Project description:Evidence indicates that transcription and mRNA export are linked processes. The molecular mechanisms of this coordination are not clear however. Sus1 (hENY2) participates in this coordination as part of two protein complexes: SAGA, a transcriptional co-activator and TREX-2 that functions in mRNA biogenesis and export. Here we investigate the coordinated action of SAGA and TREX-2 that is required for gene expression. We demonstrate that the TREX-2/proteasomal subunit Sem1, influences Sus1 role in mRNA export and TREX-2 stability. Wide analyses of gene expression reveal that Sem1 and Sus1 have also overlapping functions in transcription. In the absence of Sem1, expression of some SAGA-dependent genes is compromised with a concomitant decrease of RNAP II recruitment to promoters. Notably, ChIP experiments revealed a distinct dependency for SAGA subunits recruitment on Sem1. While absence of Sem1 lowers Ada2 and Taf9 recruitment to GAL1 promoter upon activation, association of the deubiquitylation module remains intact. However, H2B deubiquitylation activity is dramatically decreased. These results unveil a new role for Sem1 in influencing activation of SAGA-dependent H2B deubiquitylation likely mediated by stabilization of TREX-2 complex and SAGA modular assembly. Our work gives insights in how modular architecture of SAGA is determinant for its function in gene expression. Two channel microarrays were used. RNA isolated from a large amount of wt yeast from a single culture was used as a common reference. This common reference was used in one of the channels for each hybridization and used in the statistical analysis to obtain an average expression-profile for each deletion mutant relative to the wt. Two independent cultures were hybridized on two separate microarrays. For the first hybridization the Cy5 (red) labeled cRNA from the deletion mutant is hybridized together with the Cy3 (green) labeled cRNA from the common reference. For the replicate hybridization, the labels are swapped. Each gene is represented twice on the microarray, resulting in four measurements per mutant. Using the Erlenmeyer growth protocol up to five deletion strains were grown on a single day. In the tecan platereader, up to eleven deletion strains could be grown on a single day. Wt cultures were grown parallel to the deletion mutants to assess day-to-day variance.

Project description:To understand the organisation of the glucose regulatory system, we analysed 91 deletion mutants of established glucose signalling and metabolic pathway members in Saccharomyces cerevisiae by DNA microarrays. These deletion mutants do not induce pathway-specific transcriptional responses reflecting the tight interconnection between pathways of the glucose regulatory system. Instead, one main transcriptional response is discerned, which varies in direction to mimic either a high or a low glucose response. The study reveals both known and unknown relationships within and between individual pathways and their members. Metabolic components of the glucose regulatory system are most frequently affected at the transcriptional level. A new network approach is applied that exposes the hierarchical organisation of the glucose regulatory system. Tps2 and Tsl1, two enzymes involved in trehalose biosynthesis, are predicted to be the most downstream transcriptional components. This prediction is further validated by epistasis analysis of Tps2 double mutants. Taken together, this suggests that changes in perceived glucose levels ultimately lead to a shift in trehalose biosynthesis. RNA isolated from a large amount of wt yeast from a single culture was used as a common reference. This common reference was used for each separate hybridization and used in the statistical analysis to obtain an average expression-profile for each deletion mutant relative to the wt. Two independent cultures were hybridized on two separate microarrays. For the first hybridization the Cy5 (red) labeled cRNA from the deletion mutant is hybridized together with the Cy3 (green) labeled cRNA from the common reference. For the replicate hybridization, the labels are swapped. Each gene is represented twice on the microarray, resulting in four measurements per mutant. Up to five deletion strains were grown on a single day. Wt cultures were grown parallel to the deletion mutants to assess day-to-day variance.

