Molecular basis for dimer formation of TRbeta variant D355R

Area of Science:

• Structural Biology
• Protein Engineering
• Drug Discovery

Background:

• Protein stability and quality are crucial for X-ray crystallography.
• Easily manipulated and crystallizable proteins are valuable for high-throughput screening in drug design.

Purpose of the Study:

• To engineer a stable dimeric form of the human thyroid hormone receptor ligand-binding domain (TR LBD).
• To utilize X-ray crystallography to determine the structure of the engineered TR LBD dimer.

Main Methods:

• Site-directed mutagenesis to introduce the D355R mutation.
• Protein purification and crystallization.
• X-ray crystallography and structure refinement to 2.2 Å resolution.

Main Results:

• A single surface mutation (D355R) converted the monomeric TR LBD into a stable dimer.
• The crystal structure revealed a TR dimer with twofold symmetry.
• An ionic interface formed by Arg 355 and Glu 324 contributed to a 1330 Ų dimerization interface.

Conclusions:

• The D355R mutation successfully engineered a stable TR LBD dimer.
• The dimeric TR LBD structure provides insights into protein-protein interactions for drug discovery.
• This engineered protein is suitable for high-throughput crystallography applications.