Abstract
SummaryHistone acetylation has been established as a principal epigenetic regulatory mechanism in eukaryotes. Sas3, a histone acetyltransferase belonging to the largest family of acetyltransferase, MYST, is the catalytic subunit of a conserved histone acetyltransferase complex. To date, the functions of Sas3 and its orthologues have been extensively studied in yeast, humans and flies in relation to global acetylation and transcriptional regulation. However, its precise impact on development and pathogenicity in fungal plant pathogens has yet to be elucidated. Considering the importance of Sas3 in H3K14 acetylation, here we investigate the roles of its orthologue in the rice blast fungus, Magnaporthe oryzae (Pyricularia oryzae). Unlike a previously reported Sas3 deletion in yeast, which led to no remarkable phenotypic changes, we found that MoSAS3 deletion alone had a profound effect on fungal growth and development, including asexual reproduction, germination and appressorium formation in M. oryzae. Such defects in pre‐penetration development resulted in complete loss of pathogenicity in the deletion mutant. Furthermore, genetic analysis of MoSAS3 and MoGCN5 encoding a Gcn5‐related N‐acetyltransferase family histone acetyltransferase suggested that two conserved components of histone acetylation are integrated differently into epigenetic regulatory mechanisms in the yeast and a filamentous fungus. RNA‐seq analysis of ΔMosas3 showed two general trends: many DNA repair and DNA damage response genes are up‐regulated, while carbon and nitrogen metabolism genes are down‐regulated in ΔMosas3. Our work demonstrates the importance of MYST family histone acetyltransferase as a developmental regulator and illuminates a degree of functional variation in conserved catalytic subunits among different fungal species.
Highlights
Histone modification is a conserved post-translational modification (PTM) that plays a pivotal role in the epigenetic regulation of gene expression and chromatin in eukaryotes (Kouzarides, 2007)
We investigated the role of the Sas3 orthologue and its histone acetylation activity in the regulation of the growth, development and pathogenicity of M. oryzae (Couch and Kohn, 2002; Couch et al, 2005; Gomez-Rodriguez et al, 2018; Grimaldi et al, 2006; Zhang et al, 2016), combining genetic and transcriptomic approaches
A gene encoding the Sas3 orthologue in M. oryzae was designated as MoSAS3 (MGG_04615)
Summary
Histone modification is a conserved post-translational modification (PTM) that plays a pivotal role in the epigenetic regulation of gene expression and chromatin in eukaryotes (Kouzarides, 2007). Modification of histones is catalysed by specialized histone-modifying enzymes (HMEs) such as histone acetyltransferases/deacetylase (HATs/HDACs) and histone methyltransferases/demethylases (HMTs/HDMs) that function via addition or removal of acetyl and methyl residues from the histone proteins, respectively. HATs are one of the best-characterized groups of HMEs, which use acetyl-CoA as a substrate for the acetylation of lysine (K) residues within both the tail and globular domains of histones to poise the gene for active transcription (Dubey and Jeon 2017; Jeon et al, 2014; Sterner and Berger, 2000). As an increasing number of non-histone targets of previously known HATs and HDACs are being discovered, a new classification placed these enzymes under the umbrella of lysine acetyltransferase (KATs) and deacetylases (KDACs) (Allis et al, 2007). Ranging from yeast to humans, several HATs have been identified that can be classified, based on the presence of conserved structural motifs, into five families including Gcn5related N-acetyltransferase (GNAT) and MYST (members MOZ, MOF, MORF, Ybf2/Sas, Sas, Tip and HBO1) families (Jeon et al, 2014; Sterner and Berger, 2000)
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