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BBA - Gene Regulatory Mechanisms (v.1829, #1)
RNA polymerase II transcription: Structure and mechanism by Xin Liu; David A. Bushnell; Roger D. Kornberg (pp. 2-8).
A minimal RNA polymerase II (pol II) transcription system comprises the polymerase and five general transcription factors (GTFs) TFIIB, -D, -E, -F, and -H. The addition of Mediator enables a response to regulatory factors. The GTFs are required for promoter recognition and the initiation of transcription. Following initiation, pol II alone is capable of RNA transcript elongation and of proofreading. Structural studies reviewed here reveal roles of GTFs in the initiation process and shed light on the transcription elongation mechanism. This article is part of a Special Issue entitled: RNA Polymerase II Transcript Elongation.► TFIIB positions promoter DNA above the RNA polymerase II cleft. ► TFIIB guides descent of the template DNA strand into the polymerase cleft. ► TFIIB stabilizes an early transcribing complex. ► The fidelity of transcription is enhanced by the “trigger loop”. ► The translocation step may entail bending of the “bridge helix”.
Keywords: TFIIB; Trigger loop; Bridge helix; Backtracked state; Hybrid helix melting
Structural basis of transcription elongation by Fuensanta W. Martinez-Rucobo; Patrick Cramer (pp. 9-19).
For transcription elongation, all cellular RNA polymerases form a stable elongation complex (EC) with the DNA template and the RNA transcript. Since the millennium, a wealth of structural information and complementary functional studies provided a detailed three-dimensional picture of the EC and many of its functional states. Here we summarize these studies that elucidated EC structure and maintenance, nucleotide selection and addition, translocation, elongation inhibition, pausing and proofreading, backtracking, arrest and reactivation, processivity, DNA lesion-induced stalling, lesion bypass, and transcriptional mutagenesis. In the future, additional structural and functional studies of elongation factors that control the EC and their possible allosteric modes of action should result in a more complete understanding of the dynamic molecular mechanisms underlying transcription elongation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Elongation complex structure and maintenance ► Nucleotide selection and addition ► Pausing and proofreading ► Backtracking, arrest, reactivation and transcription processivity ► DNA lesions and RNA mutagenesis
Keywords: Gene transcription; RNA polymerase; Elongation complex structure
Basic mechanism of transcription by RNA polymerase II by Vladimir Svetlov; Evgeny Nudler (pp. 20-28).
RNA polymerase II-like enzymes carry out transcription of genomes in Eukaryota, Archaea, and some viruses. They also exhibit fundamental similarity to RNA polymerases from bacteria, chloroplasts, and mitochondria. In this review we take an inventory of recent studies illuminating different steps of basic transcription mechanism, likely common for most multi-subunit RNA polymerases. Through the amalgamation of structural and computational chemistry data we attempt to highlight the most feasible reaction pathway for the two-metal nucleotidyl transfer mechanism, and to evaluate the way catalysis can be linked to translocation in the mechano-chemical cycle catalyzed by RNA polymerase II. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► NTP condensation by RNA polymerase II occurs via modified two-metal catalysis ► Post-chemistry pyrophosphate release takes place in the enzyme pore via hopping mechanism ► Pyrophosphate release is linked to opening of the trigger loop
Keywords: RNA polymerase; Nucleotidyl transfer; Two-metal catalysis; Transcription; Molecular dynamics
Single-molecule studies of RNAPII elongation by Jing Zhou; Volker Schweikhard; Steven M. Block (pp. 29-38).
Elongation, the transcriptional phase in which RNA polymerase (RNAP) moves processively along a DNA template, occurs via a fundamental enzymatic mechanism that is thought to be universally conserved among multi-subunit polymerases in all kingdoms of life. Beyond this basic mechanism, a multitude of processes are integrated into transcript elongation, among them fidelity control, gene regulatory interactions involving elongation factors, RNA splicing or processing factors, and regulatory mechanisms associated with chromatin structure. Many kinetic and molecular details of the mechanism of the nucleotide addition cycle and its regulation, however, remain elusive and generate continued interest and even controversy. Recently, single-molecule approaches have emerged as powerful tools for the study of transcription in eukaryotic organisms. Here, we review recent progress and discuss some of the unresolved questions and ongoing debates, while anticipating future developments in the field. This article is part of a Special Issue entitled: RNA Polymerase II Transcript Elongation.► Transcription by eukaryotic RNA polymerase using Single-molecule approaches is reviewed. ► Single-molecule fluorescence and optical trapping techniques have been especially informative. ► Prospects for future studies are examined and discussed.
