scholarly journals Uncovering divergence in gene expression regulation in the adaptation of yeast to nitrogen scarcity

2021 ◽  
Author(s):  
Carlos A. Villarroel ◽  
Paulo Canessa ◽  
Macarena Bastias ◽  
Francisco A Cubillos

Saccharomyces cerevisiae rewires its transcriptional output to survive stressful environments, such as nitrogen scarcity under fermentative conditions. Although divergence in nitrogen metabolism has been described among natural yeast populations, the impact of regulatory genetic variants modulating gene expression and nitrogen consumption remains to be investigated. Here, we employed an F1 hybrid from two contrasting S. cerevisiae strains, providing a controlled genetic environment to map cis factors involved in the divergence of gene expression regulation in response to nitrogen scarcity. We used a dual approach to obtain genome-wide allele-specific profiles of chromatin accessibility, transcription factor binding, and gene expression through ATAC-seq and RNA-seq. We observed large variability in allele-specific expression and accessibility between the two genetic backgrounds, with a third of these differences specific to a deficient nitrogen environment. Furthermore, we discovered events of allelic bias in gene expression correlating with allelic bias in transcription factor binding solely under nitrogen scarcity, where the majority of these transcription factors orchestrates the Nitrogen Catabolite Repression regulatory pathway and demonstrates a cis x environment-specific response. Our approach allowed us to find cis variants modulating gene expression, chromatin accessibility and allelic differences in transcription factor binding in response to low nitrogen culture conditions.

2016 ◽  
Vol 135 (5) ◽  
pp. 485-497 ◽  
Author(s):  
Marco Cavalli ◽  
Gang Pan ◽  
Helena Nord ◽  
Ola Wallerman ◽  
Emelie Wallén Arzt ◽  
...  

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Lianggang Huang ◽  
Xuejie Li ◽  
Liangbo Dong ◽  
Bin Wang ◽  
Li Pan

Abstract Background The identification of open chromatin regions and transcription factor binding sites (TFBs) is an important step in understanding the regulation of gene expression in diverse species. ATAC-seq is a technique used for such purpose by providing high-resolution measurements of chromatin accessibility revealed through integration of Tn5 transposase. However, the existence of cell walls in filamentous fungi and associated difficulty in purifying nuclei have precluded the routine application of this technique, leading to a lack of experimentally determined and computationally inferred data on the identity of genome-wide cis-regulatory elements (CREs) and TFBs. In this study, we constructed an ATAC-seq platform suitable for filamentous fungi and generated ATAC-seq libraries of Aspergillus niger and Aspergillus oryzae grown under a variety of conditions. Results We applied the ATAC-seq assay for filamentous fungi to delineate the syntenic orthologue and differentially changed chromatin accessibility regions among different Aspergillus species, during different culture conditions, and among specific TF-deleted strains. The syntenic orthologues of accessible regions were responsible for the conservative functions across Aspergillus species, while regions differentially changed between culture conditions and TFs mutants drove differential gene expression programs. Importantly, we suggest criteria to determine TFBs through the analysis of unbalanced cleavage of distinct TF-bound DNA strands by Tn5 transposase. Based on this criterion, we constructed data libraries of the in vivo genomic footprint of A. niger under distinct conditions, and generated a database of novel transcription factor binding motifs through comparison of footprints in TF-deleted strains. Furthermore, we validated the novel TFBs in vivo through an artificial synthetic minimal promoter system. Conclusions We characterized the chromatin accessibility regions of filamentous fungi species, and identified a complete TFBs map by ATAC-seq, which provides valuable data for future analyses of transcriptional regulation in filamentous fungi.


