Results:

• A 2.05 Å crystal structure of apo TELSAM-SUMO1 was obtained.
• The structure revealed left-handed helical filaments of TELSAM domains with protruding SUMO1 molecules.
• Two SUMO1 chains exhibited accessible pockets for SIM binding, and the TELSAM fusion did not impede SUMO:SIM interactions or substrate attachment.

Conclusions:

• The TELSAM fusion protein approach is effective for crystallizing human SUMO1 in isolation.
• This method provides a valuable tool for structurally characterizing SUMO1-SIM complexes.
• The construct holds potential for creating crystallizable SUMOylated protein forms.