Different Putative Methyltransferases Have Different Effects on the Expression Patterns of Cellulolytic Genes.

Area of Science:

• Mycology
• Enzymology
• Molecular Biology

Background:

• Methyltransferases, including LaeA and LaeA-like proteins, are crucial for fungal development and secondary metabolite production.
• Filamentous fungi like Penicillium oxalicum produce cellulolytic enzymes essential for biomass degradation.

Purpose of the Study:

• To investigate the biological functions of eight putative methyltransferases (PoMtr23C/D/E/F/G/H and PoMtr25A/B) in Penicillium oxalicum.
• To determine the specific roles of these methyltransferases in the regulation of cellulolytic enzyme production.

Main Methods:

• Gene deletion mutant construction for eight putative methyltransferase genes.
• Assay of cellulolytic enzyme production using filter paper activity (FPA) and halo assays.
• Measurement of transcriptional levels of cellulolytic enzyme genes (Po_cbh1, Po_eg1) and transcription factors (XlnR, CreA).
• Subcellular localization and protein-protein interaction studies for PoMtr25A using tandem affinity purification-mass spectrometry.

Main Results:

• Gene deletion mutants exhibited varied cellulolytic enzyme production patterns.
• The Δmtr23G mutant showed the largest increase in FPA and a cellulolytic halo.
• Mutants Δmtr23C, Δmtr23D, and Δmtr25A also displayed increased enzyme production, while Δmtr23E and Δmtr25B showed decreased activity.
• Transcriptional analysis confirmed the correlation between cellulolytic gene expression and enzyme production.
• PoMtr25A was localized to the nucleus and interacted with the SWI/SNF chromatin-remodeling complex.

Conclusions:

• Specific methyltransferases (PoMtr23C, D, G, and PoMtr25A) play significant roles in regulating cellulolytic enzyme production in P. oxalicum.
• Regulation involves modulation of transcription factors XlnR and CreA, and potentially chromatin remodeling via SWI/SNF complex recruitment by PoMtr25A.