Peptidoglycan is an essential component of the bacterial cell wall, and enzymes involved in its biosynthesis represent validated targets for antibacterial drug discovery. MurF catalyzes the final intracellular peptidoglycan biosynthesis step: the addition of d-Ala-d-Ala to the nucleotide precursor UDP-MurNAc-l-Ala-d-Glu-meso-DAP (or l-Lys). As MurF has no human counterpart, it represents an attractive target for the development of new antibacterial drugs. Using recently published cyanothiophene inhibitors of MurF from Streptococcus pneumoniae as a starting point, we designed and synthesized a series of structurally related derivatives and investigated their inhibition of MurF enzymes from different bacterial species. Systematic structural modifications of the parent compounds resulted in a series of nanomolar inhibitors of MurF from S. pneumoniae and micromolar inhibitors of MurF from Escherichia coli and Staphylococcus aureus. Some of the inhibitors also show antibacterial activity against S. pneumoniae R6. These findings, together with two new co-crystal structures, represent an excellent starting point for further optimization towards effective novel antibacterials.
COBISS.SI-ID: 3452785
MurF is an essential bacterial enzyme that is involved in the last intracellular stage of peptidoglycan biosynthesis, and therefore it has the potential to be exploited as a target for the development of new antibacterials. Here, we report on the expression, purification and biochemical characterization of MurF from an important pathogen, Streptococcus pneumoniae. Additionally, ligand-based virtual screening was successfully used and a new hit compound with micromolar inhibitory activities against MurF enzymes from S. pneumoniae and Escherichia coli was identified.
COBISS.SI-ID: 3477105
Murein peptide ligase (Mpl) is an enzyme found in Gram-negative bacteria. It catalyses the addition of tripeptide L-Ala-g-D-Glu-meso-diaminopimelate to nucleotide precursor UDP-N-acetylmuramic acid during the recycling of peptidoglycan. Although not essential, this enzyme represents an interesting target for antibacterial compounds through the synthesis of alternate substrates whose incorporation into peptidoglycan might be deleterious for the bacterial cell. Therefore, we have synthesised 10 tripeptides L-Ala-g-D-Glu-Xaa in which Xaa represents amino acids different from diaminopimelic acid. Tripeptide with Xaa = ε-D-Lys proved to be an excellent substrate of Escherichia coli Mpl in vitro. Tripeptides with Xaa= p-amino- or p-nitro-L-phenylalanine were poor substrates, while tripeptides with Xaa= D- or L-2-aminopimelate, DL-2-aminoheptanoic acid, L-Glu, L-norleucine, L-norvaline, L-2- aminobutyric acid or L-Ala were not substrates at all. Although a good Mpl substrate, the D-Lyscontaining tripeptide was devoid of antibacterial activity against E. coli, presumably owing to poor uptake.
COBISS.SI-ID: 3374961