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2aio
From Proteopedia
(New page: 200px<br /><applet load="2aio" size="450" color="white" frame="true" align="right" spinBox="true" caption="2aio, resolution 1.70Å" /> '''Metallo beta lactama...) |
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| - | [[Image:2aio.gif|left|200px]]<br /><applet load="2aio" size=" | + | [[Image:2aio.gif|left|200px]]<br /><applet load="2aio" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2aio, resolution 1.70Å" /> | caption="2aio, resolution 1.70Å" /> | ||
'''Metallo beta lactamase L1 from Stenotrophomonas maltophilia complexed with hydrolyzed moxalactam'''<br /> | '''Metallo beta lactamase L1 from Stenotrophomonas maltophilia complexed with hydrolyzed moxalactam'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Metallo-beta-lactamases are zinc-dependent enzymes responsible for | + | Metallo-beta-lactamases are zinc-dependent enzymes responsible for resistance to beta-lactam antibiotics in a variety of host bacteria, usually Gram-negative species that act as opportunist pathogens. They hydrolyze all classes of beta-lactam antibiotics, including carbapenems, and escape the action of available beta-lactamase inhibitors. Efforts to develop effective inhibitors have been hampered by the lack of structural information regarding how these enzymes recognize and turn over beta-lactam substrates. We report here the crystal structure of the Stenotrophomonas maltophilia L1 enzyme in complex with the hydrolysis product of the 7alpha-methoxyoxacephem, moxalactam. The on-enzyme complex is a 3'-exo-methylene species generated by elimination of the 1-methyltetrazolyl-5-thiolate anion from the 3'-methyl group. Moxalactam binding to L1 involves direct interaction of the two active site zinc ions with the beta-lactam amide and C4 carboxylate, groups that are common to all beta-lactam substrates. The 7beta-[(4-hydroxyphenyl)malonyl]-amino substituent makes limited hydrophobic and hydrogen bonding contacts with the active site groove. The mode of binding provides strong evidence that a water molecule situated between the two metal ions is the most likely nucleophile in the hydrolytic reaction. These data suggest a reaction mechanism for metallo-beta-lactamases in which both metal ions contribute to catalysis by activating the bridging water/hydroxide nucleophile, polarizing the substrate amide bond for attack and stabilizing anionic nitrogen intermediates. The structure illustrates how a binuclear zinc site confers upon metallo-beta-lactamases the ability both to recognize and efficiently hydrolyze a wide variety of beta-lactam substrates. |
==About this Structure== | ==About this Structure== | ||
| - | 2AIO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Stenotrophomonas_maltophilia Stenotrophomonas maltophilia] with ZN, SO4 and MX1 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:// | + | 2AIO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Stenotrophomonas_maltophilia Stenotrophomonas maltophilia] with <scene name='pdbligand=ZN:'>ZN</scene>, <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=MX1:'>MX1</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=2AIO OCA]. |
==Reference== | ==Reference== | ||
| Line 14: | Line 14: | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Stenotrophomonas maltophilia]] | [[Category: Stenotrophomonas maltophilia]] | ||
| - | [[Category: Blackburn, G | + | [[Category: Blackburn, G M.]] |
| - | [[Category: Gamblin, S | + | [[Category: Gamblin, S J.]] |
[[Category: Howell, S.]] | [[Category: Howell, S.]] | ||
[[Category: Read, J.]] | [[Category: Read, J.]] | ||
| - | [[Category: Sessions, R | + | [[Category: Sessions, R B.]] |
[[Category: Spencer, J.]] | [[Category: Spencer, J.]] | ||
[[Category: MX1]] | [[Category: MX1]] | ||
| Line 29: | Line 29: | ||
[[Category: zinc]] | [[Category: zinc]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:27:48 2008'' |
Revision as of 14:27, 21 February 2008
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Metallo beta lactamase L1 from Stenotrophomonas maltophilia complexed with hydrolyzed moxalactam
Overview
Metallo-beta-lactamases are zinc-dependent enzymes responsible for resistance to beta-lactam antibiotics in a variety of host bacteria, usually Gram-negative species that act as opportunist pathogens. They hydrolyze all classes of beta-lactam antibiotics, including carbapenems, and escape the action of available beta-lactamase inhibitors. Efforts to develop effective inhibitors have been hampered by the lack of structural information regarding how these enzymes recognize and turn over beta-lactam substrates. We report here the crystal structure of the Stenotrophomonas maltophilia L1 enzyme in complex with the hydrolysis product of the 7alpha-methoxyoxacephem, moxalactam. The on-enzyme complex is a 3'-exo-methylene species generated by elimination of the 1-methyltetrazolyl-5-thiolate anion from the 3'-methyl group. Moxalactam binding to L1 involves direct interaction of the two active site zinc ions with the beta-lactam amide and C4 carboxylate, groups that are common to all beta-lactam substrates. The 7beta-[(4-hydroxyphenyl)malonyl]-amino substituent makes limited hydrophobic and hydrogen bonding contacts with the active site groove. The mode of binding provides strong evidence that a water molecule situated between the two metal ions is the most likely nucleophile in the hydrolytic reaction. These data suggest a reaction mechanism for metallo-beta-lactamases in which both metal ions contribute to catalysis by activating the bridging water/hydroxide nucleophile, polarizing the substrate amide bond for attack and stabilizing anionic nitrogen intermediates. The structure illustrates how a binuclear zinc site confers upon metallo-beta-lactamases the ability both to recognize and efficiently hydrolyze a wide variety of beta-lactam substrates.
About this Structure
2AIO is a Single protein structure of sequence from Stenotrophomonas maltophilia with , and as ligands. Active as Beta-lactamase, with EC number 3.5.2.6 Full crystallographic information is available from OCA.
Reference
Antibiotic recognition by binuclear metallo-beta-lactamases revealed by X-ray crystallography., Spencer J, Read J, Sessions RB, Howell S, Blackburn GM, Gamblin SJ, J Am Chem Soc. 2005 Oct 19;127(41):14439-44. PMID:16218639
Page seeded by OCA on Thu Feb 21 16:27:48 2008