Keywords: Pol II; Transcript elongation; Single-molecule
Basic mechanisms of RNA polymerase II activity and alteration of gene expression in Saccharomyces cerevisiae by Craig D. Kaplan (pp. 39-54).
Transcription by RNA polymerase II (Pol II), and all RNA polymerases for that matter, may be understood as comprising two cycles. The first cycle relates to the basic mechanism of the transcription process wherein Pol II must select the appropriate nucleoside triphosphate (NTP) substrate complementary to the DNA template, catalyze phosphodiester bond formation, and translocate to the next position on the DNA template. Performing this cycle in an iterative fashion allows the synthesis of RNA chains that can be over one million nucleotides in length in some larger eukaryotes. Overlaid upon this enzymatic cycle, transcription may be divided into another cycle of three phases: initiation, elongation, and termination. Each of these phases has a large number of associated transcription factors that function to promote or regulate the gene expression process. Complicating matters, each phase of the latter transcription cycle are coincident with cotranscriptional RNA processing events. Additionally, transcription takes place within a highly dynamic and regulated chromatin environment. This chromatin environment is radically impacted by active transcription and associated chromatin modifications and remodeling, while also functioning as a major platform for Pol II regulation. This review will focus on our basic knowledge of the Pol II transcription mechanism, and how altered Pol II activity impacts gene expression in vivo in the model eukaryote Saccharomyces cerevisiae. This article is part of a Special Issue entitled: RNA Polymerase II Transcript Elongation.► Overview of basic mechanisms of RNA polymerase II nucleotide addition and translocation cycles ► Summary of structural analyses on multisubunit RNA polymerases ► Historical overview of molecular genetics of RNA polymerase II in the S. cerevisiae model system ► Discussion of gene expression defects that arise from altered RNA polymerase II activity in S. cerevisiae
Keywords: Abbreviations; Pol II; RNA polymerase II; TL; trigger loop; BH; bridge helix; FRET; Förster resonance energy transfer; NTP; nucleoside triphosphate; EC; elongation complexRNA polymerase II; Transcription elongation; Yeast; Gene expression; Genetics
Dynamic phosphorylation patterns of RNA polymerase II CTD during transcription by Martin Heidemann; Corinna Hintermair; Voss Kirsten Voß; Dirk Eick (pp. 55-62).
The eukaryotic RNA polymerase II (RNAPII) catalyzes the transcription of all protein encoding genes and is also responsible for the generation of small regulatory RNAs. RNAPII has evolved a unique domain composed of heptapeptide repeats with the consensus sequence Tyr1–Ser2–Pro3–Thr4–Ser5–Pro6–Ser7 at the C-terminus (CTD) of its largest subunit (Rpb1). Dynamic phosphorylation patterns of serine residues in CTD during gene transcription coordinate the recruitment of factors to the elongating RNAPII and to the nascent transcript. Recent studies identified threonine 4 and tyrosine 1 as new CTD modifications and thereby expanded the “CTD code”. In this review, we focus on CTD phosphorylation and its function in the RNAPII transcription cycle. We also discuss in detail the limitations of the phosphospecific CTD antibodies, which are used in all studies. This article is part of a Special Issue entitled: RNA Polymerase II Transcript Elongation.► CTD phosphorylation undergoes dynamic changes in the transcription cycle. ► Phosphorylation of CTD enables and protects factors from binding. ► The CTD phospho-code is complete with Tyr1-P, Ser2-P, Thr4-P, Ser5-P, and Ser7-P.
Keywords: Transcription; RNA polymerase II; Carboxy-terminal domain; Posttranslational modification; Phosphorylation
Promoter clearance by RNA polymerase II by Donal S. Luse (pp. 63-68).
