Biochemical and crystallographic studies of L,D-transpeptidase 2 from Mycobacterium tuberculosis with its natural monomer substrate.

The essential L,D-transpeptidase of Mycobacterium tuberculosis (Ldt) catalyses the formation of 3 3 cross-links in cell wall peptidoglycan and is a target for development of antituberculosis therapeutics. Efforts to inhibit Ldt have been hampered by lack of knowledge of how it binds its substrate. To address this gap, we optimised the isolation of natural disaccharide tetrapeptide monomers from the Corynebacterium jeikeium bacterial cell wall through overproduction of the peptidoglycan sacculus.

How Clavulanic Acid Inhibits Serine β-Lactamases.

Clavulanic acid is a medicinally important inhibitor of serine β-lactamases (SBLs). We report studies on the mechanisms by which clavulanic acid inhibits representative Ambler class A (TEM-116), C (Escherichia coli AmpC), and D (OXA-10) SBLs using denaturing and non-denaturing mass spectrometry (MS). Similarly to observations with penam sulfones, most of the results support a mechanism involving acyl enzyme complex formation, followed by oxazolidine ring opening without efficient subsequent scaffold fragmentation (at pH 7.

High-throughput screen with the l,d-transpeptidase Ldt of reveals novel classes of covalently reacting inhibitors.

Disruption of bacterial cell wall biosynthesis in is a promising target for treating tuberculosis. The l,d-transpeptidase Ldt, which is responsible for the formation of 3 → 3 cross-links in the cell wall peptidoglycan, has been identified as essential for virulence. We optimised a high-throughput assay for Ldt, and screened a targeted library of ∼10 000 electrophilic compounds.

Resistance profiles to antifungal agents in Candida albicans isolated from human oral cavities: systematic review and meta-analysis.

Aim: To identify the antifungal susceptibility profile of Candida spp. isolated from the human oral cavity was assessed with meta-analyses of observational studies that collected samples from the oral cavity of human subjects.

Material And Methods: Isolated Candida albicans tested by E-test®; disk diffusion test; microdilution and macrodilution; Sensititre YeastOne; and/or FungiTest.

Studies on enmetazobactam clarify mechanisms of widely used β-lactamase inhibitors.

β-Lactams are the most important class of antibacterials, but their use is increasingly compromised by resistance, most importantly via serine β-lactamase (SBL)-catalyzed hydrolysis. The scope of β-lactam antibacterial activity can be substantially extended by coadministration with a penicillin-derived SBL inhibitor (SBLi), i.e.

Pretargeted PET Imaging with a TCO-Conjugated Anti-CD44v6 Chimeric mAb U36 and [Zr]Zr-DFO-PEG-Tz.

The recent advances in the production of engineered antibodies have facilitated the development and application of tailored, target-specific antibodies. Positron emission tomography (PET) of these antibody-based drug candidates can help to better understand their behavior. In this study, we report an proof-of-concept pretargeted immuno-PET study where we compare a pretargeting vs targeted approach using a new Zr-labeled tetrazine as a bio-orthogonal ligand in an inverse electron demand Diels-Alder (IEDDA) click reaction.

High-fat diet effect on periapical lesions and hepatic enzymatic antioxidant in rats.

Aims: To evaluate the effects of a high-fat diet (HFD) on the progression of apical periodontitis (AP), local inflammation, systemic antioxidant status, and blood lipid profile in rats.

Main Methods: Sixteen male Wistar rats were fed a standard diet (SD) or a HFD. At the sixth experimental week, the pulp chambers of the mandibular first molars were exposed to develop AP.

Structural Investigations of the Inhibition of Escherichia coli AmpC β-Lactamase by Diazabicyclooctanes.

β-Lactam antibiotics are presently the most important treatments for infections by pathogenic , but their use is increasingly compromised by β-lactamases, including the chromosomally encoded class C AmpC serine-β-lactamases (SBLs). The diazabicyclooctane (DBO) avibactam is a potent AmpC inhibitor; the clinical success of avibactam combined with ceftazidime has stimulated efforts to optimize the DBO core. We report kinetic and structural studies, including four high-resolution crystal structures, concerning inhibition of the AmpC serine-β-lactamase from (AmpC ) by clinically relevant DBO-based inhibitors: avibactam, relebactam, nacubactam, and zidebactam.

