Structural mapping of an aggregation nucleation site in a molten globule intermediate

Area of Science:

• Biochemistry
• Molecular Biology
• Protein Science

Background:

• Protein aggregation is implicated in various diseases and is a key consideration in biotechnology.
• Understanding the mechanisms of protein aggregation is crucial for developing therapeutic strategies and improving biotechnological processes.

Purpose of the Study:

• To investigate the molecular mechanisms underlying protein aggregation using human carbonic anhydrase II as a model system.
• To identify the specific regions and interactions involved in the formation of protein aggregates.

Main Methods:

• Utilized site-specific pyrene labeling of 20 cysteine mutants to probe intermolecular interactions.
• Measured excimer formation to localize interaction sites within the protein structure.
• Analyzed the structural characteristics of the aggregated protein states.

Main Results:

• Identified a molten globule state of human carbonic anhydrase II as the precursor to aggregate formation.
• Localized intermolecular interactions to a specific region within the large beta-sheet of the protein, between beta-strands 4 and 7.
• Demonstrated that this region is highly hydrophobic, highlighting the role of hydrophobic interactions in driving aggregation.

Conclusions:

• The study elucidates a specific mechanism of protein aggregation driven by hydrophobic interactions in a defined beta-sheet region.
• These findings provide critical insights into the structural basis of protein aggregation for human carbonic anhydrase II.
• The results contribute to a better understanding of aggregation-related diseases and inform protein engineering in biotechnology.