2018 ◽  
Author(s):  
Daniel W. Hagey ◽  
Susanne Klum ◽  
Cecile Zaouter ◽  
Jonas Muhr

AbstractTissue specific gene expression underpins cell type diversity, and arises from the cooperative activities of transcription factors and the chromatin landscape. It has been previously demonstrated that enhancers with specific arrangements of transcription factor binding motifs can bring together commonly and specifically expressed factors in order to stabilize chromatin accessibility and drive spatially restricted reporter expression within different regions of the CNS. However, when reporters were used to analyse the activity of enhancers bound differentially by a common factor in the endoderm and CNS, several examples of non-tissue specific reporter expression were observed. In order to judge whether or not this may have been due to the unregulated chromatin environment of exogenously delivered enhancer reporters, here we have analysed the chromatin landscape of cells from the CNS and endodermal tissues and find that this reflects neighbouring gene expression to a greater degree than transcription factor binding. This work demonstrates that chromatin accessibility plays an essential role in defining enhancer activity in distantly related cell types.


2019 ◽  
Author(s):  
Lianggang Huang ◽  
Xuejie Li ◽  
Liangbo Dong ◽  
Bin Wang ◽  
Li Pan

AbstractTo identify cis-regulatory elements (CREs) and motifs of TF binding is an important step in understanding the regulatory functions of TF binding and gene expression. The lack of experimentally determined and computationally inferred data means that the genome-wide CREs and TF binding sites (TFBs) in filamentous fungi remain unknown. ATAC-seq is a technique that provides a high-resolution measurement of chromatin accessibility to Tn5 transposase integration. In filamentous fungi, the existence of cell walls and the difficulty in purifying nuclei have prevented the routine application of this technique. Herein, we modified the ATAC-seq protocol in filamentous fungi to identify and map open chromatin and TF-binding sites on a genome-scale. We applied the assay for ATAC-seq among different Aspergillus species, during different culture conditions, and among TF-deficient strains to delineate open chromatin regions and TFBs across each genome. The syntenic orthologues regions and differential changes regions of chromatin accessibility were responsible for functional conservative regulatory elements and differential gene expression in the Aspergillus genome respectively. Importantly, 17 and 15 novel transcription factor binding motifs that were enriched in the genomic footprints identified from ATAC-seq data of A. niger, were verified in vivo by our artificial synthetic minimal promoter system, respectively. Furthermore, we first confirmed the strand-specific patterns of Tn5 transposase around the binding sites of known TFs by comparing ATAC-seq data of TF-deficient strains with the data from a wild-type strain.


2015 ◽  
Vol 25 (11) ◽  
pp. 1715-1726 ◽  
Author(s):  
Katharine N. Schulz ◽  
Eliana R. Bondra ◽  
Arbel Moshe ◽  
Jacqueline E. Villalta ◽  
Jason D. Lieb ◽  
...  

2019 ◽  
Author(s):  
Martin Cusack ◽  
Hamish W. King ◽  
Paolo Spingardi ◽  
Benedikt M. Kessler ◽  
Robert J. Klose ◽  
...  

AbstractEpigenetic modifications on chromatin play important roles in regulating gene expression. While chromatin states are often governed by multi-layered structure, how individual pathways contribute to gene expression remains poorly understood. For example, DNA methylation is known to regulate transcription factor binding but also to recruit methyl-CpG binding proteins that affect chromatin structure through the activity of histone deacetylase complexes (HDACs). Both of these mechanisms can potentially affect gene expression, but the importance of each, and whether these activities are integrated to achieve appropriate gene regulation, remains largely unknown. To address this important question, we measured gene expression, chromatin accessibility, and transcription factor occupancy in wild-type or DNA methylation-deficient mouse embryonic stem cells following HDAC inhibition. Interestingly, we observe widespread increases in chromatin accessibility at repeat elements when HDACs are inhibited, and this is magnified when cells also lack DNA methylation. A subset of these elements have elevated binding of the YY1 and GABPA transcription factors and increased expression. The pronounced additive effect of HDAC inhibition in DNA methylation deficient cells demonstrate that DNA methylation and histone deacetylation act largely independently to suppress transcription factor binding and gene expression.


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