scholarly journals Collective polymerase dynamics emerge from DNA Supercoiling Mediated Transcription

2021 ◽  
Author(s):  
Stuart Sevier ◽  
Sahand Hormoz
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Dna Supercoiling ◽  
Toggle Switch ◽  
Endogenous Genes ◽  
Non Local ◽  
Physical Interactions ◽  
The Impact

All biological processes ultimately come from physical interactions. The mechanical properties of DNA play a critical role in transcription. RNA polymerase can over or under twist DNA (referred to as DNA supercoiling) when it moves along a gene resulting in mechanical stresses in DNA that impact its own motion and that of other polymerases. For example, when enough supercoiling accumulates, an isolated polymerase halts and transcription stops. DNA supercoiling can also mediate non-local interactions between polymerases that shape gene expression fluctuations. Here, we construct a comprehensive model of transcription that captures how RNA polymerase motion changes the degree of DNA supercoiling which in turn feeds back into the rate at which polymerases are recruited and move along the DNA. Surprisingly, our model predicts that a group of three or more polymerases move together at a constant velocity and sustain their motion (forming what we call a polymeton) whereas one or two polymerases would have halted. We further show that accounting for the impact of DNA supercoiling on both RNA polymerase recruitment and velocity recapitulates empirical observations of gene expression fluctuations. Finally, we propose a mechanical toggle switch whereby interactions between genes are mediated by DNA twisting as opposed to proteins. Understanding the mechanical regulation of gene expression provides new insights into how endogenous genes can interact and informs the design of new forms of engineered interactions.

scholarly journals Structural Coupling between RNA Polymerase Composition and DNA Supercoiling in Coordinating Transcription: a Global Role for the Omega Subunit?

mBio ◽  
2011 ◽  
Vol 2 (4) ◽  
Author(s):  
Marcel Geertz ◽  
Andrew Travers ◽  
Sanja Mehandziska ◽  
Patrick Sobetzko ◽  
Sarath Chandra Janga ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Dna Supercoiling ◽  
Dna Topology ◽  
Chromosomal Dna ◽  
Tight Coupling ◽  
Structural Coupling ◽  
Bacterial Physiology ◽  
Transcription Machinery ◽  
The Impact

ABSTRACT In growing bacterial cells, the global reorganization of transcription is associated with alterations of RNA polymerase composition and the superhelical density of the DNA. However, the existence of any regulatory device coordinating these changes remains elusive. Here we show that in an exponentially growing Escherichia coli rpoZ mutant lacking the polymerase ω subunit, the impact of the Eσ38 holoenzyme on transcription is enhanced in parallel with overall DNA relaxation. Conversely, overproduction of σ70 in an rpoZ mutant increases both overall DNA supercoiling and the transcription of genes utilizing high negative superhelicity. We further show that transcription driven by the Eσ38 and Eσ70 holoenzymes from cognate promoters induces distinct superhelical densities of plasmid DNA in vivo. We thus demonstrate a tight coupling between polymerase holoenzyme composition and the supercoiling regimen of genomic transcription. Accordingly, we identify functional clusters of genes with distinct σ factor and supercoiling preferences arranging alternative transcription programs sustaining bacterial exponential growth. We propose that structural coupling between DNA topology and holoenzyme composition provides a basic regulatory device for coordinating genome-wide transcription during bacterial growth and adaptation. IMPORTANCE Understanding the mechanisms of coordinated gene expression is pivotal for developing knowledge-based approaches to manipulating bacterial physiology, which is a problem of central importance for applications of biotechnology and medicine. This study explores the relationships between variations in the composition of the transcription machinery and chromosomal DNA topology and suggests a tight interdependence of these two variables as the major coordinating principle of gene regulation. The proposed structural coupling between the transcription machinery and DNA topology has evolutionary implications and suggests a new methodology for studying concerted alterations of gene expression during normal and pathogenic growth both in bacteria and in higher organisms.