Many changes must occur to the RNA polymerase II (pol II) transcription complex as it makes the transition from initiation into transcript elongation. During this intermediate phase of transcription, contact with initiation factors is lost and stable association with the nascent transcript is established. These changes collectively comprise promoter clearance. Once the transcript elongation complex has reached a point where its properties are indistinguishable from those of complexes with much longer transcripts, promoter clearance is complete. The clearance process for pol II consists of a number of steps and it extends for a surprisingly long distance downstream of transcription start. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Pol II must break promoter and factor interactions to enter transcript elongation. ► Abortive initiation is not extensive for pol II. ► Clearance is driven by TFIIH and collapse of the initial transcription bubble. ► Pol II early elongation complexes backtrack, even after RNA exits the polymerase. ► Clearance is incomplete until the pol II elongation complex is fully stabilized.
Keywords: Transcript initiation; Abortive initiation; Transcript elongation; TFIIB; TFIIH
The Mediator complex and transcription elongation by Ronald C. Conaway; Joan Weliky Conaway (pp. 69-75).
Mediator is an evolutionarily conserved multisubunit RNA polymerase II (Pol II) coregulatory complex. Although Mediator was initially found to play a critical role in the regulation of the initiation of Pol II transcription, recent studies have brought to light an expanded role for Mediator at post-initiation stages of transcription.We provide a brief description of the structure of Mediator and its function in the regulation of Pol II transcription initiation, and we summarize recent findings implicating Mediator in the regulation of various stages of Pol II transcription elongation.Emerging evidence is revealing new roles for Mediator in nearly all stages of Pol II transcription, including initiation, promoter escape, elongation, pre-mRNA processing, and termination.Mediator plays a central role in the regulation of gene expression by impacting nearly all stages of mRNA synthesis. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Mediator is a large multisubunit complex conserved in eukaryotes. ► Mediator transmits signals from DNA binding transcription factors to Pol II. ► Mediator regulates transcription initiation and elongation.
Keywords: Mediator; Transcription; RNA polymerase II; Elongation; ELL; P-TEFb
Mechanism of transcription through a nucleosome by RNA polymerase II by Olga I. Kulaeva; Fu-Kai Hsieh; Han-Wen Chang; Donal S. Luse; Vasily M. Studitsky (pp. 76-83).
Efficient maintenance of chromatin structure during passage of RNA polymerase II (Pol II) is critical for cell survival and functioning. Moderate-level transcription of eukaryotic genes by Pol II is accompanied by nucleosome survival, extensive exchange of histones H2A/H2B and minimal exchange of histones H3/H4. Complementary in vitro studies have shown that transcription through chromatin by single Pol II complexes is uniquely coupled with nucleosome survival via formation of a small intranucleosomal DNA loop (Ø-loop) containing the transcribing enzyme. In contrast, transient displacement and exchange of all core histones are observed during intense transcription. Indeed, multiple transcribing Pol II complexes can efficiently overcome the high nucleosomal barrier and displace the entire histone octamer in vitro. Thus, various Pol II complexes can remodel chromatin to different extents. The mechanisms of nucleosome survival and displacement during transcription and the role of DNA–histone interactions and various factors during this process are discussed. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Chromatin recovery during transcription is essential for cell viability. ► Chromatin recovery occurs differently during moderate and intense transcription. ► Original histones remain on DNA during moderate-level transcription. ► Histone survival during moderate transcription involves DNA looping. ► Multiple transcribing complexes displace histones during intense transcription.
Keywords: Chromatin; Nucleosome; Histone; Exchange; RNA polymerase II; Transcript elongation
Transcription-associated histone modifications and cryptic transcription by Michaela Smolle; Jerry L. Workman (pp. 84-97).
