Involvement of the Methyltransferase CcLaeA in Regulating Laccase Production in Curvularia clavata J1

Laccases are synthesized by a diverse range of fungi. Nevertheless, despite the industrial significance of laccases, the regulatory mechanism governing laccase production has been relatively understudied. This research aims to explore the regulatory function of the methyltransferase CcLaeA in laccase biosynthesis using the newly isolated fungal strain Curvularia clavata J1. Through CRISPR-Cas9-mediated gene disruption, the deletion of CclaeA led to a 1.5-fold increase in extracellular laccase activity in the ΔCclaeA mutant when compared to the wild-type strain. This finding indicates that CcLaeA functions as a transcriptional repressor of laccase biosynthesis. Transcriptomic analysis demonstrated that CcLaeA does not directly regulate the expression of laccase genes. Instead, it modulates genes associated with hydrolases and peptidases. This modulation potentially reduces the enzymatic degradation of laccase at the protein level. This study significantly enhances our understanding of fungal laccase regulation. By establishing a connection between the deletion of CclaeA and the improvement of enzyme stability and activity, this research offers practical insights for engineering fungal strains to optimize laccase yields for bioremediation and biofuel applications. Furthermore, the integration of targeted gene knockout with multi-omics validation sets up a methodological framework for investigating regulatory networks in non-model fungi. This framework is expected to accelerate the development of sustainable biocatalysts, thereby contributing to the advancement of biotechnology in various industrial sectors.