Pigment biosynthesis pathway in Aspergillus ustus: a comprehensive analysis combining transcriptomics and chemical...

Area of Science:

• Mycology
• Biochemistry
• Molecular Biology

Background:

• Aspergillus ustus produces pigments, but the biosynthetic pathway remains largely uncharacterized.
• Understanding pigment biosynthesis is crucial for potential applications and controlling fungal metabolites.

Purpose of the Study:

• To elucidate the biosynthetic pathway of Aspergillus ustus pigment.
• To identify key genes and enzymes involved in pigment production.
• To investigate the effect of precursors and inhibitors on pigment formation.

Main Methods:

• Comparative transcriptomic analysis of pigment-producing and non-producing A. ustus strains.
• Bioinformatics for gene functional annotation and enrichment analysis.
• Reverse transcription quantitative PCR (RT-qPCR) for validating RNA-sequencing data.
• Treatment with various precursor molecules and enzyme inhibitors.

Main Results:

• Specific precursors (e.g., acetic acid, amino acids) enhanced pigment production, while inhibitors (e.g., iodoacetamide) suppressed it.
• Transcriptomic analysis revealed significant upregulation of non-reducing polyketide synthase (NR-PKS) genes.
• Evidence suggests pigment synthesis occurs through an iterative type I PKS pathway catalyzed by fungal NR-PKSs.
• RT-qPCR confirmed 80% concordance with RNA-seq results, validating the transcriptomic data.

Conclusions:

• Aspergillus ustus pigment is synthesized via a fungal NR-PKS-catalyzed iterative type I PKS pathway, analogous to the noranthrone pathway.
• The study provides a foundation for metabolic engineering of A. ustus for pigment production.