View source for 2qwj


==THE X-RAY STRUCTURE OF A COMPLEX OF 5-N-ACETYL-4-AMINO-6-DIETHYLCARBOXAMIDE-4,5-DIHYDRO-2H-PYRAN-2-CARBOXYLIC ACID AND A DRUG RESISTANT VARIANT R292K OF TERN N9 INFLUENZA VIRUS NEURAMINIDASE==
<StructureSection load='2qwj' size='340' side='right'caption='[[2qwj]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2qwj]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/9infa 9infa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2QWJ OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=2QWJ FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=G28:5-N-ACETYL-4-AMINO-6-DIETHYLCARBOXAMIDE-4,5-DIHYDRO-2H-PYRAN-2-CARBOXYLIC+ACID'>G28</scene>, <scene name='pdbligand=MAN:ALPHA-D-MANNOSE'>MAN</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</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://proteopedia.org/fgij/fg.htm?mol=2qwj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2qwj OCA], [http://pdbe.org/2qwj PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=2qwj RCSB], [http://www.ebi.ac.uk/pdbsum/2qwj PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=2qwj ProSAT]</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/qw/2qwj_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/main_output.php?pdb_ID=2qwj ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
BACKGROUND: Inhibitors of the influenza virus neuraminidase have been shown to be effective antiviral agents in humans. Several studies have reported the selection of novel influenza strains when the virus is cultured with neuraminidase inhibitors in vitro. These resistant viruses have mutations either in the neuraminidase or in the viral haemagglutinin. Inhibitors in which the glycerol sidechain at position 6 of 2-deoxy-2,3-dehydro-N-acetylneuraminic acid (Neu5Ac2en) has been replaced by carboxamide-linked hydrophobic substituents have recently been reported and shown to select neuraminidase variants. This study seeks to clarify the structural and functional consequences of replacing the glycerol sidechain of the inhibitor with other chemical constituents. RESULTS: The neuraminidase variant Arg292--&gt;Lys is modified in one of three arginine residues that encircle the carboxylate group of the substrate. The structure of this variant in complex with the carboxamide inhibitor used for its selection, and with other Neu5Ac2en analogues, is reported here at high resolution. The structural consequences of the mutation correlate with altered inhibitory activity of the compounds compared with wild-type neuraminidase. CONCLUSIONS: The Arg292--&gt;Lys variant of influenza neuraminidase affects the binding of substrate by modification of the interaction with the substrate carboxylate. This may be one of the structural correlates of the reduced enzyme activity of the variant. Inhibitors that have replacements for the glycerol at position 6 are further affected in the Arg292--&gt;Lys variant because of structural changes in the binding site that apparently raise the energy barrier for the conformational change in the enzyme required to accommodate such inhibitors. These results provide evidence that a general strategy for drug design when the target has a high mutation frequency is to design the inhibitor to be as closely related as possible to the natural ligands of the target.

Drug design against a shifting target: a structural basis for resistance to inhibitors in a variant of influenza virus neuraminidase.,Varghese JN, Smith PW, Sollis SL, Blick TJ, Sahasrabudhe A, McKimm-Breschkin JL, Colman PM Structure. 1998 Jun 15;6(6):735-46. PMID:9655825<ref>PMID:9655825</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 2qwj" style="background-color:#fffaf0;"></div>

==See Also==
*[[Neuraminidase 3D structures|Neuraminidase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Exo-alpha-sialidase]]
[[Category: Large Structures]]
[[Category: Varghese, J N]]
[[Category: Carboxamide derivative]]
[[Category: Dana anologue]]
[[Category: Drug resistant variant]]
[[Category: Glycosylated protein]]
[[Category: Hydrolase]]
[[Category: Influenza protein]]
[[Category: Neuraminidase]]
[[Category: Sialic acid analogue]]