Penicillin-binding proteins represent well-established, validated and still very promising targets for the design and development of new antibacterial agents. The transglycosylase domain of penicillin-binding proteins is especially important, as it catalyzes polymerization of glycan chains, using the peptidoglycan precursor lipid II as a substrate. Based on the previous discovery of a non-covalent small-molecule inhibitor of transglycosylase activity, we systematically explored the structure-activity relationships of these tryptamine-based inhibitors. The main aim was to reduce the non-specificcytotoxic properties of the initial hit compound, and concurrentlyto retain the mode of its inhibition. A focused library of tryptamine-based compounds was synthesized, characterized, and evaluated biochemically. The results presented here show the successful reduction of thenon-specific cytotoxicity, and the retention of the inhibition of transglycosylase enzymatic activity, as well as the ability of these compounds to bind to lipid II and to have antibacterial actions.
COBISS.SI-ID: 3978865
Members of the bacterial Mur ligase family MurC–MurF involved in the intracellular stages of the bacterial peptidoglycan biosynthesis have recently emerged as a collection of attractive targets for novel antibacterial drug design. In this study, we have first extended the knowledge of the class of furan-based benzene-1,3-dicarboxylic acid derivatives by first showing a multiple MurC–MurF ligase inhibition for representatives of the extended series of this class. Steady-state kinetics studies on the MurD enzyme were performed for compound 1, suggesting a competitive inhibition with respect to ATP. To the best of our knowledge, compound 1 represents the first ATP-competitive MurD inhibitor reported to date with concurrent multiple inhibition of all four Mur ligases. Subsequent computational aproaches enabled further optisation of compounds and development of novel furan-based inhibitors with antibacterial activity against S. aureus.
COBISS.SI-ID: 5677082
Erysipelothrix rhusiopathiae is a Gram-positive bacterium pathogenic to many species of birds and mammals, including humans. The main feature of its peptidoglycan is the presence of l-alanine at position 3 of the peptide stem. In the present work, we cloned the murE gene from E. rhusiopathiae and purified the corresponding protein as His6-tagged form. Enzymatic assays showed that E. rhusiopathiae MurE was indeed an l-alanine-adding enzyme. Surprisingly, it was also able, although to a lesser extent, to add meso-diaminopimelic acid, the amino acid found at position 3 in many Gram-negative bacteria, Bacilli and Mycobacteria. Sequence alignment of MurE enzymes from E. rhusiopathiae and Escherichia coli revealed that the DNPR motif that is characteristic of meso-diaminopimelate-adding enzymes was replaced by HDNR. The role of the latter motif in the interaction with l-alanine and meso-diaminopimelic acid was demonstrated by site-directed mutagenesis experiments and the construction of a homology model. The over expression of the E. rhusiopathiae murE gene in E. coli resulted in the incorporation of l-alanine at position 3 of the peptide part of peptidoglycan.
COBISS.SI-ID: 4008817