scholarly journals NB2001, a Novel Antibacterial Agent with Broad-Spectrum Activity and Enhanced Potency against β-Lactamase-Producing Strains

2002 ◽  
Vol 46 (5) ◽  
pp. 1262-1268 ◽  
Author(s):  
Qing Li ◽  
Jean Y. Lee ◽  
Rosario Castillo ◽  
Mark S. Hixon ◽  
Catherine Pujol ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Antibacterial Agent ◽  
Bacterial Resistance ◽  
Enterobacter Aerogenes ◽  
Order Rate Constant ◽  
Common Mechanism ◽  
E Coli ◽  
Lactam Ring ◽  
Spectrum Activity ◽  
Hydrolysis Of

ABSTRACT Enzyme-catalyzed therapeutic activation (ECTA) is a novel prodrug strategy to overcome drug resistance resulting from enzyme overexpression. β-Lactamase overexpression is a common mechanism of bacterial resistance to β-lactam antibiotics. We present here the results for one of the β-lactamase ECTA compounds, NB2001, which consists of the antibacterial agent triclosan in a prodrug form with a cephalosporin scaffold. Unlike conventional β-lactam antibiotics, where hydrolysis of the β-lactam ring inactivates the antibiotic, hydrolysis of NB2001 by β-lactamase releases triclosan. Evidence supporting the proposed mechanism is as follows. (i) NB2001 is a substrate for TEM-1 β-lactamase, forming triclosan with a second-order rate constant (k cat/Km ) of greater than 77,000 M−1 s−1. (ii) Triclosan is detected in NB2001-treated, β-lactamase-producing Escherichia coli but not in E. coli that does not express β-lactamase. (iii) NB2001 activity against β-lactamase-producing E. coli is decreased in the presence of the β-lactamase inhibitor clavulanic acid. NB2001 was similar to or more potent than reference antibiotics against clinical isolates of Staphylococcus aureus (including MRSA), Staphylococcus epidermidis, Streptococcus pneumoniae, vancomycin-resistant Enterococcus faecalis, Moraxella catarrhalis and Haemophilus influenzae. NB2001 is also active against Klebsiella pneumoniae, Enterobacter aerogenes, and Enterobacter cloacae. The results indicate that NB2001 is a potent, broad-spectrum antibacterial agent and demonstrate the potential of ECTA in overcoming β-lactamase-mediated resistance.

scholarly journals Mechanism of Action of NB2001 and NB2030, Novel Antibacterial Agents Activated by β-Lactamases

2004 ◽  
Vol 48 (2) ◽  
pp. 477-483 ◽  
Author(s):  
Geoffrey W. Stone ◽  
Qin Zhang ◽  
Rosario Castillo ◽  
V. Ramana Doppalapudi ◽  
Analia R. Bueno ◽  
...  
Keyword(s):  
Antibacterial Agents ◽  
Mechanisms Of Action ◽  
Enoyl Reductase ◽  
Penicillin Binding Proteins ◽  
E Coli ◽  
Class A ◽  
Biochemical Assays ◽  
Lactam Ring ◽  
A Cell ◽  
Hydrolysis Of

ABSTRACT Two potent antibacterial agents designed to undergo enzyme-catalyzed therapeutic activation were evaluated for their mechanisms of action. The compounds, NB2001 and NB2030, contain a cephalosporin with a thienyl (NB2001) or a tetrazole (NB2030) ring at the C-7 position and are linked to the antibacterial triclosan at the C-3 position. The compounds exploit β-lactamases to release triclosan through hydrolysis of the β-lactam ring. Like cephalothin, NB2001 and NB2030 were hydrolyzed by class A β-lactamases (Escherichia coli TEM-1 and, to a lesser degree, Staphylococcus aureus PC1) and class C β-lactamases (Enterobacter cloacae P99 and E. coli AmpC) with comparable catalytic efficiencies (k cat/Km ). They also bound to the penicillin-binding proteins of S. aureus and E. coli, but with reduced affinities relative to that of cephalothin. Accordingly, they produced a cell morphology in E. coli consistent with the toxophore rather than the β-lactam being responsible for antibacterial activity. In biochemical assays, they inhibited the triclosan target enoyl reductase (FabI), with 50% inhibitory concentrations being markedly reduced relative to that of free triclosan. The transport of NB2001, NB2030, and triclosan was rapid, with significant accumulation of triclosan in both S. aureus and E. coli. Taken together, the results suggest that NB2001 and NB2030 act primarily as triclosan prodrugs in S. aureus and E. coli.

