Project description:The functional determinants of histone H3 Lys-4 trimethylation (H3K4me3), their potential dependency on histone H2B monoubiquitination (H2Bub) and their contribution in defining gene expression programs are poorly defined in plant systems. Differently from S. cerevisiae in which a single SET1 protein catalyzes H3 Lys-4 trimethylation as part of COMPASS (COMPlex of proteins ASsociated with SET1), this activity involves multiple histone methyltransferases (HMTs) in Arabidopsis thaliana, among which the plant-specific SDG2 (SET DOMAIN GROUP2) has a prominent role. Here we report that SDG2 co-regulates hundreds genes with SWD2-like b (S2Lb), a plant ortholog of the Swd2 axillary subunit of the evolutionarily conserved COMPASS complex. Accordingly, S2Lb associates with the AtCOMPASS core subunit WDR5a within a high-molecular weight complex and is required for proper H3K4me3 enrichment over genes highly occupied by RNA Polymerase II. S2Lb knock-out plants display little transcriptomic defects, suggesting that H3K4me3 deposition is important for optimal gene induction rather than for determining on/off transcriptional states. We further report that S2Lb and H3K4me3 are accurately targeted over most genes in hub1 mutant plants lacking histone H2B monoubiquitination. Collectively, our study indicates that a plant-specific COMPASS-like complex acting mainly through an H2Bub-independent mechanism is a major determinant of H3K4me3 deposition in Arabidopsis.
Project description:The functional determinants of histone H3 Lys-4 trimethylation (H3K4me3), their potential dependency on histone H2B monoubiquitination (H2Bub) and their contribution in defining gene expression programs are poorly defined in plant systems. Differently from S. cerevisiae in which a single SET1 protein catalyzes H3 Lys-4 trimethylation as part of COMPASS (COMPlex of proteins ASsociated with SET1), this activity involves multiple histone methyltransferases (HMTs) in Arabidopsis thaliana, among which the plant-specific SDG2 (SET DOMAIN GROUP2) has a prominent role. Here we report that SDG2 co-regulates hundreds genes with SWD2-like b (S2Lb), a plant ortholog of the Swd2 axillary subunit of the evolutionarily conserved COMPASS complex. Accordingly, S2Lb associates with the AtCOMPASS core subunit WDR5a within a high-molecular weight complex and is required for proper H3K4me3 enrichment over genes highly occupied by RNA Polymerase II. S2Lb knock-out plants display little transcriptomic defects, suggesting that H3K4me3 deposition is important for optimal gene induction rather than for determining on/off transcriptional states. We further report that S2Lb and H3K4me3 are accurately targeted over most genes in hub1 mutant plants lacking histone H2B monoubiquitination. Collectively, our study indicates that a plant-specific COMPASS-like complex acting mainly through an H2Bub-independent mechanism is a major determinant of H3K4me3 deposition in Arabidopsis.
Project description:The functional determinants of histone H3 Lys-4 trimethylation (H3K4me3), their potential dependency on histone H2B monoubiquitination (H2Bub) and their contribution in defining gene expression programs are poorly defined in plant systems. Differently from S. cerevisiae in which a single SET1 protein catalyzes H3 Lys-4 trimethylation as part of COMPASS (COMPlex of proteins ASsociated with SET1), this activity involves multiple histone methyltransferases (HMTs) in Arabidopsis thaliana, among which the plant-specific SDG2 (SET DOMAIN GROUP2) has a prominent role. Here we report that SDG2 co-regulates hundreds genes with SWD2-like b (S2Lb), a plant ortholog of the Swd2 axillary subunit of the evolutionarily conserved COMPASS complex. Accordingly, S2Lb associates with the AtCOMPASS core subunit WDR5a within a high-molecular weight complex and is required for proper H3K4me3 enrichment over genes highly occupied by RNA Polymerase II. S2Lb knock-out plants display little transcriptomic defects, suggesting that H3K4me3 deposition is important for optimal gene induction rather than for determining on/off transcriptional states. We further report that S2Lb and H3K4me3 are accurately targeted over most genes in hub1 mutant plants lacking histone H2B monoubiquitination. Collectively, our study indicates that a plant-specific COMPASS-like complex acting mainly through an H2Bub-independent mechanism is a major determinant of H3K4me3 deposition in Arabidopsis.
