N5 Neuraminidase complexed with Laninamivir

Neuraminidase (NA) is a surface protein found on influenza A viruses. The NA enzyme is involved in the release of viruses from the infected host cell. It does so by acting on sialic acid– a receptor found on the host cell surface that hemaggluttinin (another viral surface protein) binds to. By hydrolysing sialic acid, the newly formed virus that is budding off from the host cell is able to do so without hindrance by the sialic acid-hemaggluttinin interaction. The annotations depict the important factors that are involved in the interaction between a particular type of NA (N5 serotype) and a novel neuraminidase inhibitor laninamivir. They highlight the importance of the 150-cavity (formed by amino acids 147-151 of the 150-loop) for high affinity binding of the laninamivir, structural features that confer flexibility to the 150-loop, as well as extra hydrogen bonds specific to the N5 NA serotype that may explain the high efficacy of laninamivir.