Eukaryotic genomes are packaged into chromatin, a highly organized structure consisting of DNA and histone proteins. All nuclear processes take place in the context of chromatin. Modifications of either DNA or histone proteins have fundamental effects on chromatin structure and function, and thus influence processes such as transcription, replication or recombination. In this review we highlight histone modifications specifically associated with gene transcription by RNA polymerase II and summarize their genomic distributions. Finally, we discuss how (mis-)regulation of these histone modifications perturbs chromatin organization over coding regions and results in the appearance of aberrant, intragenic transcription. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Histone modifications influence chromatin organization during transcription elongation. ► Histone chaperones and H2B ubiquitination maintain nucleosome levels over gene bodies. ► Disruption of histone H3K36 methylation leads to increased histone exchange and altered, hyperacetylated chromatin. ► Perturbation of chromatin structure over gene bodies exposes cryptic promoters. ► Cryptic transcripts are polyadenylated and even translated — their function is unclear though.
Keywords: Transcription elongation; RNA polymerase II; Histone modifying enzyme; Chromatin remodeling; Histone chaperone; Intragenic transcription
Transcription elongation factors DSIF and NELF: Promoter-proximal pausing and beyond by Yuki Yamaguchi; Hirotaka Shibata; Hiroshi Handa (pp. 98-104).
DRB sensitivity-inducing factor (DSIF) and negative elongation factor (NELF) were originally identified as factors responsible for transcriptional inhibition by 5,6-dichloro-1-beta-d-ribofuranosyl-benzimidazole (DRB) and were later found to control transcription elongation, together with P-TEFb, at the promoter-proximal region. Although there is ample evidence that these factors play roles throughout the genome, other data also suggest gene- or tissue-specific roles for these factors. In this review, we discuss how these apparently conflicting data can be reconciled. In light of recent findings, we also discuss the detailed mechanism by which these factors control the elongation process at the molecular level. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► DSIF and NELF control transcription elongation at the promoter-proximal region. ► There are apparently conflicting data as to the specificity of their target genes. ► DSIF appears to exert positive and negative effects through its interacting partners. ► Transcription elongation factors form an intricate web of interactions.
Keywords: Transcription elongation; Promoter-proximal pausing; DSIF; NELF; P-TEFb
The Spt4–Spt5 complex: A multi-faceted regulator of transcription elongation by Grant A. Hartzog; Jianhua Fu (pp. 105-115).
In all domains of life, elongating RNA polymerases require the assistance of accessory factors to maintain their processivity and regulate their rate. Among these elongation factors, the Spt5/NusG factors stand out. Members of this protein family appear to be the only transcription accessory proteins that are universally conserved across all domains of life. In archaea and eukaryotes, Spt5 associates with a second protein, Spt4. In addition to regulating elongation, the eukaryotic Spt4–Spt5 complex appears to couple chromatin modification states and RNA processing to transcription elongation. This review discusses the experimental bases for our current understanding of Spt4–Spt5 function and recent studies that are beginning to elucidate the structure of Spt4–Spt5/RNA polymerase complexes and mechanism of Spt4–Spt5 action. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Spt4–Spt5 is a positive and negative regulator of transcription elongation. ► Spt5/NusG proteins are found in all organisms and are essential for life. ► Spt4–Spt5 links transcription elongation to chromatin remodeling and RNA processing. ► Structural studies are beginning to provide insights into Spt4–Spt5 function.
Keywords: Spt4; Spt5; DSIF; NELF; P-TEFb; Transcription elongation
The many roles of the conserved eukaryotic Paf1 complex in regulating transcription, histone modifications, and disease states by Brett N. Tomson; Karen M. Arndt (pp. 116-126).
The Paf1 complex was originally identified over fifteen years ago in budding yeast through its physical association with RNA polymerase II. The Paf1 complex is now known to be conserved throughout eukaryotes and is well studied for promoting RNA polymerase II transcription elongation and transcription-coupled histone modifications. Through these critical regulatory functions, the Paf1 complex participates in numerous cellular processes such as gene expression and silencing, RNA maturation, DNA repair, cell cycle progression and prevention of disease states in higher eukaryotes. In this review, we describe the historic and current research involving the eukaryotic Paf1 complex to explain the cellular roles that underlie its conservation and functional importance. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► The Paf1 complex associates with RNA polymerase II on all active genes examined. ► The Paf1 complex couples conserved histone modifications to transcript elongation. ► The Paf1 complex regulates post-transcriptional events in gene expression. ► In higher eukaryotes, the Paf1 complex has diverse functions in cell cycle control, development, and disease.
