Migrastatin and Dorrigocins Are Shunt Metabolites of Iso-Migrastatin

Abstract

Fermentation of Streptomyces platensis NRRL18993 typically accumulated migrastation (1), dorrigocin A (2) and B (3), and 13-epi-dorrigocin A (5). Supplement of XAD-16 resin to the fermentation, in contrast, resulted in exclusive production of iso-migrastatin (4). In vitro studies showed that 1, 2, 3, and 5 are stable in aqueous solution but 4 undergoes rapid conversion into 1, 2, 3, and 5 under the same condition. These results revealed that 4 is the only bona fide natural product biosynthesized by S. platensis, and 1, 2, 3, and 5 are shunt metabolites of 4. This study also established the stereochemistry of 2-5 with the exception of C-11 for 3 and 4. A mechanism for H2O-mediated regio- and stereospecific rearrangement of 4 to 1, 2, 3, and 5 is proposed and supported by incorporation of 18O from H218O.

iso-Migrastatin, Migrastatin, and Dorrigocin Production in Streptomyces platensis NRRL 18993 Is Governed by a Single Biosynthetic Machinery Featuring an Acyltransferase-less Type I Polyketide Synthase

“…S. platensis NRRL 18993 wild-type (9 -14) and recombinant strains were grown on ISP4 for sporulation, cultured in modified ISP4 (ISP4 containing 0.1% tryptone, and 0.05% yeast extract) for intergeneric conjugation, and fermented in 2% glycerol, 2% dextrin, 1% soy peptone, 0.3% yeast extract, 0.2% (NH 4 ) 2 SO 4 , and 0.2% CaCO 3 , pH 7.0 for metabolite production (9,10). When necessary, antibiotics were added at the following concentrations of ampicillin, 100 g/ml; apramycin, 50 g/ml; chloramphenicol, 25 g/ml; kanamycin, 50 g/ml; and trimethoprim, 50 g/ml for selection (15,16).…”

“…, and the DGNs-S. platensis fermentation and isolation and analysis of iso-MGS, MGS, and the DGNs were carried out as described previously (9,10,12,13). A two-stage fermentation process was used, with both stages utilizing the same medium.…”

“…In the presence of XAD-16 or HP-20, iso-MGS was isolated as the major metabolite. In the absence of XAD-16 or HP-20, iso-MGS underwent rapid H 2 O-mediated, non-enzymatic ring-expansion and ring-opening rearrangement to afford MGS and the DGNs as the major metabolites (9,10). HPLC analysis of iso-MGS, MGS, and the DGNs were carried out on Varian HPLC system (Woburn, MA) using a Prostar 330 detector and a Prodigy ODS-2 column (150 ϫ 4.6 mm, 5 m) (9, 10).…”

“…Complementary to organic synthesis, combinatorial biosynthesis offers an alternative means of accessing natural product structural diversity. We have previously studied the biosynthetic pathway of these polyketides and shown that MGS and the DGNs are shunt metabolites of iso-MGS (9). As has been demonstrated in Streptomyces platensis NRRL 18993, one of the known iso-MGS producers, iso-MGS, MGS, and the DGNs are produced by a single biosynthetic machinery and iso-MGS undergoes H 2 O-mediated, non-enzymatic ring-expansion, and ring-opening rearrangements to afford MGS and the DGNs as shunt metabolites.…”

Chemistry and Biology in Search of Antimetastatic Agents

“…The most potent compound identified from the quinic acid analogue series is macrolide 1 (Figure 1), a 12-membered macrocycle that contains a cis double bond. It has an IC 50 of 77 nM in murine 4T1 breast tumor cells and is reminiscent of the natural product isomigrastatin, which Shen and coworkers (19) had earlier identified as the bona fide natural product from which migrastatin and the dorrigocins are shunt metabolites.…”