scholarly journals Nucleosomal DNA dynamics mediate Oct4 pioneer factor binding

2019 ◽  
Author(s):  
Jan Huertas ◽  
Caitlin M. MacCarthy ◽  
Hans Schöler ◽  
Vlad Cojocaru
Keyword(s):  
Binding Sites ◽  
Dna Curvature ◽  
Dna Dynamics ◽  
Regulate Gene Expression ◽  
Nucleosomal Dna ◽  
Dna Binding Sites ◽  
Protein Dna Interactions ◽  
Stem Cell Pluripotency ◽  
Pioneer Factor ◽  
Chromatin Opening

AbstractTranscription factor (TF) proteins bind to DNA to regulate gene expression. Normally, accessibility to DNA is required for their function. However, in the nucleus the DNA is often inaccessible, wrapped around histone proteins in nucleosomes forming the chromatin. Pioneer TFs are thought to induce chromatin opening by recognizing their DNA binding sites on nucleosomes. For example, Oct4, a master regulator and inducer of stem cell pluripotency, binds to DNA in nucleosomes in a sequence specific manner. Here we reveal the structural dynamics of nucleosomes that mediate Oct4 binding. Nucleosome mobility and the amplitude of nucleosome motions such as breathing and twisting correlate with the number of Oct4 binding sites available. Moreover, the regions around the binding sites display higher local mobility. Probing different structures of Oct4-nucleosome complexes, we show that alternative configurations display stable protein-DNA interactions and are compatible with the DNA curvature and DNA-histone interactions.

scholarly journals Pre-marked chromatin and transcription factor co-binding shape the pioneering activity of Foxa2

2019 ◽  
Vol 47 (17) ◽  
pp. 9069-9086 ◽  
Author(s):  
Filippo M Cernilogar ◽  
Stefan Hasenöder ◽  
Zeyang Wang ◽  
Katharina Scheibner ◽  
Ingo Burtscher ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Binding Sites ◽  
Specific Binding ◽  
Embryonic Stem ◽  
Chromatin Accessibility ◽  
Specific Binding Sites ◽  
Nucleosomal Dna ◽  
Cell Type Specific ◽  
Chromatin Opening ◽  
Selection Of

Abstract Pioneer transcription factors (PTF) can recognize their binding sites on nucleosomal DNA and trigger chromatin opening for recruitment of other non-pioneer transcription factors. However, critical properties of PTFs are still poorly understood, such as how these transcription factors selectively recognize cell type-specific binding sites and under which conditions they can initiate chromatin remodelling. Here we show that early endoderm binding sites of the paradigm PTF Foxa2 are epigenetically primed by low levels of active chromatin modifications in embryonic stem cells (ESC). Priming of these binding sites is supported by preferential recruitment of Foxa2 to endoderm binding sites compared to lineage-inappropriate binding sites, when ectopically expressed in ESCs. We further show that binding of Foxa2 is required for chromatin opening during endoderm differentiation. However, increased chromatin accessibility was only detected on binding sites which are synergistically bound with other endoderm transcription factors. Thus, our data suggest that binding site selection of PTFs is directed by the chromatin environment and that chromatin opening requires collaboration of PTFs with additional transcription factors.

scholarly journals Pre-marked chromatin and transcription factor co-binding shape the pioneering activity of Foxa2

2019 ◽  
Author(s):  
Filippo M. Cernilogar ◽  
Stefan Hasenöder ◽  
Zeyang Wang ◽  
Katharina Scheibner ◽  
Ingo Burtscher ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Binding Sites ◽  
Specific Binding ◽  
Embryonic Stem ◽  
Chromatin Accessibility ◽  
Specific Binding Sites ◽  
Nucleosomal Dna ◽  
Cell Type Specific ◽  
Chromatin Opening ◽  
Selection Of

AbstractPioneer transcription factors (PTF) can recognize their binding sites on nucleosomal DNA and trigger chromatin opening for recruitment of other non-pioneer transcription factors. However, critical properties of PTFs are still poorly understood, such as how these transcription factors selectively recognize cell type-specific binding sites and under which conditions can they can initiate chromatin remodelling. Here we show that early endoderm binding sites of the paradigm PTF Foxa2 are epigenetically primed by low levels of active chromatin modifications in embryonic stem cells (ESC). Priming of these binding sites is supported by preferential recruitment of Foxa2 to endoderm binding sites compared to lineage-inappropriate binding sites, when ectopically expressed in ESCs. We further show that binding of Foxa2 is required for chromatin opening during endoderm differentiation. However, increased chromatin accessibility was only detected on binding sites which are synergistically bound with other endoderm transcription factors. Thus, our data suggest that binding site selection of PTFs is directed by the chromatin environment and that chromatin opening requires collaboration of PTFs with additional transcription factors.

