Butkinaree, Chutikarn. Win D. Cheung, Sungjin Park, Kyoungsook Park, Megan Barber, and Gerald W. Hart1, 2008, J. Biol. Chem., 283:23557-23566.
From the Departments of Biological Chemistry and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185
β-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 β-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-GlcNAcase fragments 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.
Note: The Anti-IgY agarose used in this publication was manufactured by Gallus Immunotech Inc.