3gs6
Vibrio Cholerea family 3 glycoside hydrolase (NagZ)in complex with N-butyryl-PUGNAc
Structural highlights
FunctionNAGZ_VIBCH Plays a role in peptidoglycan recycling by cleaving the terminal beta-1,4-linked N-acetylglucosamine (GlcNAc) from peptide-linked peptidoglycan fragments, giving rise to free GlcNAc, anhydro-N-acetylmuramic acid and anhydro-N-acetylmuramic acid-linked peptides. Plays a role in beta-lactam antibiotic resistance via its role in generating anhydro-N-acetylmuramic acid-linked peptides; these peptides function as signaling molecules that induce high-level expression of the beta-lactamase AmpC.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedNagZ is an exo-N-acetyl-beta-glucosaminidase, found within Gram-negative bacteria, that acts in the peptidoglycan recycling pathway to cleave N-acetylglucosamine residues off peptidoglycan fragments. This activity is required for resistance to cephalosporins mediated by inducible AmpC beta-lactamase. NagZ uses a catalytic mechanism involving a covalent glycosyl enzyme intermediate, unlike that of the human exo-N-acetyl-beta-glucosaminidases: O-GlcNAcase and the beta-hexosaminidase isoenzymes. These latter enzymes, which remove GlcNAc from glycoconjugates, use a neighboring-group catalytic mechanism that proceeds through an oxazoline intermediate. Exploiting these mechanistic differences we previously developed 2-N-acyl derivatives of O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate (PUGNAc), which selectively inhibits NagZ over the functionally related human enzymes and attenuate antibiotic resistance in Gram-negatives that harbor inducible AmpC. To understand the structural basis for the selectivity of these inhibitors for NagZ, we have determined its crystallographic structure in complex with N-valeryl-PUGNAc, the most selective known inhibitor of NagZ over both the human beta-hexosaminidases and O-GlcNAcase. The selectivity stems from the five-carbon acyl chain of N-valeryl-PUGNAc, which we found ordered within the enzyme active site. In contrast, a structure determination of a human O-GlcNAcase homologue bound to a related inhibitor N-butyryl-PUGNAc, which bears a four-carbon chain and is selective for both NagZ and O-GlcNAcase over the human beta-hexosamnidases, reveals that this inhibitor induces several conformational changes in the active site of this O-GlcNAcase homologue. A comparison of these complexes, and with the human beta-hexosaminidases, reveals how selectivity for NagZ can be engineered by altering the 2-N-acyl substituent of PUGNAc to develop inhibitors that repress AmpC mediated beta-lactam resistance. Insight into a strategy for attenuating AmpC-mediated beta-lactam resistance: Structural basis for selective inhibition of the glycoside hydrolase NagZ.,Balcewich MD, Stubbs KA, He Y, James TW, Davies GJ, Vocadlo DJ, Mark BL Protein Sci. 2009 Apr 16. PMID:19499593[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
| ||||||||||||||||||||
