Title : Structural Basis for Ceramide Recognition and Hydrolysis by
Human Neutral Ceramidase
Abstract :
- Neutral ceramidase ( nCDase ) catalyzes conversion of the apoptosis-associated lipid ceramide to sphingosine, the precursor for the proliferative factor sphingosine-1-phosphate
- As an enzyme regulating the balance of ceramide and sphingosine-1-phosphate, nCDase is emerging as a therapeutic target for cancer
- Here, we present the 2.6-Å crystal structure of human nCDase in complex with phosphate that reveals a striking, 20-Å deep, hydrophobic active site pocket stabilized by a eukaryotic-specific subdomain not present in bacterial ceramidases
- Utilizing flexible ligand docking, we predict a likely binding mode for ceramide that superimposes closely with the crystallographically observed transition state analog phosphate
- Our results suggest that nCDase uses a new catalytic strategy for Zn(2+)-dependent amidases, and generates ceramide specificity by sterically excluding sphingolipids with bulky headgroups and specifically recognizing the small hydroxyl head group of ceramide
- Together, these data provide a foundation to aid drug development and establish common themes for how proteins recognize the bioactive lipid ceramide