scholarly journals RstA is a Major Regulator ofClostridioides difficileToxin Production and Motility

2018 ◽  
Author(s):  
Adrianne N. Edwards ◽  
Brandon R. Anjuwon-Foster ◽  
Shonna M. McBride
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Toxin Production ◽  
Binding Domain ◽  
Toxin Gene ◽  
Dna Binding Domain ◽  
Toxin Genes ◽  
Clostridioides Difficile ◽  
Species Specific ◽  
Toxin Gene Expression

ABSTRACTClostridioides difficileinfection (CDI) is a toxin-mediated disease. Several factors have been identified that influence the production of the two majorC. difficiletoxins, TcdA and TcdB, but prior published evidence suggested that additional unknown factors were involved in toxin regulation. Previously, we identified aC. difficileregulator, RstA, that promotes sporulation and represses motility and toxin production. We observed that the predicted DNA-binding domain of RstA was required for RstA-dependent repression of toxin genes, motility genes andrstAtranscription. In this study, we further investigated the regulation of toxin and motility gene expression by RstA. DNA pulldown assays confirmed that RstA directly binds therstApromoter via the predicted DNA-binding domain. Through mutational analysis of therstApromoter, we identified several nucleotides that are important for RstA-dependent transcriptional regulation. Further, we observed that RstA directly binds and regulates the promoters of the toxin genes,tcdAandtcdB, as well as the promoters for thesigDandtcdRgenes, which encode regulators of toxin gene expression. Complementation analyses with theClostridium perfringensRstA ortholog and a multi-species chimeric RstA protein revealed that theC. difficileC-terminal domain is required for RstA DNA-binding activity, suggesting that species-specific signaling controls RstA function. Our data demonstrate that RstA is a transcriptional repressor that autoregulates its own expression and directly inhibits transcription of the two toxin genes and two positive toxin regulators, thereby acting at multiple regulatory points to control toxin production.IMPORTANCEClostridioides difficileis an anaerobic, gastrointestinal pathogen of humans and other mammals.C. difficileproduces two major toxins, TcdA and TcdB, which cause the symptoms of the disease, and forms dormant endospores to survive the aerobic environment outside of the host. A recently discovered regulatory factor, RstA, inhibits toxin production and positively influences spore formation. Herein, we determine that RstA directly represses toxin gene expression and gene expression of two toxin gene activators, TcdR and SigD, creating a complex regulatory network to tightly control toxin production. In addition, the ability for RstA to bind DNA and repress toxin production requires the species-specific domain predicted to respond to small quorum-sensing peptides. This study provides a novel regulatory link betweenC. difficilesporulation and toxin production. Further, our data suggest thatC. difficiletoxin production is regulated through a direct sensing mechanism.

scholarly journals RstA Is a Major Regulator ofClostridioides difficileToxin Production and Motility

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Adrianne N. Edwards ◽  
Brandon R. Anjuwon-Foster ◽  
Shonna M. McBride
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Toxin Production ◽  
Toxin Gene ◽  
Dna Binding Domain ◽  
Content Type ◽  
Toxin Genes ◽  
Clostridioides Difficile ◽  
Species Specific ◽  
Toxin Gene Expression