Regulation of RNA Polymerase II Activity is Essential for Terminal Erythroid Maturation

Blood ◽  
2021 ◽  
Author(s):  
Zachary Murphy ◽  
Kristin Murphy ◽  
Jacquelyn A Myers ◽  
Michael Roger Getman ◽  
Tyler Couch ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcriptional Repression ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Maturation Stage ◽  
Nuclear Condensation ◽  
Erythroid Maturation ◽  
Specific Regulation

The terminal maturation of human erythroblasts requires significant changes in gene expression in the context of dramatic nuclear condensation. Defects in this process are associated with inherited anemias and myelodysplastic syndromes. The progressively dense appearance of the condensing nucleus in maturing erythroblasts led to the assumption that heterochromatin accumulation underlies this process, but despite extensive study, the precise mechanisms underlying this essential biologic process remain elusive. To delineate the epigenetic changes associated with the terminal maturation of human erythroblasts, we performed mass spectrometry of histone post-translational modifications combined with ChIP-seq, ATAC-seq, and RNA-seq. Our studies revealed that the terminal maturation of human erythroblasts is associated with a dramatic decline in histone marks associated with active transcription elongation, without accumulation of heterochromatin. Chromatin structure and gene expression were instead correlated with dynamic changes in occupancy of elongation competent RNA polymerase II, suggesting that terminal erythroid maturation is controlled largely at the level of transcription. We further demonstrate that RNA Polymerase II "pausing" is highly correlated with transcriptional repression, with elongation competent RNA polymerase II becoming a scare resource in late stage erythroblasts, allocated to erythroid-specific genes. Functional studies confirmed an essential role for maturation stage-specific regulation of RNA polymerase II activity during erythroid maturation, and demonstrate a critical role for HEXIM1 in the regulation of gene expression and RNA polymerase II activity in maturing erythroblasts. Taken together, our findings reveal important insights into the mechanisms that regulate terminal erythroid maturation, and provide a novel paradigm for understanding normal and perturbed erythropoiesis.

scholarly journals Chlamydia trachomatis Type III Secretion Proteins Regulate Transcription

2015 ◽  
Vol 197 (20) ◽  
pp. 3238-3244 ◽  
Author(s):  
Brett R. Hanson ◽  
Anatoly Slepenkin ◽  
Ellena M. Peterson ◽  
Ming Tan
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Chlamydia Trachomatis ◽  
Rna Polymerase ◽  
Type Iii Secretion ◽  
Regulation Of Gene Expression ◽  
Pathogenic Bacterium ◽  
Content Type ◽  
Type Iii ◽  
Physical Interactions

ABSTRACTThe Scc4 protein (CT663) of the pathogenic bacteriumChlamydiahas been described as a type III secretion (T3S) chaperone as well as an inhibitor of RNA polymerase. To examine if these roles are connected, we first investigated physical interactions betweenChlamydia trachomatisScc4 and the T3S chaperone Scc1 and a T3S substrate, CopN. In a yeast 3-hybrid assay, Scc4, Scc1, and CopN were all required to detect an interaction, which suggests that these proteins form a trimolecular complex. We also detected interactions between any two of these three T3S proteins in a pulldown assay using only recombinant proteins. We next determined whether these interactions affected the function of Scc4 as an inhibitor of RNA transcription. UsingEscherichia colias a heterologousin vivosystem, we demonstrated that expression ofC. trachomatisScc4 led to a drastic decrease in transcript levels for multiple genes. However, coexpression of Scc4 with Scc1, CopN, or both alleviated Scc4-mediated inhibition of transcription. Scc4 expression also severely impairedE. coligrowth, but this growth defect was reversed by coexpression of Scc4 with Scc1, CopN, or both, suggesting that the inhibitory effect of Scc4 on transcription and growth can be antagonized by interactions between Scc4, Scc1, and CopN. These findings suggest that the dual functions of Scc4 may serve as a bridge to link T3S and the regulation of gene expression inChlamydia.IMPORTANCEThis study investigates a novel mechanism for regulating gene expression in the pathogenic bacteriumChlamydia. TheChlamydiatype III secretion (T3S) chaperone Scc4 has been shown to inhibit transcription by RNA polymerase. This study describes physical interactions between Scc4 and the T3S proteins Scc1 and CopN. Furthermore,ChlamydiaScc1 and CopN antagonized the inhibitory effects of Scc4 on transcription and growth in a heterologousEscherichia colisystem. These results provide evidence that transcription inChlamydiacan be regulated by the T3S system through interactions between T3S proteins.

