A histone H3K9 methyltransferase Dim5 mediates repression of sorbicillinoid biosynthesis in Trichoderma reesei

Abstract

Sorbicillinoids (also termed yellow pigment) are derived from either marine or terrestrial fungi, exhibit various biological activities and therefore show potential as commercial products for human or animal health. The cellulolytic filamentous fungus Trichoderma reesei is capable to biosynthesize sorbicillinoids, but the underlying regulatory mechanism is not yet completely clear. Herein, we identified a histone H3 lysine 9 (H3K9) methyltransferase, Dim5, in T. reesei. TrDIM5 deletion caused an impaired vegetative growth as well as conidiation, whereas the ∆Trdim5 strain displayed a remarkable increase in sorbicillinoid production. Post TrDIM5 deletion, the transcription of sorbicillinoid biosynthesis‐related (SOR) genes was significantly upregulated with a more open chromatin structure. Intriguingly, hardly any expression changes occurred amongst those genes located on both flanks of the SOR gene cluster. In addition, the assays provided evidence that H3K9 triple methylation (H3K9me3) modification acted as a repressive marker at the SOR gene cluster and thus directly mediated the repression of sorbicillinoid biosynthesis. Transcription factor Ypr1 activated the SOR gene cluster by antagonizing TrDim5‐mediated repression and therefore contributed to forming a relatively more open local chromatin environment, which further facilitated its binding and SOR gene expression. The results of this study will contribute to understanding the intricate regulatory network in sorbicillinoid biosynthesis and facilitate the endowment of T. reesei with preferred features for sorbicillinoid production by genetic engineering.

Normal distribution of H3K9me3 occupancy co-mediated by histone methyltransferase BcDIM5 and histone deacetylase BcHda1 maintains stable ABA synthesis in Botrytis cinerea TB-31

“…Current studies suggest that H3K9me3 is commonly associated with the repression of biosynthetic gene clusters, and has been further identified as a mark of constitutive heterochromatin, principally associated with centromeric heterochromatin ( Wiles and Selker, 2017 ; Torres-Garcia et al, 2020 ). Therefore, knockdown of DIM5 in pathogenic fungi leads to increased production of some secondary metabolites ( Wang et al, 2022 ). However, DIM5 is often associated with the pathogenicity of the strain.…”

Histone Methyltransferase SsDim5 Regulates Fungal Virulence through H3K9 Trimethylation in Sclerotinia sclerotiorum

“…Through a gene knockout study of SsDim5 in S. sclerotiorum, we discovered an indispensable role for SsDim5 in the virulence of the fungus, without affecting its hyphal development and sclerotium formation. In the case of Trichoderma reesei, the absence of TrDim5 resulted in impaired vegetative growth and conidiation [44]. The deletion mutant of FvDim5 in Fusarium graminearum (∆FvDim5) exhibited significant defects in conidiation, perithecium formation, and fungal virulence [29].…”

Current genetic strategies to investigate gene functions in Trichoderma reesei

“…However, this strategy usually exhibits a low recombination rate (5%~10%) at the desired position [ 45 ]. Considering the long homologous arm is beneficial to facilitate the HR probability, more than 2000 bp homologous sequence was employed in gene knockout events in some tests [ 46 – 48 ]. Even so, the increment in HR efficiency does not seem to be remarkable.…”

“…In a few cases, gene mutants severely affect the receptivity of exogenous DNA, resulting in failure of the next gene complementation [ 120 ]. Therefore, three independent transformants at least are necessary to exclude the possible effects of mutant cassette insertion into the genome [ 48 ].…”