The Indispensable Role of Histone Methyltransferase Dot1 in Extracellular Glycoside Hydrolase Biosynthesis of .

Histone methylation is associated with transcription regulation, but its role for glycoside hydrolase (GH) biosynthesis is still poorly understood. We identified the histone H3 lysine 79 (H3K79)-specific methyltransferase Dot1 in . Dot1 affects conidiation by regulating the transcription of key regulators (BrlA, FlbC, and StuA) of asexual development and is required in normal hyphae septum and branch formation by regulating the transcription of five septin-encoding genes, namely, , , , , and . Tandem affinity purification/mass spectrometry showed that Dot1 has no direct interaction with transcription machinery, but it affects the expressions of extracellular GH genes extensively. The expression of genes (, , , , , , , , , and ) that encode the top 10 GHs was remarkably downregulated by deletion (Δ). Consistent with the decrease in gene transcription level, the activities of amylases and cellulases were significantly decreased in Δ mutants in agar (solid) and fermentation (liquid) media. The repression of GH gene expressions caused by Dot1 deletion was not mediated by key transcription factors, such as AmyR, ClrB, CreA, and XlnR, but was accompanied by defects in global demethylated H3K79 (H3K79me2) and trimethylated H3K79 (H3K79me3). The impairment of H3K79me2 on specific GH gene loci was observed due to Dot1 deletion. The results implies that defects of H3K79 methylation is the key reason of the downregulated transcription level of GH-encoding genes and reveals the indispensable role of PoDot1 in extracellular GH biosynthesis.