scholarly journals DksA-dependent regulation of RpoS contributes to Borrelia burgdorferi tick-borne transmission and mammalian infectivity

2021 ◽  
Vol 17 (2) ◽  
pp. e1009072
Author(s):  
William K. Boyle ◽  
Crystal L. Richards ◽  
Daniel P. Dulebohn ◽  
Amanda K. Zalud ◽  
Jeff A. Shaw ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Rna Polymerase ◽  
Nutrient Limitation ◽  
Pathogenic Bacteria ◽  
Transcriptional Control ◽  
Ixodes Scapularis ◽  
Stringent Response ◽  
Transcriptional Responses

Throughout its enzootic cycle, the Lyme disease spirochete Borreliella (Borrelia) burgdorferi, senses and responds to changes in its environment using a small repertoire of transcription factors that coordinate the expression of genes required for infection of Ixodes ticks and various mammalian hosts. Among these transcription factors, the DnaK suppressor protein (DksA) plays a pivotal role in regulating gene expression in B. burgdorferi during periods of nutrient limitation and is required for mammalian infectivity. In many pathogenic bacteria, the gene regulatory activity of DksA, along with the alarmone guanosine penta- and tetra-phosphate ((p)ppGpp), coordinate the stringent response to various environmental stresses, including nutrient limitation. In this study, we sought to characterize the role of DksA in regulating the transcriptional activity of RNA polymerase and its role in the regulation of RpoS-dependent gene expression required for B. burgdorferi infectivity. Using in vitro transcription assays, we observed recombinant DksA inhibits RpoD-dependent transcription by B. burgdorferi RNA polymerase independent of ppGpp. Additionally, we determined the pH-inducible expression of RpoS-dependent genes relies on DksA, but this relationship is independent of (p)ppGpp produced by Relbbu. Subsequent transcriptomic and western blot assays indicate DksA regulates the expression of BBD18, a protein previously implicated in the post-transcriptional regulation of RpoS. Moreover, we observed DksA was required for infection of mice following intraperitoneal inoculation or for transmission of B. burgdorferi by Ixodes scapularis nymphs. Together, these data suggest DksA plays a central role in coordinating transcriptional responses in B. burgdorferi required for infectivity through DksA’s interactions with RNA polymerase and post-transcriptional control of RpoS.

scholarly journals DksA-dependent regulation of RpoS contributes to Borrelia burgdorferi tick-borne transmission and mammalian infectivity

2020 ◽  
Author(s):  
William K. Boyle ◽  
Crystal L. Richards ◽  
Daniel P. Dulebohn ◽  
Amanda K. Zalud ◽  
Jeff A. Shaw ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Rna Polymerase ◽  
Nutrient Limitation ◽  
Expression Of Genes ◽  
Gene Regulatory ◽  
Transcription Assays

