nagZ

NagZ is a cytoplasmic beta-N-acetylglucosaminidase encoded by nagZ and found in a wide range of bacteria. It belongs to the glycoside hydrolase family 84 (GH84) and catalyzes the hydrolysis of the beta-(1,4) glycosidic bond between N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc) in peptidoglycan-derived muropeptides. The reaction releases GlcNAc and leaves MurNAc-containing peptides for further processing in the cell-wall recycling pathway.

Biological role and significance: NagZ contributes to the recycling of peptidoglycan components, helping to salvage carbohydrate units and maintain cell-wall homeostasis. In many Gram-negative bacteria, NagZ activity also influences signaling networks that regulate beta-lactamase expression through the AmpR regulator. By shaping the pool of cytoplasmic muropeptide signals, NagZ can affect inducible beta-lactamase production, impacting antibiotic resistance in species such as Pseudomonas aeruginosa and related pathogens.

Localization and interactions: The enzyme is typically cytoplasmic and functions alongside other cell-wall–recycling enzymes, including AmpG, AmpD, and AmpR, forming part of an integrated system that connects peptidoglycan turnover with gene regulation.

Clinical and research relevance: Because NagZ activity can promote AmpC beta-lactamase induction, it has been explored as a potential target for adjuvant therapies aimed at reducing beta-lactam resistance. Structural and kinetic studies across species have advanced understanding of NagZ catalysis and substrate specificity within GH84 enzymes.

See also: AmpC beta-lactamase, AmpR regulator, peptidoglycan recycling.