Conformational changes in two neurotoxic proteins from snake venoms

Area of Science:

• Biochemistry
• Structural Biology
• Neuroscience

Background:

• Neurotoxins are proteins that affect nerve function.
• Homologous neurotoxins share structural similarities but can exhibit different behaviors in varying environments.
• Understanding neurotoxin structure is crucial for developing treatments and studying neurological processes.

Purpose of the Study:

• To investigate the structural changes of alpha-neurotoxin and erabutoxin b in water/trifluoroethanol mixtures.
• To identify conserved structural elements within homologous neurotoxins.
• To explore the functional implications of structural modifications in neurotoxins.

Main Methods:

• Circular dichroism spectroscopy
• Ultraviolet spectroscopy
• Fluorescence spectroscopy
• Analysis of protein structure in mixed aqueous-organic solvents

Main Results:

• Alpha-neurotoxin's beta structure remained stable in both water and trifluoroethanol.
• Erabutoxin b transitioned from a beta structure in water to an alpha-helix structure in trifluoroethanol.
• Trifluoroethanol induced structural changes around conserved tryptophan 29 and tyrosine 25 residues in both toxins, suggesting a flexible aromatic region.

Conclusions:

• A specific structural region around aromatic residues (Trp29, Tyr25) is conserved and adaptable in neurotoxins.
• This conserved region can undergo independent structural rearrangement, suggesting significant biological importance.
• The differential response of alpha-neurotoxin and erabutoxin b highlights the nuanced structure-function relationships in homologous neurotoxins.