scholarly journals Endurance Training Regulates Expression of Some Angiogenesis-Related Genes in Cardiac Tissue of Experimentally Induced Diabetic Rats

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 498
Author(s):  
Mojdeh Khajehlandi ◽  
Lotfali Bolboli ◽  
Marefat Siahkuhian ◽  
Mohammad Rami ◽  
Mohammadreza Tabandeh ◽  
...  
Keyword(s):  
Gene Expression ◽  
Endurance Training ◽  
Molecular Mechanisms ◽  
Cardiac Tissue ◽  
Critical Role ◽  
Diabetic Rats ◽  
Moderate Intensity ◽  
Pcr Analysis ◽  
Cardiac Tissues ◽  
The Impact

Exercise can ameliorate cardiovascular dysfunctions in the diabetes condition, but its precise molecular mechanisms have not been entirely understood. The aim of the present study was to determine the impact of endurance training on expression of angiogenesis-related genes in cardiac tissue of diabetic rats. Thirty adults male Wistar rats were randomly divided into three groups (N = 10) including diabetic training (DT), sedentary diabetes (SD), and sedentary healthy (SH), in which diabetes was induced by a single dose of streptozotocin (50 mg/kg). Endurance training (ET) with moderate-intensity was performed on a motorized treadmill for six weeks. Training duration and treadmill speed were increased during five weeks, but they were kept constant at the final week, and slope was zero at all stages. Real-time polymerase chain reaction (RT-PCR) analysis was used to measure the expression of myocyte enhancer factor-2C (MEF2C), histone deacetylase-4 (HDAC4) and Calmodulin-dependent protein kinase II (CaMKII) in cardiac tissues of the rats. Our results demonstrated that six weeks of ET increased gene expression of MEF2C significantly (p < 0.05), and caused a significant reduction in HDAC4 and CaMKII gene expression in the DT rats compared to the SD rats (p < 0.05). We concluded that moderate-intensity ET could play a critical role in ameliorating cardiovascular dysfunction in a diabetes condition by regulating the expression of some angiogenesis-related genes in cardiac tissues.

Speciation and changes in male gene expression in Drosophila

Genome ◽  
2020 ◽  
pp. 1-11
Author(s):  
Bahar Patlar ◽  
Alberto Civetta
Keyword(s):  
Gene Expression ◽  
Reproductive Isolation ◽  
Potential Role ◽  
Regulation Of Gene Expression ◽  
Drosophila Model ◽  
Depth Analysis ◽  
The Impact ◽  
Plastic Responses ◽  
Male Gene

It has long been acknowledged that changes in the regulation of gene expression may account for major organismal differences. However, we still do not fully understand how changes in gene expression evolve and how do such changes influence organisms’ differences. We are even less aware of the impact such changes might have in restricting gene flow between species. Here, we focus on studies of gene expression and speciation in the Drosophila model. We review studies that have identified gene interactions in post-mating reproductive isolation and speciation, particularly those that modulate male gene expression. We also address studies that have experimentally manipulated changes in gene expression to test their effect in post-mating reproductive isolation. We highlight the need for a more in-depth analysis of the role of selection causing disrupted gene expression of such candidate genes in sterile/inviable hybrids. Moreover, we discuss the relevance to incorporate more routinely assays that simultaneously evaluate the potential effects of environmental factors and genetic background in modulating plastic responses in male genes and their potential role in speciation.

scholarly journals The gammaherpesvirus 68 viral cyclin facilitates reactivation by promoting latent gene expression

2019 ◽  
Author(s):  
Brian F Niemeyer ◽  
Joy E Gibson ◽  
Jennifer N Berger ◽  
Lauren M Oko ◽  
Eva Medina ◽  
...  
Keyword(s):  
Gene Expression ◽  
Critical Role ◽  
Productive Infection ◽  
Viral Gene ◽  
Cellular Distribution ◽  
Viral Cyclin ◽  
Latently Infected ◽  
Infected Cells ◽  
Virally Encoded ◽  
The Impact

