1hzo
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STRUCTURE OF CLASS A CEPHALOSPORINASE FROM PROTEUS VULGARIS K1
OverviewOverview
The structure of a chromosomal extended-spectrum beta-lactamase (ESBL) having the ability to hydrolyze cephalosporins including cefuroxime and ceftazidime has been determined by X-ray crystallography to 1.75 A resolution. The species-specific class A beta-lactamase from Proteus vulgaris K1 was crystallized at pH 6.25 and its structure solved by molecular replacement. Refinement of the model resulted in crystallographic R and R(free) of 16.9 % and 19.3 %, respectively. The folding of the K1 enzyme is broadly similar to that of non-ESBL TEM-type beta-lactamases (2 A rmsd for C(alpha)) and differs by only 0.35 A for all atoms of six conserved residues in the catalytic site. Other residues promoting extended-spectrum activity in K1 include the side-chains of atypical residues Ser237 and Lys276. These side-chains are linked by two water molecules, one of which lies in the position normally filled by the guanidinium group of Arg244, present in most non-ESBL enzymes but absent from K1. The ammonium group of Lys276, ca 3.5 A from the virtual Arg244 guanidinium position, may interact with polar R2 substitutents on the dihydrothiazene ring of cephalosporins.
About this StructureAbout this Structure
1HZO is a Single protein structure of sequence from Proteus vulgaris with as ligand. Active as Beta-lactamase, with EC number 3.5.2.6 Full crystallographic information is available from OCA.
ReferenceReference
Structure of an extended-spectrum class A beta-lactamase from Proteus vulgaris K1., Nukaga M, Mayama K, Crichlow GV, Knox JR, J Mol Biol. 2002 Mar 15;317(1):109-17. PMID:11916382
Page seeded by OCA on Thu Feb 21 13:06:27 2008