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==N. meningitidis CMP-sialic acid synthetase in the presence of CTP and Ca2+==
<StructureSection load='6ckk' size='340' side='right'caption='[[6ckk]], [[Resolution|resolution]] 1.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6ckk]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Neisseria_meningitidis Neisseria meningitidis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6CKK OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6CKK 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]] 1.8&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CTP:CYTIDINE-5-TRIPHOSPHATE'>CTP</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=6ckk FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6ckk OCA], [https://pdbe.org/6ckk PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6ckk RCSB], [https://www.ebi.ac.uk/pdbsum/6ckk PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6ckk ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/NEUA_NEIME NEUA_NEIME] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Cytidine 5'-monophosphate (CMP)-sialic acid synthetase (CSS) is an essential enzyme involved in the biosynthesis of carbohydrates and glycoconjugates containing sialic acids, a class of alpha-keto acids that are generally terminal key recognition residues by many proteins that play important biological and pathological roles. The CSS from Neisseria meningitidis (NmCSS) has been commonly used with other enzymes such as sialic acid aldolase and/or sialyltransferase in synthesizing a diverse array of compounds containing sialic acid or its naturally occurring and non-natural derivatives. To better understand its catalytic mechanism and substrate promiscuity, four NmCSS crystal structures trapped at various stages of the catalytic cycle with bound substrates, substrate analogues, and products have been obtained and are presented here. These structures suggest a mechanism for an "open" and "closed" conformational transition that occurs as sialic acid binds to the NmCSS/cytidine-5'-triphosphate (CTP) complex. The closed conformation positions critical residues to help facilitate the nucleophilic attack of sialic acid C2-OH to the alpha-phosphate of CTP, which is also aided by two observed divalent cations. Product formation drives the active site opening, promoting the release of products.

Catalytic Cycle of Neisseria meningitidis CMP-Sialic Acid Synthetase Illustrated by High-Resolution Protein Crystallography.,Matthews MM, McArthur JB, Li Y, Yu H, Chen X, Fisher AJ Biochemistry. 2019 Oct 4. doi: 10.1021/acs.biochem.9b00517. PMID:31583886<ref>PMID:31583886</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6ckk" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Neisseria meningitidis]]
[[Category: Chen X]]
[[Category: Fisher AJ]]
[[Category: Matthews MM]]