ABSTRACTThroughout its enzootic cycle, the Lyme disease spirochete Borreliella (Borrelia) burgdorferi, senses and responds to changes in its environment by using a small repertoire of transcription factors which coordinate the expression of genes required for infection of Ixodes ticks and various mammalian hosts. Among these transcription factors, the DnaK suppressor protein (DksA) plays a pivotal role in regulating gene expression in B. burgdorferi during periods of nutrient limitation and is required for mammalian infectivity. In many pathogenic bacteria, the gene regulatory activity of DksA along with the alarmone guanosine penta- and tetra-phosphate ((p)ppGpp) coordinates the stringent response to various environmental stresses including nutrient limitation. In this study, we sought to characterize the role of DksA in regulating the transcriptional activity of RNA polymerase and in the regulation of RpoS-dependent gene expression required for B. burgdorferi infectivity. Using in vitro transcription assays, we observed recombinant DksA inhibits RpoD-dependent transcription by B. burgdorferi RNA polymerase independent of ppGpp Additionally, we determined the pH-inducible expression of RpoS-dependent genes relies on DksA, but is independent of (p)ppGpp produced by Relbbu. Subsequent transcriptomic and western blot assays indicated DksA regulates the expression of BBD18, a protein previously implicated in the post-transcriptional regulation of RpoS. Moreover, we observed DksA was required for infection of mice following intraperitoneal inoculation or for transmission of B. burgdorferi by Ixodes scapularis nymphs. Together, these data suggest DksA plays a central role in coordinating transcriptional responses of B. burgdorferi required for infectivity through its interactions with RNA polymerase and post-transcriptional control of RpoS.Author SummaryLyme disease, caused by the spirochetal bacteria Borrelia burgdorferi, is the most common vector-borne illness in North America. The ability of B. burgdorferi to establish infection is predicated by its ability to coordinate the expression of virulence factors in response to diverse environmental stimuli encountered within Ixodes ticks and mammalian hosts. Previous studies have shown an essential role for the alternative sigma factor RpoS in regulating the expression of genes required for the successful transmission of B. burgdorferi by Ixodes ticks and infection of mammalian hosts. The DnaK suppressor protein (DksA) is a global gene regulator in B. burgdorferi that also contributes to the expression of RpoS-dependent genes. In this study, we determined DksA exerts its gene regulatory function through direct interactions with the B. burgdorferi RNA polymerase using in vitro transcription assays and controls the expression of RpoS-dependent genes required for mammalian infection by post-transcriptionally regulating cellular levels of RpoS. Our results demonstrate the utility of in vitro transcription assays to determine how gene regulatory proteins like DksA control gene expression in B. burgdorferi, and reveal a novel role for DksA in the infectious cycle of B. burgdorferi.

scholarly journals Emerging Functions of Transcription Factors in Malaria Parasite

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Renu Tuteja ◽  
Abulaish Ansari ◽  
Virander Singh Chauhan
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Rna Polymerase ◽  
Malaria Parasite ◽  
Transcriptional Control ◽  
Regulation Of Gene Expression ◽  
High Mobility ◽  
High Mobility Group Protein ◽  
Eukaryotic Genes ◽  
Group Protein

Transcription is a process by which the genetic information stored in DNA is converted into mRNA by enzymes known as RNA polymerase. Bacteria use only one RNA polymerase to transcribe all of its genes while eukaryotes contain three RNA polymerases to transcribe the variety of eukaryotic genes. RNA polymerase also requires other factors/proteins to produce the transcript. These factors generally termed as transcription factors (TFs) are either associated directly with RNA polymerase or add in building the actual transcription apparatus. TFs are the most common tools that our cells use to control gene expression.Plasmodium falciparumis responsible for causing the most lethal form of malaria in humans. It shows most of its characteristics common to eukaryotic transcription but it is assumed that mechanisms of transcriptional control inP. falciparumsomehow differ from those of other eukaryotes. In this article we describe the studies on the main TFs such as myb protein, high mobility group protein and ApiA2 family proteins from malaria parasite. These studies show that these TFs are slowly emerging to have defined roles in the regulation of gene expression in the parasite.

scholarly journals Modeling the transport of nuclear proteins along single skeletal muscle cells

2020 ◽  
Vol 117 (6) ◽  
pp. 2978-2986 ◽  
Author(s):  
Hermes Taylor-Weiner ◽  
Christopher L. Grigsby ◽  
Duarte M. S. Ferreira ◽  
José M. Dias ◽  
Molly M. Stevens ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Molecular Weight ◽  
Transcription Factors ◽  
Protein Transport ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Nuclear Proteins ◽  
Transcriptional Responses

