Endoplasmic reticulum chaperone GRP94 subunit assembly is regulated through a defined oligomerization domain

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• Glucose-regulated protein 94 (GRP94) is a key molecular chaperone in the endoplasmic reticulum lumen, belonging to the heat shock protein 90 (Hsp90) family.
• Understanding the structure-function relationships of GRP94 is crucial for elucidating its role in cellular processes and disease.

Purpose of the Study:

• To identify the specific structural domains responsible for GRP94 dimerization and self-assembly.
• To elucidate the molecular basis of GRP94 quaternary structure and activity.

Main Methods:

• Velocity sedimentation and gel filtration chromatography to analyze native GRP94 quaternary structure.
• Limited proteolysis to identify domains involved in assembly.
• In vitro translation and recombinant expression to synthesize and study C-terminal constructs.
• Rotary shadowing electron microscopy for molecular dimension analysis.

Main Results:

• Native GRP94 exists as an extended, rod-like dimer.
• A C-terminal domain (amino acids 676-719) was identified as critical for dimerization and displays autonomous oligomerization activity.
• A 44 amino acid domain within the C-terminus is sufficient for dimerization and confers an elongated structure.

Conclusions:

• The C-terminal domain of GRP94 is essential and sufficient for its dimerization and self-assembly.
• These findings provide a structural model for GRP94 and reveal the molecular mechanisms underlying its quaternary structure.