Neuraminidase (influenza A virus H5N1 subtype) (N1)

Neuraminidase of influenza A virus H5N1 subtype is a tetrameric glycoprotein enzyme (EC 3.2.1.18) on the viral surface that cleaves α-ketosidic linkages between sialic acid (N-acetylneuraminic acid) and adjacent sugar residues on host glycans. This sialidase activity is essential for viral replication, enabling virions to penetrate mucus barriers in the respiratory tract, prevent aggregation of newly budded viruses by counterbalancing hemagglutinin binding, and facilitate release from infected cells. Structurally, it features a propeller-like head domain with a conserved active site cavity formed by 12 flexible loops and key residues like Arg118, Arg292, and Arg371, which catalyze hydrolysis via oxocarbonium ion formation. The H5N1 N1 subtype belongs to phylogenetic group 1, sharing high structural similarity with other N1 NAs but with subtype-specific loop variations influencing inhibitor susceptibility. As a validated antiviral target, neuraminidase inhibitors like zanamivir and oseltamivir bind the active site to block activity, though resistance via mutations poses challenges for pandemic strains like H5N1. Its interplay with hemagglutinin maintains functional balance critical for host adaptation and transmission.

Other names

Influenza A virus N1 neuraminidaseNASialidase

Competitive inhibition of sialic acid cleavage by mimicking transition state. Binding to active site residues (e.g., Arg118, Arg292, Arg371) to block enzymatic activity