1we4
From Proteopedia
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|PDB= 1we4 |SIZE=350|CAPTION= <scene name='initialview01'>1we4</scene>, resolution 1.70Å | |PDB= 1we4 |SIZE=350|CAPTION= <scene name='initialview01'>1we4</scene>, resolution 1.70Å | ||
|SITE= | |SITE= | ||
| - | |LIGAND= <scene name='pdbligand=SO4:SULFATE ION'>SO4</scene> | + | |LIGAND= <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene> |
| - | |ACTIVITY= [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] | + | |ACTIVITY= <span class='plainlinks'>[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] </span> |
|GENE= | |GENE= | ||
| + | |DOMAIN= | ||
| + | |RELATEDENTRY=[[1bza|1BZA]], [[1iys|1IYS]] | ||
| + | |RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1we4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1we4 OCA], [http://www.ebi.ac.uk/pdbsum/1we4 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1we4 RCSB]</span> | ||
}} | }} | ||
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[[Category: Sakai, H.]] | [[Category: Sakai, H.]] | ||
[[Category: Shimizu-Ibuka, A.]] | [[Category: Shimizu-Ibuka, A.]] | ||
| - | [[Category: SO4]] | ||
[[Category: antibiotic resistance]] | [[Category: antibiotic resistance]] | ||
[[Category: hydrolase]] | [[Category: hydrolase]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 00:34:59 2008'' |
Revision as of 21:34, 30 March 2008
| |||||||
| , resolution 1.70Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | |||||||
| Activity: | Beta-lactamase, with EC number 3.5.2.6 | ||||||
| Related: | 1BZA, 1IYS
| ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal Structure of Class A beta-Lactamase Toho-1 G238C mutant
Overview
Previous crystallographic structural analysis of extended-spectrum beta-lactamase Toho-1 predicted that the high flexibility of beta-strand B3, the region that contains a conserved KTG motif and forms one wall of the substrate-binding site, could be one of the key features contributing to Toho-1 activity toward third-generation cephalosporins. To investigate whether this possible flexibility really affects the substrate profile of this enzyme, two Toho-1 mutants have been produced, G238C and G238C/G239in, in which the glycine residue at position 238 was replaced with a cysteine and an additional glycine residue was inserted. Our intent was to introduce a disulfide bond between the cysteine residues at positions 69 and 238, and thus to lock the position of beta-strand B3. The results of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) titration indicated formation of a new disulfide bridge in the G238C mutant, although disulfide bond formation was not confirmed in the G238C/G239in mutant. Kinetic analysis showed that the activity of the G238C mutant decreased drastically against third-generation cephalosporins, while its catalytic efficiency against penicillins and first-generation cephalosporins was almost identical to that of the wild-type enzyme. This result was consistent with the prediction that flexibility in beta-strand B3 was critical for activity against third-generation cephalosporins in Toho-1. Furthermore, we have determined the crystal structure of the G238C mutant enzyme to analyze the structural changes in detail. The structural model clearly shows the introduction of a new disulfide bridge and that there is no appreciable difference between the overall structures of the wild-type enzyme and the G238C mutant, although the introduced disulfide bond slightly influenced the positions of Ser237 on beta-strand B3 and Asn170 on the Omega loop. The results of our kinetic and structural analyses suggest that the flexibility of beta-strand B3, as well as the positions of Ser237 and the Omega loop, is critical for the substrate specificity expansion of Toho-1.
About this Structure
1WE4 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
An engineered disulfide bond between residues 69 and 238 in extended-spectrum beta-lactamase Toho-1 reduces its activity toward third-generation cephalosporins., Shimizu-Ibuka A, Matsuzawa H, Sakai H, Biochemistry. 2004 Dec 21;43(50):15737-45. PMID:15595829
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