Structural insights into calcium-induced conformational changes in human gelsolin.

Area of Science:

• Biochemistry
• Structural Biology
• Cell Biology

Background:

• Gelsolin is an actin-binding protein crucial for cytoskeleton regulation.
• It severs and caps filamentous actin, with calcium ions influencing its activity.

Purpose of the Study:

• To visualize the full-length gelsolin structure and elucidate its calcium-dependent interaction with actin filaments.
• To understand the conformational changes preceding gelsolin's active state.

Main Methods:

• Single-particle 3D reconstruction using electron microscopy (EM).
• Molecular dynamics simulations.

Main Results:

• Calcium ions induce subtle, domain-level structural changes in gelsolin prior to actin binding.
• These changes represent a preparatory phase for gelsolin's active state.
• Upon actin interaction, gelsolin undergoes more significant structural alterations for binding and severing.

Conclusions:

• This is the first visualization of full-length gelsolin, providing structural insights into its calcium-mediated activation.
• The findings clarify the mechanism by which gelsolin regulates the actin cytoskeleton.