View source for 3cxo


==Crystal structure of L-rhamnonate dehydratase from Salmonella typhimurium complexed with Mg and 3-deoxy-L-rhamnonate==
<StructureSection load='3cxo' size='340' side='right'caption='[[3cxo]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3cxo]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Salmonella_enterica_subsp._enterica_serovar_Typhimurium_str._LT2 Salmonella enterica subsp. enterica serovar Typhimurium str. LT2]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3CXO OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3CXO 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&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=1N5:(2R,4S)-2,4,7-TRIHYDROXYHEPTANOIC+ACID'>1N5</scene>, <scene name='pdbligand=3LR:3,6-DIDEOXY-L-ARABINO-HEXONIC+ACID'>3LR</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</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=3cxo FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3cxo OCA], [https://pdbe.org/3cxo PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3cxo RCSB], [https://www.ebi.ac.uk/pdbsum/3cxo PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3cxo ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/RHMD_SALTY RHMD_SALTY] Catalyzes the dehydration of L-rhamnonate to 2-keto-3-deoxy-L-rhamnonate (KDR). Can also dehydrate L-lyxonate and L-mannonate, although less efficiently, but not 2-keto-4-hydroxyheptane-1,7-dioate.<ref>PMID:18754693</ref> 
== 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/cx/3cxo_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=3cxo ConSurf].
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== Publication Abstract from PubMed ==
The l-rhamnonate dehydratase (RhamD) function was assigned to a previously uncharacterized family in the mechanistically diverse enolase superfamily that is encoded by the genome of Escherichia coli K-12. We screened a library of acid sugars to discover that the enzyme displays a promiscuous substrate specificity: l-rhamnonate (6-deoxy- l-mannonate) has the "best" kinetic constants, with l-mannonate, l-lyxonate, and d-gulonate dehydrated less efficiently. Crystal structures of the RhamDs from both E. coli K-12 and Salmonella typhimurium LT2 (95% sequence identity) were obtained in the presence of Mg (2+); the structure of the RhamD from S. typhimurium was also obtained in the presence of 3-deoxy- l-rhamnonate (obtained by reduction of the product with NaBH 4). Like other members of the enolase superfamily, RhamD contains an N-terminal alpha + beta capping domain and a C-terminal (beta/alpha) 7beta-barrel (modified TIM-barrel) catalytic domain with the active site located at the interface between the two domains. In contrast to other members, the specificity-determining "20s loop" in the capping domain is extended in length and the "50s loop" is truncated. The ligands for the Mg (2+) are Asp 226, Glu 252 and Glu 280 located at the ends of the third, fourth and fifth beta-strands, respectively. The active site of RhamD contains a His 329-Asp 302 dyad at the ends of the seventh and sixth beta-strands, respectively, with His 329 positioned to function as the general base responsible for abstraction of the C2 proton of l-rhamnonate to form a Mg (2+)-stabilized enediolate intermediate. However, the active site does not contain other acid/base catalysts that have been implicated in the reactions catalyzed by other members of the MR subgroup of the enolase superfamily. Based on the structure of the liganded complex, His 329 also is expected to function as the general acid that both facilitates departure of the 3-OH group in a syn-dehydration reaction and delivers a proton to carbon-3 to replace the 3-OH group with retention of configuration.

Evolution of enzymatic activities in the enolase superfamily: L-rhamnonate dehydratase.,Rakus JF, Fedorov AA, Fedorov EV, Glasner ME, Hubbard BK, Delli JD, Babbitt PC, Almo SC, Gerlt JA Biochemistry. 2008 Sep 23;47(38):9944-54. Epub 2008 Aug 29. PMID:18754693<ref>PMID:18754693</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Salmonella enterica subsp. enterica serovar Typhimurium str. LT2]]
[[Category: Almo SC]]
[[Category: Fedorov AA]]
[[Category: Fedorov EV]]
[[Category: Gerlt JA]]
[[Category: Hubbard BK]]
[[Category: Rakus JF]]