4ac1 | pdb_00004ac1

The structure of a fungal endo-beta-N-acetylglucosaminidase from glycosyl hydrolase family 18, at 1.3A resolution

spinqualitylabelsall models 4ac1, resolution 1.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4ac1 is a 1 chain structure with sequence from Trichoderma reesei. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ACT, NAG, ZN Activity: Mannosyl-glycoprotein endo-beta-N-acetylglucosaminidase, with EC number 3.2.1.96 Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed Endo-N-acetyl-beta-D-glucosaminidases (ENGases) hydrolyze the glycosidic linkage between the two N-acetylglucosamine units that make up the chitobiose core of N-glycans. The endo-N-acetyl-beta-D-glucosaminidases classified into glycoside hydrolase family 18 are small, bacterial proteins with different substrate specificities. Recently two eukaryotic family 18 deglycosylating enzymes have been identified. Here, the expression, purification and the 1.3A resolution structure of the ENGase (Endo T) from the mesophilic fungus Hypocrea jecorina (anamorph Trichoderma reesei) are reported. Although the mature protein is C-terminally processed with removal of a 46 amino acid peptide, the protein has a complete (beta/alpha)8 TIM-barrel topology. In the active site, the proton donor (E131) and the residue stabilizing the transition state (D129) in the substrate assisted catalysis mechanism are found in almost identical positions as in the bacterial GH18 ENGases: Endo H, Endo F1, Endo F3, and Endo BT. However, the loops defining the substrate-binding cleft vary greatly from the previously known ENGase structures, and the structures also differ in some of the alpha-helices forming the barrel. This could reflect the variation in substrate specificity between the five enzymes. This is the first three-dimensional structure of a eukaryotic endo-N-acetyl-beta-D-glucosaminidase from glycoside hydrolase family 18. A glycosylation analysis of the cellulases secreted by a Hypocrea jecorina Endo T knock-out strain shows the in vivo function of the protein. A homology search and phylogenetic analysis show that the two known enzymes and their homologues form a large but separate cluster in subgroup B of the fungal chitinases. Therefore the future use of a uniform nomenclature is proposed. High Resolution Crystal Structure of the Endo-N-Acetyl-beta-D-Glucosaminidase Responsible for the Deglycosylation of Hypocrea jecorina Cellulases.,Stals I, Karkehabadi S, Kim S, Ward M, Van Landschoot A, Devreese B, Sandgren M PLoS One. 2012;7(7):e40854. Epub 2012 Jul 30. PMID:22859955 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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