Lattice‐translocation defects in specific crystals of the catalytic head domain of influenza neuraminidase

Neuraminidase (NA) inhibitors are one of the two major classes of antivirals available for the treatment and prevention of influenza. X‐ray crystal structure determination of NA head domains and their complexes with various inhibitors are of importance for the design and optimization of anti‐influenza drugs. However, the globular tetrameric properties of NA head domains may produce crystals with pathological imperfections, lattice‐translocation defects, making structure determination no longer straightforward. In this report, using a crystal of the NA head domain from the Wuhan Asiatic toad influenza virus as an example, the identification and solution of this type of crystal pathology are presented. Furthermore, its underlying mechanism of formation is explored. Crystallization of the tetramer of the head domain of influenza neuraminidase (NA) may result in a specific crystal with space group C2221 and unit‐cell parameters a ≃ 120, b ≃ 143, c ≃ 120 Å. The molecular packing of NA tetramers in this crystal intrinsically causes pathological imperfections, lattice‐translocation defects, which complicate the structure determination.