2cbj: Difference between revisions
No edit summary |
No edit summary |
||
| Line 5: | Line 5: | ||
==Overview== | ==Overview== | ||
O-linked N-acetylglucosamine (O-GlcNAc) modification of specific, serines/threonines on intracellular proteins in higher eukaryotes has been, shown to directly regulate important processes such as the cell cycle, insulin sensitivity and transcription. The structure, molecular mechanisms, of catalysis, protein substrate recognition/specificity of the eukaryotic, O-GlcNAc transferase and hydrolase are largely unknown. Here we describe, the crystal structure, enzymology and in vitro activity on human, substrates of Clostridium perfringens NagJ, a close homologue of human, O-GlcNAcase (OGA), representing the first family 84 glycoside hydrolase, structure. The structure reveals a deep active site pocket highly, conserved with the human enzyme, compatible with binding of O-GlcNAcylated, ... | O-linked N-acetylglucosamine (O-GlcNAc) modification of specific, serines/threonines on intracellular proteins in higher eukaryotes has been, shown to directly regulate important processes such as the cell cycle, insulin sensitivity and transcription. The structure, molecular mechanisms, of catalysis, protein substrate recognition/specificity of the eukaryotic, O-GlcNAc transferase and hydrolase are largely unknown. Here we describe, the crystal structure, enzymology and in vitro activity on human, substrates of Clostridium perfringens NagJ, a close homologue of human, O-GlcNAcase (OGA), representing the first family 84 glycoside hydrolase, structure. The structure reveals a deep active site pocket highly, conserved with the human enzyme, compatible with binding of O-GlcNAcylated, peptides. Together with mutagenesis data, the structure supports a variant, of the substrate-assisted catalytic mechanism, involving two aspartic, acids and an unusually positioned tyrosine. Insights into recognition of, substrate come from a complex with the transition state mimic, O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate, (Ki=5.4 nM). Strikingly, the enzyme is inhibited by the pseudosubstrate, peptide Ala-Cys(-S-GlcNAc)-Ala, and has OGA activity against, O-GlcNAcylated human proteins, suggesting that the enzyme is a suitable, model for further studies into the function of human OGA. | ||
==About this Structure== | ==About this Structure== | ||
2CBJ is a | 2CBJ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Clostridium_perfringens Clostridium perfringens] with CL and OAN as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Hyalurononglucosaminidase Hyalurononglucosaminidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.35 3.2.1.35] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2CBJ OCA]. | ||
==Reference== | ==Reference== | ||
| Line 30: | Line 30: | ||
[[Category: o-glcnac]] | [[Category: o-glcnac]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 15:09:00 2007'' | ||