scholarly journals Growth of Escherichia coli Coexpressing Phosphotriesterase and Glycerophosphodiester Phosphodiesterase, Using Paraoxon as the Sole Phosphorus Source

2004 ◽  
Vol 70 (1) ◽  
pp. 404-412 ◽  
Author(s):  
Sean Yu McLoughlin ◽  
Colin Jackson ◽  
Jian-Wei Liu ◽  
David L. Ollis
Keyword(s):  
Escherichia Coli ◽  
Enterobacter Aerogenes ◽  
Sole Source ◽  
Limiting Factor ◽  
E Coli ◽  
Dimethyl Phosphate ◽  
Genes Encoding ◽  
Phosphorus Source ◽  
Hydrolysis Of ◽  
Methyl Phosphate

ABSTRACT Phosphotriesterases catalyze the hydrolytic detoxification of phosphotriester pesticides and chemical warfare nerve agents with various efficiencies. The directed evolution of phosphotriesterases to enhance the breakdown of poor substrates is desirable for the purposes of bioremediation. A limiting factor in the identification of phosphotriesterase mutants with increased activity is the ability to effectively screen large mutant libraries. To this end, we have investigated the possibility of coupling phosphotriesterase activity to cell growth by using methyl paraoxon as the sole phosphorus source. The catabolism of paraoxon to phosphate would occur via the stepwise enzymatic hydrolysis of paraoxon to dimethyl phosphate, methyl phosphate, and then phosphate. The Escherichia coli strain DH10B expressing the phosphotriesterase from Agrobacterium radiobacter P230 (OpdA) is unable to grow when paraoxon is used as the sole phosphorus source. Enterobacter aerogenes is an organism capable of growing when dimethyl phosphate is the sole phosphorus source. The enzyme responsible for hydrolyzing dimethyl phosphate has been previously characterized as a nonspecific phosphohydrolase. We isolated and characterized the genes encoding the phosphohydrolase operon. The operon was identified from a shotgun clone that enabled E. coli to grow when dimethyl phosphate is the sole phosphorus source. E. coli coexpressing the phosphohydrolase and OpdA grew when paraoxon was the sole phosphorus source. By constructing a short degradative pathway, we have enabled E. coli to use phosphotriesters as a sole source of phosphorus.

scholarly journals Analysis of the Degradation of Broad-Spectrum Cephalosporins by OXA-48-Producing Enterobacteriaceae Using MALDI-TOF MS

2019 ◽  
Vol 7 (12) ◽  
pp. 614
Author(s):  
Marina Oviaño ◽  
María Rosario Rodicio ◽  
Jürgen J. Heinisch ◽  
Rosaura Rodicio ◽  
Germán Bou ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Negative Control ◽  
Point Of View ◽  
Reaction Products ◽  
Beta Lactam ◽  
Maldi Tof Ms ◽  
E Coli ◽  
Maldi Tof ◽  
Lactam Ring ◽  
Tof Ms

