Molecular shape of vinculin in aqueous solution

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Vinculin is a key protein in cell-cell and cell-matrix adhesion.
• Understanding vinculin's molecular structure is crucial for elucidating its function in cellular processes.

Purpose of the Study:

• To investigate the molecular structure and shape of chicken gizzard vinculin in solution.
• To characterize the hydrodynamic properties of intact vinculin and its amino-terminal head fragment.

Main Methods:

• Photon correlation spectroscopy was used to determine the translational diffusion coefficient.
• Hydrodynamic calculations were performed, modeling the macromolecule's shape with spherical subunits.
• Proteolytic digestion was employed to obtain the amino-terminal head fragment.

Main Results:

• Results support a "balloon on a string" model for native vinculin's molecular shape.
• Dimer and oligomer structures in low ionic strength buffer were excluded.
• The head fragment, estimated as a sphere of r = 3.3 nm, showed a slightly anisotropic shape.
• The rod-like tail exhibited flexibility, likely in the neck region.

Conclusions:

• Chicken gizzard vinculin adopts a "balloon on a string" conformation in solution.
• The amino-terminal head fragment possesses a defined size with some anisotropy.
• The tail region displays flexibility, contributing to vinculin's overall structural dynamics.