Anaerobic fixed-target serial crystallography.

Cryogenic X-ray diffraction is a powerful tool for crystallographic studies on enzymes including oxygenases and oxidases. Amongst the benefits that cryo-conditions (usually employing a nitro-gen cryo-stream at 100 K) enable, is data collection of di-oxy-gen-sensitive samples. Although not strictly anaerobic, at low temperatures the vitreous ice conditions severely restrict O diffusion into and/or through the protein crystal.

Bicyclic Boronates as Potent Inhibitors of AmpC, the Class C β-Lactamase from .

Resistance to β-lactam antibacterials, importantly via production of β-lactamases, threatens their widespread use. Bicyclic boronates show promise as clinically useful, dual-action inhibitors of both serine- (SBL) and metallo- (MBL) β-lactamases. In combination with cefepime, the bicyclic boronate taniborbactam is in phase 3 clinical trials for treatment of complicated urinary tract infections.

Bicyclic Boronate VNRX-5133 Inhibits Metallo- and Serine-β-Lactamases.

The bicyclic boronate VNRX-5133 (taniborbactam) is a new type of β-lactamase inhibitor in clinical development. We report that VNRX-5133 inhibits serine-β-lactamases (SBLs) and some clinically important metallo-β-lactamases (MBLs), including NDM-1 and VIM-1/2. VNRX-5133 activity against IMP-1 and tested B2/B3 MBLs was lower/not observed.

Molecular Basis of Class A β-Lactamase Inhibition by Relebactam.

β-Lactamase production is the major β-lactam resistance mechanism in Gram-negative bacteria. β-Lactamase inhibitors (BLIs) efficacious against serine β-lactamase (SBL) producers, especially strains carrying the widely disseminated class A enzymes, are required. Relebactam, a diazabicyclooctane (DBO) BLI, is in phase 3 clinical trials in combination with imipenem for the treatment of infections by multidrug-resistant We show that relebactam inhibits five clinically important class A SBLs (despite their differing spectra of activity), representing both chromosomal and plasmid-borne enzymes, i.

Targeting the Mycobacterium tuberculosis transpeptidase Ldt with cysteine-reactive inhibitors including ebselen.

The l,d-transpeptidases (Ldts) are promising antibiotic targets for treating tuberculosis. We report screening of cysteine-reactive inhibitors against LdtMt2 from Mycobacterium tuberculosis. Structural studies on LdtMt2 with potent inhibitor ebselen reveal opening of the benzisoselenazolone ring by a nucleophilic cysteine, forming a complex involving extensive hydrophobic interactions with a substrate-binding loop.

Will morphing boron-based inhibitors beat the β-lactamases?

The β-lactams remain the most important antibacterials, but their use is increasingly compromised by resistance, importantly by β-lactamases. Although β-lactam and non-β-lactam inhibitors forming stable acyl-enzyme complexes with nucleophilic serine β-lactamases (SBLs) are widely used, these are increasingly susceptible to evolved SBLs and do not inhibit metallo-β-lactamases (MBLs). Boronic acids and boronate esters, especially cyclic ones, can potently inhibit both SBLs and MBLs.

Studies on the Interaction of the Histone Demethylase KDM5B with Tricarboxylic Acid Cycle Intermediates.

Methylation of lysine-4 of histone H3 (H3K4me) is an important regulatory factor in eukaryotic transcription. Removal of the transcriptionally activating H3K4 methylation is catalyzed by histone demethylases, including the Jumonji C (JmjC) KDM5 subfamily. The JmjC KDMs are Fe(II) and 2-oxoglutarate (2OG)-dependent oxygenases, some of which are associated with cancer.

Resistance profiles to antimicrobial agents in bacteria isolated from acute endodontic infections: systematic review and meta-analysis.

Infected root canal or acute apical abscess exudates can harbour several species, including Fusobacterium, Porphyromonas, Prevotella, Parvimonas, Streptococcus, Treponema, Olsenella and not-yet cultivable species. A systematic review and meta-analysis was performed to assess resistance rates to antimicrobial agents in clinical studies that isolated bacteria from acute endodontic infections. Electronic databases and the grey literature were searched up to May 2015.