The objective of the study was to evaluate the activity of OXA-48 against different broad-spectrum cephalosporins and to identify the reaction products by MALDI-TOF MS. The action of OXA-48 on cefotaxime, ceftazidime, and ceftriaxone was assessed by this method, using an Escherichia coli J53 transconjugant carrying only the ~62 Kb IncL plasmid containing the blaOXA-48 gene, and the same strain without any plasmid was included as a negative control. In addition, a collection of 17 clinical OXA-48-producing Enterobacteriaceae, which were susceptible to broad-spectrum cephalosporins, was evaluated. MALDI-TOF MS-based analysis of the E. coli transconjugant carrying the blaOXA-48-harboring plasmid, and also the clinical isolates, showed degradation of cefotaxime into two inactive compounds—decarboxylated and deacetylated cefotaxime (~370 Da) and deacetyl cefotaxime (~414 Da), both with the hydrolyzed beta-lactam ring. Reaction products were not obtained when the experiment was performed with ceftriaxone or ceftazidime. From a clinical point of view, our study supports the idea that the efficacy of cefotaxime against OXA-48-producing Enterobacteriaceae is doubtful, in contrast to ceftazidime and ceftriaxone which could be valid choices for treating infections caused by these bacteria. However, further clinical studies confirming this hypothesis are required.

scholarly journals In Vitro Activities of the Potent, Broad-Spectrum Carbapenem MK-0826 (L-749,345) against Broad-Spectrum β-Lactamase-and Extended-Spectrum β-Lactamase-Producing Klebsiella pneumoniae and Escherichia coli Clinical Isolates

1999 ◽  
Vol 43 (5) ◽  
pp. 1170-1176 ◽  
Author(s):  
Joyce Kohler ◽  
Karen L. Dorso ◽  
Katherine Young ◽  
Gail G. Hammond ◽  
Hugh Rosen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Broad Spectrum ◽  
Bacterial Resistance ◽  
Clinical Isolates ◽  
Inoculum Level ◽  
E Coli ◽  
Extended Spectrum ◽  
Group 1

ABSTRACT An important mechanism of bacterial resistance to β-lactam antibiotics is inactivation by β-lactam-hydrolyzing enzymes (β-lactamases). The evolution of the extended-spectrum β-lactamases (ESBLs) is associated with extensive use of β-lactam antibiotics, particularly cephalosporins, and is a serious threat to therapeutic efficacy. ESBLs and broad-spectrum β-lactamases (BDSBLs) are plasmid-mediated class A enzymes produced by gram-negative pathogens, principallyEscherichia coli and Klebsiella pneumoniae. MK-0826 was highly potent against all ESBL- and BDSBL-producingK. pneumoniae and E. coli clinical isolates tested (MIC range, 0.008 to 0.12 μg/ml). In E. coli, this activity was associated with high-affinity binding to penicillin-binding proteins 2 and 3. When the inoculum level was increased 10-fold, increasing the amount of β-lactamase present, the MK-0826 MIC range increased to 0.008 to 1 μg/ml. By comparison, similar observations were made with meropenem while imipenem MICs were usually less affected. Not surprisingly, MIC increases with noncarbapenem β-lactams were generally substantially greater, resulting in resistance in many cases. E. coli strains that produce chromosomal (Bush group 1) β-lactamase served as controls. All three carbapenems were subject to an inoculum effect with the majority of the BDSBL- and ESBL-producers but not the Bush group 1 strains, implying some effect of the plasmid-borne enzymes on potency. Importantly, MK-0826 MICs remained at or below 1 μg/ml under all test conditions.

scholarly journals The Role of the Ω-Loop in Regulation of the Catalytic Activity of TEM-Type β-Lactamases

Biomolecules ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 854 ◽  
Author(s):  
Alexey Egorov ◽  
Maya Rubtsova ◽  
Vitaly Grigorenko ◽  
Igor Uporov ◽  
Alexander Veselovsky
Keyword(s):  
Active Site ◽  
Bacterial Resistance ◽  
Structural Flexibility ◽  
Allosteric Inhibitors ◽  
Penicillin Binding Proteins ◽  
Global Challenge ◽  
Class A ◽  
Lactam Ring ◽  
Hydrolysis Of

