From Proteopediaproteopedia link
Cyrstal structure of the native 1918 H1N1 neuraminidase from a crystal with lattice-translocation defects
[NRAM_I18A0] Catalyzes the removal of terminal sialic acid residues from viral and cellular glycoconjugates. Cleaves off the terminal sialic acids on the glycosylated HA during virus budding to facilitate virus release. Additionally helps virus spread through the circulation by further removing sialic acids from the cell surface. These cleavages prevent self-aggregation and ensure the efficient spread of the progeny virus from cell to cell. Otherwise, infection would be limited to one round of replication. Described as a receptor-destroying enzyme because it cleaves a terminal sialic acid from the cellular receptors. May facilitate viral invasion of the upper airways by cleaving the sialic acid moities on the mucin of the airway epithelial cells. Likely to plays a role in the budding process through its association with lipid rafts during intracellular transport. May additionally display a raft-association independent effect on budding. Plays a role in the determination of host range restriction on replication and virulence. Sialidase activity in late endosome/lysosome traffic seems to enhance virus replication (By similarity). Unlike other strains, A/WSN/33 neuraminidase binds and activates plasminogen into plasmin in the vicinity of HA so that activated plasmin cleaves HA rendering the virus infectious (By similarity).
Publication Abstract from PubMed
Few examples of macromolecular crystals containing lattice-translocation defects have been published in the literature. Lattice translocation and twinning are believed to be two common but different crystal-growth anomalies. While the successful use of twinned data for structure determination has become relatively routine in recent years, structure determination of crystals with lattice-translocation defects has not often been reported. To date, only four protein crystal structures containing such a crystal defect have been determined, using corrected, but not uncorrected, intensity data. In this report, the crystallization, structure determination and refinement of N1 neuraminidase derived from the 1918 H1N1 influenza virus (18NA) at 1.65 A resolution are described. The crystal was indexed in space group C222(1), with unit-cell parameters a = 117.7, b = 138.5, c = 117.9 A, and the structure was solved by molecular replacement. The lattice-translocation vector in the 18NA crystal was (0, 1/2, 1/2) or its equivalent vector (1/2, 0, 1/2) owing to the C lattice symmetry. Owing to this special lattice-translocation vector in space group C222(1), structure refinement could be achieved in two different ways: using corrected or uncorrected diffraction data. In the refinement with uncorrected data, a composite model was built to represent the molecules in the translated and untranslated layers, respectively. This composite structure model provided a unique example to examine how the molecules were arranged in the two lattice domains resulting from lattice-translocation defects.
Structure determination of the 1918 H1N1 neuraminidase from a crystal with lattice-translocation defects.,Zhu X, Xu X, Wilson IA Acta Crystallogr D Biol Crystallogr. 2008 Aug;64(Pt 8):843-50. Epub 2008, Jul 17. PMID:18645233
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.