Real-Time Dynamics of RNA Polymerase II Clustering in Live Human Cells

Science ◽  
2013 ◽  
Vol 341 (6146) ◽  
pp. 664-667 ◽  
Author(s):  
Ibrahim I. Cisse ◽  
Ignacio Izeddin ◽  
Sebastien Z. Causse ◽  
Lydia Boudarene ◽  
Adrien Senecal ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Single Molecule ◽  
Eukaryotic Cells ◽  
Average Lifetime ◽  
Pol Ii ◽  
Time Dynamics ◽  
External Signals ◽  
Rate Limiting

Transcription is reported to be spatially compartmentalized in nuclear transcription factories with clusters of RNA polymerase II (Pol II). However, little is known about when these foci assemble or their relative stability. We developed a quantitative single-cell approach to characterize protein spatiotemporal organization, with single-molecule sensitivity in live eukaryotic cells. We observed that Pol II clusters form transiently, with an average lifetime of 5.1 (± 0.4) seconds, which refutes the notion that they are statically assembled substructures. Stimuli affecting transcription yielded orders-of-magnitude changes in the dynamics of Pol II clusters, which implies that clustering is regulated and plays a role in the cell’s ability to effect rapid response to external signals. Our results suggest that transient crowding of enzymes may aid in rate-limiting steps of gene regulation.

scholarly journals Live-cell single particle imaging reveals the role of RNA polymerase II in histone H2A.Z eviction

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Anand Ranjan ◽  
Vu Q Nguyen ◽  
Sheng Liu ◽  
Jan Wisniewski ◽  
Jee Min Kim ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Single Molecule ◽  
Transcription Initiation ◽  
General Mechanism ◽  
Pol Ii ◽  
Promoter Escape ◽  
Genome Wide ◽  
A Genome ◽  
Particle Imaging

The H2A.Z histone variant, a genome-wide hallmark of permissive chromatin, is enriched near transcription start sites in all eukaryotes. H2A.Z is deposited by the SWR1 chromatin remodeler and evicted by unclear mechanisms. We tracked H2A.Z in living yeast at single-molecule resolution, and found that H2A.Z eviction is dependent on RNA Polymerase II (Pol II) and the Kin28/Cdk7 kinase, which phosphorylates Serine 5 of heptapeptide repeats on the carboxy-terminal domain of the largest Pol II subunit Rpb1. These findings link H2A.Z eviction to transcription initiation, promoter escape and early elongation activities of Pol II. Because passage of Pol II through +1 nucleosomes genome-wide would obligate H2A.Z turnover, we propose that global transcription at yeast promoters is responsible for eviction of H2A.Z. Such usage of yeast Pol II suggests a general mechanism coupling eukaryotic transcription to erasure of the H2A.Z epigenetic signal.

scholarly journals Single molecule studies reveal branched pathways for activator-dependent pre-initiation complex assembly

2021 ◽  
Author(s):  
Inwha Baek ◽  
Larry J. Friedman ◽  
Jeff Gelles ◽  
Stephen Buratowski
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Single Molecule ◽  
Tata Box ◽  
Initiation Complex ◽  
Kinetic Measurements ◽  
Pol Ii ◽  
Nuclear Extracts ◽  
Nucleotide Triphosphates ◽  
Single Molecule Studies

RNA polymerase II (Pol II) transcription reconstituted from purified factors suggests pre-initiation complexes (PICs) can assemble by sequential incorporation of factors at the TATA box. However, these basal transcription reactions are generally independent of activators and co-activators. To study PIC assembly under more realistic conditions, we used single-molecule microscopy to visualize factor dynamics during activator-dependent reactions in nuclear extracts. Surprisingly, Pol II, TFIIF, and TFIIE can pre-assemble on enhancer-bound activators before loading into PICs, and multiple Pol II complexes can bind simultaneously to create a localized cluster. Unlike TFIIF and TFIIE, TFIIH binding is singular and dependent on the basal promoter. Activator-tethered factors exhibit dwell times on the order of seconds. In contrast, PICs can persist on the order of minutes in the absence of nucleotide triphosphates, although TFIIE remains unexpectedly dynamic even after TFIIH incorporation. Our kinetic measurements lead to a new branched model for activator-dependent PIC assembly.

