Project description:Chromatin endogenous cleavage (ChEC) uses fusion of a protein of interest to micrococcal nuclease (MNase) to target calcium-dependent cleavage to specific genomic loci in vivo. Here we report the combination of ChEC with high-throughput sequencing (ChEC-seq) to determine genomic occupancy of the generalist transcription factor Nsi1 and the catalytic subunit of the SWI/SNF chromatin remodelling complex Snf2 in the opportunistic yeast Candida albicans. Time-based analysis of ChEC-seq data reveals two classes of sites for each transcriptional regulator, one exhibiting rapid cleavage during the first 5 min with robust consensus motifs and the second showing slow cleavage at largely unique sites with low-scoring motifs. The ChEC-seq procedure described here will allow a high-resolution genomic location definition which will enable a better understanding of transcriptional regulatory circuits that govern fungal fitness and drug resistance in these medically important fungi.
Project description:This data set contains ChEC-seq binding profiles of various TF in yeast strains deleted of other TFs. Each sample has a pair-end sequencing file and a processed file (.out) is a genomic signal track after alignment to S.cerevisiae (R64) reference genome. Mapping was done using the read end. This dataset also contains raw and processed MNase-seq data files for nucleosome occupancy. Data related to manuscript: The architecture of binding cooperativity between densely bound transcription factors.
Project description:Chromatin endogenous cleavage (ChEC) uses fusion of a protein of interest to micrococcal nuclease (MNase) to target calcium-dependent cleavage to specific genomic loci in vivo. Here we report the combination of ChEC with high-throughput sequencing (ChEC-seq) to map budding yeast transcription factor (TF) binding. Temporal analysis of ChEC-seq data reveals two classes of sites for TFs, one displaying rapid cleavage at sites with robust consensus motifs and the second showing slow cleavage at largely unique sites with low-scoring motifs. Sites with high-scoring motifs also display asymmetric cleavage, indicating that ChEC-seq provides information on the directionality of TF-DNA interactions. Strikingly, similar DNA shape patterns are observed regardless of motif strength, indicating that the kinetics of ChEC-seq discriminates DNA recognition through sequence and/or shape. We propose that time-resolved ChEC-seq detects both high-affinity interactions of TFs with consensus motifs and sites preferentially sampled by TFs during diffusion and sliding.
Project description:Here we show that the ChEC-Seq technique is able to differentiate the binding specificities of Esa1 and Gcn5 two chromatin-binding factors displaying widespread genome-wide associations. We also show that the ChEC-Seq technique reveals strong binding of the transcription factor Sfp1 at Ribi gene promoters. Furthermore, our data provide the first evidence that a specific DNA motif previously identified by ChEC-Seq (Albert 2019 PMID: 30804227) is in fact an in vivo binding site for Sfp1.
