Genome-wide regulations of the pre-initiation complex formation and elongating RNA polymerase II by an E3 ubiquitin ligase, San1.

Author(s):  
Priyanka Barman ◽  
Rwik Sen ◽  
Amala Kaja ◽  
Jannatul Ferdoush ◽  
Shalini Guha ◽  
...  

San1 ubiquitin ligase is involved in nuclear protein quality control via its interaction with intrinsically disordered proteins for ubiquitylation and proteasomal degradation. Since several transcription/chromatin regulatory factors contain intrinsically disordered domains and can be inhibitory to transcription when in excess, San1 might be involved in transcription regulation. To address this, we analyzed the role of San1 in genome-wide association of TBP [that nucleates pre-initiation complex (PIC) formation for transcription initiation] and RNA polymerase II (Pol II). Our results reveal the roles of San1 in regulating TBP recruitment to the promoters and Pol II association with the coding sequences, and hence PIC formation and coordination of elongating Pol II, respectively. Consistently, transcription is altered in the absence of San1. Such transcriptional alteration is associated with impaired ubiquitylation and proteasomal degradation of Spt16 and gene association of Paf1, but not the incorporation of centromeric histone, Cse4, into the active genes in Δsan1 . Collectively, our results demonstrate distinct functions of a nuclear protein quality control factor in regulating the genome-wide PIC formation and elongating Pol II (and hence transcription), thus unraveling new gene regulatory mechanisms.

2018 ◽  
Author(s):  
David T McSwiggen ◽  
Anders S Hansen ◽  
Hervé Marie-Nelly ◽  
Sheila Teves ◽  
Alec B Heckert ◽  
...  

SummaryDuring lytic infection, Herpes Simplex Virus 1 generates replication compartments (RCs) in host nuclei that efficiently recruit protein factors, including host RNA Polymerase II (Pol II). Pol II and other cellular factors form hubs in uninfected cells that are proposed to phase separate via multivalent protein-protein interactions mediated by their intrinsically disordered regions. Using a battery of live cell microscopic techniques, we show that although RCs superficially exhibit many characteristics of phase separation, the recruitment of Pol II instead derives from nonspecific interactions with the viral DNA. We find that the viral genome remains nucleosome-free, profoundly affecting the way Pol II explores RCs by causing it to repetitively visit nearby binding sites, thereby creating local Pol II accumulations. This mechanism, distinct from phase separation, allows viral DNA to outcompete host DNA for cellular proteins. Our work provides new insights into the strategies used to create local molecular hubs in cells.


2007 ◽  
Vol 27 (5) ◽  
pp. 1631-1648 ◽  
Author(s):  
Igor Chernukhin ◽  
Shaharum Shamsuddin ◽  
Sung Yun Kang ◽  
Rosita Bergström ◽  
Yoo-Wook Kwon ◽  
...  

ABSTRACT CTCF is a transcription factor with highly versatile functions ranging from gene activation and repression to the regulation of insulator function and imprinting. Although many of these functions rely on CTCF-DNA interactions, it is an emerging realization that CTCF-dependent molecular processes involve CTCF interactions with other proteins. In this study, we report the association of a subpopulation of CTCF with the RNA polymerase II (Pol II) protein complex. We identified the largest subunit of Pol II (LS Pol II) as a protein significantly colocalizing with CTCF in the nucleus and specifically interacting with CTCF in vivo and in vitro. The role of CTCF as a link between DNA and LS Pol II has been reinforced by the observation that the association of LS Pol II with CTCF target sites in vivo depends on intact CTCF binding sequences. “Serial” chromatin immunoprecipitation (ChIP) analysis revealed that both CTCF and LS Pol II were present at the β-globin insulator in proliferating HD3 cells but not in differentiated globin synthesizing HD3 cells. Further, a single wild-type CTCF target site (N-Myc-CTCF), but not the mutant site deficient for CTCF binding, was sufficient to activate the transcription from the promoterless reporter gene in stably transfected cells. Finally, a ChIP-on-ChIP hybridization assay using microarrays of a library of CTCF target sites revealed that many intergenic CTCF target sequences interacted with both CTCF and LS Pol II. We discuss the possible implications of our observations with respect to plausible mechanisms of transcriptional regulation via a CTCF-mediated direct link of LS Pol II to the DNA.


eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Anand Ranjan ◽  
Vu Q Nguyen ◽  
Sheng Liu ◽  
Jan Wisniewski ◽  
Jee Min Kim ◽  
...  