scholarly journals Complete dissection of transcription elongation reveals slow translocation of RNA polymerase II in a linear ratchet mechanism

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Manchuta Dangkulwanich ◽  
Toyotaka Ishibashi ◽  
Shixin Liu ◽  
Maria L Kireeva ◽  
Lucyna Lubkowska ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Single Molecule ◽  
Transcription Elongation ◽  
Energy Landscape ◽  
Ratchet Mechanism ◽  
Elongation Cycle ◽  
Nucleotide Addition ◽  
Single Molecule Studies ◽  
Rate Limiting

During transcription elongation, RNA polymerase has been assumed to attain equilibrium between pre- and post-translocated states rapidly relative to the subsequent catalysis. Under this assumption, recent single-molecule studies proposed a branched Brownian ratchet mechanism that necessitates a putative secondary nucleotide binding site on the enzyme. By challenging individual yeast RNA polymerase II with a nucleosomal barrier, we separately measured the forward and reverse translocation rates. Surprisingly, we found that the forward translocation rate is comparable to the catalysis rate. This finding reveals a linear, non-branched ratchet mechanism for the nucleotide addition cycle in which translocation is one of the rate-limiting steps. We further determined all the major on- and off-pathway kinetic parameters in the elongation cycle. The resulting translocation energy landscape shows that the off-pathway states are favored thermodynamically but not kinetically over the on-pathway states, conferring the enzyme its propensity to pause and furnishing the physical basis for transcriptional regulation.

scholarly journals PTEN modulates gene transcription by redistributing genome-wide RNA polymerase II occupancy

2019 ◽  
Vol 28 (17) ◽  
pp. 2826-2834 ◽  
Author(s):  
Ata Abbas ◽  
Roshan Padmanabhan ◽  
Todd Romigh ◽  
Charis Eng
Keyword(s):  
Gene Regulation ◽  
Transcriptional Regulation ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Elongation Factor ◽  
Control Of Gene Expression ◽  
Pol Ii ◽  
Genome Wide ◽  
Pol Ii Pausing

Abstract Control of gene expression is one of the most complex yet continuous physiological processes impacting cellular homeostasis. RNA polymerase II (Pol II) transcription is tightly regulated at promoter-proximal regions by intricate dynamic processes including Pol II pausing, release into elongation and premature termination. Pol II pausing is a phenomenon where Pol II complex pauses within 30–60 nucleotides after initiating the transcription. Negative elongation factor (NELF) and DRB sensitivity inducing factor (DSIF) contribute in the establishment of Pol II pausing, and positive transcription elongation factor b releases (P-TEFb) paused complex after phosphorylating DSIF that leads to dissociation of NELF. Pol II pausing is observed in most expressed genes across the metazoan. The precise role of Pol II pausing is not well understood; however, it’s required for integration of signals for gene regulation. In the present study, we investigated the role of phosphatase and tensin homolog (PTEN) in genome-wide transcriptional regulation using PTEN overexpression and PTEN knock-down models. Here we identify that PTEN alters the expression of hundreds of genes, and its restoration establishes genome-wide Pol II promoter-proximal pausing in PTEN null cells. Furthermore, PTEN re-distributes Pol II occupancy across the genome and possibly impacts Pol II pause duration, release and elongation rate in order to enable precise gene regulation at the genome-wide scale. Our observations demonstrate an imperative role of PTEN in global transcriptional regulation that will provide a new direction to understand PTEN-associated pathologies and its management.

scholarly journals High-resolution and High-accuracy Topographic and Transcriptional Maps of the Nucleosome Barrier

