Complete Characterization of the Seventeen Step Moenomycin Biosynthetic Pathway

Abstract

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 seventeen moenomycin biosynthetic genes involved in the synthesis 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 analogs. This work will enable both in vitro and fermentation-based reconstitution of phosphoglycolipid scaffolds so that chemoenzymatic approaches to novel analogs can be explored.

Nosokomycins, new antibiotics discovered in an in vivo-mimic infection model using silkworm larvae. I: Fermentation, isolation and biological properties

“…Furthermore, nosokomycins A and B were recently reported to be biosynthetic intermediates of moenomycin A in a comprehensive set of genetic and enzymatic experiments that illuminated the moenomycin biosynthetic pathway. 12 In this study, nosokomycins were discovered as potential end products using the silkworm larvae system to detect anti-MRSA compounds.…”

Nosokomycins, new antibiotics discovered in an in vivo-mimic infection model using silkworm larvae. II: Structure elucidation

“…10,11 They described that MoeA4 functions as an acyl-CoA ligase that cyclizes aminolevulinate to form the cyclopentenone (A ring) moiety and that MoeB4 functions as an amide synthetase that couples the A ring moiety to the C-6 of the B ring of moenomycin A. As described above, all nosokomycins lack the chromophoric cyclopentenone moiety, and no members of the moenomycin family were detected in the culture broth of the nosokomycin-producing strain, Streptomyces sp.…”

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

“…Most of moe cluster 1 was heterologously expressed in Streptomyces lividans TK24 to produce compound 2 (Ostash et al, 2007; Figure 1). Coexpressing or deleting genes in this heterologous system led to the identification and biosynthetic assignment of all genes necessary to produce MmA (Ostash et al, 2009).…”

“…Coupling of 3-phosphoglycerate (3-PG) to a C 15 isoprene moiety is followed by subsequent glycosylations, sugar and lipid tailoring, and chromophore attachment. In an unprecedented reaction in bacterial metabolism, enzyme MoeO5 controls the formation of the initial z-farnesyl-3-PG intermediate in MmA biosynthesis (Ostash et al, 2009). MoeO5 shows low homology to isoprenylglyceryl diphosphate synthases from Archaea, which couple either C 20 or C 25 isoprene chains to sn-glycerol-1-phosphate in the first dedicated step in the synthesis of Archaeal membrane lipids (Payandeh et al, 2006).…”

“…Likewise, an MmA analog containing C 10 lipid (5; Figure 1) is shown to efficiently inhibit PGTs in vitro, although its antibacterial activity in vivo is negligible (Adachi et al, 2006). Recently, C 15 lipid Mm's were produced heterologously and shown to possess measurable antibiotic activity, establishing a minimum lipid length required for in vivo activity (Ostash et al, 2009). Overall, MmA appears to be uniquely shaped to fit the PGT active site, and the available structural information will aid in the structure-based design of improved PGT inhibitors.…”