Keywords: Paf1 complex; Histone modification; Transcription elongation; RNA polymerase II; Parafibromin
The control of elongation by the yeast Ccr4–Not complex by Joseph C. Reese (pp. 127-133).
The Ccr4–Not complex is a highly conserved nine-subunit protein complex that has been implicated in virtually all aspects of gene control, including transcription, mRNA decay and quality control, RNA export, translational repression and protein ubiquitylation. Understanding its mechanisms of action has been difficult due to the size of the complex and the fact that it regulates mRNAs and proteins at many levels in both the cytoplasm and the nucleus. Recently, biochemical and genetic studies on the yeast Ccr4–Not complex have revealed insights into its role in promoting elongation by RNA polymerase II. This review will describe what is known about the Ccr4–Not complex in regulating transcription elongation and its possible collaboration with other factors traveling with RNAPII across genes. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Ccr4–Not has many genetic and physical interactions with RNAPII elongation factors. ► Ccr4–Not associates with RNAPII in solution and within functional elongation complexes. ► Ccr4–Not promotes elongation through genes in vivo. ► Ccr4–Not directly activates arrested RNAPII. ► Not4 regulates co-transcriptional histone modifications through the destruction of Jhd2.
Keywords: Ccr4–Not; Transcription elongation; Histone methylation; Not4; TFIIS
Transcriptional elongation and alternative splicing by Gwendal Dujardin; Celina Lafaille; Ezequiel Petrillo; Valeria Buggiano; Acuna Luciana I. Gómez Acuña; Ana Fiszbein; Micaela A. Godoy Herz; Nicolás Nieto Moreno; Munoz Manuel J. Muñoz; Allo Mariano Alló; Ignacio E. Schor; Alberto R. Kornblihtt (pp. 134-140).
Alternative splicing has emerged as a key contributor to proteome diversity, highlighting the importance of understanding its regulation. In recent years it became apparent that splicing is predominantly cotranscriptional, allowing for crosstalk between these two nuclear processes. We discuss some of the links between transcription and splicing, with special emphasis on the role played by transcription elongation in the regulation of alternative splicing events and in particular the kinetic model of alternative splicing regulation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Splicing is mostly cotranscriptional. ► Alternative splicing is coupled to transcription. ► The rate of pol II elongation affects alternative splicing decisions. ► Chromatin structure and histone modifications affect alternative splicing decisions. ► DNA damage affects alternative splicing via its kinetic coupling with transcription.
Keywords: Alternative splicing; Transcription; Pol II elongation
Transcription coupled repair at the interface between transcription elongation and mRNP biogenesis by Hélène Gaillard; Andrés Aguilera (pp. 141-150).
During transcription, the nascent pre-mRNA associates with mRNA-binding proteins and undergoes a series of processing steps, resulting in export competent mRNA ribonucleoprotein complexes (mRNPs) that are transported into the cytoplasm. Throughout transcription elongation, RNA polymerases frequently deal with a number of obstacles that need to be removed for transcription resumption. One important type of hindrance consists of helix-distorting DNA lesions. Transcription-coupled repair (TC-NER), a specific sub-pathway of nucleotide excision repair, ensures a fast repair of such transcription-blocking lesions. While the nucleotide excision repair reaction is fairly well understood, its regulation and the way it deals with DNA transcription remains largely unknown. In this review, we update our current understanding of the factors involved in TC-NER and discuss their functional interplay with the processes of transcription elongation and mRNP biogenesis. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Present view of transcription-coupled repair ► Factors involved in transcription-coupled repair ► Interplay of DNA repair with transcription elongation and mRNP biogenesis ► Fate of an RNA polymerase stalled at DNA damage
Keywords: Nucleotide excision repair; Transcription coupled repair; RNAPII transcription; mRNP biogenesis; CSB/Rad26; THO
Ubiquitylation and degradation of elongating RNA polymerase II: The last resort by Marcus D. Wilson; Michelle Harreman; Jesper Q. Svejstrup (pp. 151-157).