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.


2021 ◽  
Author(s):  
Hamideh Hajiabadi ◽  
Irina Mamontova ◽  
Roshan Prizak ◽  
Agnieszka Pancholi ◽  
Anne Koziolek ◽  
...  

AbstractFluorescence microscopy, a central tool of biological research, is subject to inherent trade-offs in experiment design. For instance, image acquisition speed can only be increased in exchange for a lowered signal quality, or for an increased rate of photo-damage to the specimen. Computational denoising can recover some loss of signal, extending the trade-off margin for high-speed imaging. Recently proposed denoising on the basis of neural networks shows exceptional performance but raises concerns of errors typical of neural networks. Here, we present a work-flow that supports an empirically optimized reduction of exposure times, as well as per-image quality control to exclude images with reconstruction errors. We implement this work-flow on the basis of the denoising tool Noise2Void and assess the molecular state and three-dimensional shape of RNA Polymerase II (Pol II) clusters in live zebrafish embryos. Image acquisition speed could be tripled, achieving 2-second time resolution and 350-nanometer lateral image resolution. The obtained data reveal stereotyped events of approximately 10 seconds duration: initially, the molecular mark for initiated Pol II increases, then the mark for active Pol II increases, and finally Pol II clusters take on a stretched and unfolded shape. An independent analysis based on fixed sample images reproduces this sequence of events, and suggests that they are related to the transient association of genes with Pol II clusters. Our work-flow consists of procedures that can be implemented on commercial fluorescence microscopes without any hardware or software modification, and should therefore be transferable to many other applications.


2018 ◽  
Author(s):  
M. Boehning ◽  
C. Dugast-Darzacq ◽  
M. Rankovic ◽  
A. S. Hansen ◽  
T. Yu ◽  
...  

The carboxy-terminal domain (CTD) of RNA polymerase (Pol) II is an intrinsically disordered low-complexity region that is critical for pre-mRNA transcription and processing. The CTD consists of hepta-amino acid repeats varying in number from 52 in humans to 26 in yeast. Here we report that human and yeast CTDs undergo cooperative liquid phase separation at increasing protein concentration, with the shorter yeast CTD forming less stable droplets. In human cells, truncation of the CTD to the length of the yeast CTD decreases Pol II clustering and chromatin association whereas CTD extension has the opposite effect. CTD droplets can incorporate intact Pol II and are dissolved by CTD phosphorylation with the transcription initiation factor IIH kinase CDK7. Together with published data, our results suggest that Pol II forms clusters/hubs at active genes through interactions between CTDs and with activators, and that CTD phosphorylation liberates Pol II enzymes from hubs for promoter escape and transcription elongation.


Author(s):  
Søren Lykke-Andersen ◽  
Jérôme O. Rouvière ◽  
Torben Heick Jensen

ARS2/SRRT is an essential eukaryotic protein that has emerged as a critical factor in the sorting of functional from non-functional RNA polymerase II (Pol II) transcripts. Through its interaction with the Cap Binding Complex (CBC), it associates with the cap of newly made RNAs and acts as a hub for competitive exchanges of protein factors that ultimately determine the fate of the associated RNA. The central position of the protein within the nuclear gene expression machinery likely explains why its depletion causes a broad range of phenotypes, yet an exact function of the protein remains elusive. Here, we consider the literature on ARS2/SRRT with the attempt to garner the threads into a unifying working model for ARS2/SRRT function at the nexus of Pol II transcription, transcript maturation and quality control.


