Project description:Genomic features of DSB re-landscaping in rtf1 mutants. Histone modification is a critical determinant of frequency and location of double-strand breaks (DSBs), which induce recombination during meiosis. The Set1-dependent histone H3K4 and Dot1-dependent H3K79 methylations play an important role in DSB formations in budding yeast. Both methylations are promoted by the RNA polymerase II associated factor 1 (Paf1) complex, Paf1C. This study addressed a role of the Paf1C component Rtf1, which is critical for H3K4 and H3K79 methylations, for the regulation of meiotic DSB formation. Similar to set1 mutation, rtf1 mutation decreased the occurrence of DSBs in the genome. The rtf1 set1 double mutant exhibited a larger reduction in the levels of DSBs than the frequency of DSBs detected in either of the single mutants; this indicates independent roles of Rtf1 and Set1 in DSB formation. Importantly, the distribution of DSBs along chromosomes in the rtf1 mutant changed in a different manner than the pattern observed in the set1 and set1 dot1 mutants; this was characterized by enhanced DSB formation at some DSB-cold regions. These observations suggest that Rtf1, and, possibly, the Paf1C, determine DSB landscape in the genome, independent of H3K4 methylation.
Project description:project abstract : H3K4 methylation is a well-conserved histone modification from yeast to human. Because H3K4 methylase Set1 and its complex, COMPASS (Complex of proteins associated with Set1), are conserved from yeast to humans, budding yeast has been studied as an acceptable model organism. Since COMPASS components affect Set1 protein stability and H3K4 methylation activity variously, it is important to study how Set1 is regulated by complex components. However, deletion mutant of Swd2 component of COMPASS is not viable, although overexpression of Sen1 fragment enables the construction of Swd2 deletion mutant. This study found that positioning epitope tag to the N-terminal of Swd2 did not decrease interaction between Swd2 and Set1, but reduced the stability of both proteins, Swd2 and Set1, and global H3K4 methylation. Also, we observed that overexpression of N-terminal tagged Swd2 caused increased Set1 protein level and bulk H3K4 methylation. Therefore, Set1 protein can maintain its protein level only when enough Swd2 exist to cover the protein amount of Set1. Also, by comparing RNA sequencing analysis of N-terminal tagged Swd2 and Swd2 deletion mutant with Sen1 fragment overexpression, we isolated genes regulated by Swd2. In conclusion, we suggest that the abundance of Swd2 is important to regulate the protein stability of Set1 and the regulation of gene expression.
Project description:Histone H3K4 methylation is connected to gene transcription from yeast to humans, but its mechanistic role in transcription and chromatin dynamics remains poorly understood. Here, we investigated the functions for Set1 and Jhd2, the sole H3K4 methyltransferase and H3K4 demethylase, respectively, in S. cerevisiae. Our data show that Set1 and Jhd2 predominantly co-regulate transcription. To further understand the role for H3K4 methylation, we overexpressed Flag epitope-tagged SET1-G990E (a dominant hyperactive allele of SET1) in yeast using the constitutive ADH1 promoter (ADH1p). As a control, we also overexpressed Flag epitope-tagged wild type SET1 in yeast. Analysis of gene expression in set1-null, jhd2-null and wild type SET1 or hypeactive SET1-G990E overexpressing mutants together revealed that the transcriptional regulation at a sub-set of genes, inclduing those governing glycogen metabolism and ribosome biogenesis, is highly sensitive to any change (i.e., loss or gain) in H3K4 methylation levels. Overall, we find combined activities of Set1 and Jhd2 via dynamic modulation of H3K4 methylation contribute to positive or negative transcriptional regulation at shared target genes. Gene expression changes were generated from five different yeast strains representing wild type control, set1 null and jhd2 null mutants, and wild type SET1 or dominant hyperacive SET1-G990E overexpressing mutants. Three independent biological samples were grown for each strain, total RNA was isolated, libraries were prepared, sequenced, and analyzed separately.
Project description:Histone H3K4 methylation is connected to gene transcription from yeast to humans, but its mechanistic role in transcription and chromatin dynamics remains poorly understood. Here, we investigated the functions for Set1 and Jhd2, the sole H3K4 methyltransferase and H3K4 demethylase, respectively, in S. cerevisiae. Our data show that Set1 and Jhd2 predominantly co-regulate transcription. We find combined activities of Set1 and Jhd2 via H3K4 methylation contribute to positive or negative transcriptional regulation at shared target genes. Providing mechanistic insights, our data reveal that Set1 and Jhd2 together control nucleosomal occupancy during transcriptional co-regulation. Moreover, we find a remarkable genome-wide co-regulation of nucleosome and chromatin structure by Set1 and Jhd2 at different groups of transcriptionally active or inactive genes and at different regions within yeast genes. Overall, our study prompts a model wherein combined actions of Set1 and Jhd2 via H3K4 methylationâdemethylation control chromatin dynamics during various facets of transcriptional regulation. Genome-wide nucleosome maps were generated from three different yeast strains representing wild type control, set1 null and jhd2 null mutants. Three independent biological samples were grown for each strain, nucleosomes were prepared by micrococcal nuclease digestion, libraries were prepared, mononculeosomal DNA was isolated, sequenced, and analyzed separately.
Project description:Histone H3K4 methylation is connected to gene transcription from yeast to humans, but its mechanistic role in transcription and chromatin dynamics remains poorly understood. Here, we investigated the functions for Set1 and Jhd2, the sole H3K4 methyltransferase and H3K4 demethylase, respectively, in S. cerevisiae. Our data show that Set1 and Jhd2 predominantly co-regulate transcription. To further understand the role for H3K4 methylation, we overexpressed Flag epitope-tagged SET1-G990E (a dominant hyperactive allele of SET1) in yeast using the constitutive ADH1 promoter (ADH1p). As a control, we also overexpressed Flag epitope-tagged wild type SET1 in yeast. Analysis of gene expression in set1-null, jhd2-null and wild type SET1 or hypeactive SET1-G990E overexpressing mutants together revealed that the transcriptional regulation at a sub-set of genes, inclduing those governing glycogen metabolism and ribosome biogenesis, is highly sensitive to any change (i.e., loss or gain) in H3K4 methylation levels. Overall, we find combined activities of Set1 and Jhd2 via dynamic modulation of H3K4 methylation contribute to positive or negative transcriptional regulation at shared target genes.