Skeletal muscle cells contain hundreds of myonuclei within a shared cytoplasm, presenting unique challenges for regulating gene expression. Certain transcriptional programs (e.g., postsynaptic machinery) are segregated to specialized domains, while others (e.g., contractile proteins) do not show spatial confinement. Furthermore, local stimuli, such as denervation, can induce transcriptional responses that are propagated along the muscle cells. Regulated transport of nuclear proteins (e.g., transcription factors) between myonuclei represents a potential mechanism for coordinating gene expression. However, the principles underlying the transport of nuclear proteins within multinucleated cells remain poorly defined. Here we used a mosaic transfection model to create myotubes that contained exactly one myonucleus expressing a fluorescent nuclear reporter and monitored its distribution among all myonuclei. We found that the transport properties of these model nuclear proteins in myotubes depended on molecular weight and nuclear import rate, as well as on myotube width. Interestingly, muscle hypertrophy increased the transport of high molecular weight nuclear proteins, while atrophy restricted the transport of smaller nuclear proteins. We have developed a mathematical model of nuclear protein transport within a myotube that recapitulates the results of our in vitro experiments. To test the relevance to nuclear proteins expressed in skeletal muscle, we studied the transport of two transcription factors—aryl hydrocarbon receptor nuclear translocator and sine oculis homeobox 1—and found that their distributions were similar to the reporter proteins with corresponding molecular weights. Together, these results define a set of variables that can be used to predict the spatial distributions of nuclear proteins within a myotube.

Nutrient-regulated gene expression in eukaryotes

2006 ◽  
Vol 73 ◽  
pp. 85-96 ◽  
Author(s):  
Richard J. Reece ◽  
Laila Beynon ◽  
Stacey Holden ◽  
Amanda D. Hughes ◽  
Karine Rébora ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcriptional Control ◽  
Direct Interaction ◽  
Signalling Pathways ◽  
A Cell ◽  
One Step ◽  
Higher Eukaryotes ◽  
Regulated Gene Expression

The recognition of changes in environmental conditions, and the ability to adapt to these changes, is essential for the viability of cells. There are numerous well characterized systems by which the presence or absence of an individual metabolite may be recognized by a cell. However, the recognition of a metabolite is just one step in a process that often results in changes in the expression of whole sets of genes required to respond to that metabolite. In higher eukaryotes, the signalling pathway between metabolite recognition and transcriptional control can be complex. Recent evidence from the relatively simple eukaryote yeast suggests that complex signalling pathways may be circumvented through the direct interaction between individual metabolites and regulators of RNA polymerase II-mediated transcription. Biochemical and structural analyses are beginning to unravel these elegant genetic control elements.

Subnuclear compartmentalization of sequence-specific transcription factors and regulation of eukaryotic gene expression

2005 ◽  
Vol 83 (4) ◽  
pp. 535-547 ◽  
Author(s):  
Gareth N Corry ◽  
D Alan Underhill
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Transcriptional Activation ◽  
Current Knowledge ◽  
Nuclear Architecture ◽  
Subnuclear Localization ◽  
Modular Structures

To date, the majority of the research regarding eukaryotic transcription factors has focused on characterizing their function primarily through in vitro methods. These studies have revealed that transcription factors are essentially modular structures, containing separate regions that participate in such activities as DNA binding, protein–protein interaction, and transcriptional activation or repression. To fully comprehend the behavior of a given transcription factor, however, these domains must be analyzed in the context of the entire protein, and in certain cases the context of a multiprotein complex. Furthermore, it must be appreciated that transcription factors function in the nucleus, where they must contend with a variety of factors, including the nuclear architecture, chromatin domains, chromosome territories, and cell-cycle-associated processes. Recent examinations of transcription factors in the nucleus have clarified the behavior of these proteins in vivo and have increased our understanding of how gene expression is regulated in eukaryotes. Here, we review the current knowledge regarding sequence-specific transcription factor compartmentalization within the nucleus and discuss its impact on the regulation of such processes as activation or repression of gene expression and interaction with coregulatory factors.Key words: transcription, subnuclear localization, chromatin, gene expression, nuclear architecture.

scholarly journals Mediator complex subunit Med19 binds directly GATA transcription factors and is required with Med1 for GATA-driven gene regulation in vivo

