Evidence for the combined participation of a C10 and a C15 precursor in the biosynthesis of moenocinol, the lipid part of the moenomycin antibiotics

Moenomycin family antibiotics: chemical synthesis, biosynthesis, and biological activity

The review (with 214 references cited) is devoted to moenomycins, the only known group of antibiotics that directly inhibit bacterial peptidoglycan glycosytransferases. Naturally occurring moenomycins and chemical and biological approaches to their derivatives are described. The biological properties of moenomycins and plausible mechanisms of bacterial resistance to them are also covered here, portraying a complete picture of the chemistry and biology of these fascinating natural products

The molecular biology of moenomycins: towards novel antibiotics based on inhibition of bacterial peptidoglycan glycosyltransferases

Moenomycins are phosphoglycolipid antibiotics and the only known natural product inhibitors of peptidoglycan glycosytransferases (PGTs). Techniques that would allow facile diversification of the moenomycin structure would facilitate the development of novel antibiotics, which are urgently needed in the wake of multidrug resistant bacterial infections. The cloning and initial characterization of the moenomycin biosynthetic genes has already redefined the minimal moenomycin pharmacophore and now opens the door for the biocombinatorial generation of bioactive moenomycin fragments. Here, we highlight the importance of research on the genetic mechanisms that regulate moenomycin biosynthesis and that confer moenomycin resistance to bacteria in the development of novel anti-infectives based on PGT inhibition.

Complete characterization of the seventeen step moenomycin biosynthetic pathway

The moenomycins are phosphoglycolipid antibiotics produced by Streptomyces ghanaensis and related organisms. The phosphoglycolipids are the only known active site inhibitors of the peptidoglycan glycosyltransferases, an important family of enzymes involved in the biosynthesis of the bacterial cell wall. Although these natural products have exceptionally potent antibiotic activity, pharmacokinetic limitations have precluded their clinical use. We previously identified the moenomycin biosynthetic gene cluster in order to facilitate biosynthetic approaches to new derivatives. Here, we report a comprehensive set of genetic and enzymatic experiments that establish functions for the 17 moenomycin biosynthetic genes involved in the synthesis of moenomycin and variants. These studies reveal the order of assembly of the full molecular scaffold and define a subset of seven genes involved in the synthesis of bioactive analogues. This work will enable both in vitro and fermentation-based reconstitution of phosphoglycolipid scaffolds so that chemoenzymatic approaches to novel analogues can be explored.

A streamlined metabolic pathway for the biosynthesis of moenomycin A

Moenomycin A (MmA) is a member of the phosphoglycolipid family of antibiotics, which are the only natural products known to directly target the extracellular peptidoglycan glycosyltransferases involved in bacterial cell wall biosynthesis. The structural and biological uniqueness of MmA make it an attractive starting point for the development of new antibacterial drugs. In order both to elucidate the biosynthesis of this unusual compound and to develop tools to manipulate its structure, we have identified the MmA biosynthetic genes in Streptomyces ghanaensis (ATCC14672). We show via heterologous expression of a subset of moe genes that the economy of the MmA pathway is enabled through the use of sugar-nucleotide and isoprenoid building blocks derived from primary metabolism. The work reported lays the foundation for genetic engineering of MmA biosynthesis to produce novel derivatives.

Characterization of moenomycin antibiotic complex by multistage MALDI-IT/RTOF-MS and ESI-IT-MS

Flavomycin is a commercially available antimicrobial growth promoter and an authorized additive for feeding stuffs in the EU and in the USA. As most antibiotically active products biosynthesized by microorganisms, it contains not only a single active compound but is a complex mixture of structurally closely related substances. Multistage matrix-assisted laser desorption/ionization-ion trap/reflectron time-of-flight mass spectrometry (MALDI-IT/RTOF-MS) and liquid chromatography-electrospray ionization-ion trap-mass spectrometry (LC-ESI-IT-MS) were utilized for a detailed analysis of the constituents of the Flavomycin complex based on low-energy collision induced dissociation (CID). An optimal sample preparation for negative ion vacuum MALDI-MS for this compound class was developed. The MALDI-IT/RTOF-MS2 and -MS3 analysis starting with the precursor [M - H]- ions of these interesting phosphoglycolipids, named moenomycins, yielded a large variety of product ions that facilitated the structural characterization of this class of compounds. Based on the derived CID fragmentation pathway of the five known major constituents, namely moenomycin A, moenomycin A12, moenomycin C4, moenomycin C3. and moenomycin C1, four not yet described moenomycin-type constituents could be characterized. They were assigned as 4F-demethyl-6E-O-de-beta-D-glucopyranosyl-moenomycin A, 6B-N-de(2-hydroxy-5-oxo-1-cyclopenten-1-yl)-moenomycin A, 6B-hydroxy-6B-de[N-(2-hydroxy-5-oxo-1-cyclopenten-1-yl)amino]-moenomycin A, and 6C-hydroxy-moenomycin A. In addition, a moenomycin A carrying an oxygen in the moenocinol-group was found, which is most probably a chemical degradation product. These new compounds were verified by LC-ESI-IT-MS.