Project description:Transcription termination in Saccharomyces cerevisiae can be performed by at least two distinct pathways and is directed by the phosphorylation status of the carboxy-terminal domain (CTD) of RNA polymerase II (Pol II). Late termination of mRNAs is performed by the CPF/CF complex and requires CTD-Ser2 phosphorylation. Early termination of shorter cryptic unstable transcripts (CUTs) and small nucleolar RNAs (snoRNAs) is preformed by the Nrd1 complex, and requires CTD-Ser5 phosphorylation. In this study, mutants of the different termination pathways were compared by genome-wide expression analysis. Surprisingly, the expression changes observed upon loss of the CTD-Ser2 kinase Ctk1 are more similar to loss of a subunit of the Ser5P binding Nrd1-complex, than to loss of Ser2P binding factors. Tiling array analysis of ctk1Δ reveals readthrough at several hundred sites, including snoRNAs, as reported previously, but also many cryptic unstable transcripts, stable untranslated transcripts (SUTs) and other transcripts. Surprisingly, neither loss of CTK1 nor a Pol II CTD-Ser2 substitution mutant results in a global defect in termination of mRNAs, indicating that Ser2P is not essential for proper termination of most mRNAs. At snoRNA, Nrd1 location is shifted downstream in ctk1∆, indicating defective release rather than recruitment of Nrd1. Weakening the interaction between Nrd1 and Pol II rescues the readthrough in ctk1∆, likely by facilitating Nrd1 release. The termination defect is kinase activity dependent, but cannot be completely explained by loss of CTD-Ser2 phosphorylation , a major substrate of Ctk1, suggesting the involvement of an additional substrate. Mutant alleles of the elongation factor Spt5 rescue ctk1∆-dependent readthrough, indicating a role for Spt5 in this process, perhaps as a substrate of Ctk1. The results show that Ctk1 is more intimately involved in termination of small non-coding RNAs than was previously assumed and lead to a model in which Ctk1 influences Spt5 activity to achieve this. Two channel microarrays were used. RNA isolated from a large amount of wt yeast from a single culture was used as a common reference. This common reference was used in one of the channels for each hybridization and used in the statistical analysis to obtain an average expression-profile for each deletion mutant relative to the wt. Two independent cultures were hybridized on two separate microarrays. For the first hybridization the Cy5 (red) labeled cRNA from the deletion mutant is hybridized together with the Cy3 (green) labeled cRNA from the common reference. For the replicate hybridization, the labels are swapped. Each gene is represented twice on the microarray, resulting in four measurements per mutant. Using the Erlenmeyer growth protocol up to five deletion strains were grown on a single day. In the tecan platereader, up to eleven deletion strains could be grown on a single day. Wt cultures were grown parallel to the deletion mutants to assess day-to-day variance.

Project description:The Saccharomyces cerevisiae Slx5/8 complex is the founding member of a recently defined class of ubiquitin ligases (STUbLs) that target sumoylated substrates. Slx5/8 has been implicated in genome stability and transcription, but the precise contribution to these processes is not clear. To characterize Slx5/8 function, we determined genome-wide changes in gene expression upon loss of either subunit. The majority of mRNA changes are part of a general stress response, also exhibited by mutants of other genome integrity pathways and therefore indicative of an indirect effect on transcription. Genome-wide binding analysis reveals a uniquely centromeric location for Slx5. Detailed phenotype analyses of slx5D and slx8D mutants show severe mitotic defects that include aneuploidy, spindle mispositioning, fish hook spindles and aberrant spindle kinetics. This is associated with accumulation of the PP2A regulatory subunit Rts1 at centromeres prior to entry into anaphase. Knockdown of the human STUbL orthologue RNF4 also results in chromosome segregation defects due to formation of chromosome bridges. The study shows that STUbLs have a conserved role in maintenance of chromosomal stability and the results link SUMO-dependent ubiquitination to a centromere-specific function during mitosis. Two channel microarrays were used. RNA isolated from a large amount of wt yeast from a single culture was used as a common reference. This common reference was used in one of the channels for each hybridization and used in the statistical analysis to obtain an average expression-profile for each deletion mutant relative to the wt. Two independent cultures were hybridized on two separate microarrays. For the first hybridization the Cy5 (red) labeled cRNA from the deletion mutant is hybridized together with the Cy3 (green) labeled cRNA from the common reference. For the replicate hybridization, the labels are swapped. Each gene is represented twice on the microarray, resulting in four measurements per mutant. Using the Erlenmeyer growth protocol up to five deletion strains were grown on a single day. In the tecan platereader, up to eleven deletion strains could be grown on a single day. Wt cultures were grown parallel to the deletion mutants to assess day-to-day variance.

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Compendium of deletion mutant gene expression profiles

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