During its journey across a gene, RNA polymerase II has to contend with a number of obstacles to its progression, including nucleosomes, DNA-binding proteins, DNA damage, and sequences that are intrinsically difficult to transcribe. Not surprisingly, a large number of elongation factors have evolved to ensure that transcription stalling or arrest does not occur. If, however, the polymerase cannot be restarted, it becomes poly-ubiquitylated and degraded by the proteasome. This process is highly regulated, ensuring that only RNAPII molecules that cannot otherwise be salvaged are degraded. In this review, we describe the mechanisms and factors responsible for the last resort mechanism of transcriptional elongation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Ubiquitylation and degradation of RNA polymerase II is a last resort pathway. ► Ubiquitylation occurs via a multi-step mechanism involving two distinct E3s and proofreading by ubiquitin proteases. ► The stopped form of RNA polymerase II is specifically targeted.
Keywords: RNA polymerase II; Ubiquitin; Elongin; Rsp5; NEDD4; Transcript elongation
Transcription-associated quality control of mRNP by Manfred Schmid; Torben Heick Jensen (pp. 158-168).
Although a prime purpose of transcription is to produce RNA, a substantial amount of transcript is nevertheless turned over very early in its lifetime. During transcription RNAs are matured by nucleases from longer precursors and activities are also employed to exert quality control over the RNA synthesis process so as to discard, retain or transcriptionally silence unwanted molecules. In this review we discuss the somewhat paradoxical circumstance that the retention or turnover of RNA is often linked to its synthesis. This occurs via the association of chromatin, or the transcription elongation complex, with RNA degradation (co)factors. Although our main focus is on protein-coding genes, we also discuss mechanisms of transcription-connected turnover of non-protein-coding RNA from where important general principles are derived. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Aspects of co-transcriptional quality control in yeast and metazoans. ► Transcript 5′–3′ decay can occur during transcription. ► Transcript 3′–5′ decay can occur in close relation with transcription. ► Transcript release from RNA polymerase and chromatin is a regulated process.
Keywords: mRNA quality control; RNA decay; Rat1p/XRN2; RNA exosome; mRNP retention
The eukaryotic transcriptional machinery regulates mRNA translation and decay in the cytoplasm by Nili Dahan; Mordechai Choder (pp. 169-173).
In eukaryotes, nuclear mRNA synthesis is physically separated from its cytoplasmic translation and degradation. Recent unexpected findings have revealed that, despite this separation, the transcriptional machinery can remotely control the cytoplasmic stages. Key to this coupling is the capacity of the transcriptional machinery to “imprint” the transcript with factors that escort it to the cytoplasm and regulate its localization, translation and decay. Some of these factors are known transcriptional regulators that also function in mRNA decay and are hence named “synthegradases”. Imprinting can be carried out and/or regulated by RNA polymerase II or by promoter cis- and trans-acting elements. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► RNA polymerase II can control mRNA translation and decay in the cytoplasm. ► Pol II transcript can be “imprinted” with factors that accompany the mRNA and regulate its fate. ► “Synthegradases” can simultaneously regulate mRNA synthesis, imprinting and decay.
Keywords: Transcription; Translation; mRNA decay
Disengaging polymerase: Terminating RNA polymerase II transcription in budding yeast by Hannah E. Mischo; Nick J. Proudfoot (pp. 174-185).
Termination of transcription by RNA polymerase II requires two distinct processes: The formation of a defined 3′ end of the transcribed RNA, as well as the disengagement of RNA polymerase from its DNA template. Both processes are intimately connected and equally pivotal in the process of functional messenger RNA production. However, research in recent years has elaborated how both processes can additionally be employed to control gene expression in qualitative and quantitative ways. This review embraces these new findings and attempts to paint a broader picture of how this final step in the transcription cycle is of critical importance to many aspects of gene regulation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.► Pol II transcription termination and 3′ end processing are different processes. ► Termination and 3′ end processing are intimately connected and influence each other. ► Pol II transcription termination employs two non-mutually exclusive pathways. ► Many cues transmitted to Pol II influence its choice of termination pathway. ► Termination choice is affected by external stimuli, which controls gene expression.
Keywords: Eukaryotic RNA transcription; RNA polymerase II; 3′ end processing; Transcription termination