1gce: Difference between revisions

|PDB= 1gce |SIZE=350|CAPTION= <scene name='initialview01'>1gce</scene>, resolution 1.8&Aring;

|SITE= <scene name='pdbsite=ASA:Catalytic+Site'>ASA</scene>

|LIGAND=  

|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=  

|DOMAIN=

|RELATEDENTRY=[[2blt|2BLT]]

|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1gce FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1gce OCA], [http://www.ebi.ac.uk/pdbsum/1gce PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1gce RCSB]</span>

'''STRUCTURE OF THE BETA-LACTAMASE OF ENTEROBACTER CLOACAE GC1'''

==Overview==

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.

 

==About this Structure==

1GCE is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Enterobacter_cloacae Enterobacter cloacae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GCE OCA].

 

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:[http://www.ncbi.nlm.nih.gov/pubmed/10441119 10441119]

[[Category: Single protein]]

[[Category: Crichlow, G V.]]

[[Category: Knox, J R.]]

[[Category: Kuzin, A P.]]

[[Category: Nukaga, M.]]

[[Category: Sawai, T.]]