AbstractGammaherpesviruses establish life-long infections within their host and have been shown to be the causative agents of devastating malignancies. Chronic infection within the host is mediated through cycles of transcriptionally quiescent stages of latency with periods of reactivation into more active lytic and productive infection. The mechanisms that regulate reactivation from latency remain poorly understood. Previously, we defined a critical role for the viral cyclin in promoting reactivation from latency. Disruption of the viral cyclin had no impact on the frequency of cells containing viral genome during latency, yet it remains unclear whether the viral cyclin influences latently infected cells in a qualitative manner. To define the impact of the viral cyclin on latent gene expression, we utilized a viral cyclin deficient variant expressing a LANA-beta-lactamase fusion protein (LANA::βla), to enumerate both the cellular distribution and frequency of latent gene expression. Disruption of the viral cyclin did not affect the cellular distribution of latently infected cells, but did result in a significant decrease in the frequency of cells that expressed LANA::βla across multiple tissues and in both immunocompetent and immunodeficient hosts. Strikingly, whereas the cyclin-deficient virus had a reactivation defect in bulk culture, sort purified cyclin-deficient LANA::βla expressing cells were fully capable of reactivation. These data emphasize that the γHV68 latent reservoir is comprised of at least two distinct stages of infection characterized by differential latent gene expression, and that a primary function of the viral cyclin is to promote latent gene expression within infected cells in vivo.AUTHOR SUMMARYGammaherpesviruses are ubiquitous viruses with oncogenic potential that establish latency for the life of the host. These viruses can emerge from latency through reactivation, a process that is controlled by the immune system. Control of viral latency and reactivation is thought to be critical to prevent γHV-associated disease. This study focuses on a virally-encoded cyclin that is required for reactivation from latency. By characterizing how the viral cyclin influences latent infection in pure cell populations, we find that the viral cyclin has a vital role in promoting viral gene expression during latency. This work provides new insight into the function of a virally encoded cyclin in promoting reactivation from latency.

Chromatin-Modifying Enzymes in T Cell Development

2020 ◽  
Vol 38 (1) ◽  
pp. 397-419
Author(s):  
Michael J. Shapiro ◽  
Virginia Smith Shapiro
Keyword(s):  
Gene Expression ◽  
T Cell ◽  
Biological Effects ◽  
Critical Role ◽  
T Cell Development ◽  
Regulation Of Gene Expression ◽  
Chromatin Accessibility ◽  
Cell Development ◽  
Specific Gene ◽  
Dynamic Regulation

T cell development involves stepwise progression through defined stages that give rise to multiple T cell subtypes, and this is accompanied by the establishment of stage-specific gene expression. Changes in chromatin accessibility and chromatin modifications accompany changes in gene expression during T cell development. Chromatin-modifying enzymes that add or reverse covalent modifications to DNA and histones have a critical role in the dynamic regulation of gene expression throughout T cell development. As each chromatin-modifying enzyme has multiple family members that are typically all coexpressed during T cell development, their function is sometimes revealed only when two related enzymes are concurrently deleted. This work has also revealed that the biological effects of these enzymes often involve regulation of a limited set of targets. The growing diversity in the types and sites of modification, as well as the potential for a single enzyme to catalyze multiple modifications, is also highlighted.

scholarly journals Structure-Function Analysis of VapB4 Antitoxin Identifies Critical Features of a Minimal VapC4 Toxin-Binding Module

2015 ◽  
Vol 197 (7) ◽  
pp. 1197-1207 ◽  
Author(s):  
Guangze Jin ◽  
Martin S. Pavelka ◽  
J. Scott Butler
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Function Analysis ◽  
Critical Role ◽  
Regulation Of Gene Expression ◽  
Binding Domain ◽  
Type Ii ◽  
Toxin Binding ◽  
Dna Binding Specificity ◽  
Amino Acid Side Chains

