Expanding the Ajudazol Cytotoxin Scaffold: Insights from Genome Mining, Biosynthetic Investigations, and Novel Derivatives

J Nat Prod. 2022 Nov 25;85(11):2610-2619. doi: 10.1021/acs.jnatprod.2c00637. Epub 2022 Nov 4.

Abstract

Myxobacteria have proven to be a rich source of natural products, but their biosynthetic potential seems to be underexplored given the high number of biosynthetic gene clusters present in their genomes. In this study, a truncated ajudazol biosynthetic gene cluster in Cystobacter sp. SBCb004 was identified using mutagenesis and metabolomics analyses and a set of novel ajudazols (named ajudazols C-J, 3-10, respectively) were detected and subsequently isolated. Their structures were elucidated using comprehensive HR-MS and NMR spectroscopy. Unlike the known ajudazols A (1) and B (2), which utilize acetyl-CoA as the biosynthetic starter unit, these novel ajudazols were proposed to incorporate 3,3-dimethylacrylyl CoA as the starter. Ajudazols C-J (3-10, respectively) are characterized by varying degrees of hydroxylation, desaturation, and different glycosylation patterns. Two P450-dependent enzymes and one glycosyltransferase are shown to be responsible for the hydroxylation at C-8, the desaturation at C-15 and C-33, and the transfer of a d-β-glucopyranose, respectively, based on mutagenesis results. One of the cytochrome P450-dependent enzymes and the glycosyltransferase were found to be encoded by genes located outside the biosynthetic gene cluster. Ajudazols C-H (3-8, respectively) exhibit cytotoxicity against various cancer cell lines.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cytotoxins* / biosynthesis
  • Cytotoxins* / genetics
  • Genome, Bacterial
  • Glycosyltransferases
  • Multigene Family
  • Mutagenesis
  • Myxococcales* / genetics
  • Myxococcales* / metabolism

Substances

  • Cytotoxins
  • Glycosyltransferases