1n9b

Ultrahigh resolution structure of a class A beta-lactamase: On the mechanism and specificity of the extended-spectrum SHV-2 enzymeUltrahigh resolution structure of a class A beta-lactamase: On the mechanism and specificity of the extended-spectrum SHV-2 enzyme

Structural highlights 1n9b is a 1 chain structure with sequence from Klebsiella pneumoniae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 0.9Å Ligands: , , Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function BLA3_KLEPN This enzyme hydrolyzes cefotaxime, ceftazidime and other broad spectrum 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 Bacterial beta-lactamases hydrolyze beta-lactam antibiotics such as penicillins and cephalosporins. The TEM-type class A beta-lactamase SHV-2 is a natural variant that exhibits activity against third-generation cephalosporins normally resistant to hydrolysis by class A enzymes. SHV-2 contains a single Gly238Ser change relative to the wild-type enzyme SHV-1. Crystallographic refinement of a model including hydrogen atoms gave R and R(free) of 12.4% and 15.0% for data to 0.91 A resolution. The hydrogen atom on the O(gamma) atom of the reactive Ser70 is clearly seen for the first time, bridging to the water molecule activated by Glu166. Though hydrogen atoms on the nearby Lys73 are not seen, this observation of the Ser70 hydrogen atom and the hydrogen bonding pattern around Lys73 indicate that Lys73 is protonated. These findings support a role for the Glu166-water couple, rather than Lys73, as the general base in the deprotonation of Ser70 in the acylation process of class A beta-lactamases. Overlay of SHV-2 with SHV-1 shows a significant 1-3 A displacement in the 238-242 beta-strand-turn segment, making the beta-lactam binding site more open to newer cephalosporins with large C7 substituents and thereby expanding the substrate spectrum of the variant enzyme. The OH group of the buried Ser238 side-chain hydrogen bonds to the main-chain CO of Asn170 on the Omega loop, that is unaltered in position relative to SHV-1. This structural role for Ser238 in protein-protein binding makes less likely its hydrogen bonding to oximino cephalosporins such as cefotaxime or ceftazidime. Ultrahigh resolution structure of a class A beta-lactamase: on the mechanism and specificity of the extended-spectrum SHV-2 enzyme.,Nukaga M, Mayama K, Hujer AM, Bonomo RA, Knox JR J Mol Biol. 2003 Apr 18;328(1):289-301. PMID:12684014 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Beta-lactamase 3D structures

spinqualitylabelsall models 1n9b, resolution 0.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image