View source for 1nnc

==INFLUENZA VIRUS NEURAMINIDASE SUBTYPE N9 (TERN) COMPLEXED WITH 4-GUANIDINO-NEU5AC2EN INHIBITOR==
<StructureSection load='1nnc' size='340' side='right' caption='[[1nnc]], [[Resolution|resolution]] 1.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1nnc]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Influenza_a_virus_(a/tern/australia/g70c/1975(h11n9)) Influenza a virus (a/tern/australia/g70c/1975(h11n9))]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NNC OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1NNC FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=MAN:ALPHA-D-MANNOSE'>MAN</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=ZMR:ZANAMIVIR'>ZMR</scene></td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Exo-alpha-sialidase Exo-alpha-sialidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.18 3.2.1.18] </span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1nnc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1nnc OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1nnc RCSB], [http://www.ebi.ac.uk/pdbsum/1nnc PDBsum]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/NRAM_I75A5 NRAM_I75A5]] 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. 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/nn/1nnc_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/chain_selection.php?pdb_ID=2ata ConSurf].
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== Publication Abstract from PubMed ==
The three-dimensional X-ray structure of a complex of the potent neuraminidase inhibitor 4-guanidino-Neu5Ac2en and influenza virus neuraminidase (Subtype N9) has been obtained utilizing diffraction data to 1.8 A resolution. The interactions of the inhibitor, solvent water molecules, and the active site residues have been accurately determined. Six water molecules bound in the native structure have been displaced by the inhibitor, and the active site residues show no significant conformational changes on binding. Sialic acid, the natural substrate, binds in a half-chair conformation that is isosteric to the inhibitor. The conformation of the inhibitor in the active site of the X-ray structure concurs with that obtained by theoretical calculations and validates the structure-based design of the inhibitor. Comparison of known high-resolution structures of neuraminidase subtypes N2, N9, and B shows good structural conservation of the active site protein atoms, but the location of the water molecules in the respective active sites is less conserved. In particular, the environment of the 4-guanidino group of the inhibitor is strongly conserved and is the basis for the antiviral action of the inhibitor across all presently known influenza strains. Differences in the solvent structure in the active site may be related to variation in the affinities of inhibitors to different subtypes of neuraminidase.

Three-dimensional structure of the complex of 4-guanidino-Neu5Ac2en and influenza virus neuraminidase.,Varghese JN, Epa VC, Colman PM Protein Sci. 1995 Jun;4(6):1081-7. PMID:7549872<ref>PMID:7549872</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[Neuraminidase|Neuraminidase]]
== References ==
<references/>
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</StructureSection>
[[Category: Exo-alpha-sialidase]]
[[Category: Colman, P M]]
[[Category: Varghese, J N]]
[[Category: Neuraminidase]]
[[Category: Sialidase]]