Influence of Cmr1 in the Regulation of Antioxidant Function Melanin Biosynthesis in Aureobasidium pullulans

We have successfully identified the transcription factor Cmr1 from the fungus Aureobasidium pullulans Hit-lcy3T, which regulates melanin biosynthesis genes. Bioinformatics analysis revealed that the Cmr1 gene encodes a protein of 945 amino acids, containing two Cys₂His₂ zinc finger domains and a Zn(II)₂Cys₆ binuclear cluster domain located at the N-terminus of Cmr1. To investigate the function of the Cmr1 gene, we performed gene knockout and overexpression experiments. Our results showed that Cmr1 is a key regulator of melanin synthesis in Hit-lcy3^T, and its absence caused developmental defects. Conversely, overexpression of Cmr1 significantly increased the number of chlamydospores in Hit-lcy3^T and improved melanin production. RT-qPCR analysis further revealed that overexpression of Cmr1 enhanced the expression of several genes involved in melanin biosynthesis, including Cmr1, PKS, SCD1, and THR1. Melanin extracted from the Hit-lcy3^T was characterized using UV and IR spectroscopy. Furthermore, we assessed the antioxidant properties of Hit-lcy3^T melanin and found that it possesses strong scavenging activity against DPPH·, ABTS·, and OH·, but weaker activity against O₂⁻·. These findings suggest that Hit-lcy3^T melanin holds promise for future development as a functional food additive.