The Sequence and a Three-Dimensional Structural Analysis Reveal Substrate Specificity Among Snake Venom...

Area of Science:

• Biochemistry
• Structural Biology
• Toxicology

Background:

• Snake venom phosphodiesterases (SVPDEs) are understudied enzymes implicated in envenomation pathologies.
• Previous lack of 3D structures hindered detailed structure-function relationship studies of SVPDEs.

Purpose of the Study:

• To perform model-based structural and functional characterization of a phosphodiesterase from Crotalus adamanteus venom (PDE_Ca).
• To enable structure-function analysis of SVPDEs through 3D model development.

Main Methods:

• Utilized multiple software packages (I-TESSER, MODELLER 9v19, Swiss-Model) for PDE_Ca structure model building.
• Validated the model using PROCHECK, ERRAT, Molecular Dynamic Simulation, and Verif3D.

Main Results:

• The PDE_Ca model reveals a four-domain structure: somatomedin B, somatomedin B-like, ectonucleotide pyrophosphatase, and DNA/RNA non-specific domains.
• Sequence and structural analyses suggest domain composition and active site cavity properties influence substrate specificity among SVPDEs.

Conclusions:

• SVPDEs share high sequence identity among themselves but low identity with mammalian and bacterial phosphodiesterases.
• The developed 3D model provides a foundation for understanding SVPDE function and substrate specificity.