View source for 6rjc


==E.coli transketolase apoenzyme==
<StructureSection load='6rjc' size='340' side='right'caption='[[6rjc]], [[Resolution|resolution]] 1.05&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6rjc]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Ecoli Ecoli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6RJC OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6RJC FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene></td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">tktA, tkt, b2935, JW5478 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=83333 ECOLI])</td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Transketolase Transketolase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.2.1.1 2.2.1.1] </span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6rjc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6rjc OCA], [http://pdbe.org/6rjc PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6rjc RCSB], [http://www.ebi.ac.uk/pdbsum/6rjc PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6rjc ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/TKT1_ECOLI TKT1_ECOLI]] Catalyzes the reversible transfer of a two-carbon ketol group from sedoheptulose-7-phosphate to glyceraldehyde-3-phosphate, producing xylulose-5-phosphate and ribose-5-phosphate. Catalyzes the transfer of a two-carbon ketol group from a ketose donor to an aldose acceptor, via a covalent intermediate with the cofactor thiamine pyrophosphate.<ref>PMID:17914867</ref>  
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== Publication Abstract from PubMed ==
The underlying molecular mechanisms of cooperativity and allosteric regulation are well understood for many proteins, with haemoglobin and aspartate transcarbamoylase serving as prototypical examples(1,2). The binding of effectors typically causes a structural transition of the protein that is propagated through signalling pathways to remote sites and involves marked changes on the tertiary and sometimes even the quaternary level(1-5). However, the origin of these signals and the molecular mechanism of long-range signalling at an atomic level remain unclear(5-8). The different spatial scales and timescales in signalling pathways render experimental observation challenging; in particular, the positions and movement of mobile protons cannot be visualized by current methods of structural analysis. Here we report the experimental observation of fluctuating low-barrier hydrogen bonds as switching elements in cooperativity pathways of multimeric enzymes. We have observed these low-barrier hydrogen bonds in ultra-high-resolution X-ray crystallographic structures of two multimeric enzymes, and have validated their assignment using computational calculations. Catalytic events at the active sites switch between low-barrier hydrogen bonds and ordinary hydrogen bonds in a circuit that consists of acidic side chains and water molecules, transmitting a signal through the collective repositioning of protons by behaving as an atomistic Newton's cradle. The resulting communication synchronizes catalysis in the oligomer. Our studies provide several lines of evidence and a working model for not only the existence of low-barrier hydrogen bonds in proteins, but also a connection to enzyme cooperativity. This finding suggests new principles of drug and enzyme design, in which sequences of residues can be purposefully included to enable long-range communication and thus the regulation of engineered biomolecules.

Low-barrier hydrogen bonds in enzyme cooperativity.,Dai S, Funk LM, von Pappenheim FR, Sautner V, Paulikat M, Schroder B, Uranga J, Mata RA, Tittmann K Nature. 2019 Sep;573(7775):609-613. doi: 10.1038/s41586-019-1581-9. Epub 2019 Sep, 18. PMID:31534226<ref>PMID:31534226</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6rjc" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Ecoli]]
[[Category: Large Structures]]
[[Category: Transketolase]]
[[Category: Pappenheim, F Rabe von]]
[[Category: Tittmann, K]]
[[Category: Enzyme catalysis]]
[[Category: Pentose phosphate pathway]]
[[Category: Thiamin diphosphate]]
[[Category: Transferase]]