A new ?-helical motif in membrane active peptides

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Neurotoxins like apamin and charybdotoxin, and the hormone endothelin, exhibit distinct biological functions.
• Understanding the structural basis of their activity is crucial for molecular and pharmacological research.

Purpose of the Study:

• To comparatively analyze the primary and secondary structures of apamin, charybdotoxin, and endothelin.
• To identify conserved structural elements and their potential correlation with biological activity.

Main Methods:

• Comparative structural analysis of neurotoxins and a hormone.
• Identification of homologous sequence portions and secondary structure elements.
• Assessment of disulfide bridging patterns and amphiphilicity.

Main Results:

• A homologous structural motif, an alpha-helical stretch (Cys X-X-X Cys) disulfide-bonded to a beta-folded Cys X Cys sequence, was identified.
• This motif confers amphiphilicity, potentially linking to membrane-level bioactivities of neurotoxins.
• The identical motif was found in endothelin, suggesting a role in its hormonal activity.

Conclusions:

• A conserved structural motif exists across neurotoxins and endothelin.
• This motif may be key to the membrane-associated bioactivities of these molecules.
• Further investigation is warranted to elucidate endothelin's biological activity through this structural element.