The Set1/COMPASS Histone H3 Methyltransferase Helps Regulate Mitosis With the CDK1 and NIMA Mitotic Kinases in Aspergillus nidulans

Abstract

Mitosis is promoted and regulated by reversible protein phosphorylation catalyzed by the essential NIMA and CDK1 kinases in the model filamentous fungus Aspergillus nidulans. Protein methylation mediated by the Set1/COMPASS methyltransferase complex has also been shown to regulate mitosis in budding yeast with the Aurora mitotic kinase. We uncover a genetic interaction between An-swd1, which encodes a subunit of the Set1 protein methyltransferase complex, with NIMA as partial inactivation of nimA is poorly tolerated in the absence of swd1. This genetic interaction is additionally seen without the Set1 methyltransferase catalytic subunit. Importantly partial inactivation of NIMT, a mitotic activator of the CDK1 kinase, also causes lethality in the absence of Set1 function, revealing a functional relationship between the Set1 complex and two pivotal mitotic kinases. The main target for Set1-mediated methylation is histone H3K4. Mutational analysis of histone H3 revealed that modifying the H3K4 target residue of Set1 methyltransferase activity phenocopied the lethality seen when either NIMA or CDK1 are partially functional. We probed the mechanistic basis of these genetic interactions and find that the Set1 complex performs functions with CDK1 for initiating mitosis and with NIMA during progression through mitosis. The studies uncover a joint requirement for the Set1 methyltransferase complex with the CDK1 and NIMA kinases for successful mitosis. The findings extend the roles of the Set1 complex to include the initiation of mitosis with CDK1 and mitotic progression with NIMA in addition to its previously identified interactions with Aurora and type 1 phosphatase in budding yeast.D URING the transition from interphase into mitosis, chromatin undergoes dramatic global restructuring to go from a relaxed interphase configuration amenable to gene expression to a condensed form characteristic of mitotic chromosomes. Chromatin condensation not only marks mitosis but is also essential for the normal segregation of the duplicated sister chromatids into daughter nuclei. On the other hand, during mitotic exit, decondensation of chromatin needs to be triggered in a correct temporal manner to enable successful transition into interphase. In Aspergillus nidulans, a model filamentous fungus that enabled discovery of cell cycle-specific genes, mitotic initiation requires the function of the essential NIMA mitotic kinase (Oakley and Morris 1983;Osmani et al. 1987). Early evidence pointed to a role for NIMA in regulating chromatin compaction through the cell cycle since overexpression of NIMA was sufficient to induce chromatin condensation independent of cell cycle phase (Osmani et al. 1988;. Importantly, NIMA is required for, and can promote, the phosphorylation of histone H3 at serine 10 (De Souza et al. 2000), a universal marker of mitotic chromatin. In addition, NIMA has been shown to regulate the partial disassembly of nuclear pore complexes, allowing the access of mitotic regulators to the nucleus (Wu et al. 1998;De S...

Set1 and Kdm5 are antagonists for H3K4 methylation and regulators of the major conidiation‐specific transcription factor gene ABA1 in Fusarium fujikuroi

“…C). Contrary to S. cerevisae and A. nidulans (Fingerman et al ., ; Govindaraghavan et al ., ), but in agreement with F. graminearum (Liu et al ., ), a faint band was still detectable for H3K4me1. However, it remains unclear at this moment whether there are indeed residual monomethylation levels in Δ set1 or whether this band is due to insufficient antibody specificity.…”

“…Identification of the H3K4 methyltransferase Set1 and demethylase Kdm5 in F. fujikuroi After analyzing the COMPASS component Ccl1 in F. fujikuroi (Studt et al, 2017), we have now identified the putative methyltransferase of this complex by determining the ortholog using QuartetS . The predicted protein FFUJ_02475 is the ortholog of the wellcharacterized H3K4-specific methyltransferases Set1 in S. cerevisiae and SetA in A. nidulans (Briggs et al, 2001;Govindaraghavan et al, 2014). FFUJ_02475 contains the catalytically active SET (IPR001214), N-SET (IPR024657) and Post-SET (IPR003616) domains as well as an RNA-binding (IPR035979) domain also present in Set1 and SetA from S. cerevisiae and A. nidulans, respectively (Fig.…”

“…The methylation of H3K4 has been studied in a number of different organisms from yeast to humans, and has been shown to depend on the conserved Su(var)3-9, Enhancer-of-zeste, Trithorax (SET) domain-containing methyltransferase Set1 (Briggs et al, 2001;Lee and Skalnik, 2005;Freitag, 2017). The genomes of yeast and filamentous fungi, such as A. nidulans, F. graminearum and Fusarium verticillioides, encode one Set1 homologue that is responsible for all three methylation states H3K4me1/me2/me3 (Briggs et al, 2001;Fingerman et al, 2005;Harting et al, 2013;Govindaraghavan et al, 2014;Liu et al, 2015;Gu et al, 2017). As a counterpart, the Jumonji C (JmjC) domain-containing demethylase Jhd2 has been identified in S. cerevisiae (Liang et al, 2007;Seward et al, 2007), and later also in A. nidulans (Gacek-Matthews et al, 2016).…”

Lack of the COMPASS Component Ccl1 Reduces H3K4 Trimethylation Levels and Affects Transcription of Secondary Metabolite Genes in Two Plant–Pathogenic Fusarium Species

“…In Neurospora crassa Set1 is not essential and has been shown to regulate the circadian rhythm (Raduwan et al, 2013). Also in A. nidulans set1 Δ alone is viable but synthetic lethal with regulators of mitosis which provides a link between H3K4 methylation and H3S10 phosphorylation (Govindaraghavan et al, 2014). Cells of the rice pathogen M. oryzae lacking MoSet1 cannot develop proper infection and asexual reproduction structures (Pham et al, 2015).…”

Restraint of the G2/M Transition by the SR/RRM Family mRNA Shuttling Binding Protein SNXAHRB1 in Aspergillus nidulans

“…immunoprecipitation approach, using antibodies against a variety of modified histones, may be required to reveal the biochemical nature of snxA defects. Of interest in this regard is the recent finding of a functional relationship between the Set1/ COMPASS complex (Set1c), an H3K4 methyltransferase, and both the CDK1 and NIMA mitotic kinases, in which Set1c and the two kinases are required for mitotic induction and progression (Govindaraghavan et al 2014). In general, H3K4 di-and trimethylation by Set1c has been associated with gene activation in euchromatin, and in humans has been suggested to "bookmark" active genes so that they can resume transcription following exit from mitosis (Blobel et al 2009;Kelly et al 2010).…”