References of "Mercuri, Paola"
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See detailKinetic Study of Laboratory Mutants of NDM-1 Metallo-beta-Lactamase and the Importance of an Isoleucine at Position 35.
Marcoccia, Francesca; Bottoni, Carlo; Sabatini, Alessia et al

in Antimicrobial agents and chemotherapy (2016), 60(4), 2366-72

Two laboratory mutants of NDM-1 were generated by replacing the isoleucine at position 35 with threonine and serine residues: the NDM-1(I35T)and NDM-1(I35S)enzymes. These mutants were well characterized ... [more ▼]

Two laboratory mutants of NDM-1 were generated by replacing the isoleucine at position 35 with threonine and serine residues: the NDM-1(I35T)and NDM-1(I35S)enzymes. These mutants were well characterized, and their kinetic parameters were compared with those of the NDM-1 wild type. Thekcat,Km, andkcat/Kmvalues calculated for the two mutants were slightly different from those of the wild-type enzyme. Interestingly, thekcat/Kmof NDM-1(I35S)for loracarbef was about 14-fold higher than that of NDM-1. Far-UV circular dichroism (CD) spectra of NDM-1 and NDM-1(I35T)and NDM-1(I35S)enzymes suggest local structural rearrangements in the secondary structure with a marked reduction of alpha-helix content in the mutants. [less ▲]

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See detailStudy of a Natural Mutant SHV-Type beta-Lactamase, SHV-104, from Klebsiella pneumoniae
Achour, Nahed Ben; Belhadj, Omrane; Galleni, Moreno ULg et al

in International journal of microbiology (2014), 2014

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See detailR164H and V240H replacements by site-directed mutagenesis of TEM-149 extended-spectrum beta-lactamase: kinetic analysis of TEM-149H240 and TEM-149H164-H240 laboratory mutants.
Perilli, Mariagrazia; Celenza, Giuseppe; Mercuri, Paola ULg et al

in Antimicrobial agents and chemotherapy (2013), 57(2), 1047-9

Two laboratory mutant forms, TEM-149(H240) and TEM-149(H164-H240), of the TEM-149 extended-spectrum beta-lactamase enzyme were constructed by site-directed mutagenesis. TEM-149(H240) and TEM-149(H164-H240 ... [more ▼]

Two laboratory mutant forms, TEM-149(H240) and TEM-149(H164-H240), of the TEM-149 extended-spectrum beta-lactamase enzyme were constructed by site-directed mutagenesis. TEM-149(H240) and TEM-149(H164-H240) were similar in kinetic behavior, except with respect to benzylpenicillin and ceftazidime. Molecular modeling of the two mutant enzymes demonstrated the role of histidine at position 240 in the reduction of the affinity of the enzyme for ceftazidime. [less ▲]

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See detailNovel fragments of clavulanate observed in the structure of the class A b-lactamase from Bacillus licheniformis BS3
Power, Pablo; Mercuri, Paola ULg; Herman, Raphaël ULg et al

in Journal of Antimicrobial Chemotherapy (2012), 67(10), 2379-2387

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See detailMercaptophosphonate Compounds as Broad-Spectrum Inhibitors of the Metallo-β-lactamases
Lassaux, Patricia ULg; Hamel, Matthieu; Gulea, Mihaela et al

in Journal of Medicinal Chemistry (2010), 53

In this paper, we investigated the inhibitory effect of mercaptophosphonate derivatives against the three subclasses of MBLs (B1, B2, and B3). All 14 tested mercaptophosphonates, with the exception of one ... [more ▼]

In this paper, we investigated the inhibitory effect of mercaptophosphonate derivatives against the three subclasses of MBLs (B1, B2, and B3). All 14 tested mercaptophosphonates, with the exception of one, behaved as competitive inhibitors for the three subclasses. <br />Apart from two compounds, all the mercaptophosphonates tested exhibit a good inhibitory effect on the subclass B2 MBL CphA with low inhibition constants (Ki<15 μM). Interestingly, compound 18 turned out to be a potent broad spectrum MBL inhibitor. <br />The crystallographic structures of the CphA-10a and CphA-18 complexes indicated that the sulfur atom of 10a and the phosphonato group of 18 interact with the Zn2þ ion, respectively. Molecular modeling studies of the interactions between two compounds and the VIM-4 (B1), CphA (B2), and FEZ-1 (B3) enzymes brought to light different binding modes depending on the enzyme and the inhibitor, consistent with the crystallographic structures. [less ▲]