2019 ◽  
Author(s):  
Zhijie Chen ◽  
Ronen Gabizon ◽  
Aidan I. Brown ◽  
Antony Lee ◽  
Aixin Song ◽  
...  
Keyword(s):  
High Resolution ◽  
Rna Polymerase Ii ◽  
Single Molecule ◽  
High Accuracy ◽  
List Type ◽  
Control Of Gene Expression ◽  
Pol Ii ◽  
Time Dynamics ◽  
Crossing Time ◽  
Transcriptional Landscape

AbstractNucleosomes represent mechanical and energetic barriers that RNA Polymerase II (Pol II) must overcome during transcription. A high-resolution description of the barrier topography, its modulation by epigenetic modifications, and their effects on Pol II nucleosome crossing dynamics, is still missing. Here, we obtain topographic and transcriptional (Pol II residence time) maps of canonical, H2A.Z, and monoubiquitinated H2B (uH2B) nucleosomes at near base-pair resolution and accuracy. Pol II crossing dynamics are complex, displaying pauses at specific loci, backtracking, and nucleosome hopping between wrapped states. While H2A.Z widens the barrier, uH2B heightens it, and both modifications greatly lengthen Pol II crossing time. Using the dwell times of Pol II at each nucleosomal position we extract the energetics of the barrier. The orthogonal barrier modifications of H2A.Z and uH2B, and their effects on Pol II dynamics rationalize their observed enrichment in +1 nucleosomes and suggest a mechanism for selective control of gene expression.HighlightsA single-molecule unzipping assay mimics DNA unwinding by Pol II and maps the topography of human canonical, H2A.Z and uH2B nucleosome barriers at high resolutionReal-time dynamics and full molecular trajectories of Pol II crossing the nucleosomal barrier reveal the transcriptional landscape of the barrier at high accuracyH2A.Z enhances the width and uH2B the height of the barrierA unified mechanical model links position-dependent dwell times of Pol II on the nucleosome with energetics of the barrier

scholarly journals Nucleosomal arrangement affects single-molecule transcription dynamics

2016 ◽  
Vol 113 (45) ◽  
pp. 12733-12738 ◽  
Author(s):  
Veronika Fitz ◽  
Jaeoh Shin ◽  
Christoph Ehrlich ◽  
Lucas Farnung ◽  
Patrick Cramer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Optical Tweezers ◽  
Single Molecule ◽  
Pol Ii ◽  
Dna Molecule ◽  
Chromatin Arrangement ◽  
Dna Template ◽  
Drift Coefficient

In eukaryotes, gene expression depends on chromatin organization. However, how chromatin affects the transcription dynamics of individual RNA polymerases has remained elusive. Here, we use dual trap optical tweezers to study single yeast RNA polymerase II (Pol II) molecules transcribing along a DNA template with two nucleosomes. The slowdown and the changes in pausing behavior within the nucleosomal region allow us to determine a drift coefficient, χ, which characterizes the ability of the enzyme to recover from a nucleosomal backtrack. Notably, χ can be used to predict the probability to pass the first nucleosome. Importantly, the presence of a second nucleosome changes χ in a manner that depends on the spacing between the two nucleosomes, as well as on their rotational arrangement on the helical DNA molecule. Our results indicate that the ability of Pol II to pass the first nucleosome is increased when the next nucleosome is turned away from the first one to face the opposite side of the DNA template. These findings help to rationalize how chromatin arrangement affects Pol II transcription dynamics.

scholarly journals Live-cell single particle imaging reveals the role of RNA polymerase II in histone H2A.Z eviction

2020 ◽  
Author(s):  
Anand Ranjan ◽  
Vu Q. Nguyen ◽  
Sheng Liu ◽  
Jan Wisniewski ◽  
Jee Min Kim ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Single Molecule ◽  
Transcription Initiation ◽  
General Mechanism ◽  
Pol Ii ◽  
Promoter Escape ◽  
Genome Wide ◽  
A Genome ◽  
Particle Imaging