ABSTRACTClostridioides difficileinfection (CDI) is a toxin-mediated diarrheal disease. Several factors have been identified that influence the production of the two majorC. difficiletoxins, TcdA and TcdB, but prior published evidence suggested that additional unknown factors were involved in toxin regulation. Previously, we identified aC. difficileregulator, RstA, that promotes sporulation and represses motility and toxin production. We observed that the predicted DNA-binding domain of RstA was required for RstA-dependent repression of toxin genes, motility genes, andrstAtranscription. In this study, we further investigated the regulation of toxin and motility gene expression by RstA. DNA pulldown assays confirmed that RstA directly binds therstApromoter via the predicted DNA-binding domain. Through mutational analysis of therstApromoter, we identified several nucleotides that are important for RstA-dependent transcriptional regulation. Further, we observed that RstA directly binds and regulates the promoters of the toxin genestcdAandtcdB, as well as the promoters for thesigDandtcdRgenes, which encode regulators of toxin gene expression. Complementation analyses with theClostridium perfringensRstA ortholog and a multispecies chimeric RstA protein revealed that theC. difficileC-terminal domain is required for RstA DNA-binding activity, suggesting that species-specific signaling controls RstA function. Our data demonstrate that RstA is a transcriptional repressor that autoregulates its own expression and directly inhibits transcription of the two toxin genes and two positive toxin regulators, thereby acting at multiple regulatory points to control toxin production.IMPORTANCEClostridioides difficileis an anaerobic, gastrointestinal pathogen of humans and other mammals.C. difficileproduces two major toxins, TcdA and TcdB, which cause the symptoms of the disease, and forms dormant endospores to survive the aerobic environment outside the host. A recently discovered regulatory factor, RstA, inhibits toxin production and positively influences spore formation. Herein, we determine that RstA directly binds its own promoter DNA to repress its own gene transcription. In addition, our data demonstrate that RstA directly represses toxin gene expression and gene expression of two toxin gene activators, TcdR and SigD, creating a complex regulatory network to tightly control toxin production. This study provides a novel regulatory link betweenC. difficilesporulation and toxin production. Further, our data suggest thatC. difficiletoxin production is regulated through a direct, species-specific sensing mechanism.

scholarly journals Strain-Dependent RstA Regulation of Clostridioides difficile Toxin Production and Sporulation

2019 ◽  
Vol 202 (2) ◽  
Author(s):  
Adrianne N. Edwards ◽  
Ellen G. Krall ◽  
Shonna M. McBride
Keyword(s):  
Gene Expression ◽  
Gastrointestinal Tract ◽  
Toxin Production ◽  
Spore Formation ◽  
Toxin Gene ◽  
Disease Symptoms ◽  
Content Type ◽  
Clostridioides Difficile ◽  
Toxin Gene Expression ◽  
Strain Dependent

ABSTRACT The anaerobic spore former Clostridioides difficile causes significant diarrheal disease in humans and other mammals. Infection begins with the ingestion of dormant spores, which subsequently germinate within the host gastrointestinal tract. There, the vegetative cells proliferate and secrete two exotoxins, TcdA and TcdB, which cause disease symptoms. Although spore formation and toxin production are critical for C. difficile pathogenesis, the regulatory links between these two physiological processes are not well understood and are strain dependent. Previously, we identified a conserved C. difficile regulator, RstA, that promotes sporulation initiation through an unknown mechanism and directly and indirectly represses toxin and motility gene transcription in the historical isolate 630Δerm. To test whether perceived strain-dependent differences in toxin production and sporulation are mediated by RstA, we created an rstA mutant in the epidemic ribotype 027 strain R20291. RstA affected sporulation and toxin gene expression similarly but more robustly in R20291 than in 630Δerm. In contrast, no effect on motility gene expression was observed in R20291. Reporter assays measuring transcriptional regulation of tcdR, the sigma factor gene essential for toxin gene expression, identified sequence-dependent effects influencing repression by RstA and CodY, a global nutritional sensor, in four diverse C. difficile strains. Finally, sequence- and strain-dependent differences were evident in RstA negative autoregulation of rstA transcription. Altogether, our data suggest that strain-dependent differences in RstA regulation contribute to the sporulation and toxin phenotypes observed in R20291. Our data establish RstA as an important regulator of C. difficile virulence traits. IMPORTANCE Two critical traits of Clostridioides difficile pathogenesis are toxin production, which causes disease symptoms, and spore formation, which permits survival outside the gastrointestinal tract. The multifunctional regulator RstA promotes sporulation and prevents toxin production in the historical strain 630Δerm. Here, we show that RstA exhibits stronger effects on these phenotypes in an epidemic isolate, R20291, and additional strain-specific effects on toxin and rstA expression are evident. Our data demonstrate that sequence-specific differences within the promoter for the toxin regulator TcdR contribute to the regulation of toxin production by RstA and CodY. These sequence differences account for some of the variability in toxin production among isolates and may allow strains to differentially control toxin production in response to a variety of signals.