Bacterial resistance to β-lactams, the most commonly used class of antibiotics, poses a global challenge. This resistance is caused by the production of bacterial enzymes that are termed β-lactamases (βLs). The evolution of serine-class A β-lactamases from penicillin-binding proteins (PBPs) is related to the formation of the Ω-loop at the entrance to the enzyme’s active site. In this loop, the Glu166 residue plays a key role in the two-step catalytic cycle of hydrolysis. This residue in TEM–type β-lactamases, together with Asn170, is involved in the formation of a hydrogen bonding network with a water molecule, leading to the deacylation of the acyl–enzyme complex and the hydrolysis of the β-lactam ring of the antibiotic. The activity exhibited by the Ω-loop is attributed to the positioning of its N-terminal residues near the catalytically important residues of the active site. The structure of the Ω-loop of TEM-type β-lactamases is characterized by low mutability, a stable topology, and structural flexibility. All of the revealed features of the Ω-loop, as well as the mechanisms related to its involvement in catalysis, make it a potential target for novel allosteric inhibitors of β-lactamases.

scholarly journals NUDT18 catalyzes hydrolysis of active metabolites of the antivirals Remdesivir and Ribavirin

2021 ◽  
Author(s):  
Ann-Sofie Jemth ◽  
Emma Rose Scaletti ◽  
Evert Jan Homan ◽  
Pal Stenmark ◽  
Thomas Helleday ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Nudix Hydrolase ◽  
Active Metabolites ◽  
Lower Efficiency ◽  
Dna Viruses ◽  
Antiviral Efficacy ◽  
Km Value ◽  
Spectrum Activity ◽  
Respiratory Epithelial ◽  
Hydrolysis Of

Remdesivir (GS-5734) has gained considerable interest due to its activity against replication of SARS-CoV2. Remdesivir is a broad-spectrum antiviral prodrug that is hydrolyzed intracellularly and phosphorylated by cellular kinases to its active triphosphate form (Remdesivir-TP). Here we tested Remdesivir-TP as a substrate for a panel of human hydrolases and found that NUDIX hydrolase 18 (NUDT18) catalyzes the hydrolysis of Remdesivir-TP. NUDT18 is expressed in respiratory epithelial cells suggesting that NUDT18 may limit the antiviral efficacy of Remdesivir by decreasing the intracellular concentration of its active metabolite at its intended site of action. The kcat of NUDT18 for Remdesivir-TP was determined to 2.6 s-1 and the Km value was 156 μM, suggesting that NUDT18 catalyzed hydrolysis occurs in cells. In addition, we found that the triphosphate of the antiviral Ribavirin, with broad-spectrum activity against several RNA and DNA viruses, was hydrolyzed by NUDT18, albeit with a lower efficiency compared to Remdesivir-TP. NUDT18 activity was also tested with the triphosphates of the antivirals Sofosbuvir and Aciclovir for which low activity, in comparison to activities with Remdesivir-TP and Ribavirin-TP, was detected. These results suggest that NUDT18 can act as a cellular sanitizer and may influence the antiviral efficacy of Remdesivir and Ribavirin.

scholarly journals Crystal Structure of Phosphoserine BlaC from Mycobacterium tuberculosis Inactivated by Bis(Benzoyl) Phosphate

2019 ◽  
Vol 20 (13) ◽  
pp. 3247
Author(s):  
Timothy W. Moural ◽  
Dawanna Shar-Day White ◽  
Cindy J. Choy ◽  
Chulhee Kang ◽  
Clifford E. Berkman
Keyword(s):  
Crystal Structure ◽  
Mycobacterium Tuberculosis ◽  
Bacterial Resistance ◽  
Crystallographic Analysis ◽  
Dependent Manner ◽  
Serine Residue ◽  
Class A ◽  
Protein X ◽  
Lactam Ring ◽  
Hydrolysis Of

Mycobacterium tuberculosis, the pathogen responsible for tuberculosis (TB), is the leading cause of death from infectious disease worldwide. The class A serine β-lactamase BlaC confers Mycobacterium tuberculosis resistance to conventional β-lactam antibiotics. As the primary mechanism of bacterial resistance to β-lactam antibiotics, the expression of a β-lactamase by Mycobacterium tuberculosis results in hydrolysis of the β-lactam ring and deactivation of these antibiotics. In this study, we conducted protein X-ray crystallographic analysis of the inactivation of BlaC, upon exposure to the inhibitor bis(benzoyl) phosphate. Crystal structure data confirms that serine β-lactamase is phosphorylated at the catalytic serine residue (Ser-70) by this phosphate-based inactivator. This new crystallographic evidence suggests a mechanism for phosphorylation of BlaC inhibition by bis(benzoyl) phosphate over acylation. Additionally, we confirmed that bis(benzoyl) phosphate inactivated BlaC in a time-dependent manner.