AbstractThe H2A.Z histone variant, a genome-wide hallmark of permissive chromatin, is enriched near transcription start sites in all eukaryotes. H2A.Z is deposited by the SWR1 chromatin remodeler and evicted by unclear mechanisms. We tracked H2A.Z in living yeast at single-molecule resolution, and found that H2A.Z eviction is dependent on RNA Polymerase II (Pol II) and the Kin28/Cdk7 kinase, which phosphorylates Serine 5 of heptapeptide repeats on the carboxy-terminal domain of the largest Pol II subunit Rpb1. These findings link H2A.Z eviction to transcription initiation, promoter escape and early elongation activities of Pol II. Because passage of Pol II through +1 nucleosomes genome-wide would obligate H2A.Z turnover, we propose that global transcription of noncoding RNAs prior to premature termination, in addition to transcription of mRNAs, are responsible for eviction of H2A.Z. Such usage of yeast Pol II suggests a general mechanism coupling eukaryotic transcription to erasure of the H2A.Z epigenetic signal.

scholarly journals Structure of the p53/RNA polymerase II assembly

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Shu-Hao Liou ◽  
Sameer K. Singh ◽  
Robert H. Singer ◽  
Robert A. Coleman ◽  
Wei-Li Liu
Keyword(s):  
Dna Binding ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Conformational Changes ◽  
P53 Protein ◽  
Binding Activity ◽  
Transactivation Domain ◽  
Pol Ii ◽  
Dna Binding Activity ◽  
Regulated Gene Expression

AbstractThe tumor suppressor p53 protein activates expression of a vast gene network in response to stress stimuli for cellular integrity. The molecular mechanism underlying how p53 targets RNA polymerase II (Pol II) to regulate transcription remains unclear. To elucidate the p53/Pol II interaction, we have determined a 4.6 Å resolution structure of the human p53/Pol II assembly via single particle cryo-electron microscopy. Our structure reveals that p53’s DNA binding domain targets the upstream DNA binding site within Pol II. This association introduces conformational changes of the Pol II clamp into a further-closed state. A cavity was identified between p53 and Pol II that could possibly host DNA. The transactivation domain of p53 binds the surface of Pol II’s jaw that contacts downstream DNA. These findings suggest that p53’s functional domains directly regulate DNA binding activity of Pol II to mediate transcription, thereby providing insights into p53-regulated gene expression.

scholarly journals RecQL5 Promotes Genome Stabilization through Two Parallel Mechanisms—Interacting with RNA Polymerase II and Acting as a Helicase

2010 ◽  
Vol 30 (10) ◽  
pp. 2460-2472 ◽  
Author(s):  
M. Nurul Islam ◽  
David Fox ◽  
Rong Guo ◽  
Takemi Enomoto ◽  
Weidong Wang
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Genome Stability ◽  
Transcriptional Regulators ◽  
Helicase Activity ◽  
Parallel Mechanisms ◽  
Recq Helicase ◽  
Pol Ii ◽  
Kix Domain ◽  
Genome Stabilization

ABSTRACT The RecQL5 helicase is essential for maintaining genome stability and reducing cancer risk. To elucidate its mechanism of action, we purified a RecQL5-associated complex and identified its major component as RNA polymerase II (Pol II). Bioinformatics and structural modeling-guided mutagenesis revealed two conserved regions in RecQL5 as KIX and SRI domains, already known in transcriptional regulators for Pol II. The RecQL5-KIX domain binds both initiation (Pol IIa) and elongation (Pol IIo) forms of the polymerase, whereas the RecQL5-SRI domain interacts only with the elongation form. Fully functional RecQL5 requires both helicase activity and associations with the initiation polymerase, because mutants lacking either activity are partially defective in the suppression of sister chromatid exchange and resistance to camptothecin-induced DNA damage, and mutants lacking both activities are completely defective. We propose that RecQL5 promotes genome stabilization through two parallel mechanisms: by participation in homologous recombination-dependent DNA repair as a RecQ helicase and by regulating the initiation of Pol II to reduce transcription-associated replication impairment and recombination.

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