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See detailIdentification of bla(IMP-22) in Pseudomonas spp. in urban wastewater and nosocomial environments: biochemical characterization of a new IMP metallo-enzyme variant and its genetic location.
Pellegrini, Cristina; Mercuri, Paola ULg; Celenza, Giuseppe et al

in The Journal of antimicrobial chemotherapy (2009), 63(5), 901-8

OBJECTIVES: The aim of the study was the biochemical characterization of a new variant of the metallo-beta-lactamase, IMP-22. Moreover, the genetic environment of the bla(IMP-22) gene was investigated in ... [more ▼]

OBJECTIVES: The aim of the study was the biochemical characterization of a new variant of the metallo-beta-lactamase, IMP-22. Moreover, the genetic environment of the bla(IMP-22) gene was investigated in Pseudomonas fluorescens and Pseudomonas aeruginosa collected from urban wastewater and a teaching hospital in L'Aquila, Italy. METHODS: Molecular characterization of genetic elements was carried out by PCR and DNA sequencing methods. The new enzyme was purified from recombinant Escherichia coli BL21(DE)Rosetta/pBC-SK/IMP-22. Steady-state kinetic parameters (K(m) and V(max)) were determined for a large pattern of substrates. RESULTS: A new IMP metallo-beta-lactamase gene was found in a class 1 integron and in one case, in a plasmid of Pseudomonas spp. The bla(IMP-22) encodes for a pre-protein of 246 amino acids and the N-terminus of the mature beta-lactamase (NH(2)-PDLK) was also determined. The molecular mass and pI were 24 930 Da and 6.2, respectively. On the basis of the kinetic parameters calculated (K(m) and V(max)), IMP-22 was found to hydrolyse narrow- and extended-spectrum beta-lactams. Enzyme activity was found to be inhibited by metal chelators such as EDTA, 1,10-o-phenathroline and dipicolinic acid with an IC(50) of 800, 750 and 300 microM, respectively. CONCLUSIONS: The finding of the bla(IMP-22) gene in P. fluorescens environmental strains and P. aeruginosa clinical isolate suggests the ongoing spread of bla(MBL) genes in several bacterial species and in different environments. [less ▲]

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See detailFirst detection of CTX-M-28 in a Tunisian hospital from a cefotaxime-resistant Klebsiella pneumoniae strain.
Ben Achour, N.; Mercuri, Paola ULg; Power, P. et al

in Pathologie-biologie (2009), 57(5), 343-8

A cefotaxime-resistant Klebsiella pneumoniae ML4313 was obtained from a patient from intensive care unit of Military hospital in Tunisia. This strain was resistant to beta-lactams, aminoglycosides ... [more ▼]

A cefotaxime-resistant Klebsiella pneumoniae ML4313 was obtained from a patient from intensive care unit of Military hospital in Tunisia. This strain was resistant to beta-lactams, aminoglycosides, quinolones and phenicols, and tetracyclines. It was identified as producer of extended-spectrum beta-lactamases (ESBL) by double-disk synergy test between amoxicillin-clavulanate and cefotaxime, ceftriaxone, ceftazidime and aztreonam. The ESBL was identified as CTX-M-28 by sequencing of PCR products and by isoelectric focusing. The ESBL resistance was transferred by a 50kb plasmid. CTX-M-28 is closely related to CTX-M-15. This is the first description of this enzyme in Tunisia. [less ▲]

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See detailCharacterization of a novel extended-spectrum TEM-type beta-lactamase, TEM-164, in a clinical strain of Klebsiella pneumoniae in Tunisia.
Ben Achour, Nahed; Mercuri, Paola ULg; Ben Moussa, Mohamed et al

in Microbial drug resistance (Larchmont, N.Y.) (2009), 15(3), 195-9

Klebsiella pneumoniae ML1708 exhibited a multiresistance phenotype, including resistance to all beta-lactams tested, chloramphenicol, ciprofloxacin, nalidixic acid, tetracycline, and streptomycin. The ... [more ▼]

Klebsiella pneumoniae ML1708 exhibited a multiresistance phenotype, including resistance to all beta-lactams tested, chloramphenicol, ciprofloxacin, nalidixic acid, tetracycline, and streptomycin. The double-disk synergy test was positive. ML1708 harbored a 50 kb conjugative plasmid that encoded a beta-lactamase of pI 5.5. The corresponding bla gene was identified by polymerase chain reaction and sequencing as a bla(TEM) gene. The deduced protein sequence revealed a new variant of TEM-1 beta-lactamase designated TEM-164. TEM-164 contains the unusual following mutations: L40V and I279T. These modifications may result in a change of the pI to 5.5 and hydrolyze cefotaxime and ceftazidime. [less ▲]

