LaeA Orchestrates Iron-Heme Supply and P450 Catalytic Efficiency for Enhanced Echinocandin B Biosynthesis in Aspergillus nidulans.

Echinocandin B (ECB), a fungal non-ribosomal lipopeptide, serves as the exclusive natural precursor of the front-line antifungal anidulafungin. Despite its clinical importance, ECB production remains suboptimal due to incomplete understanding of its biosynthesis mechanism. The global regulator LaeA has been implicated in secondary metabolite production, yet its specific role in ECB biosynthesis remains unexplored. To address this, we successfully constructed laeA deletion and overexpression strains, and demonstrated that LaeA functionally couples morphological development with ECB productivity. Transcriptomic analysis revealed LaeA directly activated the sterigmatocystin cluster via pathway-specific regulator AflR, but indirectly influenced ECB through iron-heme cofactor synchronization rather than direct gene cluster activation. LaeA overexpression upregulated siderophore iron transporters and heme biosynthetic genes, with supplementation of Fe2 + or 5-ALA further boosting titers to 2487 ± 123 and 2697 ± 16 mg/L, respectively. To overcome P450s catalytic constraints, we screened out a novel cytochrome P450 reductase CPR2 as the optimal redox partner. Co-expression of CPR2 with bacterial hemoglobin VHb achieved synergistic enhancement, improving the ECB titer to 3170 ± 41 mg/L. This study provided a practical strategy for improving ECB production and offering insights into the versatile regulatory modes of global secondary metabolite regulators.