1xx2

Refinement of P99 beta-lactamase from Enterobacter cloacaeRefinement of P99 beta-lactamase from Enterobacter cloacae

Structural highlights 1xx2 is a 2 chain structure with sequence from Enterobacter cloacae. This structure supersedes the now removed PDB entry 2blt. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 1bls, 2blt Activity: Beta-lactamase, with EC number 3.5.2.6 Resources: FirstGlance, OCA, RCSB, PDBsum Function [AMPC_ENTCL] This protein is a serine beta-lactamase with a substrate specificity for cephalosporins. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The structure of the class C ampC beta-lactamase (cephalosporinase) from Enterobacter cloacae strain P99 has been established by x-ray crystallography to 2-A resolution and compared to a class A beta-lactamase (penicillinase) structure. The binding site for beta-lactam (penicillinase) structure. The binding site for beta-lactam antibiotics is generally more open than that in penicillinases, in agreement with the ability of the class C beta-lactamases to better bind third-generation cephalosporins. Four corresponding catalytic residues (Ser-64/70, Lys-67/73, Lys-315/234, and Tyr-150/Ser-130 in class C/A) lie in equivalent positions within 0.4 A. Significant differences in positions and accessibilities of Arg-349/244 may explain the inability of clavulanate-type inhibitors to effectively inactivate the class C beta-lactamases. Glu-166, required for deacylation of the beta-lactamoyl intermediate in class A penicillinases, has no counterpart in this cephalosporinase; the nearest candidate, Asp-217, is 10 A from the reactive Ser-64. A comparison of overall tertiary folding shows that the cephalosporinase, more than the penicillinase, is broadly similar to the ancestral beta-lactam-inhibited enzymes of bacterial cell wall synthesis. On this basis, it is proposed that the cephalosporinase is the older of the two beta-lactamases, and, therefore, that a local refolding in the active site, rather than a simple point mutation, was required for the primordial class C beta-lactamase to evolve to the class A beta-lactamase having an improved ability to catalyze the deacylation step of beta-lactam hydrolysis. Evolution of an enzyme activity: crystallographic structure at 2-A resolution of cephalosporinase from the ampC gene of Enterobacter cloacae P99 and comparison with a class A penicillinase.,Lobkovsky E, Moews PC, Liu H, Zhao H, Frere JM, Knox JR Proc Natl Acad Sci U S A. 1993 Dec 1;90(23):11257-61. PMID:8248237 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Beta-lactamase

spinqualitylabelsall models 1xx2, resolution 1.88Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image