Direct Structural Annotation of Membrane Protein Aggregation Loci using Peptide-Based Reverse Mapping.

Area of Science:

• Biochemistry
• Molecular Biology
• Neuroscience

Background:

• Membrane protein aggregation is implicated in neurodegenerative diseases.
• The molecular determinants driving the transition from functional proteins to amyloidogenic aggregates are not fully understood.

Purpose of the Study:

• To develop and validate a reverse-mapping method for identifying molecular elements responsible for protein aggregation.
• To elucidate the structural switch from functional human β-barrel nanopore ion channels to amyloidogenic aggregates.

Main Methods:

• Coupling bottom-up synthesis with time-resolved aggregation kinetics.
• Utilizing high-resolution imaging techniques.
• Applying a novel reverse-mapping strategy to identify aggregation loci.

Main Results:

• Identified specific molecular elements that trigger the transition of folded channels to polymeric, β-rich aggregates.
• Demonstrated that protein aggregation and amyloidogenicity are determined by single residue differences in primary sequence, not total hydrophobicity.
• Validated the reverse-mapping method using human β-barrel nanopore ion channels.

Conclusions:

• The developed reverse-mapping method effectively identifies molecular drivers of protein aggregation.
• Sequence-specific interactions, rather than bulk hydrophobicity, are critical for amyloid formation in membrane proteins.
• This approach provides a foundation for designing sequence-based aggregation inhibitors for neurodegenerative diseases.