Structural basis of the inhibition of class A beta-lactamases and penicillin-binding proteins by 6-beta-iodopenicillanate.

6-Beta-halogenopenicillanates are powerful, irreversible inhibitors of various beta-lactamases and penicillin-binding proteins. Upon acylation of these enzymes, the inhibitors are thought to undergo a structural rearrangement associated with the departure of the iodide and formation of a dihydrothiazine ring, but, to date, no structural evidence has proven this. 6-Beta-iodopenicillanic acid (BIP) is shown here to be an active antibiotic against various bacterial strains and an effective inhibitor of the class A beta-lactamase of Bacillus subtilis BS3 (BS3) and the D,D-peptidase of Actinomadura R39 (R39).

Crystal structure of the Mycobacterium fortuitum class A beta-lactamase: structural basis for broad substrate specificity.

beta-Lactamases are the main cause of bacterial resistance to penicillins and cephalosporins. Class A beta-lactamases, the largest group of beta-lactamases, have been found in many bacterial strains, including mycobacteria, for which no beta-lactamase structure has been previously reported. The crystal structure of the class A beta-lactamase from Mycobacterium fortuitum (MFO) has been solved at 2.

Crystal structure of the sensor domain of the BlaR penicillin receptor from Bacillus licheniformis.

As in several staphylococci, the synthesis of the Bacillus licheniformis 749/I beta-lactamase is an inducible phenomenon regulated by a signal-transducing membrane protein BlaR. The C-terminal domain of this multimodular protein is an extracellular domain which specifically recognizes beta-lactam antibiotics. When it binds a beta-lactam, a signal is transmitted by the transmembrane region to the intracellular loops.

Crystal structure of Enterobacter cloacae 908R class C beta-lactamase bound to iodo-acetamido-phenyl boronic acid, a transition-state analogue.

The structures of the class C beta-lactamase from Enterobacter cloacae 908R alone and in complex with a boronic acid transition-state analogue were determined by X-ray crystallography at 2.1 and 2.3 A, respectively.

Catalytic mechanism of the Streptomyces K15 DD-transpeptidase/penicillin-binding protein probed by site-directed mutagenesis and structural analysis.

The Streptomyces K15 penicillin-binding DD-transpeptidase is presumed to be involved in peptide cross-linking during bacterial cell wall peptidoglycan assembly. To gain insight into the catalytic mechanism, the roles of residues Lys38, Ser96, and Cys98, belonging to the structural elements defining the active site cleft, have been investigated by site-directed mutagenesis, biochemical studies, and X-ray diffraction analysis. The Lys38His and Ser96Ala mutations almost completely abolished the penicillin binding and severely impaired the transpeptidase activities while the geometry of the active site was essentially the same as in the wild-type enzyme.