View source for 3byj


==Crystal structure of B. subtilis levansucrase mutant D86A==
<StructureSection load='3byj' size='340' side='right'caption='[[3byj]], [[Resolution|resolution]] 2.10&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3byj]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Bacillus_subtilis Bacillus subtilis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3BYJ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3BYJ 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]] 2.1&#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></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=3byj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3byj OCA], [https://pdbe.org/3byj PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3byj RCSB], [https://www.ebi.ac.uk/pdbsum/3byj PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3byj ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/SACB_BACSU SACB_BACSU] 
== 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/by/3byj_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=3byj ConSurf].
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== Publication Abstract from PubMed ==
BACKGROUND: Fructans - beta-D-fructofuranosyl polymers with a sucrose starter unit - constitute a carbohydrate reservoir synthesised by a considerable number of bacteria and plant species. Biosynthesis of levan (alphaGlc(1-2)betaFru [(2-6)betaFru]n), an abundant form of bacterial fructan, is catalysed by levansucrase (sucrose:2,6-beta-D-fructan-6-beta-D-fructosyl transferase), utilizing sucrose as the sole substrate. Previously, we described the tertiary structure of Bacillus subtilis levansucrase in the ligand-free and sucrose-bound forms, establishing the mechanistic roles of three invariant carboxylate side chains, Asp86, Asp247 and Glu342, which are central to the double displacement reaction mechanism of fructosyl transfer. Still, the structural determinants of the fructosyl transfer reaction thus far have been only partially defined. RESULTS: Here, we report high-resolution structures of three levansucrase point mutants, D86A, D247A, and E342A, and that of raffinose-bound levansucrase-E342A. The D86A and D247A substitutions have little effect on the active site geometry. In marked contrast, the E342A mutant reveals conformational flexibility of functionally relevant side chains in the vicinity of the general acid Glu342, including Arg360, a residue required for levan polymerisation. The raffinose-complex reveals a conserved mode of donor substrate binding, involving minimal contacts with the raffinose galactosyl unit, which protrudes out of the active site, and specificity-determining contacts essentially restricted to the sucrosyl moiety. CONCLUSION: The present structures, in conjunction with prior biochemical data, lead us to hypothesise that the conformational flexibility of Arg360 is linked to it forming a transient docking site for the fructosyl-acceptor substrate, through an interaction network involving nearby Glu340 and Asn242 at the rim of a central pocket forming the active site.

Donor substrate recognition in the raffinose-bound E342A mutant of fructosyltransferase Bacillus subtilis levansucrase.,Meng G, Futterer K BMC Struct Biol. 2008 Mar 17;8:16. doi: 10.1186/1472-6807-8-16. PMID:18366639<ref>PMID:18366639</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 3byj" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Bacillus subtilis]]
[[Category: Large Structures]]
[[Category: Futterer K]]
[[Category: Meng G]]