Structural Basis for Tetramerization of Klebsiella pneumoniae N-Acetylglucosamine-6-Phosphate Deacetylase.

N-acetylglucosamine-6-phosphate deacetylase (NagA) is a conserved enzyme involved in bacterial amino sugar metabolism, catalyzing the conversion of GlcNAc-6-phosphate to GlcN-6-phosphate and acetate. While NagA typically function as dimers, its quaternary diversity across species remains underexplored. Here, we present the crystal structure of Klebsiella pneumoniae (kpNagA), which forms a homotetrameric assembly both in crystal and in solution, as confirmed by SEC-MALS. Each monomer adopts a canonical (β/α)₈ TIM barrel fold with a β-sandwich subdomain, and its active site, located around β10-β11 and α3-α4, coordinates a divalent zinc ion. Comparative analyses revealed conserved dimer interfaces but divergent tetrameric arrangements. Notably, Pasteurella multocida NagA also forms a stable tetramer, albeit via a distinct interface. These findings suggest species-specific tetramerization and broaden our understanding of NagA structural diversity and potential antibiotic targets.