2020 ◽  
Vol 295 (39) ◽  
pp. 13617-13629
Author(s):  
Clément Immarigeon ◽  
Sandra Bernat-Fabre ◽  
Emmanuelle Guillou ◽  
Alexis Verger ◽  
Elodie Prince ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Target Genes ◽  
Direct Interaction ◽  
Mediator Complex ◽  
Loss Of Function ◽  
Transcriptional Responses ◽  
Rna Pol Ii ◽  
Evolutionarily Conserved

The evolutionarily conserved multiprotein Mediator complex (MED) serves as an interface between DNA-bound transcription factors (TFs) and the RNA Pol II machinery. It has been proposed that each TF interacts with a dedicated MED subunit to induce specific transcriptional responses. But are these binary partnerships sufficient to mediate TF functions? We have previously established that the Med1 Mediator subunit serves as a cofactor of GATA TFs in Drosophila, as shown in mammals. Here, we observe mutant phenotype similarities between another subunit, Med19, and the Drosophila GATA TF Pannier (Pnr), suggesting functional interaction. We further show that Med19 physically interacts with the Drosophila GATA TFs, Pnr and Serpent (Srp), in vivo and in vitro through their conserved C-zinc finger domains. Moreover, Med19 loss of function experiments in vivo or in cellulo indicate that it is required for Pnr- and Srp-dependent gene expression, suggesting general GATA cofactor functions. Interestingly, Med19 but not Med1 is critical for the regulation of all tested GATA target genes, implying shared or differential use of MED subunits by GATAs depending on the target gene. Lastly, we show a direct interaction between Med19 and Med1 by GST pulldown experiments indicating privileged contacts between these two subunits of the MED middle module. Together, these findings identify Med19/Med1 as a composite GATA TF interface and suggest that binary MED subunit–TF partnerships are probably oversimplified models. We propose several mechanisms to account for the transcriptional regulation of GATA-targeted genes.

scholarly journals The Mycobacterium tuberculosis sRNA F6 regulates expression of groEL/S

2020 ◽  
Author(s):  
Joanna Houghton ◽  
Angela Rodgers ◽  
Graham Rose ◽  
Kristine B. Arnvig
Keyword(s):  
Gene Expression ◽  
Mycobacterium Tuberculosis ◽  
Small Rnas ◽  
Transcriptional Control ◽  
Cold Shock ◽  
Control Of Gene Expression ◽  
Rna Biology ◽  
Mouse Model Of Infection

ABSTRACTAlmost 140 years after the identification of Mycobacterium tuberculosis as the etiological agent of tuberculosis, important aspects of its biology remain poorly described. Little is known about the role of post-transcriptional control of gene expression and RNA biology, including the role of most of the small RNAs (sRNAs) identified to date. We have carried out a detailed investigation of the M. tuberculosis sRNA, F6, and show it to be dependent on SigF for expression and significantly induced during in vitro starvation and in a mouse model of infection. However, we found no evidence of attenuation of a ΔF6 strain within the first 20 weeks of infection. A further exploration of F6 using in vitro models of infection suggests a role for F6 as a highly specific regulator of the heat shock repressor, HrcA. Our results point towards a role for F6 during periods of low metabolic activity similar to cold shock and associated with nutrient starvation such as that found in human granulomas in later stages of infection.

scholarly journals The neutrophil-mobilizing cytokine interleukin-26 in the airways of long-term tobacco smokers

2018 ◽  
Vol 132 (9) ◽  
pp. 959-983 ◽  
Author(s):  
Karlhans Fru Che ◽  
Ellen Tufvesson ◽  
Sara Tengvall ◽  
Elisa Lappi-Blanco ◽  
Riitta Kaarteenaho ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chronic Bronchitis ◽  
Pathogenic Bacteria ◽  
Cell Model ◽  
Water Soluble ◽  
Chronic Obstructive ◽  
Neutrophil Accumulation

