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==Crystal structure of a Neisseria meningitidis serogroup A capsular oligosaccharide bound to a functional Fab==
<StructureSection load='6y54' size='340' side='right'caption='[[6y54]], [[Resolution|resolution]] 2.67&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6y54]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6Y54 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6Y54 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]] 2.67&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=IOD:IODIDE+ION'>IOD</scene>, <scene name='pdbligand=OA8:[(2~{R},3~{S},4~{R},5~{S})-5-acetamido-4,6-bis(oxidanyl)-2-(phosphonooxymethyl)oxan-3-yl]+ethanoate'>OA8</scene>, <scene name='pdbligand=OAB:[(3~{S},4~{R},5~{S},6~{R})-3-acetamido-2,5-bis(oxidanyl)-6-(phosphonooxymethyl)oxan-4-yl]+ethanoate'>OAB</scene>, <scene name='pdbligand=OOW:[(2~{R},3~{S},4~{R},5~{S},6~{R})-3-acetamido-5-oxidanyl-2-phosphonooxy-6-(phosphonooxymethyl)oxan-4-yl]+ethanoate'>OOW</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=6y54 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6y54 OCA], [https://pdbe.org/6y54 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6y54 RCSB], [https://www.ebi.ac.uk/pdbsum/6y54 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6y54 ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Meningococcal meningitis remains a substantial cause of mortality and morbidity worldwide. Until recently, countries in the African meningitis belt were susceptible to devastating outbreaks, largely attributed to serogroup A Neisseria meningitidis (MenA). Vaccination with glycoconjugates of MenA capsular polysaccharide led to an almost complete elimination of MenA clinical cases. To understand the molecular basis of vaccine-induced protection, we generated a panel of oligosaccharide fragments of different lengths and tested them with polyclonal and monoclonal antibodies by inhibition enzyme-linked immunosorbent assay, surface plasmon resonance, and competitive human serum bactericidal assay, which is a surrogate for protection. The epitope was shown to optimize between three and six repeating units and to be O-acetylated. The molecular interactions between a protective monoclonal antibody and a MenA capsular polysaccharide fragment were further elucidated at the atomic level by saturation transfer difference NMR spectroscopy and X-ray crystallography. The epitope consists of a trisaccharide anchored to the antibody via the O- and N-acetyl moieties through either H-bonding or CH-pi interactions. In silico docking showed that 3-O-acetylation of the upstream residue is essential for antibody binding, while O-acetate could be equally accommodated at three and four positions of the other two residues. These results shed light on the mechanism of action of current MenA vaccines and provide a foundation for the rational design of improved therapies.

Structure of a protective epitope reveals the importance of acetylation of Neisseria meningitidis serogroup A capsular polysaccharide.,Henriques P, Dello Iacono L, Gimeno A, Biolchi A, Romano MR, Arda A, Bernardes GJL, Jimenez-Barbero J, Berti F, Rappuoli R, Adamo R Proc Natl Acad Sci U S A. 2020 Nov 6. pii: 2011385117. doi:, 10.1073/pnas.2011385117. PMID:33158970<ref>PMID:33158970</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6y54" style="background-color:#fffaf0;"></div>

==See Also==
*[[Monoclonal Antibodies 3D structures|Monoclonal Antibodies 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Mus musculus]]
[[Category: Adamo R]]
[[Category: Dello Iacono L]]
[[Category: Henriques P]]