1bue | pdb_00001bue
NMC-A CARBAPENEMASE FROM ENTEROBACTER CLOACAE
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Overview
The treatment of infectious diseases by penicillin and cephalosporin antibiotics is continuously challenged by the emergence and the dissemination of the numerous TEM and SHV mutant beta-lactamases with extended substrate profiles. These class A beta-lactamases nevertheless remain inefficient against carbapenems, the most effective antibiotics against clinically relevant pathogens. A new member of this enzyme class, NMC-A, was recently reported to hydrolyze at high rates, and hence destroy, all known beta-lactam antibiotics, including carbapenems and cephamycins. The crystal structure of NMC-A was solved to 1.64-A resolution, and reveals modifications in the topology of the substrate-binding site. While preserving the geometry of the essential catalytic residues, the active site of the enzyme presents a disulfide bridge between residues 69 and 238, and certain other structural differences compared with the other beta-lactamases. These unusual features in class A beta-lactamases involve amino acids that participate in enzyme-substrate interactions, which suggested that these structural factors should be related to the very broad substrate specificity of this enzyme. The comparison of the NMC-A structure with those of other class A enzymes and enzyme-ligand complexes, indicated that the position of Asn-132 in NMC-A provides critical additional space in the region of the protein where the poorer substrates for class A beta-lactamases, such as cephamycins and carbapenems, need to be accommodated.
About this Structure
1BUE is a Single protein structure of sequence from Enterobacter cloacae. Active as Beta-lactamase, with EC number 3.5.2.6 Full crystallographic information is available from OCA.
Reference
X-ray analysis of the NMC-A beta-lactamase at 1.64-A resolution, a class A carbapenemase with broad substrate specificity., Swaren P, Maveyraud L, Raquet X, Cabantous S, Duez C, Pedelacq JD, Mariotte-Boyer S, Mourey L, Labia R, Nicolas-Chanoine MH, Nordmann P, Frere JM, Samama JP, J Biol Chem. 1998 Oct 9;273(41):26714-21. PMID:9756914
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