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See detailCharacterization of the cattle serum antibody responses against TEM beta-lactamase and the nonimmunogenic Escherichia coli heat-stable enterotoxin (STaI)
Zervosen, Astrid ULg; Saegerman, Claude ULg; Antoniotti, Ingrid et al

in FEMS Immunology & Medical Microbiology (2008), 54(3), 319-329

In order to test the use of a subunit recombinant vaccine for its capacity to induce antibodies against the nonimmunogenic heat-stable enterotoxin STa from Escherichia coli and the TEM-1 beta-lactamase ... [more ▼]

In order to test the use of a subunit recombinant vaccine for its capacity to induce antibodies against the nonimmunogenic heat-stable enterotoxin STa from Escherichia coli and the TEM-1 beta-lactamase, cattle were immunized with a hybrid protein created by insertion of the STa sequence at position 197 of the TEM-1 beta-lactamase. Specific anti-STa IgG and IgG1 antibodies were detected at low levels, while no IgG2 antibodies were detected. In contrast, high levels of the different anti-TEM IgG subtypes were detected in cattle sera. In addition, beta-lactamase activity was inhibited by the sera. The presence of antibodies against STa and TEM-1 beta-lactamase was assessed in sera from 366 cattle taken from the field. No significant level of IgGs against the toxin or the TEM-1 was detected. A comparison of the antibody level between the immunized and the nonimmunized animals clearly demonstrated that STa was not able to induce a significant level of antibodies in the vaccinated animals. In contrast, a strong antibody response against TEM-1 beta-lactamase was demonstrated. [less ▲]

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See detailSynthesis of copolymer brushes endowed with adhesion to stainless steel surfaces and antibacterial properties by controlled nitroxide-mediated radical polymerization
Ignatova, Miléna; Voccia, Samuel; Gilbert, Bernard ULg et al

in Langmuir (2004), 20(24), 10718-10726

Novel copolymer brushes have been synthesized by a two-step "grafting from" method that consists of the electrografting of poly(2-phenyl-2-(2,2,6,6-tetramethyl-piperidin-1-yloxy)-ethylacrylate) onto ... [more ▼]

Novel copolymer brushes have been synthesized by a two-step "grafting from" method that consists of the electrografting of poly(2-phenyl-2-(2,2,6,6-tetramethyl-piperidin-1-yloxy)-ethylacrylate) onto stainless steel, followed by the nitroxide-mediated radical polymerization of 2-(dimethylamino ethyl)acrylate and styrene or n-butyl acrylate, initiated from the electrografted polyacrylate chains. The grafted copolymers were quaternized in order to endow them with antibacterial properties. Peeling tests have confirmed the strong adhesion of the grafted copolymer onto the stainless steel substrate. Quartz crystal microbalance experiments have proven that fibrinogen adhesion is lower on the hydrophilic quaternized films compared to the nonionic counterpart. Such quaternized copolymers exhibit significant antibacterial activity against the Gram-positive bacteria S. aureus and the Gram-negative bacteria E. coli. [less ▲]

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See detailUpdate of the standard numbering scheme for class B beta-lactamases
Garau, G.; Garcia-Saez, I.; Bebrone, Carine ULg et al

in Antimicrobial Agents and Chemotherapy (2004), 48(7), 2347-2349

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See detailInactivation of Aeromonas Hydrophila Metallo-Beta-Lactamase by Cephamycins and Moxalactam
Zervosen, Astrid ULg; Valladares, Maria Hernandez; Devreese, Bart et al

in European Journal of Biochemistry (2001), 268(13), 3840-50

Incubation of moxalactam and cefoxitin with the Aeromonas hydrophila metallo-beta-lactamase CphA leads to enzyme-catalyzed hydrolysis of both compounds and to irreversible inactivation of the enzyme by ... [more ▼]

