1iyp: Difference between revisions
New page: left|200px<br /><applet load="1iyp" size="450" color="white" frame="true" align="right" spinBox="true" caption="1iyp, resolution 2.Å" /> '''Toho-1 beta-Lactamase ... |
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[[Image:1iyp.jpg|left|200px]]<br /><applet load="1iyp" size=" | [[Image:1iyp.jpg|left|200px]]<br /><applet load="1iyp" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1iyp, resolution 2.Å" /> | caption="1iyp, resolution 2.Å" /> | ||
'''Toho-1 beta-Lactamase In Complex With Cephalothin'''<br /> | '''Toho-1 beta-Lactamase In Complex With Cephalothin'''<br /> | ||
==Overview== | ==Overview== | ||
Bacterial resistance to beta-lactam antibiotics is a serious problem | Bacterial resistance to beta-lactam antibiotics is a serious problem limiting current clinical therapy. The most common form of resistance is the production of beta-lactamases that inactivate beta-lactam antibiotics. Toho-1 is an extended-spectrum beta-lactamase that has acquired efficient activity not only to penicillins but also to cephalosporins including the expanded-spectrum cephalosporins that were developed to be stable in former beta-lactamases. We present the acyl-intermediate structures of Toho-1 in complex with cefotaxime (expanded-spectrum cephalosporin), cephalothin (non-expanded-spectrum cephalosporin), and benzylpenicillin at 1.8-, 2.0-, and 2.1-A resolutions, respectively. These structures reveal distinct features that can explain the ability of Toho-1 to hydrolyze expanded-spectrum cephalosporins. First, the Omega-loop of Toho-1 is displaced to avoid the steric contacts with the bulky side chain of cefotaxime. Second, the conserved residues Asn(104) and Asp(240) form unique interactions with the bulky side chain of cefotaxime to fix it tightly. Finally, the unique interaction between the conserved Ser(237) and cephalosporins probably helps to bring the beta-lactam carbonyl group to the suitable position in the oxyanion hole, thus increasing the cephalosporinase activity. | ||
==About this Structure== | ==About this Structure== | ||
1IYP 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 SO4 and CEP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Beta-lactamase Beta-lactamase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.2.6 3.5.2.6] Full crystallographic information is available from [http:// | 1IYP 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=SO4:'>SO4</scene> and <scene name='pdbligand=CEP:'>CEP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Beta-lactamase Beta-lactamase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.2.6 3.5.2.6] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IYP OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: complex]] | [[Category: complex]] | ||
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Revision as of 14:17, 21 February 2008
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Toho-1 beta-Lactamase In Complex With Cephalothin
OverviewOverview
Bacterial resistance to beta-lactam antibiotics is a serious problem limiting current clinical therapy. The most common form of resistance is the production of beta-lactamases that inactivate beta-lactam antibiotics. Toho-1 is an extended-spectrum beta-lactamase that has acquired efficient activity not only to penicillins but also to cephalosporins including the expanded-spectrum cephalosporins that were developed to be stable in former beta-lactamases. We present the acyl-intermediate structures of Toho-1 in complex with cefotaxime (expanded-spectrum cephalosporin), cephalothin (non-expanded-spectrum cephalosporin), and benzylpenicillin at 1.8-, 2.0-, and 2.1-A resolutions, respectively. These structures reveal distinct features that can explain the ability of Toho-1 to hydrolyze expanded-spectrum cephalosporins. First, the Omega-loop of Toho-1 is displaced to avoid the steric contacts with the bulky side chain of cefotaxime. Second, the conserved residues Asn(104) and Asp(240) form unique interactions with the bulky side chain of cefotaxime to fix it tightly. Finally, the unique interaction between the conserved Ser(237) and cephalosporins probably helps to bring the beta-lactam carbonyl group to the suitable position in the oxyanion hole, thus increasing the cephalosporinase activity.
About this StructureAbout this Structure
1IYP is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Beta-lactamase, with EC number 3.5.2.6 Full crystallographic information is available from OCA.
ReferenceReference
Acyl-intermediate structures of the extended-spectrum class A beta-lactamase, Toho-1, in complex with cefotaxime, cephalothin, and benzylpenicillin., Shimamura T, Ibuka A, Fushinobu S, Wakagi T, Ishiguro M, Ishii Y, Matsuzawa H, J Biol Chem. 2002 Nov 29;277(48):46601-8. Epub 2002 Sep 8. PMID:12221102
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