Long-term tobacco smokers with chronic obstructive pulmonary disease (COPD) or chronic bronchitis display an excessive accumulation of neutrophils in the airways; an inflammation that responds poorly to established therapy. Thus, there is a need to identify new molecular targets for the development of effective therapy. Here, we hypothesized that the neutrophil-mobilizing cytokine interleukin (IL)-26 (IL-26) is involved in airway inflammation amongst long-term tobacco smokers with or without COPD, chronic bronchitis or colonization by pathogenic bacteria. By analyzing bronchoalveolar lavage (BAL), bronchail wash (BW) and induced sputum (IS) samples, we found increased extracellular IL-26 protein in the airways of long-term smokers in vivo without further increase amongst those with clinically stable COPD. In human alveolar macrophages (AM) in vitro, the exposure to water-soluble tobacco smoke components (WTC) enhanced IL-26 gene and protein. In this cell model, the same exposure increased gene expression of the IL-26 receptor complex (IL10R2 and IL20R1) and nuclear factor κ B (NF-κB); a proven regulator of IL-26 production. In the same cell model, recombinant human IL-26 in vitro caused a concentration-dependent increase in the gene expression of NF-κB and several pro-inflammatory cytokines. In the long-term smokers, we also observed that extracellular IL-26 protein in BAL samples correlates with measures of lung function, tobacco load, and several markers of neutrophil accumulation. Extracellular IL-26 was further increased in long-term smokers with exacerbations of COPD (IS samples), with chronic bronchitis (BAL samples ) or with colonization by pathogenic bacteria (IS and BW samples). Thus, IL-26 in the airways emerges as a promising target for improving the understanding of the pathogenic mechanisms behind several pulmonary morbidities in long-term tobacco smokers.

scholarly journals Hierarchical Transcriptional Control of the LuxR Quorum-Sensing Regulon of Vibrio harveyi

2020 ◽  
Vol 202 (14) ◽  
Author(s):  
Ryan R. Chaparian ◽  
Alyssa S. Ball ◽  
Julia C. van Kessel
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Quorum Sensing ◽  
Cell Density ◽  
Regulatory Networks ◽  
Vibrio Harveyi ◽  
Sugar Transport ◽  
Content Type ◽  
Second Tier

ABSTRACT In vibrios, quorum sensing controls hundreds of genes that are required for cell density-specific behaviors including bioluminescence, biofilm formation, competence, secretion, and swarming motility. The central transcription factor in the quorum-sensing pathway is LuxR/HapR, which directly regulates ∼100 genes in the >400-gene regulon of Vibrio harveyi. Among these directly controlled genes are 15 transcription factors, which we predicted would comprise the second tier in the hierarchy of the LuxR regulon. We confirmed that LuxR binds to the promoters of these genes in vitro and quantified the extent of LuxR activation or repression of transcript levels. Transcriptome sequencing (RNA-seq) indicates that most of these transcriptional regulators control only a few genes, with the exception of MetJ, which is a global regulator. The genes regulated by these transcription factors are predicted to be involved in methionine and thiamine biosynthesis, membrane stability, RNA processing, c-di-GMP degradation, sugar transport, and other cellular processes. These data support a hierarchical model in which LuxR directly regulates 15 transcription factors that drive the second level of the gene expression cascade to influence cell density-dependent metabolic states and behaviors in V. harveyi. IMPORTANCE Quorum sensing is important for survival of bacteria in nature and influences the actions of bacterial groups. In the relatively few studied examples of quorum-sensing-controlled genes, these genes are associated with competition or cooperation in complex microbial communities and/or virulence in a host. However, quorum sensing in vibrios controls the expression of hundreds of genes, and their functions are mostly unknown or uncharacterized. In this study, we identify the regulators of the second tier of gene expression in the quorum-sensing system of the aquaculture pathogen Vibrio harveyi. Our identification of regulatory networks and metabolic pathways controlled by quorum sensing can be extended and compared to other Vibrio species to understand the physiology, ecology, and pathogenesis of these organisms.

Sign in / Sign up

Export Citation Format

Share Document