Project description:Compared to other model organisms and despite the clinical relevance of the pathogenic yeast Candida albicans, no comprehensive analysis has been done to provide experimental support of its in silico-based genome annotation. Here we have undertaken a genome-wide experimental annotation to accurately uncover the transcriptional landscape of the pathogenic yeast C. albicans using strand-specific high-density tiling arrays. RNAs were purified from cells growing under conditions relevant to C. albicans pathogenicity, including biofilm, lab-grown yeast and serum-induced hyphae as well as cells isolated from the mouse caecum. This work provides a genome-wide experimental validation for a large number of predicted ORFs for which transcription had not been detected by other approaches. Additionally, we identified more than 2000 novel transcriptional segments, including new ORFs and exons, non-coding RNAs (ncRNA) as well as convincing cases of antisense gene transcription. We also characterized the 5’- and 3’-untranslated regions (UTR) of expressed ORFs, and established that genes with long 5’UTRs are significantly enriched in regulatory functions controlling filamentous growth. Furthermore, we found that genomic regions adjacent to telomeres harbor a cluster of expressed ncRNAs. To validate and confirm new ncRNA candidates, we adapted an iterative strategy combining both genome-wide occupancy of the different subunits of RNA polymerases I, II and III, and expression data. This comprehensive approach allowed the identification of different families of ncRNA. In summary, we provide a comprehensive expression atlas that covers relevant C. albicans pathogenic developmental stages in addition to a discovery of new ORF and non-coding genetic elements. We have undertaken a genome-wide experimental annotation to accurately uncover the transcriptional landscape of the pathogenic yeast C. albicans using strand-specific high-density tiling arrays. RNAs were purified from cells growing under conditions relevant to Candida albicans pathogenicity, including biofilm, lab-grown yeast and serum-induced hyphae as well as cells isolated from the mouse caecum. We also adapted a strategy in which genome-wide occupancy of different subunits of RNA polymerases (RNAP) I, II and III, is combined with expression data to annotate ncRNAs resulting from real transcriptional events. For this purpose we have performed ChIP-chip of subunits that represent the three RNAP machines in C. albicans cells growing in rich media (YPD) at 30°C. In this study, we performed peak detection only for RNA Polymerase III (Rpc82p). All detected peaks and their genomic features are included as a supplementary file on the Sample record (GSM561024).
Project description:Candidiasis affects a wide variety of immunocompromised individuals, including HIV/AIDS patients and cancer patients on chemotherapy. Candida albicans, a major human fungal pathogen, accounts for about 50% of all cases, while the remainder are caused by the less pathogenic non-albicans Candida species (NACS). These species are believed to be less pathogenic, in part, because they do not filament as readily or robustly as C. albicans, although definitive evidence is lacking. To address this question, we used strains for two NACS, Candida tropicalis and Candida parapsilosis, that are genetically engineered to constitutively express the key transcriptional regulator UME6 and drive strong filamentation both in vitro and during infection in vivo. Unexpectedly, both strains showed a dramatic reduction in organ fungal burden and clearance of infection in response to UME6 expression. Consistent with these findings, we observed that a C. tropicalis hyperfilamentous mutant was significantly reduced and a filamentation-defective mutant was slightly increased for organ fungal burden. Comprehensive immune profiling did not reveal any significant changes in the host immune response to UME6 expression in the NACS. Interestingly, however, whole-genome transcriptional profiling indicated that while genes important for filamentation were induced by UME6 expression in C. tropicalis and C. parapsilosis, other genes involved in a variety of processes important for pathogenesis were strongly down-regulated. Our findings are significant because they suggest fundamental evolutionary differences in the relationship between morphology and pathogenicity among Candida species and that NACS do not necessarily possess the same virulence properties as C. albicans.
Project description:Candidiasis is an infection caused by yeasts of the genus Candida that ranges in severity from debilitating mucosal infections to disseminated disease with high mortality rates. C. albicans is the most common cause of infection, but non-albicans species collectively represent a significant disease burden. Disseminated disease rarely affects immunocompetent individuals, largely due to the action of innate immune cells, including macrophages, in controlling infection. The interaction of C. albicans with macrophages has been subject to extensive study, but there has been little investigation of the macrophage response to non-albicans Candida species. Here, we used RNA-seq to investigate global transcriptional changes within primary murine macrophages after one hour in response to four species: C. albicans, C. parapsilosis, C. tropicalis and Clavispora lusitaniae. We identified a strong pro-inflammatory response to C. albicans that was largely independent of fungal variability and found that this was highly correlated with the response to C. parapsilosis and C. tropicalis. In contrast, C. lusitaniae elicited a broadly weaker response, including reduced induction of cytokine genes. Several chemokine genes also showed weaker induction in response to both C. lusitaniae and C. parapsilosis than to C. albicans, although significantly reduced secretion of CCL3 protein was only evident in response to C. lusitaniae. These data indicate a high degree of similarity in early macrophage recognition of multiple important Candida pathogens, but also suggest that weaker recognition of C. lusitaniae by immune cells may aid immune evasion by this species.