1m6k
From Proteopedia
(New page: 200px<br /><applet load="1m6k" size="450" color="white" frame="true" align="right" spinBox="true" caption="1m6k, resolution 1.50Å" /> '''Structure of the OXA...) |
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| - | [[Image:1m6k.jpg|left|200px]]<br /><applet load="1m6k" size=" | + | [[Image:1m6k.jpg|left|200px]]<br /><applet load="1m6k" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1m6k, resolution 1.50Å" /> | caption="1m6k, resolution 1.50Å" /> | ||
'''Structure of the OXA-1 class D beta-lactamase'''<br /> | '''Structure of the OXA-1 class D beta-lactamase'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The crystallographic structure of the Escherichia coli OXA-1 | + | The crystallographic structure of the Escherichia coli OXA-1 beta-lactamase has been established at 1.5-A resolution and refined to R = 0.18. The 28.2-kD oxacillinase is a class D serine beta-lactamase that is especially active against the penicillin-type beta-lactams oxacillin and cloxacillin. In contrast to the structures of OXA-2, OXA-10, and OXA-13 belonging to other subclasses, the OXA-1 molecule is monomeric rather than dimeric and represents the subclass characterized by an enlarged Omega loop near the beta-lactam binding site. The 6-residue hydrophilic insertion in this loop cannot interact directly with substrates and, instead, projects into solvent. In this structure at pH 7.5, carboxylation of the conserved Lys 70 in the catalytic site is observed. One oxygen atom of the carboxylate group is hydrogen bonded to Ser 120 and Trp 160. The other oxygen atom is more exposed and hydrogen bonded to the Ogamma of the reactive Ser 67. In the overlay of the class D and class A binding sites, the carboxylate group is displaced ca. 2.6 A from the carboxylate group of Glu 166 of class A enzymes. However, each group is equidistant from the site of the water molecule expected to function in hydrolysis, and which could be activated by the carboxylate group of Lys 70. In this ligand-free OXA-1 structure, no water molecule is seen in this site, so the water molecule must enter after formation of the acyl-Ser 67 intermediate. |
==About this Structure== | ==About this Structure== | ||
| - | 1M6K 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 MPD as [http://en.wikipedia.org/wiki/ligand ligand]. 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:// | + | 1M6K 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=MPD:'>MPD</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. 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=1M6K OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Braswell, E | + | [[Category: Braswell, E H.]] |
| - | [[Category: Knox, J | + | [[Category: Knox, J R.]] |
[[Category: Mayama, K.]] | [[Category: Mayama, K.]] | ||
[[Category: Nukaga, M.]] | [[Category: Nukaga, M.]] | ||
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[[Category: side chain modification]] | [[Category: side chain modification]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:52:06 2008'' |
Revision as of 11:52, 21 February 2008
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Structure of the OXA-1 class D beta-lactamase
Overview
The crystallographic structure of the Escherichia coli OXA-1 beta-lactamase has been established at 1.5-A resolution and refined to R = 0.18. The 28.2-kD oxacillinase is a class D serine beta-lactamase that is especially active against the penicillin-type beta-lactams oxacillin and cloxacillin. In contrast to the structures of OXA-2, OXA-10, and OXA-13 belonging to other subclasses, the OXA-1 molecule is monomeric rather than dimeric and represents the subclass characterized by an enlarged Omega loop near the beta-lactam binding site. The 6-residue hydrophilic insertion in this loop cannot interact directly with substrates and, instead, projects into solvent. In this structure at pH 7.5, carboxylation of the conserved Lys 70 in the catalytic site is observed. One oxygen atom of the carboxylate group is hydrogen bonded to Ser 120 and Trp 160. The other oxygen atom is more exposed and hydrogen bonded to the Ogamma of the reactive Ser 67. In the overlay of the class D and class A binding sites, the carboxylate group is displaced ca. 2.6 A from the carboxylate group of Glu 166 of class A enzymes. However, each group is equidistant from the site of the water molecule expected to function in hydrolysis, and which could be activated by the carboxylate group of Lys 70. In this ligand-free OXA-1 structure, no water molecule is seen in this site, so the water molecule must enter after formation of the acyl-Ser 67 intermediate.
About this Structure
1M6K is a Single protein structure of sequence from Escherichia coli with as ligand. Active as Beta-lactamase, with EC number 3.5.2.6 Full crystallographic information is available from OCA.
Reference
Comparison of beta-lactamases of classes A and D: 1.5-A crystallographic structure of the class D OXA-1 oxacillinase., Sun T, Nukaga M, Mayama K, Braswell EH, Knox JR, Protein Sci. 2003 Jan;12(1):82-91. PMID:12493831
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