The repeat region of cortactin is intrinsically disordered in solution

Area of Science:

• Biochemistry
• Molecular Biology
• Protein Structure

Background:

• Cortactin is a multi-domain protein involved in actin dynamics.
• A key functional region of cortactin consists of multiple 37-residue repeats that bind actin filaments.

Purpose of the Study:

• To investigate the structural properties and fold of the cortactin repeat region.
• To determine if the cortactin repeat region undergoes homo-oligomerization in solution.

Main Methods:

• Size exclusion chromatography with multi-angle light scattering (SEC-MALS) to assess oligomerization.
• Circular dichroism (CD) spectroscopy to analyze protein secondary structure.
• Small-angle X-ray scattering (SAXS) to probe overall protein shape and folding.
• Hydrogen-deuterium exchange mass spectrometry (HDX-MS) to identify stable hydrophobic core regions.

Main Results:

• SEC-MALS demonstrated that cortactin repeat constructs do not homo-oligomerize.
• CD spectroscopy indicated a coil-like, intrinsically disordered structure in solution.
• SAXS data supported an unfolded conformation, consistent with theoretical calculations for unfolded peptides.
• HDX-MS revealed limited hydrophobic core formation within the repeat region.

Conclusions:

• The cortactin repeat region is intrinsically disordered in solution.
• This disordered nature may be important for its function in binding actin filaments.
• The findings provide insights into the structural flexibility of cortactin.