1iyp
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Toho-1 beta-Lactamase In Complex With Cephalothin
OverviewOverview
Bacterial resistance to beta-lactam antibiotics is a serious problem, limiting current clinical therapy. The most common form of resistance is, the production of beta-lactamases that inactivate beta-lactam antibiotics., Toho-1 is an extended-spectrum beta-lactamase that has acquired efficient, activity not only to penicillins but also to cephalosporins including the, expanded-spectrum cephalosporins that were developed to be stable in, former beta-lactamases. We present the acyl-intermediate structures of, Toho-1 in complex with cefotaxime (expanded-spectrum cephalosporin), cephalothin (non-expanded-spectrum cephalosporin), and benzylpenicillin at, 1.8-, 2.0-, and 2.1-A resolutions, respectively. These structures reveal, distinct features that can explain the ability of Toho-1 to hydrolyze, expanded-spectrum cephalosporins. First, the Omega-loop of Toho-1 is, displaced to avoid the steric contacts with the bulky side chain of, cefotaxime. Second, the conserved residues Asn(104) and Asp(240) form, unique interactions with the bulky side chain of cefotaxime to fix it, tightly. Finally, the unique interaction between the conserved Ser(237), and cephalosporins probably helps to bring the beta-lactam carbonyl group, to the suitable position in the oxyanion hole, thus increasing the, cephalosporinase activity.
About this StructureAbout this Structure
1IYP is a Single protein structure of sequence from Escherichia coli with SO4 and CEP as ligands. Active as Beta-lactamase, with EC number 3.5.2.6 Full crystallographic information is available from OCA.
ReferenceReference
Acyl-intermediate structures of the extended-spectrum class A beta-lactamase, Toho-1, in complex with cefotaxime, cephalothin, and benzylpenicillin., Shimamura T, Ibuka A, Fushinobu S, Wakagi T, Ishiguro M, Ishii Y, Matsuzawa H, J Biol Chem. 2002 Nov 29;277(48):46601-8. Epub 2002 Sep 8. PMID:12221102
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