View source for 1hgi


==BINDING OF INFLUENZA VIRUS HEMAGGLUTININ TO ANALOGS OF ITS CELL-SURFACE RECEPTOR, SIALIC ACID: ANALYSIS BY PROTON NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY AND X-RAY CRYSTALLOGRAPHY==
<StructureSection load='1hgi' size='340' side='right'caption='[[1hgi]], [[Resolution|resolution]] 2.70&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1hgi]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Influenza_A_virus_(A/X-31(H3N2)) Influenza A virus (A/X-31(H3N2))]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HGI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1HGI FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.7&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ANA:4-O-ACETYL-ALPHA-2-OMETHYL-5-N-ACETYL-ALPHA-D-NEURAMINIC+ACID'>ANA</scene>, <scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1hgi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1hgi OCA], [https://pdbe.org/1hgi PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1hgi RCSB], [https://www.ebi.ac.uk/pdbsum/1hgi PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1hgi ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/HEMA_I000X HEMA_I000X] Binds to sialic acid-containing receptors on the cell surface, bringing about the attachment of the virus particle to the cell. This attachment induces virion internalization of about two third of the virus particles through clathrin-dependent endocytosis and about one third through a clathrin- and caveolin-independent pathway. Plays a major role in the determination of host range restriction and virulence. Class I viral fusion protein. Responsible for penetration of the virus into the cell cytoplasm by mediating the fusion of the membrane of the endocytosed virus particle with the endosomal membrane. Low pH in endosomes induces an irreversible conformational change in HA2, releasing the fusion hydrophobic peptide. Several trimers are required to form a competent fusion pore.<ref>PMID:15122347</ref>   Binds to sialic acid-containing receptors on the cell surface, bringing about the attachment of the virus particle to the cell. This attachment induces virion internalization either through clathrin-dependent endocytosis or through clathrin- and caveolin-independent pathway. Plays a major role in the determination of host range restriction and virulence. Class I viral fusion protein. Responsible for penetration of the virus into the cell cytoplasm by mediating the fusion of the membrane of the endocytosed virus particle with the endosomal membrane. Low pH in endosomes induces an irreversible conformational change in HA2, releasing the fusion hydrophobic peptide. Several trimers are required to form a competent fusion pore.[HAMAP-Rule:MF_04072]
== 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/hg/1hgi_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.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=1hgi ConSurf].
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== Publication Abstract from PubMed ==
The interaction between influenza virus hemagglutinin and its cell-surface receptor, 5-N-acetylneuraminic acid (sialic acid), was probed by the synthesis of 12 sialic acid analogs, including derivatives at the 2-carboxylate, 5-acetamido, 4-, 7-, and 9-hydroxyl, and glycosidic positions. The equilibrium dissociation constants of these analogs were determined by nuclear magnetic resonance spectroscopy. Ligand modifications that reduced or abolished binding included the replacement of the 2-carboxylate with a carboxamide, the substitution of azido or N-benzyloxycarbonyl groups for the 5-acetamido group, and the replacement of the 9-hydroxyl with amino or O-acetyl moieties. Modifications having little effect on binding included the introduction of longer chains at the 4-hydroxyl position, the replacement of the acetamido methyl group with an ethyl group, and the removal of the 7-hydroxyl group. X-ray diffraction studies yielded 3 A resolution crystal structures of hemagglutinin in complex with four of the synthetic analogs [alpha-2-O-methyl-, 4-O-acetyl-alpha-2-O-methyl-, 9-amino-9-deoxy-alpha-2-O-methyl-, and alpha-2-O-(4'-benzylamidocarboxybutyl)-N-acetylneuraminic acid] and with the naturally occurring cell-surface saccharide (alpha 2-3)sialyllactose. The X-ray studies unambiguously establish the position and orientation of bound sialic acid, indicate the position of the lactose group of (alpha 2-3)sialyllactose, and suggest the location of an alpha-glycosidic chain (4'-benzylamidocarboxybutyl) that increases the binding affinity of sialic acid by a factor of about 3. Although the protein complexed with alpha-2-O-methylsialic acid contains the mutation Gly-135--&gt;Arg near the ligand binding site, the mutation apparently does not affect the ligand's position. The X-ray studies allow us to interpret the binding affinities in terms of the crystallographic structure. The results suggest further experiments which could lead to the design of tight binding inhibitors of possible therapeutic value.

Binding of influenza virus hemagglutinin to analogs of its cell-surface receptor, sialic acid: analysis by proton nuclear magnetic resonance spectroscopy and X-ray crystallography.,Sauter NK, Hanson JE, Glick GD, Brown JH, Crowther RL, Park SJ, Skehel JJ, Wiley DC Biochemistry. 1992 Oct 13;31(40):9609-21. PMID:1327122<ref>PMID:1327122</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[Hemagglutinin 3D structures|Hemagglutinin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Brown JH]]
[[Category: Crowther RL]]
[[Category: Glick GD]]
[[Category: Hanson JE]]
[[Category: Park S-J]]
[[Category: Sauter NK]]
[[Category: Skehel JJ]]
[[Category: Wiley DC]]