scholarly journals Engineering of Antimicrobial Surfaces by Using Temporin Analogs to Tune the Biocidal/antiadhesive Effect

Molecules ◽  
2019 ◽  
Vol 24 (4) ◽  
pp. 814 ◽  
Author(s):  
Pierre-Carl Oger ◽  
Christophe Piesse ◽  
Ali Ladram ◽  
Vincent Humblot
Keyword(s):  
Broad Spectrum ◽  
Bacterial Resistance ◽  
Antibacterial Properties ◽  
Covalent Immobilization ◽  
Resistant Bacteria ◽  
Gold Surfaces ◽  
Cationic Antimicrobial Peptide ◽  
Bacterial Membranes ◽  
Spectrum Activity ◽  
Broad Spectrum Activity

Proliferation of resistant bacteria on biomaterials is a major problem leading to nosocomial infections. Due to their broad-spectrum activity and their ability to disrupt bacterial membranes through a rapid membranolytic mechanism, antimicrobial peptides (AMPs) are less susceptible to the development of bacterial resistance and therefore represent good candidates for surface coating strategies to prevent biofilm formation. In this study, we report on the covalent immobilization of temporin-SHa, a small hydrophobic and low cationic antimicrobial peptide exhibiting broad-spectrum activity, and (SHa) analogs on modified gold surfaces. Several analogs derived from SHa with either a carboxamidated ([K3]SHa, d-[K3]SHa) or a carboxylated C-terminus ([K3]SHa-COOH) were used to achieve peptide grafting on gold surfaces modified by a thiolated self-assembled monolayer (SAM). Surface functionalization was characterized by polarization modulation infrared reflection absorption spectroscopy (PM-RAIRS) and X-ray photoemission spectroscopy (XPS). The antibacterial properties of the temporin-functionalized surfaces were tested against the Gram-positive Listeria ivanovii. Direct visualization of the peptide effects on the bacterial membrane was investigated by scanning electron microscopy equipped with a field emission gun (SEM-FEG). All active temporin analogs were successfully grafted and display significant antibacterial activity (from 80 to 90% killing efficiency) in addition to a 2-fold decrease of bacterial adhesion when all d-SHa analogs were used.

scholarly journals Tigecycline: a review of the literature

2006 ◽  
Vol 7 (4) ◽  
pp. 211-222
Author(s):  
Mario Venditti ◽  
Maria Elena Pompeo ◽  
Flavia Fabi
Keyword(s):  
Antimicrobial Agent ◽  
Broad Spectrum ◽  
Bacterial Infections ◽  
Bacterial Resistance ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Resistant Bacteria ◽  
Antibiotic Administration ◽  
Spectrum Activity

Tigecycline is a new first-in-class glycylcycline antimicrobial agent with expanded broad-spectrum activity. It was developed to overcome the two key resistance mechanisms, efflux pumps and ribosomal protection, that limit the use of tetracycline. The spectrum of activity extends to clinically relevant susceptible and multidrug resistant bacteria, as methicillin resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, vancomycin resistant Enterococci, Acinetobacter spp, Acinetobacter baumannii and Enterobacteriaceae, including extended-spectrum β-lactamase-producing strains (ESBLs). Tigecycline has been introduced into clinical practice as part of the effort to combat the growing problem of bacterial resistance to anti-infective therapy: tigecycline could replace some broad-spectrum agents for approved indications reducing the selective pressure provided by antibiotic administration. The expanded in vitro activity against a broad range of bacteria, including resistant pathogens, of tigecycline suggest that this novel antimicrobial agent should offer clinicians an option for the treatment of patients with serious bacterial infections.

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