Title : Characterization of beta-N-acetylglucosaminidase cleavage by caspase-3 during apoptosis
Abstract :
Beta-O-linked N-acetylglucosamine is a dynamic post-translational modification involved in protein regulation in a manner similar to phosphorylation
Removal of N-acetylglucosamine is regulated by beta-N-acetylglucosaminidase ( O-GlcNAcase ), which was previously shown to be a substrate of caspase-3 in vitro
Here we show that O-GlcNAcase is cleaved by caspase-3 into two fragments during apoptosis, an N-terminal fragment containing the O-GlcNAcase active site and a C-terminal fragment containing a region with homology to GCN5 histone acetyl-transferases
The caspase-3 cleavage site of O-GlcNAcase , mapped by Edman sequencing, is a noncanonical recognition site that occurs after Asp-413 of the SVVD sequence in human O-GlcNAcase
A point mutation, D413A, abrogates cleavage by caspase-3 both in vitro and in vivo
Finally, we show that O-GlcNAcase activity is not affected by caspase-3 cleavage because the N- and C-terminal O-GlcNAcasefragments remain associated after the cleavage
Furthermore, when co-expressed simultaneously in the same cell, the N-terminal and C-terminal caspase fragments associate to reconstitute O-GlcNAcase enzymatic activity
These studies support the identification of O-GlcNAcase as a caspase-3 substrate with a novel caspase-3 cleavage site and provide insight about O-GlcNAcase regulation during apoptosis