scholarly journals Nucleosomal DNA Dynamics Mediate Oct4 Pioneer Factor Binding

2020 ◽  
Vol 118 (9) ◽  
pp. 2280-2296 ◽  
Author(s):  
Jan Huertas ◽  
Caitlin M. MacCarthy ◽  
Hans R. Schöler ◽  
Vlad Cojocaru
Keyword(s):  
Dna Dynamics ◽  
Factor Binding ◽  
Nucleosomal Dna ◽  
Pioneer Factor

scholarly journals Pax7 pioneer factor action requires both paired and homeo DNA binding domains

2020 ◽  
Author(s):  
Audrey Pelletier ◽  
Alexandre Mayran ◽  
Arthur Gouhier ◽  
James G Omichinski ◽  
Aurelio Balsalobre ◽  
...  
Keyword(s):  
Dna Binding ◽  
Binding Site ◽  
Dna Sequence ◽  
Binding Sites ◽  
Paired Domain ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Target Sites ◽  
Pioneer Factor ◽  
Chromatin Opening

AbstractThe pioneer transcription factor Pax7 contains two DNA binding domains (DBD), a paired and a homeo domain. Previous work on Pax7 and the related Pax3 had shown that each DBD can bind a cognate DNA sequence, thus defining two targets of binding and possibly modalities of action. Genomic targets of Pax7 pioneer action leading to chromatin opening are enriched for composite DNA target sites containing juxtaposed binding sites for both paired and homeo domains. The present work investigated the implication of both DBDs in pioneer action. We now show that the composite sequence is a higher affinity Pax7 binding site compared to either paired or homeo binding sites and that efficient binding to this site involves both DBDs. We also show that a Pax7 monomer binds composite sites and that methylation of cytosines within the binding site does not affect binding, which is consistent with pioneer action exerted at methylated DNA sites within nucleosomal heterochromatin. Finally, introduction of single amino acid mutations in either the paired or homeo domain that impair binding to cognate DNA sequences showed that both DBDs must be intact for pioneer action. In contrast, only the paired domain is required for low affinity binding of heterochromatin sites. Thus, Pax7 pioneer action on heterochromatin requires unique protein:DNA interactions that are more complex compared to its simpler DNA binding modalities at accessible enhancer target sites.Significance StatementPioneer transcription factors have the unique ability to recognize DNA target sites within closed heterochromatin and to trigger chromatin opening. Only a fraction of the heterochromatin recruitment sites of pioneers are subject to chromatin opening. The molecular basis for this selectivity is unknown and the present work addressed the importance of DNA sequence affinity for selection of sites to open. The pioneering ability of the pioneer factor Pax7 is not strictly determined by affinity or DNA sequence of binding sites, nor by number or methylation status of DNA sites. Mutation analyses showed that recruitment to heterochromatin is primarily dependent on the Pax7 paired domain whereas the ability to open chromatin requires both paired and homeo DNA binding domains.

scholarly journals High throughput screening identifies SOX2 as a Super Pioneer Factor that inhibits DNA methylation maintenance at its binding sites

2020 ◽  
Author(s):  
Ludovica Vanzan ◽  
Hadrien Soldati ◽  
Victor Ythier ◽  
Santosh Anand ◽  
Nicole Francis ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Transcription Factors ◽  
Binding Sites ◽  
High Throughput Screening ◽  
Dna Demethylation ◽  
Active Dna Demethylation ◽  
Nucleosomal Dna ◽  
Select Group ◽  
Pioneer Factor ◽  
Set Up

AbstractAccess of mammalian transcription factors (TFs) to regulatory regions, an essential event for transcription regulation, is hindered by chromatin compaction involving nucleosome wrapping, repressive histone modifications and DNA methylation. Moreover, methylation of TF binding sites (TBSs) affects TF binding affinity to these sites. Remarkably, a special class of TFs called pioneer transcription factors (PFs) can access nucleosomal DNA, leading to nucleosome remodelling and chromatin opening. However, whether PFs can bind to methylated sites and induce DNA demethylation is largely unknown.Here, we set up a highly parallelized approach to investigate PF ability to bind methylated DNA and induce demethylation. Our results indicate that the interdependence between DNA methylation and TF binding is more complex than previously thought, even within a select group of TFs that have a strong pioneering activity; while most PFs do not induce changes in DNA methylation at their binding sites, we identified PFs that can protect DNA from methylation and PFs that can induce DNA demethylation at methylated binding sites. We called the latter “super pioneer transcription factors” (SPFs), as they are seemingly able to overcome several types of repressive epigenetic marks. Importantly, while most SPFs induce TET-dependent active DNA demethylation, SOX2 binding leads to passive demethylation by inhibition of the maintenance methyltransferase DNMT1 during replication. This important finding suggests a novel mechanism allowing TFs to interfere with the epigenetic memory during DNA replication.

scholarly journals Analysis of two distinct single-stranded DNA binding sites on the recA nucleoprotein filament.

1993 ◽  
Vol 268 (30) ◽  
pp. 22525-22530
Author(s):  
A Zlotnick ◽  
R.S. Mitchell ◽  
R.K. Steed ◽  
S.L. Brenner
Keyword(s):  
Dna Binding ◽  
Binding Sites ◽  
Single Stranded Dna ◽  
Dna Binding Sites
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