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[[Image:1a59.gif|left|200px]]<br /><applet load="1a59" size="350" color="white" frame="true" align="right" spinBox="true"
caption="1a59, resolution 2.09&Aring;" />
'''COLD-ACTIVE CITRATE SYNTHASE'''<br />


==Overview==
==COLD-ACTIVE CITRATE SYNTHASE==
BACKGROUND: The structural basis of adaptation of enzymes to low temperature is poorly understood. Dimeric citrate synthase has been used as a model enzyme to study the structural basis of thermostability, the structure of the enzyme from organisms living in habitats at 55 degrees C and 100 degrees C having previously been determined. Here the study is extended to include a citrate synthase from an Antarctic bacterium, allowing us to explore the structural basis of cold activity and thermostability across the whole temperature range over which life is known to exit. RESULTS: We report here the first crystal structure of a cold-active enzyme, citrate synthase, isolated from an Antarctic bacterium, at a resolution of 2.09 A. In comparison with the same enzyme from a hyperthermophilic host, the cold-active enzyme has a much more accessible active site, an unusual electrostatic potential distribution and an increased relative flexibility of the small domain compared to the large domain. Several other features of the cold-active enzyme were also identified: reduced subunit interface interactions with no intersubunit ion-pair networks; loops of increased length carrying more charge and fewer proline residues; an increase in solvent-exposed hydrophobic residues; and an increase in intramolecular ion pairs. CONCLUSIONS: Enzymes from organisms living at the temperature extremes of life need to avoid hot or cold denaturation yet maintain sufficient structural integrity to allow catalytic efficiency. For hyperthermophiles, thermal denaturation of the citrate synthase dimer appears to be resisted by complex networks of ion pairs at the dimer interface, a feature common to other hyperthermophilic proteins. For the cold-active citrate synthase, cold denaturation appears to be resisted by an increase in intramolecular ion pairs compared to the hyperthermophilic enzyme. Catalytic efficiency of the cold-active enzyme appears to be achieved by a more accessible active site and by an increase in the relative flexibility of the small domain compared to the large domain.
<StructureSection load='1a59' size='340' side='right'caption='[[1a59]], [[Resolution|resolution]] 2.09&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1a59]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Antarctic_bacterium_DS2-3R Antarctic bacterium DS2-3R]. The September 2007 RCSB PDB [https://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month] feature on ''Citrate Synthase''  by David S. Goodsell is [https://dx.doi.org/10.2210/rcsb_pdb/mom_2007_9 10.2210/rcsb_pdb/mom_2007_9]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1A59 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1A59 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]] 2.09&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CIT:CITRIC+ACID'>CIT</scene>, <scene name='pdbligand=COA:COENZYME+A'>COA</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=1a59 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1a59 OCA], [https://pdbe.org/1a59 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1a59 RCSB], [https://www.ebi.ac.uk/pdbsum/1a59 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1a59 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/PRPC_ABDS2 PRPC_ABDS2] Involved in the catabolism of short chain fatty acids (SCFA) via the tricarboxylic acid (TCA)(acetyl degradation route) and via the 2-methylcitrate cycle I (propionate degradation route). Catalyzes the Claisen condensation of propionyl-CoA and oxaloacetate (OAA) to yield 2-methylcitrate (2-MC) and CoA. Also catalyzes the condensation of oxaloacetate with acetyl-CoA but with a lower specificity.<ref>PMID:9310359</ref> <ref>PMID:9579066</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/a5/1a59_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=1a59 ConSurf].
<div style="clear:both"></div>


==About this Structure==
==See Also==
1A59 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacteria Bacteria] with <scene name='pdbligand=COA:'>COA</scene> and <scene name='pdbligand=CIT:'>CIT</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. The following page contains interesting information on the relation of 1A59 with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb93_1.html Citrate Synthase]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1A59 OCA].
*[[Citrate Synthase 3D structures|Citrate Synthase 3D structures]]
 
== References ==
==Reference==
<references/>
Structural adaptations of the cold-active citrate synthase from an Antarctic bacterium., Russell RJ, Gerike U, Danson MJ, Hough DW, Taylor GL, Structure. 1998 Mar 15;6(3):351-61. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=9551556 9551556]
__TOC__
[[Category: Bacteria]]
</StructureSection>
[[Category: Antarctic bacterium DS2-3R]]
[[Category: Citrate Synthase]]
[[Category: Citrate Synthase]]
[[Category: Single protein]]
[[Category: Large Structures]]
[[Category: Danson, M J.]]
[[Category: RCSB PDB Molecule of the Month]]
[[Category: Gerike, U.]]
[[Category: Danson MJ]]
[[Category: Hough, D W.]]
[[Category: Gerike U]]
[[Category: Russell, R J.M.]]
[[Category: Hough DW]]
[[Category: Taylor, G L.]]
[[Category: Russell RJM]]
[[Category: CIT]]
[[Category: Taylor GL]]
[[Category: COA]]
[[Category: cold-activity]]
 
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:41:00 2008''

Latest revision as of 09:27, 7 February 2024

COLD-ACTIVE CITRATE SYNTHASECOLD-ACTIVE CITRATE SYNTHASE

Structural highlights

1a59 is a 1 chain structure with sequence from Antarctic bacterium DS2-3R. The September 2007 RCSB PDB Molecule of the Month feature on Citrate Synthase by David S. Goodsell is 10.2210/rcsb_pdb/mom_2007_9. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 2.09Å
Ligands:,
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

PRPC_ABDS2 Involved in the catabolism of short chain fatty acids (SCFA) via the tricarboxylic acid (TCA)(acetyl degradation route) and via the 2-methylcitrate cycle I (propionate degradation route). Catalyzes the Claisen condensation of propionyl-CoA and oxaloacetate (OAA) to yield 2-methylcitrate (2-MC) and CoA. Also catalyzes the condensation of oxaloacetate with acetyl-CoA but with a lower specificity.[1] [2]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

See Also

References

  1. ↑ Gerike U, Danson MJ, Russell NJ, Hough DW. Sequencing and expression of the gene encoding a cold-active citrate synthase from an Antarctic bacterium, strain DS2-3R. Eur J Biochem. 1997 Aug 15;248(1):49-57. PMID:9310359 doi:10.1111/j.1432-1033.1997.00049.x
  2. ↑ Gerike U, Hough DW, Russell NJ, Dyall-Smith ML, Danson MJ. Citrate synthase and 2-methylcitrate synthase: structural, functional and evolutionary relationships. Microbiology (Reading). 1998 Apr;144 ( Pt 4):929-935. doi: , 10.1099/00221287-144-4-929. PMID:9579066 doi:http://dx.doi.org/10.1099/00221287-144-4-929

1a59, resolution 2.09Å

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