2007 ◽  
Vol 27 (8) ◽  
pp. 3211-3216 ◽  
Author(s):  
Balazs Ribar ◽  
Louise Prakash ◽  
Satya Prakash

ABSTRACT Treatment of yeast and human cells with DNA-damaging agents elicits lysine 48-linked polyubiquitylation of Rpb1, the largest subunit of RNA polymerase II (Pol II), which targets Pol II for proteasomal degradation. However, the ubiquitin ligase (E3) responsible for Pol II polyubiquitylation has not been identified in humans or the yeast Saccharomyces cerevisiae . Here we show that elongin A (Ela1) and cullin 3 (Cul3) are required for Pol II polyubiquitylation and degradation in yeast cells, and on the basis of these and other observations, we propose that an E3 comprised of elongin C (Elc1), Ela1, Cul3, and the RING finger protein Roc1 (Rbx1) mediates this process in yeast cells. This study provides, in addition to the identification of the E3 required for Pol II polyubiquitylation and degradation in yeast cells, the first evidence for a specific function in yeast for a member of the elongin C/BC-box protein/cullin family of ligases. Also, these observations raise the distinct possibility that the elongin C-containing ubiquitin ligase, the von Hippel-Lindau tumor suppressor complex, promotes Pol II polyubiquitylation and degradation in human cells.


2006 ◽  
Vol 26 (11) ◽  
pp. 3999-4005 ◽  
Author(s):  
Balazs Ribar ◽  
Louise Prakash ◽  
Satya Prakash

ABSTRACT Treatment of Saccharomyces cerevisiae and human cells with DNA-damaging agents such as UV light or 4-nitroquinoline-1-oxide induces polyubiquitylation of the largest RNA polymerase II (Pol II) subunit, Rpb1, which results in rapid Pol II degradation by the proteasome. Here we identify a novel role for the yeast Elc1 protein in mediating Pol II polyubiquitylation and degradation in DNA-damaged yeast cells and propose the involvement of a ubiquitin ligase, of which Elc1 is a component, in this process. In addition, we present genetic evidence for a possible involvement of Elc1 in Rad7-Rad16-dependent nucleotide excision repair (NER) of lesions from the nontranscribed regions of the genome and suggest a role for Elc1 in increasing the proficiency of repair of nontranscribed DNA, where as a component of the Rad7-Rad16-Elc1 ubiquitin ligase, it would promote the efficient turnover of the NER ensemble from the lesion site in a Rad23-19S proteasomal complex-dependent reaction.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Isaac Fianu ◽  
Christian Dienemann ◽  
Shintaro Aibara ◽  
Sandra Schilbach ◽  
Patrick Cramer

AbstractNuclear import of RNA polymerase II (Pol II) involves the conserved factor RPAP2. Here we report the cryo-electron microscopy (cryo-EM) structure of mammalian Pol II in complex with human RPAP2 at 2.8 Å resolution. The structure shows that RPAP2 binds between the jaw domains of the polymerase subunits RPB1 and RPB5. RPAP2 is incompatible with binding of downstream DNA during transcription and is displaced upon formation of a transcription pre-initiation complex.


2020 ◽  
Vol 48 (14) ◽  
pp. 7712-7727
Author(s):  
Michael Tellier ◽  
Justyna Zaborowska ◽  
Livia Caizzi ◽  
Eusra Mohammad ◽  
Taras Velychko ◽  
...  

Abstract Cyclin-dependent kinase 12 (CDK12) phosphorylates the carboxyl-terminal domain (CTD) of RNA polymerase II (pol II) but its roles in transcription beyond the expression of DNA damage response genes remain unclear. Here, we have used TT-seq and mNET-seq to monitor the direct effects of rapid CDK12 inhibition on transcription activity and CTD phosphorylation in human cells. CDK12 inhibition causes a genome-wide defect in transcription elongation and a global reduction of CTD Ser2 and Ser5 phosphorylation. The elongation defect is explained by the loss of the elongation factors LEO1 and CDC73, part of PAF1 complex, and SPT6 from the newly-elongating pol II. Our results indicate that CDK12 is a general activator of pol II transcription elongation and indicate that it targets both Ser2 and Ser5 residues of the pol II CTD.


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