1k55 | pdb_00001k55

OXA 10 class D beta-lactamase at pH 7.5

spinqualitylabelsall models 1k55, resolution 1.39Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1k55 is a 4 chain structure with sequence from Pseudomonas aeruginosa. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.39Å Ligands: EDO, KCX, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function BLO10_PSEAI Hydrolyzes both carbenicillin and oxacillin. 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 beta-Lactamases are the resistance enzymes for beta-lactam antibiotics, of which four classes are known. beta-lactamases hydrolyze the beta-lactam moieties of these antibiotics, rendering them inactive. It is shown herein that the class D OXA-10 beta-lactamase depends critically on an unusual carbamylated lysine as the basic residue for both the enzyme acylation and deacylation steps of catalysis. The formation of carbamylated lysine is reversible. Evidence is presented that this enzyme is dimeric and carbamylated in living bacteria. High-resolution x-ray structures for the native enzyme were determined at pH values of 6.0, 6.5, 7.5, and 8.5. Two dimers are present per asymmetric unit. One monomer in each dimer was carbamylated at pH 6.0, whereas all four monomers were fully carbamylated at pH 8.5. At the intermediate pH values, one monomer of each dimer was carbamylated, and the other showed a mixture of carbamylated and non-carbamylated lysines. It would appear that, as the pH increased for the sample, additional lysines were "titrated" by carbamylation. A handful of carbamylated lysines are known from protein crystallographic data, all of which have been attributed roles in structural stabilization (mostly as metal ligands) of the proteins. This paper reports a previously unrecognized role for a noncoordinated carbamylate lysine as a basic residue involved in mechanistic reactions of an enzyme, which indicates another means for expansion of the catalytic capabilities of the amino acids in nature beyond the 20 common amino acids in development of biological catalysts. Critical involvement of a carbamylated lysine in catalytic function of class D beta-lactamases.,Golemi D, Maveyraud L, Vakulenko S, Samama JP, Mobashery S Proc Natl Acad Sci U S A. 2001 Dec 4;98(25):14280-5. Epub 2001 Nov 27. PMID:11724923 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Beta-lactamase 3D structures

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