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See detailCrystal structure of Enterobacter cloacae 908R class C beta-lactamase bound to iodo-acetamido-phenyl boronic acid, a transition-state analogue
Wouters, J.; Fonze, E.; Vermeire, M. et al

in Cellular and Molecular Life Sciences (2003), 60(8), 1764-1773

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

The structures of the, class C beta-lactamase from Enterobacter cloacae 908R alone and in complex with a baronic acid transition-state analogue were determined by X-ray crystallography at 2.1 and 2.3 Angstrom, respectively. The structure of the enzyme resembles those of other class C beta-lactamases. The structure of the. complex with the transition-state analogue, iodo-acetamido-phenyl boronic acid, shows that the inhibitor is covalently, bound to the active-site serine (Ser64). Binding of the inhibitor within the active site is compared with previously determined structures of complexes with other class C enzymes. The structure of the boronic acid adduct indicates ways to improve the affinity of this class of inhibitors. This structure of 908R class C beta-lactamase in complex with a transitionstate analogue provides further insights into the mechanism of action of these hydrolases. [less ▲]

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See detailThe Crystal Structure Of A Penicilloyl-Serine Transferase Of Intermediate Penicillin Sensitivity - The Dd-Transpeptidase Of Streptomyces K15
Fonze, E.; Vermeire, M.; Nguyen-Disteche, M. et al

in Journal of Biological Chemistry (1999), 274(31), 21853-60

The serine DD-transpeptidase/penicillin-binding protein of Streptomyces K15 catalyzes peptide bond formation in a way that mimics the penicillin-sensitive peptide cross-linking reaction involved in ... [more ▼]

The serine DD-transpeptidase/penicillin-binding protein of Streptomyces K15 catalyzes peptide bond formation in a way that mimics the penicillin-sensitive peptide cross-linking reaction involved in bacterial cell wall peptidoglycan assembly. The Streptomyces K15 enzyme is peculiar in that it can be considered as an intermediate between classical penicillin-binding proteins, for which benzylpenicillin is a very efficient inactivator, and the resistant penicillin-binding proteins that have a low penicillin affinity. With its moderate penicillin sensitivity, the Streptomyces K15 DD-transpeptidase would be helpful in the understanding of the structure-activity relationship of this penicillin-recognizing protein superfamily. The structure of the Streptomyces K15 enzyme has been determined by x-ray crystallography at 2.0-A resolution and refined to an R-factor of 18.6%. The fold adopted by this 262-amino acid polypeptide generates a two-domain structure that is close to those of class A beta-lactamases. However, the Streptomyces K15 enzyme has two particular structural features. It lacks the amino-terminal alpha-helix found in the other penicilloyl-serine transferases, and it exhibits, at its surface, an additional four-stranded beta-sheet. These two characteristics might serve to anchor the enzyme in the plasma membrane. The overall topology of the catalytic pocket of the Streptomyces K15 enzyme is also comparable to that of the class A beta-lactamases, except that the Omega-loop, which bears the essential catalytic Glu(166) residue in the class A beta-lactamases, is entirely modified. This loop adopts a conformation similar to those found in the Streptomyces R61 DD-carboxypeptidase and class C beta-lactamases, with no equivalent acidic residue. [less ▲]

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See detailTEM1 beta-lactamase structure solved by molecular replacement and refined structure of the S235A mutant.
Fonze, E.; Charlier, Paulette ULg; To'th, Y. et al

in Acta Crystallographica Section D-Biological Crystallography (1995), 51(Pt 5), 682-94

beta-Lactamases are bacterial enzymes which catalyse the hydrolysis of the beta-lactam ring of penicillins, cephalosporins and related compounds, thus inactivating these antibiotics. The crystal structure ... [more ▼]

beta-Lactamases are bacterial enzymes which catalyse the hydrolysis of the beta-lactam ring of penicillins, cephalosporins and related compounds, thus inactivating these antibiotics. The crystal structure of the TEM1 beta-lactamase has been determined at 1.9 A resolution by the molecular-replacement method, using the atomic coordinates of two homologous beta-lactamase refined structures which show about 36% strict identity in their amino-acid sequences and 1.96 A r.m.s. deviation between equivalent Calpha atoms. The TEM1 enzyme crystallizes in space group P2(1)2(1)2(1) and there is one molecule per asymmetric unit. The structure was refined by simulated annealing to an R-factor of 15.6% for 15 086 reflections with I >/= 2sigma(I) in the resolution range 5.0-1.9 A. The final crystallographic structure contains 263 amino-acid residues, one sulfate anion in the catalytic cleft and 135 water molecules per asymmetric unit. The folding is very similar to that of the other known class A beta-lactamases. It consists of two domains, the first is formed by a five-stranded beta-sheet covered by three alpha-helices on one face and one alpha-helix on the other, the second domain contains mainly alpha-helices. The catalytic cleft is located at the interface between the two domains. We also report the crystallographic study of the TEM S235A mutant. This mutation of an active-site residue specifically decreases the acylation rate of cephalosporins. This TEM S235A mutant crystallizes under the same conditions as the wild-type protein and its structure was refined at 2.0 A resolution with an R value of 17.6%. The major modification is the appearance of a water molecule near the mutated residue, which is incompatible with the OG 235 present in the wild-type enzyme, and causes very small perturbations in the interaction network in the active site. [less ▲]

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See detailCrystallization and X-ray diffraction study of the Streptomyces K15 penicillin-binding DD-transpeptidase.
Englebert, S.; Charlier, Paulette ULg; Fonze, E. et al

in Journal of Molecular Biology (1994), 241(2), 295-7

The 262 amino acid residue long DD-transpeptidase/penicillin-binding protein of Streptomyces K15 has been crystallized at room temperature by using the hanging drop vapour diffusion technique. The ... [more ▼]

The 262 amino acid residue long DD-transpeptidase/penicillin-binding protein of Streptomyces K15 has been crystallized at room temperature by using the hanging drop vapour diffusion technique. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit cell parameters a = 46.4 A, b = 54.1 A and c = 108.3 A. They contain one protein molecule per asymmetric unit and diffract to about 1.9 A. X-ray data have been collected to 2.0 A from a native crystal. The previously published amino acid sequence of the protein has been corrected at positions 71, 72, 113, 114 and 156. [less ▲]

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