Structures of human O-GlcNAcase and its complexes reveal a new substrate recognition mode

Area of Science:

• Biochemistry
• Structural Biology
• Glycobiology

Background:

• Human O-GlcNAcase (hOGA) catalyzes the removal of O-linked β-N-acetyl glucosamine (O-GlcNAc) modifications.
• O-GlcNAc is a dynamic post-translational modification regulating protein function in response to cellular signals.

Purpose of the Study:

• To elucidate the structural basis of hOGA function.
• To provide the first structural model of a eukaryotic glycoside hydrolase 84 (GH84) family enzyme.

Main Methods:

• X-ray crystallography was used to determine the structures of a truncated hOGA.
• Structures were obtained in apo form, complexed with an inhibitor, and complexed with a glycopeptide substrate.

Main Results:

• hOGA forms an unusual arm-in-arm homodimer where stalk domains obscure catalytic domains.
• A distinct substrate-binding cleft is formed by the dimeric interface, interacting uniquely with peptide substrates.
• The observed substrate recognition mode differs significantly from bacterial homologs.

Conclusions:

• These structures provide unprecedented insight into the architecture and substrate recognition of eukaryotic GH84 enzymes.
• Understanding hOGA's structure is critical for elucidating its role in diverse biological and pathological processes.
• The findings serve as a foundation for future drug development targeting hOGA.