ABSTRACTBacterial toxin-antitoxin systems play a critical role in the regulation of gene expression, leading to developmental changes, reversible dormancy, and cell death. Type II toxin-antitoxin pairs, composed of protein toxins and antitoxins, exist in nearly all bacteria and are classified into six groups on the basis of the structure of the toxins. The VapBC group comprises the most common type II system and, like other toxin-antitoxin systems, functions to elicit dormancy by inhibiting protein synthesis. Activation of toxin function requires protease degradation of the VapB antitoxin, which frees the VapC toxin from the VapBC complex, allowing it to hydrolyze the RNAs required for translation. Generally, type II antitoxins bind with high specificity to their cognate toxins via a toxin-binding domain and endow the complex with DNA-binding specificity via a DNA-binding domain. Despite the ubiquity of VapBC systems and their critical role in the regulation of gene expression, few functional studies have addressed the details of VapB-VapC interactions. Here we report on the results of experiments designed to identify molecular determinants of the specificity of theMycobacterium tuberculosisVapB4 antitoxin for its cognate VapC4 toxin. The results identify the minimal domain of VapB4 required for this interaction as well as the amino acid side chains required for binding to VapC4. These findings have important implications for the evolution of VapBC toxin-antitoxin systems and their potential as targets of small-molecule protein-protein interaction inhibitors.IMPORTANCEVapBC toxin-antitoxin pairs are the most widespread type II toxin-antitoxin systems in bacteria, where they are thought to play key roles in stress-induced dormancy and the formation of persisters. The VapB antitoxins are critical to these processes because they inhibit the activity of the toxins and provide the DNA-binding specificity that controls the synthesis of both proteins. Despite the importance of VapB antitoxins and the existence of several VapBC crystal structures, little is known about their functional featuresin vivo. Here we report the findings of the first comprehensive structure-function analysis of a VapB toxin. The results identify the minimal toxin-binding domain, its modular antitoxin function, and the specific amino acid side chains required for its activity.

The critical role of surgical pathology in personalized medicine: The impact of biopsy cavities in breast cancer samples on recurrence risk when assessed by quantitative RT-PCR

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. e22016-e22016
Author(s):  
F. L. Baehner ◽  
J. Anderson ◽  
C. Millward ◽  
C. Sangli ◽  
C. Quale ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Gene Expression ◽  
Expression Profiles ◽  
Critical Role ◽  
Recurrence Score ◽  
Pcr Analysis ◽  
Breast Cancers ◽  
Rt Pcr ◽  
Poorly Differentiated ◽  
The Impact

e22016 Background: Tumor gene expression analysis using the Recurrence Score (RS) assay is frequently used in ER+ breast cancer. Manual microdissection is performed in cases where biopsy cavities (BxC) are present in the submitted specimen. The objective of this was to characterize by quantitative RT-PCR the impact of BxC on 21 gene expression profiles and the RS. Methods: 48 (15 well, 18 moderate, and 15 poorly differentiated) breast cancers were evaluated for gene expression differences between whole sections (WS; containing BxC) and enriched tumor (ET; BxC excluded). Standardized quantitative RT-PCR analysis for the 21 Oncotype DX genes was performed; reference normalized gene expression measurements ranged from 0 to 15, where each 1-unit reflects an approximate 2-fold change in RNA. Analyses of individual genes and the RS were performed on the entire sample set and stratified by tumor grade. Correlation analyses used Pearson's R, concordance analysis used Lin's sample concordance and paired t- tests to characterize differences. Results: There were statistically significant differences in reference normalized gene expression between ET and WS in 6 genes: BAG1 (ET-WS: 0.13 units, p=0.0025), CD68 (ET-WS: -0.64 units, p<0.0001), ER (ET-WS: 0.29 units, p=0.0012), GSTM1 (ET-WS: 0.18 units p=0.0025), STK15 (ET-WS: -0.18 units, p=0.0041) and STMY3 (ET-WS: 0.62 units, p<0.0001). Expression of the macrophage marker CD68 was higher and expression of ER was lower in WS containing BxC. The correlation (0.95) and concordance (0.92) were generally high between WS and ET for RS overall however among moderately differentially tumors, there was a statistically significant mean increase in RS for WS of 3.3 units (p = 0.0012) while among poorly differentiated tumors there was a trend toward a statistically significant decrease in RS for WS of 2.2 units (p=0.0569). Conclusions: Histologic identification of invasive carcinoma and exclusion of BxC is essential for precise RS assessment. Inclusion of BxC in breast cancer specimens is associated with significant changes in the expression of individual genes and impacts the RS. Removal of BxC from breast cancer specimens assessed for gene expression levels is warranted. [Table: see text]

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