Biosynthesis and Regulation of Secondary Metabolites in Fungi

Fungal organisms produce a diverse repertoire of secondary metabolites—polyketides, non-ribosomal peptides, terpenoids and alkaloids—that are not essential for primary growth yet confer competitive, defensive and signalling advantages. These compounds are synthesised by multi-enzyme assemblies encoded within biosynthetic gene clusters and are regulated at multiple levels. Global nutrient sensors, such as GATA transcription factors governing nitrogen metabolite repression, integrate signals from the environment to modulate cluster activation. Chromatin-based mechanisms, including histone methylation and acetylation, further determine cluster accessibility, while pathway-specific transcription factors and protein scaffolds refine gene expression patterns in response to pH, temperature and inter-organismic cues. The resulting chemical diversity underpins the discovery of antibiotics and immunosuppressants, influences crop health through mycotoxin production and drives innovations in biotechnology and agriculture.

Research from Nature Portfolio

Recent work has elucidated the genetic architecture underlying perithecial pigmentation in Fusarium species. Over-expression of a cluster-specific transcription factor revealed a seven-gene locus anchored by a polyketide synthase responsible for producing 5-deoxybostrycoidin derivatives. Targeted gene disruptions confirmed the essential roles of pathway enzymes in melanin assembly and identified novel anthrone intermediates. One dimeric melanin precursor demonstrated potent antifungal activity, suggesting that pigment biosynthesis not only protects reproductive structures from environmental stress but also mediates interspecies antagonism.

Research from all publishers

In the mycoparasitic fungus Trichoderma atroviride, functional characterisation of the GATA-type transcription factor Are1 revealed its dual role in nitrogen sensing and iron homeostasis. Deletion of Are1 impaired growth on diverse nitrogen sources, heightened sensitivity to oxidative and cell-wall stress, and altered the spectrum of secondary metabolites deployed during antagonism, uncovering a regulatory link between nutrient availability and defensive metabolite synthesis.

Studies of the facultative heterochromatin mark H3K27me3 in Fusarium proliferatum demonstrated its critical function in silencing secondary metabolite gene clusters and directing fungal development. Loss of the H3K27 methyltransferase resulted in derepression of nearly half of previously silenced clusters, accompanied by compensatory changes in H3K9 methylation and acetylation. Notably, genes for gibberellin biosynthesis became markedly upregulated, highlighting the importance of chromatin state in controlling phytohormone production.

An integrated transcriptomic and metabolomic analysis in Fusarium sacchari shed light on nitrogen-dependent modulation of secondary metabolism. Cultivation on distinct nitrogen sources produced differential expression of polyketide synthase, non-ribosomal peptide synthetase and cytochrome P450 genes, with concordant shifts in metabolite profiles. Detailed examination of the gibberellin cluster revealed changes in metabolic flux and synthesis steps, providing a comprehensive view of how nitrogen availability balances primary growth with secondary metabolite output.

Biosynthesis and Regulation of Secondary Metabolites in Fungi publication trend

The graph below shows the total number of articles in biosynthesis and regulation of secondary metabolites in fungi across all publications each year (not limited to Nature Index journals).

Technical terms

Secondary metabolites: Bioactive small molecules produced by fungi that are not required for basic growth but mediate ecological interactions.

Biosynthetic gene cluster (BGC): A contiguous set of co-regulated genes encoding enzymes and regulators for synthesis of a specific secondary metabolite.

Polyketide synthase (PKS): A multi-domain enzyme that assembles polyketide backbones by sequential condensation of acyl-CoA units.

Non-ribosomal peptide synthetase (NRPS): A modular enzyme complex that synthesises peptides independently of the ribosome, incorporating diverse amino acid substrates.

H3K27me3: Trimethylation of lysine 27 on histone H3, a chromatin mark associated with gene silencing in facultative heterochromatin.

Nitrogen metabolite repression: A regulatory mechanism by which preferred nitrogen sources suppress genes involved in utilisation of alternative nitrogen sources and secondary metabolism.

References

1. Black perithecial pigmentation in Fusarium species is due to the accumulation of 5-deoxybostrycoidin-based melanin. Scientific Reports (2016).
2. Are1-mediated nitrogen metabolism is associated with iron regulation in the mycoparasite Trichoderma atroviride. Microbiological Research (2024).
3. H3K27me3 is vital for fungal development and secondary metabolite gene silencing, and substitutes for the loss of H3K9me3 in the plant pathogen Fusarium proliferatum. PLOS Genetics (2024).
4. Integration of Transcriptomic and Metabolomic Profiles Provides Insights into the Influence of Nitrogen on Secondary Metabolism in Fusarium sacchari. International Journal of Molecular Sciences (2023).