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| | {{STRUCTURE_1gce| PDB=1gce | SCENE= }} | | {{STRUCTURE_1gce| PDB=1gce | SCENE= }} |
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| - | '''STRUCTURE OF THE BETA-LACTAMASE OF ENTEROBACTER CLOACAE GC1'''
| + | ===STRUCTURE OF THE BETA-LACTAMASE OF ENTEROBACTER CLOACAE GC1=== |
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| - | ==Overview==
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| - | A class C beta-lactamase from a clinical isolate of Enterobacter cloacae strain GC1 with improved hydrolytic activity for oxyimino beta-lactam antibiotics has been analyzed by X-ray crystallography to 1.8 A resolution. Relative to the wild-type P99 beta-lactamase, this natural mutant contains a highly unique tandem repeat Ala211-Val212-Arg213 [Nugaka et al. (1995) J. Biol. Chem. 270, 5729-5735]. The 39.4 kDa chromosomal beta-lactamase crystallizes from poly(ethylene glycol) 8000 in potassium phosphate in space group P2(1)2(1)2 with cell dimensions a = 78.0 A, b = 69.5 A, and c = 63.1 A. The crystal structure was solved by the molecular replacement method, and the model has been refined to an R-factor of 0.20 for all nonzero data from 8 to 1.8 A. Deviations of model bonds and angles from ideal values are 0.008 A and 1.4 degrees, respectively. Overlay of alpha-carbon atoms in the GC1 and P99 beta-lactamases results in an rms deviation of 0.6 A. Largest deviations occur in a loop containing Gln120 and in the Omega loop region (200-218) where the three residues 213-215 are disordered. Possibly as a result of this disorder, the width of the opening to the substrate binding cavity, as measured from the 318-324 beta-strand to two loops containing Gln120 and Tyr150 on the other side, is 0.6-1.4 A wider than in P99. It is suggested that conformational flexibility in the expanded Omega loop, and its influence on adjacent protein structure, may facilitate hydrolysis of oxyimino beta-lactams by making the acyl intermediate more open to attack by water. Nevertheless, backbone atoms in core catalytic site residues Ser64, Lys67, Tyr150, Asn152, Lys318, and Ser321 deviate only 0.4 A (rmsd) from atoms in P99. A rotation of a potential catalytic base, Tyr150, relative to P99 at pH 8, is consistent with the requirement for a lower than normal pK(a) for this residue.
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| | + | (as it appears on PubMed at http://www.pubmed.gov), where 10441119 is the PubMed ID number. |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Drug design]] | | [[Category: Drug design]] |
| | [[Category: Extended-spectrum beta- lactamase]] | | [[Category: Extended-spectrum beta- lactamase]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 17:24:38 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 05:04:35 2008'' |
Revision as of 02:04, 1 July 2008
Template:STRUCTURE 1gce
STRUCTURE OF THE BETA-LACTAMASE OF ENTEROBACTER CLOACAE GC1
Template:ABSTRACT PUBMED 10441119
About this Structure
1GCE is a Single protein structure of sequence from Enterobacter cloacae. Full crystallographic information is available from OCA.
Reference
Structure of the extended-spectrum class C beta-lactamase of Enterobacter cloacae GC1, a natural mutant with a tandem tripeptide insertion., Crichlow GV, Kuzin AP, Nukaga M, Mayama K, Sawai T, Knox JR, Biochemistry. 1999 Aug 10;38(32):10256-61. PMID:10441119
Page seeded by OCA on Tue Jul 1 05:04:35 2008
