Molecular interactions of a semisynthetic glycopeptide antibiotic with D-alanyl-D-alanine and D-alanyl-D-lactate residues

Abstract

LY191145 is an N-alkylated glycopeptide antibiotic (the p-chlorobenzyl derivative of LY264826) with activity against vancomycin-susceptible and -resistant bacteria. Similar to vancomycin, LY191145 inhibited polymerization of peptidoglycan when muramyl pentapeptide served as a substrate but not when muramyl tetrapeptide was used, signifying a substrate-dependent mechanism of inhibition. Examination of ligand binding affinities for LY191145 and the effects of this agent on R39 D,D-carboxypeptidase action showed that, similar to vancomycin, LY191145 had an 800-fold greater affinity for N,N'-diacetyl-L-Lys-D-Ala-D-Ala than for N,N'-diacetyl-L-Lys-D-Ala-D-Lac. The antibacterial activity of LY191145 was antagonized by N,N'-diacetyl-L-Lys-D-Ala-D-Ala, but the molar excess required for complete suppression exceeded that needed to suppress inhibition by vancomycin. LY191145 is strongly dimerized and the p-chlorobenzyl side chain facilitates interactions with bacterial membranes. These findings are consistent with a mechanism of inhibition where interactions between antibiotic and D-Ala-D-Ala or D-Ala-D-Lac residues depend on intramolecular effects occurring at the subcellular target site.

Inhibition of Transglycosylation Involved in Bacterial Peptidoglycan Synthesis

“…A subsequent study revealed that like vancomycin, LY191145 inhibited in vitro peptidoglycan synthesis when UDP-MurNAcpentapeptide (the native D-ala-D-ala analog) was used a substrate, but not when UDP-MurNAc-tetrapeptide (the single D-ala analog) was the substrate. Substrate binding again appeared to form the basis for the antibacterial activity [103]. However, in this same test system using Aerococcus viridans, moenomycin, which is a very potent inhibitor of transglycosylation in E. coli, was a very poor inhibitor, producing less than 40% inhibition at 10,000 times the IC 50 reported by others for the E. coli system [74,83].…”

“…These studies reveal that specific modifications to natural product glycopeptide structures can lead to compounds that possess activity on VRE, and raises the important question: what is their mode of action on VRE? detailed evaluation of its mode of action on vancomycin resistant bacteria [101][102][103]. Results from these studies led to the conclusion that antibacterial activity on VRE was mechanistically similar to the action of vancomycin on sensitive strains.…”

Estimation of binding constants between ristocetin and teicoplanin and peptides using on-column ligand derivatization coupled to affinity capillary electrophoresis

“…Analysis of the magnitude of the change in mobility, ∆µ P,A , as a function of the concentration [A] of receptor yields K b (Eq. 1): (1) where ∆µ P,A is the change in mobility of the peptide as a function of the concentration of Rist, t P,A and t m,A are the measured migration times of the sample peak (2) and the non-interacting standard (CBSA) at the concentration of antibiotic, respectively, l c (cm) is the total length of the capillary, l d (cm) is the length of capillary from the inlet end of the capillary to the detector, t m (s) is the measured migration time of the non-interacting standard, t P is the measured migration time of the D-Ala-D-Ala terminus peptide, and V is the voltage across the capillary. The values of ∆µ P,A obtained using Eq.…”

“…Historically, glycopeptide antibiotics, and, in particular, vancomycin (Van) from Streptomyces orientalis, have been the standard class of molecules used to treat bacterial infections. Glycopeptide antibiotics inhibit the growth of Gram-positive bacteria by hindering cell wall peptidoglycan biosynthesis [1,2,3,4,5,6,7,8,9,10,11,12]. These drugs bind to the D-Ala-D-Ala portion of peptidoglycan intermediates, thereby, inhibiting the transpeptidation reaction required for cross-linking of the cell wall [10].…”

Molecular interactions of glycopeptide antibiotics investigated by affinity capillary electrophoresis and bioaffinity electrospray ionization‐mass spectrometry

“…Not binding [7] Ac 2 -L-Lys-D-Ala-D-Ala 240 000 [49], 375 000 a) , 500 000 [77], 410 000 [87], 435 000 [53] 730 000 [76] 1 500 000 [7] 1 000 000 [88] ,500 [76] 410 [90] 330 [88] Ac-L-Ala-L-Ala Not binding [50] ,500 [25] Not binding [ a) New data b) Lac, lactate electropherograms. We used plots of mobility versus ligand concentration to obtain binding constants which we calculated by nonlinear regression [56] using Eq.…”