View source for 2bfb


==Reactivity modulation of human branched-chain alpha-ketoacid dehydrogenase by an internal molecular switch==
<StructureSection load='2bfb' size='340' side='right'caption='[[2bfb]], [[Resolution|resolution]] 1.77&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2bfb]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2BFB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2BFB 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]] 1.77&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=K:POTASSIUM+ION'>K</scene>, <scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</scene>, <scene name='pdbligand=MRD:(4R)-2-METHYLPENTANE-2,4-DIOL'>MRD</scene>, <scene name='pdbligand=TPP:THIAMINE+DIPHOSPHATE'>TPP</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=2bfb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2bfb OCA], [https://pdbe.org/2bfb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2bfb RCSB], [https://www.ebi.ac.uk/pdbsum/2bfb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2bfb ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/ODBA_HUMAN ODBA_HUMAN] Defects in BCKDHA are a cause of maple syrup urine disease type IA (MSUD1A) [MIM:[https://omim.org/entry/248600 248600]. MSUD is an autosomal recessive disorder characterized by mental and physical retardation, feeding problems, and a maple syrup odor to the urine.<ref>PMID:2060625</ref> <ref>PMID:8037208</ref> <ref>PMID:2703538</ref> <ref>PMID:2241958</ref> <ref>PMID:1867199</ref> <ref>PMID:1885764</ref> <ref>PMID:8161368</ref> <ref>PMID:7883996</ref> 
== Function ==
[https://www.uniprot.org/uniprot/ODBA_HUMAN ODBA_HUMAN] The branched-chain alpha-keto dehydrogenase complex catalyzes the overall conversion of alpha-keto acids to acyl-CoA and CO(2). It contains multiple copies of three enzymatic components: branched-chain alpha-keto acid decarboxylase (E1), lipoamide acyltransferase (E2) and lipoamide dehydrogenase (E3).
== 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/bf/2bfb_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=2bfb ConSurf].
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== Publication Abstract from PubMed ==
The dehydrogenase/decarboxylase (E1b) component of the 4 MD human branched-chain alpha-ketoacid dehydrogenase complex (BCKDC) is a thiamin diphosphate (ThDP)-dependent enzyme. We have determined the crystal structures of E1b with ThDP bound intermediates after decarboxylation of alpha-ketoacids. We show that a key tyrosine residue in the E1b active site functions as a conformational switch to reduce the reactivity of the ThDP cofactor through interactions with its thiazolium ring. The intermediates do not assume the often-postulated enamine state, but likely a carbanion state. The carbanion presumably facilitates the second E1b-catalyzed reaction, involving the transfer of an acyl moiety from the intermediate to a lipoic acid prosthetic group in the transacylase (E2b) component of the BCKDC. The tyrosine switch further remodels an E1b loop region to promote E1b binding to E2b. Our results illustrate the versatility of the tyrosine switch in coordinating the catalytic events in E1b by modulating the reactivity of reaction intermediates.

A versatile conformational switch regulates reactivity in human branched-chain alpha-ketoacid dehydrogenase.,Machius M, Wynn RM, Chuang JL, Li J, Kluger R, Yu D, Tomchick DR, Brautigam CA, Chuang DT Structure. 2006 Feb;14(2):287-98. PMID:16472748<ref>PMID:16472748</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 2bfb" style="background-color:#fffaf0;"></div>

==See Also==
*[[2-oxoisovalerate dehydrogenase 3D structures|2-oxoisovalerate dehydrogenase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Brautigam CA]]
[[Category: Chuang DT]]
[[Category: Chuang JL]]
[[Category: Machius M]]
[[Category: Tomchick DR]]
[[Category: Wynn RM]]