1g6a: Difference between revisions
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'''PSE-4 CARBENICILLINASE, R234K MUTANT''' | {{Structure | ||
|PDB= 1g6a |SIZE=350|CAPTION= <scene name='initialview01'>1g6a</scene>, resolution 1.75Å | |||
|SITE= | |||
|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] | |||
|GENE= | |||
}} | |||
'''PSE-4 CARBENICILLINASE, R234K MUTANT''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
1G6A is a [ | 1G6A is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_aeruginosa Pseudomonas aeruginosa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1G6A OCA]. | ||
==Reference== | ==Reference== | ||
Insights into the molecular basis for the carbenicillinase activity of PSE-4 beta-lactamase from crystallographic and kinetic studies., Lim D, Sanschagrin F, Passmore L, De Castro L, Levesque RC, Strynadka NC, Biochemistry. 2001 Jan 16;40(2):395-402. PMID:[http:// | Insights into the molecular basis for the carbenicillinase activity of PSE-4 beta-lactamase from crystallographic and kinetic studies., Lim D, Sanschagrin F, Passmore L, De Castro L, Levesque RC, Strynadka NC, Biochemistry. 2001 Jan 16;40(2):395-402. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/11148033 11148033] | ||
[[Category: Beta-lactamase]] | [[Category: Beta-lactamase]] | ||
[[Category: Pseudomonas aeruginosa]] | [[Category: Pseudomonas aeruginosa]] | ||
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[[Category: r234k mutant]] | [[Category: r234k mutant]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 11:18:48 2008'' | ||
Revision as of 12:18, 20 March 2008
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| , resolution 1.75Å | |||||||
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| Ligands: | |||||||
| Activity: | Beta-lactamase, with EC number 3.5.2.6 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
PSE-4 CARBENICILLINASE, R234K MUTANT
OverviewOverview
PSE-4 is a class A beta-lactamase produced by strains of Pseudomonas aeruginosa and is highly active for the penicillin derivative carbenicillin. The crystal structure of the wild-type PSE-4 carbenicillinase has been determined to 1.95 A resolution by molecular replacement and represents the first structure of a carbenicillinase published to date. A superposition of the PSE-4 structure with that of TEM-1 shows a rms deviation of 1.3 A for 263 Calpha atoms. Most carbenicillinases are unique among class A beta-lactamases in that residue 234 is an arginine (ABL standard numbering scheme), while in all other class A enzymes this residue is a lysine. Kinetic characterization of a R234K PSE-4 mutant reveals a 50-fold reduction in k(cat)/K(m) and confirms the importance of Arg 234 for carbenicillinase activity. A comparison of the structure of the R234K mutant refined to 1.75 A resolution with the wild-type structure shows that Arg 234 stabilizes an alternate conformation of the Ser 130 side chain, not seen in other class A beta-lactamase structures. Our molecular modeling studies suggest that the position of a bound carbenicillin would be shifted relative to that of a bound benzylpenicillin in order to avoid a steric clash between the carbenicillin alpha-carboxylate group and the conserved side chain of Asn 170. The alternate conformation of the catalytic Ser 130 in wild-type PSE-4 may be involved in accommodating this shift in the bound substrate position.
About this StructureAbout this Structure
1G6A is a Single protein structure of sequence from Pseudomonas aeruginosa. Full crystallographic information is available from OCA.
ReferenceReference
Insights into the molecular basis for the carbenicillinase activity of PSE-4 beta-lactamase from crystallographic and kinetic studies., Lim D, Sanschagrin F, Passmore L, De Castro L, Levesque RC, Strynadka NC, Biochemistry. 2001 Jan 16;40(2):395-402. PMID:11148033
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