Incubation of moxalactam and cefoxitin with the Aeromonas hydrophila metallo-beta-lactamase CphA leads to enzyme-catalyzed hydrolysis of both compounds and to irreversible inactivation of the enzyme by the reaction products. As shown by electrospray mass spectrometry, the inactivation of CphA by cefoxitin and moxalactam is accompanied by the formation of stable adducts with mass increases of 445 and 111 Da, respectively. The single thiol group of the inactivated enzyme is no longer titrable, and dithiothreitol treatment of the complexes partially restores the catalytic activity. The mechanism of inactivation by moxalactam was studied in detail. Hydrolysis of moxalactam is followed by elimination of the 3' leaving group (5-mercapto-1-methyltetrazole), which forms a disulfide bond with the cysteine residue of CphA located in the active site. Interestingly, this reaction is catalyzed by cacodylate. [less ▲]

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See detailThe Legionella (Fluoribacter) gormanii metallo-beta-lactamase: a new member of the highly divergent lineage of molecular-subclass B3 beta-lactamases.
Boschi, L.; Mercuri, Paola ULg; Riccio, M. L. et al

in Antimicrobial agents and chemotherapy (2000), 44(6), 1538-43

A metallo-beta-lactamase determinant was cloned from a genomic library of Legionella (Fluoribacter) gormanii ATCC 33297(T) constructed in the plasmid vector pACYC184 and transformed into Escherichia coli ... [more ▼]

A metallo-beta-lactamase determinant was cloned from a genomic library of Legionella (Fluoribacter) gormanii ATCC 33297(T) constructed in the plasmid vector pACYC184 and transformed into Escherichia coli DH5alpha, by screening for clones showing a reduced susceptibility to imipenem. The product of the cloned determinant, named FEZ-1, contains a 30-kDa polypeptide and exhibits an isoelectric pH of 7.6. Sequencing revealed that FEZ-1 is a molecular-class B beta-lactamase which shares the closest structural similarity (29.7% of identical residues) with the L1 enzyme of Stenotrophomonas maltophilia, being a new member of the highly divergent subclass B3 lineage. All the residues that in L1 are known to be directly or indirectly involved in coordination of the zinc ions were found to be conserved also in FEZ-1, suggesting that the geometry of zinc coordination in the active site of the latter enzyme is identical to that of L1. Unlike L1, however, FEZ-1 appeared to be monomeric in gel permeation chromatography experiments and exhibited a distinctive substrate specificity with a marked preference for cephalosporins and meropenem. The properties of FEZ-1 overall resembled those of a beta-lactamase previously purified from the same strain of L. gormanii (T. Fujii, K. Sato, K. Miyata, M. Inoue, and S. Mitsuhashi, Antimicrob. Agents Chemother. 29:925-926, 1986) and are as yet unique among class B enzymes, reinforcing the notion that considerable functional heterogeneity can be encountered among members of this class. A system for overexpression of the bla(FEZ-1) gene in E. coli, based on the T7 phage promoter, was also developed. [less ▲]

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See detailCharacterization and sequence of the Chryseobacterium (Flavobacterium) meningosepticum carbapenemase: a new molecular class B beta-lactamase showing a broad substrate profile.
Rossolini, G. M.; Franceschini, N.; Riccio, M. L. et al

in The Biochemical journal (1998), 332 ( Pt 1)

The metallo-beta-lactamase produced by Chryseobacterium (formerly Flavobacterium) meningosepticum, which is the flavobacterial species of greatest clinical relevance, was purified and characterized. The ... [more ▼]

The metallo-beta-lactamase produced by Chryseobacterium (formerly Flavobacterium) meningosepticum, which is the flavobacterial species of greatest clinical relevance, was purified and characterized. The enzyme, named BlaB, contains a polypeptide with an apparent Mr of 26000, and has a pI of 8.5. It hydrolyses penicillins, cephalosporins (including cefoxitin), carbapenems and 6-beta-iodopenicillanate, a mechanism-based inactivator of active-site serine beta-lactamases. The enzyme was inhibited by EDTA, 1-10 phenanthroline and pyridine-2,6-dicarboxylic acid, with different inactivation parameters for each chelating agent. The C. meningosepticum blaB gene was cloned and sequenced. According to the G+C content and codon usage, the blaB gene appeared to be endogenous to the species. The BlaB enzyme showed significant sequence similarity to other class B beta-lactamases, being overall more similar to members of subclass B1, which includes the metallo-enzymes of Bacillus cereus (Bc-II) and Bacteroides fragilis (CcrA) and the IMP-1 enzyme found in various microbial species, and more distantly related to the metallo-beta-lactamases of Aeromonas spp. (CphA, CphA2 and ImiS) and of Stenotrophomonas maltophilia (L1). [less ▲]

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