Rtt109-dependent histone H3 K56 acetylation and gene activity are essential for the biological control potential of Beauveria bassiana

Background: Rtt109 is a histone acetyltransferase that catalyzes histone H3K56 acetylation required for genomic stability, DNA damage repair and virulence-related gene activity in yeast-like human pathogens but remains functionally unknown in fungal insect pathogens. This study seeks to elucidate the catalytic activity of a Rtt109 orthologue and its possible role in sustaining the biological control potential of Beauveria bassiana, a fungal entomopathogen.

Results: Deletion of rtt109 in B. bassiana abolished histone H3K56 acetylation and triggered histone H2A-S129 phosphorylation. Consequently, the deletion mutant showed increased sensitivity to the stresses of DNA damage, oxidation, cell wall perturbation, high osmolarity and heat shock during colony growth, severe conidiation defects under normal culture conditions, reduced conidial hydrophobicity, decreased conidial UV-B resistance, and attenuated virulence through normal cuticle infection. These phenotypic changes correlated well with reduced transcript levels of many genes that encode the families of H2A-S129 dephosphorylation-related protein phosphatases, DNA damage-repairing factors, antioxidant enzymes, heat-shock proteins, key developmental activators, hydrophobins and cuticle-degrading Pr1 proteases respectively.

Conclusion: Rtt109 can acetylate H3K56 and dephosphorylate H2A-S129 in direct and indirect ways respectively, and hence has an essential role in sustaining the genomic stability and global gene activity required for conidiation capacity, environmental fitness and pest control potential in B. bassiana. © 2018 Society of Chemical Industry.