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[[Image:1cla.png|left|200px]]
==EVIDENCE FOR TRANSITION-STATE STABILIZATION BY SERINE-148 IN THE CATALYTIC MECHANISM OF CHLORAMPHENICOL ACETYLTRANSFERASE==
<StructureSection load='1cla' size='340' side='right' caption='[[1cla]], [[Resolution|resolution]] 2.34&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1cla]] is a 1 chain structure with 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=1CLA OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1CLA FirstGlance]. <br>
</td></tr><tr><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CLM:CHLORAMPHENICOL'>CLM</scene>, <scene name='pdbligand=CO:COBALT+(II)+ION'>CO</scene><br>
<tr><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Chloramphenicol_O-acetyltransferase Chloramphenicol O-acetyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.1.28 2.3.1.28] </span></td></tr>
<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1cla FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1cla OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1cla RCSB], [http://www.ebi.ac.uk/pdbsum/1cla PDBsum]</span></td></tr>
<table>
== 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/cl/1cla_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/chain_selection.php?pdb_ID=2ata ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The function of conserved Ser-148 of chloramphenicol acetyltransferase (CAT) has been investigated by site-directed mutagenesis. Modeling studies (P. C. E. Moody and A. G. W. Leslie, unpublished results) suggested that the hydroxyl group of Ser-148 could be involved in transition-state stabilization via a hydrogen bond to the oxyanion of the putative tetrahedral intermediate. Replacement of serine by alanine results in a mutant enzyme (Ala-148 CAT) with kcat reduced 53-fold and only minor changes in Km values for chloramphenicol and acetyl-CoA. The Ser-148----Gly substitution gives rise to a mutant enzyme (Gly-148 CAT) with kcat reduced only 10-fold. A water molecule may partially replace the hydrogen-bonding potential of Ser-148 in Gly-148 CAT. The three-dimensional structure of Ala-148 CAT at 2.34-A resolution is isosteric with that of wild-type CAT with two exceptions: the absence of the Ser-148 hydroxyl group and the loss of one poorly ordered water molecule from the active site region. The results are consistent with a catalytic role for Ser-148 rather than a structural one and support the hypothesis that Ser-148 is involved in transition-state stabilization. Ser-148 has also been replaced with cysteine and asparagine; the Ser-148----Cys mutation results in a 705-fold decrease in kcat and the Ser-148----Asn substitution in a 214-fold reduction in kcat. Removing the hydrogen bond donor (Ser-148----Ala or Gly) is less deleterious than replacing Ser-148 with alternative possible hydrogen bond donors (Ser-148----Cys or Asn).


{{STRUCTURE_1cla|  PDB=1cla  |  SCENE=  }}
Evidence for transition-state stabilization by serine-148 in the catalytic mechanism of chloramphenicol acetyltransferase.,Lewendon A, Murray IA, Shaw WV, Gibbs MR, Leslie AG Biochemistry. 1990 Feb 27;29(8):2075-80. PMID:2109633<ref>PMID:2109633</ref>


===EVIDENCE FOR TRANSITION-STATE STABILIZATION BY SERINE-148 IN THE CATALYTIC MECHANISM OF CHLORAMPHENICOL ACETYLTRANSFERASE===
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
 
</div>
{{ABSTRACT_PUBMED_2109633}}
 
==About this Structure==
[[1cla]] is a 1 chain structure with 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=1CLA OCA].


==See Also==
==See Also==
*[[Chloramphenicol acetyltransferase|Chloramphenicol acetyltransferase]]
*[[Chloramphenicol acetyltransferase|Chloramphenicol acetyltransferase]]
 
== References ==
==Reference==
<references/>
<ref group="xtra">PMID:002109633</ref><references group="xtra"/>
__TOC__
</StructureSection>
[[Category: Chloramphenicol O-acetyltransferase]]
[[Category: Chloramphenicol O-acetyltransferase]]
[[Category: Escherichia coli]]
[[Category: Escherichia coli]]
[[Category: Gibbs, M R.]]
[[Category: Gibbs, M R.]]
[[Category: Leslie, A G.W.]]
[[Category: Leslie, A G.W.]]
Retrieved from "https://proteopedia.org/1cla"