Sequence Context Influences the Structure and Aggregation Behavior of a PolyQ Tract.

Area of Science:

• Neurodegenerative diseases
• Protein aggregation
• Molecular biology

Background:

• Expansions of polyglutamine (polyQ) tracts in proteins cause neurodegenerative polyQ diseases.
• Understanding polyQ tract conformation and aggregation is crucial for therapeutic development.
• Spinobulbar muscular atrophy (Kennedy disease) is a polyQ disease linked to androgen receptor mutations.

Purpose of the Study:

• To investigate the structural conformation of polyQ tracts within their native sequence context.
• To determine how flanking sequences influence polyQ tract aggregation.
• To identify potential therapeutic strategies for polyQ diseases.

Main Methods:

• Solution Nuclear Magnetic Resonance (NMR) spectroscopy.
• Single-residue resolution analysis.
• Study of a 156-residue androgen receptor fragment.

Main Results:

• A Leu-rich region preceding the polyQ tract induced an alpha-helical conformation.
• This helical structure appeared to protect the protein fragment from aggregation.
• This represents a novel mechanism for sequence context to mitigate harmful polyQ properties.

Conclusions:

• Flanking sequences, specifically Leu-rich regions, can significantly alter polyQ tract behavior.
• The protective effect against aggregation suggests new therapeutic avenues.
• Targeting residues flanking polyQ tracts may be a viable strategy for drug discovery in polyQ diseases.