3cla
From Proteopedia
(New page: 200px<br /><applet load="3cla" size="450" color="white" frame="true" align="right" spinBox="true" caption="3cla, resolution 1.75Å" /> '''REFINED CRYSTAL STRU...) |
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| - | [[Image:3cla.gif|left|200px]]<br /><applet load="3cla" size=" | + | [[Image:3cla.gif|left|200px]]<br /><applet load="3cla" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="3cla, resolution 1.75Å" /> | caption="3cla, resolution 1.75Å" /> | ||
'''REFINED CRYSTAL STRUCTURE OF TYPE III CHLORAMPHENICOL ACETYLTRANSFERASE AT 1.75 ANGSTROMS RESOLUTION'''<br /> | '''REFINED CRYSTAL STRUCTURE OF TYPE III CHLORAMPHENICOL ACETYLTRANSFERASE AT 1.75 ANGSTROMS RESOLUTION'''<br /> | ||
==Overview== | ==Overview== | ||
| - | High level bacterial resistance to chloramphenicol is generally due to | + | High level bacterial resistance to chloramphenicol is generally due to O-acetylation of the antibiotic in a reaction catalysed by chloramphenicol acetyltransferase (CAT, EC 2.3.1.28) in which acetyl-coenzyme A is the acyl donor. The crystal structure of the type III enzyme from Escherichia coli with chloramphenicol bound has been determined and refined at 1.75 A resolution, using a restrained parameter reciprocal space least squares procedure. The refined model, which includes chloramphenicol, 204 solvent molecules and two cobalt ions has a crystallographic R-factor of 18.3% for 27,300 reflections between 6 and 1.75 A resolution. The root-mean-square deviation in bond lengths from ideal values is 0.02 A. The cobalt ions play a crucial role in stabilizing the packing of the molecule in the crystal lattice. CAT is a trimer of identical subunits (monomer Mr 25,000) and the trimeric structure is stabilized by a number of hydrogen bonds, some of which result in the extension of a beta-sheet across the subunit interface. Chloramphenicol binds in a deep pocket located at the boundary between adjacent subunits of the trimer, such that the majority of residues forming the binding pocket belong to one subunit while the catalytically essential histidine belongs to the adjacent subunit. His195 is appropriately positioned to act as a general base catalyst in the reaction, and the required tautomeric stabilization is provided by an unusual interaction with a main-chain carbonyl oxygen. |
==About this Structure== | ==About this Structure== | ||
| - | 3CLA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with CO and CLM as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [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] Full crystallographic information is available from [http:// | + | 3CLA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=CO:'>CO</scene> and <scene name='pdbligand=CLM:'>CLM</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [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] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3CLA OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Leslie, A | + | [[Category: Leslie, A G.W.]] |
[[Category: CLM]] | [[Category: CLM]] | ||
[[Category: CO]] | [[Category: CO]] | ||
[[Category: transferase (acyltransferase)]] | [[Category: transferase (acyltransferase)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:08:49 2008'' |
Revision as of 17:08, 21 February 2008
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REFINED CRYSTAL STRUCTURE OF TYPE III CHLORAMPHENICOL ACETYLTRANSFERASE AT 1.75 ANGSTROMS RESOLUTION
Overview
High level bacterial resistance to chloramphenicol is generally due to O-acetylation of the antibiotic in a reaction catalysed by chloramphenicol acetyltransferase (CAT, EC 2.3.1.28) in which acetyl-coenzyme A is the acyl donor. The crystal structure of the type III enzyme from Escherichia coli with chloramphenicol bound has been determined and refined at 1.75 A resolution, using a restrained parameter reciprocal space least squares procedure. The refined model, which includes chloramphenicol, 204 solvent molecules and two cobalt ions has a crystallographic R-factor of 18.3% for 27,300 reflections between 6 and 1.75 A resolution. The root-mean-square deviation in bond lengths from ideal values is 0.02 A. The cobalt ions play a crucial role in stabilizing the packing of the molecule in the crystal lattice. CAT is a trimer of identical subunits (monomer Mr 25,000) and the trimeric structure is stabilized by a number of hydrogen bonds, some of which result in the extension of a beta-sheet across the subunit interface. Chloramphenicol binds in a deep pocket located at the boundary between adjacent subunits of the trimer, such that the majority of residues forming the binding pocket belong to one subunit while the catalytically essential histidine belongs to the adjacent subunit. His195 is appropriately positioned to act as a general base catalyst in the reaction, and the required tautomeric stabilization is provided by an unusual interaction with a main-chain carbonyl oxygen.
About this Structure
3CLA is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Chloramphenicol O-acetyltransferase, with EC number 2.3.1.28 Full crystallographic information is available from OCA.
Reference
Refined crystal structure of type III chloramphenicol acetyltransferase at 1.75 A resolution., Leslie AG, J Mol Biol. 1990 May 5;213(1):167-86. PMID:2187098
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