View source for 2wqq


==Crystallographic analysis of monomeric CstII==
<StructureSection load='2wqq' size='340' side='right'caption='[[2wqq]], [[Resolution|resolution]] 2.25&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2wqq]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Campylobacter_jejuni Campylobacter jejuni]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2WQQ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2WQQ 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]] 2.25&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CSF:CYTIDINE-5-MONOPHOSPHATE-3-FLUORO-N-ACETYL-NEURAMINIC+ACID'>CSF</scene>, <scene name='pdbligand=PEG:DI(HYDROXYETHYL)ETHER'>PEG</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=2wqq FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2wqq OCA], [https://pdbe.org/2wqq PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2wqq RCSB], [https://www.ebi.ac.uk/pdbsum/2wqq PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2wqq ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/Q9LAK3_CAMJU Q9LAK3_CAMJU] 
== 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/wq/2wqq_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=2wqq ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Cell surface glycans are often terminated by sialic acid, which is incorporated onto sugar acceptors by sialyltransferases. The crystal structure of the GT family 42 Campylobacter jejuni alpha-2,3/2,8-sialyltransferase (CstII) provides key insights into the sialyl-transfer mechanism, including tentative identification of His188 as the catalytic base. In support of this hypothesis, the CstII-H188A mutant is able to catalyze sialyl transfer from CMP-Neu5Ac to added anions such as azide and formate, but not to its natural sugar acceptor lactose. Complementing this work, NMR spectroscopy was used to investigate the structure and dynamics of CstII and to measure the intrinsic pKa value of His188 for comparison with the pKa determined from the pH-dependent kcat/KM of enzyme. By systematically introducing point mutations at the subunit interfaces, two active monomeric variants, CstII-F121D and CstII-Y125Q, were obtained and characterized. In contrast to the wild-type tetramer, the monomeric CstII variants yielded good quality 1H/15N-HSQC and 1H/13C methyl-TROSY NMR spectra. However, the absence of signals from approximately one half of the amides in the 1H/15N-HSQC spectra of both monomeric forms suggests that the enzyme undergoes substantial conformational motions on a msec-musec timescale. The histidine pKa values of CstII-F121D in its apo form were measured by monitoring the pH-dependent chemical shifts of [13Cepsilon1]-histidine, biosynthetically incorporated into the otherwise uniformly deuterated protein. Consistent with its proposed catalytic role, the site-specific pKa value ~ 6.6 of His188 matches the apparent pKa value ~ 6.5 governing the pH-dependence of kcat/KM for CstII towards CMP-Neu5Ac in the presence of saturating acceptor substrate.

NMR Spectroscopic Characterization of the Sialyltransferase CstII from Camplyobacter jejuni: Histidine 188 is the General Base.,Chan PH, Lairson LL, Lee HJ, Wakarchuk WW, Strynadka NC, Withers SG, McIntosh LP Biochemistry. 2009 Oct 13. PMID:19824695<ref>PMID:19824695</ref>

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

==See Also==
*[[Sialyltransferase 3D structures|Sialyltransferase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Campylobacter jejuni]]
[[Category: Large Structures]]
[[Category: Chan PHW]]
[[Category: Lairson LL]]
[[Category: Lee HJ]]
[[Category: McIntosh LP]]
[[Category: Strynadka NCJ]]
[[Category: Wakarchuk WW]]
[[Category: Withers SG]]