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[[Image:2him.jpg|left|200px]]


{{Structure
==Crystal Structure and Allosteric Regulation of the Cytoplasmic Escherichia coli L-Asparaginase I==
|PDB= 2him |SIZE=350|CAPTION= <scene name='initialview01'>2him</scene>, resolution 1.82&Aring;
<StructureSection load='2him' size='340' side='right'caption='[[2him]], [[Resolution|resolution]] 1.82&Aring;' scene=''>
|SITE=  
== Structural highlights ==
|LIGAND= <scene name='pdbligand=ASN:ASPARAGINE'>ASN</scene>, <scene name='pdbligand=ASP:ASPARTIC+ACID'>ASP</scene>, <scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>
<table><tr><td colspan='2'>[[2him]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HIM OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2HIM FirstGlance]. <br>
|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Asparaginase Asparaginase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.1.1 3.5.1.1] </span>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.82&#8491;</td></tr>
|GENE= ansA ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli])
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ASN:ASPARAGINE'>ASN</scene>, <scene name='pdbligand=ASP:ASPARTIC+ACID'>ASP</scene>, <scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene></td></tr>
|DOMAIN=
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2him FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2him OCA], [https://pdbe.org/2him PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2him RCSB], [https://www.ebi.ac.uk/pdbsum/2him PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2him ProSAT]</span></td></tr>
|RELATEDENTRY=[[2p2d|2P2D]], [[2p2n|2P2N]]
</table>
|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2him FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2him OCA], [http://www.ebi.ac.uk/pdbsum/2him PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=2him RCSB]</span>
== Function ==
}}
[https://www.uniprot.org/uniprot/ASPG1_ECOLI ASPG1_ECOLI]
== 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/hi/2him_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.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=2him ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
AnsA is the cytoplasmic asparaginase from Escherichia coli involved in intracellular asparagine utilization. Analytical ultracentifugation and X-ray crystallography reveal that AnsA forms a tetrameric structure as a dimer of two intimate dimers. Kinetic analysis of the enzyme reveals that AnsA is positively cooperative, displaying a sigmoidal substrate dependence curve with an [S](0.5) of 1 mM L-asparagine and a Hill coefficient (n(H)) of 2.6. Binding of L-asparagine to an allosteric site was observed in the crystal structure concomitant with a reorganization of the quarternary structure, relative to the apo enzyme. The carboxyl group of the bound asparagine makes salt bridges and hydrogen bonds to Arg240, while the N(delta2) nitrogen interacts with Thr162. Mutation of Arg240 to Ala increases the [S](0.5) value to 5.9 mM, presumably by reducing the affinity of the site for L-asparagine, although the enzyme retains cooperativity. Mutation of Thr162 to Ala results in an active enzyme with no cooperativity. Transmission of the signal from the allosteric site to the active site appears to involve subtle interactions at the dimer-dimer interface and relocation of Gln118 into the vicinity of the active site to position the probable catalytic water molecule. These data define the structural basis for the cooperative regulation of the intracellular asparaginase that is required for proper functioning within the cell.


'''Crystal Structure and Allosteric Regulation of the Cytoplasmic Escherichia coli L-Asparaginase I'''
Crystal structure and allosteric regulation of the cytoplasmic Escherichia coli L-asparaginase I.,Yun MK, Nourse A, White SW, Rock CO, Heath RJ J Mol Biol. 2007 Jun 8;369(3):794-811. Epub 2007 Mar 30. PMID:17451745<ref>PMID:17451745</ref>


From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 2him" style="background-color:#fffaf0;"></div>


==Overview==
==See Also==
AnsA is the cytoplasmic asparaginase from Escherichia coli involved in intracellular asparagine utilization. Analytical ultracentifugation and X-ray crystallography reveal that AnsA forms a tetrameric structure as a dimer of two intimate dimers. Kinetic analysis of the enzyme reveals that AnsA is positively cooperative, displaying a sigmoidal substrate dependence curve with an [S](0.5) of 1 mM L-asparagine and a Hill coefficient (n(H)) of 2.6. Binding of L-asparagine to an allosteric site was observed in the crystal structure concomitant with a reorganization of the quarternary structure, relative to the apo enzyme. The carboxyl group of the bound asparagine makes salt bridges and hydrogen bonds to Arg240, while the N(delta2) nitrogen interacts with Thr162. Mutation of Arg240 to Ala increases the [S](0.5) value to 5.9 mM, presumably by reducing the affinity of the site for L-asparagine, although the enzyme retains cooperativity. Mutation of Thr162 to Ala results in an active enzyme with no cooperativity. Transmission of the signal from the allosteric site to the active site appears to involve subtle interactions at the dimer-dimer interface and relocation of Gln118 into the vicinity of the active site to position the probable catalytic water molecule. These data define the structural basis for the cooperative regulation of the intracellular asparaginase that is required for proper functioning within the cell.
*[[Asparaginase 3D structures|Asparaginase 3D structures]]
 
== References ==
==About this Structure==
<references/>
2HIM is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HIM OCA].
__TOC__
 
</StructureSection>
==Reference==
Crystal structure and allosteric regulation of the cytoplasmic Escherichia coli L-asparaginase I., Yun MK, Nourse A, White SW, Rock CO, Heath RJ, J Mol Biol. 2007 Jun 8;369(3):794-811. Epub 2007 Mar 30. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/17451745 17451745]
[[Category: Asparaginase]]
[[Category: Escherichia coli]]
[[Category: Escherichia coli]]
[[Category: Single protein]]
[[Category: Large Structures]]
[[Category: Heath, R J.]]
[[Category: Heath RJ]]
[[Category: Nourse, A.]]
[[Category: Nourse A]]
[[Category: Rock, C O.]]
[[Category: Rock CO]]
[[Category: White, S W.]]
[[Category: White SW]]
[[Category: Yun, M K.]]
[[Category: Yun MK]]
[[Category: asparaginase]]
 
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