Project description:The functional determinants of histone H3 Lys-4 trimethylation (H3K4me3), their potential dependency on histone H2B monoubiquitination (H2Bub) and their contribution in defining gene expression programs are poorly defined in plant systems. Differently from S. cerevisiae in which a single SET1 protein catalyzes H3 Lys-4 trimethylation as part of COMPASS (COMPlex of proteins ASsociated with SET1), this activity involves multiple histone methyltransferases (HMTs) in Arabidopsis thaliana, among which the plant-specific SDG2 (SET DOMAIN GROUP2) has a prominent role. Here we report that SDG2 co-regulates hundreds genes with SWD2-like b (S2Lb), a plant ortholog of the Swd2 axillary subunit of the evolutionarily conserved COMPASS complex. Accordingly, S2Lb associates with the AtCOMPASS core subunit WDR5a within a high-molecular weight complex and is required for proper H3K4me3 enrichment over genes highly occupied by RNA Polymerase II. S2Lb knock-out plants display little transcriptomic defects, suggesting that H3K4me3 deposition is important for optimal gene induction rather than for determining on/off transcriptional states. We further report that S2Lb and H3K4me3 are accurately targeted over most genes in hub1 mutant plants lacking histone H2B monoubiquitination. Collectively, our study indicates that a plant-specific COMPASS-like complex acting mainly through an H2Bub-independent mechanism is a major determinant of H3K4me3 deposition in Arabidopsis.
Project description:We analyzed by RNA-seq the transcriptome of 8-day old Arabidopsis thaliana seedlings for wild-type (Col-0), single mutant for FPA (fpa/AT2G43410, line fpa-7) or a triple mutant of all three BDR proteins (bdrs: cross of bdr1/AT5G25520 mutant SALK_142108C, bdr2/AT5G11430 mutant CS852350 and bdr3/AT2G25640 mutant SALK_059905). We identified hundreds of genes differentially expressed between wild-type and bdrs triple mutant and a significant overlap in DE genes with the fpa mutant. We also analyzed the binding of BDR1 and BDR2 as well as RNA polymerase II and histone marks by ChIP-seq in wild-type, bdrs and fpa-deficient seedlings. Our data support a role of BDRs as negative elongation factors. They occupy the gene body and regulate the expression of genes involved in defense response pathways. Strikingly, by modulating 3' pausing of RNA polymerase II and possibly contributing to gene looping, they also protect a number of genes from transcriptional interferences originating from a highly expressed upstream tandem gene. Thus BDRs proteins are negative elongation factors that act as transcriptional "gatekeepers" in the Arabidopsis thaliana genome.
Project description:We analyzed by RNA-seq the transcriptome of 8-day old Arabidopsis thaliana seedlings for wild-type (Col-0), single mutants for BDR proteins (bdr1/AT5G25520 ; bdr2/AT5G11430 or bdr3/AT2G25640), single mutant for FPA (fpa/AT2G43410, line fpa-7) or a triple mutant of all three BDR proteins (bdrs: cross of bdr1/AT5G25520 mutant SALK_142108C, bdr2/AT5G11430 mutant CS852350 and bdr3/AT2G25640 mutant SALK_059905). We identified hundreds of genes differentially expressed between wild-type and bdrs triple mutant and a significant overlap in DE genes with the fpa mutant. We also analyzed the binding of BDR1 and BDR2 as well as RNA polymerase II and histone marks by ChIP-seq in wild-type, bdrs and fpa-deficient seedlings. Our data support a role of BDRs as negative elongation factors. They bind on the gene body and regulate the expression of genes involved in defense response pathways. Strikingly, by modulating 3' pausing of RNA polymerase II and possibly contributing to gene looping, they also protect a number of genes from transcriptional interferences originating from a highly expressed upstream tandem gene. Thus BDRs proteins are negative elongation factors that act as transcriptional "gatekeepers" in the Arabidopsis thaliana genome.