Biosynthesis of Angucycline Natural Products

Angucyclines constitute a prominent family of type II polyketide natural products characterised by a tetracyclic aromatic core. Biosynthesis initiates with the stepwise condensation of acetate units by polyketide synthase machinery, yielding a nascent polyketide chain. Programmed cyclisation and aromatisation establish the angucycline scaffold, which is subsequently tailored by a suite of oxygenases, glycosyltransferases and other modifying enzymes. These tailoring steps introduce oxygen functionalities, epoxide rings, sugar moieties and, in some cases, facilitate cleavage or rearrangement of the core rings. Such modifications underpin the structural diversity of angucyclines and govern their biological activities, ranging from antibiotic to antitumour effects. Advances in genome mining have revealed numerous biosynthetic gene clusters encoding type II PKS pathways across actinomycetes, many of which remain cryptic under standard culture conditions. Strategies to activate these clusters—such as manipulation of global regulators or co-expression of pathway-specific transcription factors—have unlocked new angucycline derivatives. The elucidation of enzymatic mechanisms, particularly oxidative steps leading to ring cleavage and sugar decoration, provides a foundation for engineering biosynthesis towards novel therapeutic leads.

Research from Nature Portfolio

Recent studies have delineated the enzymatic sequence responsible for C-ring cleavage in the biosynthesis of a highly rearranged angucycline derivative, lugdunomycin. Targeted gene deletions coupled with molecular networking and structural analysis revealed that a dedicated oxygenase initiates C12 oxidation, generating a keto intermediate that is further reduced by a second enzyme. A third enzyme installs an epoxide moiety, which is stabilised by a fourth protein to effect the subsequent ring cleavage. This work clarifies the oxidative transformations at the heart of unusual angucycline rearrangements and establishes a mechanistic blueprint for generating diverse angucycline architectures.

Biosynthesis of Angucycline Natural Products publication trend

The graph below shows the total number of articles in biosynthesis of angucycline natural products across all publications each year (not limited to Nature Index journals).

Technical terms

Angucycline: Polyketide-derived tetracyclic aromatic natural product with diverse bioactivities.

Polyketide synthase (PKS): Multi-enzyme complex that catalyses assembly of polyketide backbones via successive condensation of simple carboxylic acids.

Biosynthetic gene cluster (BGC): Co-located genes encoding the enzymes required for the complete biosynthesis of a natural product.

Oxygenase: Enzyme that incorporates oxygen atoms into substrates, often initiating or modifying molecular frameworks.

Glycosyltransferase: Enzyme that attaches sugar residues to aglycone scaffolds, modulating solubility and bioactivity.

References

1. Unravelling key enzymatic steps in C-ring cleavage during angucycline biosynthesis. Communications Chemistry (2023).
2. Overexpression of Global Regulator SCrp Leads to the Discovery of New Angucyclines in Streptomyces sp. XS-16. Marine Drugs (2023).
3. Marine actinomycetes-derived angucyclines and angucyclinones with biosynthesis and activity--past 10 years (2014–2023). European Journal of Medicinal Chemistry (2024).
4. Co-expression of a pair of interdependent regulators coding genes ovmZ and ovmW awakens the production of angucyclinones antibiotics in Streptomyces neyagawaensis. Microbial Cell Factories (2024).