The Many Faces of Amphipathic Helices

Area of Science:

• Biochemistry
• Structural Biology
• Cell Biology

Background:

• Amphipathic helices (AHs) are protein secondary structures characterized by segregated hydrophobic and polar residues.
• This amphipathic nature allows AHs to interact with polar-apolar interfaces, such as lipid bilayers of cellular membranes.

Purpose of the Study:

• To discuss how variations in AH structure influence their interfacial properties and membrane interactions.
• To highlight the diverse roles of AHs in cellular processes based on their tunable properties.

Main Methods:

• Review and discussion of various examples of amphipathic helices.
• Analysis of key structural parameters influencing AH-membrane interactions: residue properties (size, nature, charge, distribution), density, and helix length.

Main Results:

• Variations in hydrophobic and polar residue characteristics, density, and helix length dictate specific interfacial properties of AHs.
• These tunable properties enable AHs to deform lipid bilayers, sense curvature, recognize lipids, coat lipid droplets, and protect membranes.

Conclusions:

• Amphipathic helices exhibit diverse membrane-interacting capabilities driven by their structural parameters.
• AHs play essential roles in numerous cellular processes through their ability to modulate membrane properties and functions.