ABSTRACT
Novel bis-phosphonate derivatives of carbaboranes, which might be potential boron-delivery agents for boron neutron capture therapy, are described. Conceivable synthetic routes which failed to give the desired compounds are discussed, and finally, a highly selective route to the target molecules is reported.
Subject(s)
Boranes/chemical synthesis , Diphosphonates/chemistry , Boranes/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , StereoisomerismSubject(s)
Peptidoglycan/biosynthesis , Carbohydrate Conformation , Carbohydrate Sequence , Cyclization , Glycosylation , Molecular Sequence Data , Molecular Structure , Peptidoglycan/chemistry , Stereoisomerism , Uridine Diphosphate N-Acetylmuramic Acid/analogs & derivatives , Uridine Diphosphate N-Acetylmuramic Acid/chemical synthesis , Uridine Diphosphate N-Acetylmuramic Acid/chemistryABSTRACT
Moenomycin A is an amphiphilic phosphoglycolipid antibiotic that interferes with the transglycosylation step in peptidoglycan biosynthesis. The antibiotic consists of a branched pentasaccharide moiety, connected to the moenocinol lipid via a glycerophosphate linker. We have previously described the selection of aptamers that require the lipid group and the disaccharide epitopes of the oligosaccharide moiety for moenomycin binding. Here we report that the enriched moenomycin-binding library contains sequences that evolved for specific recognition of the unpolar lipid group of the antibiotic. These results suggest that the evolution of hydrophobic binding pockets in RNA molecules may be much more common than previously assumed.
Subject(s)
Anti-Bacterial Agents/chemistry , Bambermycins/chemistry , Lipids/chemistry , Bambermycins/biosynthesis , Base Sequence , Binding Sites , Carbohydrate Sequence , Chromatography, Affinity , Consensus Sequence , Disaccharides/chemistry , Disaccharides/metabolism , Epitope Mapping , Glycerophosphates/chemistry , Glycolipids/chemistry , Glycolipids/genetics , Glycolipids/metabolism , Hydrophobic and Hydrophilic Interactions , Ligands , Molecular Sequence Data , Oligosaccharides/chemistry , Oligosaccharides/metabolism , Phosphorus Radioisotopes , RNA/analysis , RNA/chemistryABSTRACT
Upon feeding of [2-(13)C,4-(2)H]-1-deoxy-D-xylulose to Streptomyces ghanaensis, the deuterium label was retained exclusively at positions C-7 and C-17 in the moenocinol part of the moenomycin antibiotics. This result vindicates the hypothesis that the C(25) structure of moenocinol is assembled from a C(10) and a C(15) precursor, each of which requires for its formation the involvement of a dimethylallyl diphosphate starter unit.
Subject(s)
Anti-Bacterial Agents/biosynthesis , Oligosaccharides/biosynthesis , Streptomyces/metabolism , Terpenes/blood , Xylulose/analogs & derivatives , Anti-Bacterial Agents/chemistry , Hemiterpenes/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , Oligosaccharides/chemistry , Organophosphorus Compounds/chemistry , Terpenes/chemistry , Xylulose/metabolismABSTRACT
The interaction of a moenomycin derivative with the enzyme penicillin binding protein 1b (PBP 1b) has been studied by means of STD NMR. The results obtained initiated the synthesis of a number of moenomycin derivatives modified in unit A including a moenomycin-ampicillin conjugate and determination of their antibiotic activities. A protocol is described that allows studying the interaction of moenomycin analogues with PBP 1b by fluorescence correlation spectroscopy.
Subject(s)
Anti-Bacterial Agents/chemical synthesis , Bacterial Proteins/antagonists & inhibitors , Bambermycins/pharmacology , Carrier Proteins/antagonists & inhibitors , Hexosyltransferases/antagonists & inhibitors , Muramoylpentapeptide Carboxypeptidase/antagonists & inhibitors , Peptidyl Transferases/antagonists & inhibitors , Anti-Bacterial Agents/pharmacology , Bambermycins/chemical synthesis , Diffusion , Microbial Sensitivity Tests , Nuclear Magnetic Resonance, Biomolecular/methods , Octoxynol , Penicillin-Binding Proteins , Protein Binding , Spectrometry, FluorescenceABSTRACT
The antibiotic moenomycin A inhibits the biosynthesis of peptidoglycan, the main structural polymer of the bacterial cell wall. The inhibition is based on a reversible binding of the antibiotic to one of the substrate binding sites in enzymes such as penicillin-binding protein (PBP) 1b. A novel assay based on surface plasmon resonance (SPR) has been established that can be used to investigate selective binding of the moenomycin sugar moiety and other transglycosylase inhibitors to this enzyme. Suitable ligands were prepared from moenomycin A and coupled to SPR sensor surfaces. Moenomycin analogues with structural variations were used to perform competitive SPR experiments with PBP 1b. The SPR results confirm for the first time that the trisaccharide fragment of moenomycin A (C-E-F-G-H-I) is the minimal structure that possesses all moieties sufficient for biological activity and for affinity towards PBP 1b. The method seems to be appropriate for use in screens for transglycosylase inhibitors that bind to the moenomycin-binding site of the enzyme.
Subject(s)
Bacterial Proteins , Bambermycins/metabolism , Carrier Proteins , Hexosyltransferases/metabolism , Multienzyme Complexes/metabolism , Muramoylpentapeptide Carboxypeptidase , Peptidyl Transferases/metabolism , Bambermycins/chemistry , Bambermycins/pharmacology , Binding Sites , Binding, Competitive , Escherichia coli/drug effects , Glycosyltransferases/antagonists & inhibitors , Microbial Sensitivity Tests , Oligosaccharides/chemistry , Penicillin-Binding Proteins , Peptidoglycan/biosynthesis , Protein Binding , Staphylococcus aureus/drug effects , Surface Plasmon ResonanceABSTRACT
The photolytic decomposition of trifunctional carbene generating photoaffinity probes in methanolic solution was studied, a cleavage reaction with butylamine in water, the conjugation with a ligand (moenomycin), and experiments that demonstrate that the fully armed probes interact with penicillin-binding protein 1b.
Subject(s)
Bacterial Proteins , Biotin/chemistry , Carrier Proteins , Hexosyltransferases/chemistry , Multienzyme Complexes/chemistry , Muramoylpentapeptide Carboxypeptidase , Peptidyl Transferases/chemistry , Serine/analogs & derivatives , Serine/chemistry , Butylamines , Indicators and Reagents , Mass Spectrometry , Oligosaccharides/chemistry , Penicillin-Binding Proteins , Photoaffinity Labels , Photochemistry , PhotolysisABSTRACT
The antibiotic moenomycin A inhibits the biosynthesis of peptidoglycan, the main structural polymer of the bacterial cell wall. The inhibition is based on a reversible binding of the antibiotic to one of the substrate binding sites at enzymes such as the penicillin binding protein 1b (PBP 1b). This binding has been employed to isolate PBP 1b by affinity chromatography. Suitable ligands have been prepared from moenomycin A and coupled both to affinity supports and to surface plasmon resonance sensor surfaces. The reactions that take place upon immobilization of the ligands to the affinity support and the sensor surface, respectively, have been studied in detail. With the help of surface plasmon resonance the optimal conditions for binding of PBP 1b to moenomycin-derivated ligands have been established. For the first time the selective binding of the moenomycin sugar moiety to the enzyme has been demonstrated.