scholarly journals RstA Regulation ofClostridioides difficileToxin Production and Sporulation in Phenotypically Diverse Strains

2019 ◽  
Author(s):  
Adrianne N. Edwards ◽  
Ellen G. Krall ◽  
Shonna M. McBride
Keyword(s):  
Gene Expression ◽  
Gastrointestinal Tract ◽  
Diarrheal Disease ◽  
Toxin Production ◽  
Toxin Gene ◽  
Disease Symptoms ◽  
Clostridioides Difficile ◽  
Sequence Dependent ◽  
Toxin Gene Expression ◽  
Strain Dependent

ABSTRACTThe anaerobic spore-former,Clostridioides difficile, causes significant diarrheal disease in humans and other mammals. Infection begins with the ingestion of dormant spores which subsequently germinate within the host gastrointestinal tract. Here, the vegetative cells proliferate and secrete two exotoxins, TcdA and TcdB, which cause disease symptoms. Although spore formation and toxin production are critical forC. difficilepathogenesis, the regulatory links between these two physiological processes are not well understood and are strain-dependent. Previously, we identified a conservedC. difficileregulator, RstA, that promotes sporulation initiation through an unknown mechanism and directly and indirectly represses toxin gene transcription in the historical isolate, 630Δerm. To test whether perceived strain-dependent differences in toxin production and sporulation are mediated by RstA, we created anrstAmutant in the epidemic 027 ribotype strain, R20291. RstA affects sporulation and toxin gene expression similarly in R20291, although more robust regulatory effects are observed in this strain than in 630Δerm. Reporter assays measuring transcriptional regulation oftcdR, the sigma factor essential for toxin gene expression, identified sequence-dependent effects influencing repression by RstA and CodY, a global nutritional sensor, in four diverseC. difficilestrains. We provide evidence that RstA contributes totcdRbistability in R20291 by biasing cells to a toxin-OFF state. Finally, sequence-dependent and strain-dependent differences were evident in RstA negative autoregulation ofrstAtranscription. Our data establish RstA as an important regulator ofC. difficilevirulence traits, and implicate RstA as a contributor to the variety of sporulation and toxin phenotypes observed in distinct isolates.IMPORTANCETwo critical traits ofClostridioides difficilepathogenesis are the production of toxins, which cause disease symptoms, and the formation of spores, which permit survival outside of the gastrointestinal tract. The multifunctional regulator, RstA, promotes sporulation and prevents toxin production in the historical strain, 630Δerm. Here, we show that RstA functions similarly in an epidemic isolate, R20291, although strain-specific effects on toxin andrstAexpression are evident. Our data demonstrate that sequence-specific differences within the promoter for the toxin regulator, TcdR, contribute to regulation of toxin production by RstA and CodY. These sequence differences account for some of the variability in toxin production among isolates, and may allow strains to differentially control toxin production in response to a variety of signals.

Steroid receptor-mediated inhibition of rat prolactin gene expression does not require the receptor DNA-binding domain

Cell ◽  
1988 ◽  
Vol 52 (5) ◽  
pp. 685-695 ◽  
Author(s):  
Stuart Adler ◽  
Marian L. Waterman ◽  
Xi He ◽  
Michael G. Rosenfeld
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Steroid Receptor ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Prolactin Gene

scholarly journals Adaptive evolution of transcription factor binding affinities

2017 ◽  
Author(s):  
Jungeui Hong ◽  
Nathan Brandt ◽  
Ally Yang ◽  
Tim Hughes ◽  
David Gresham
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Dna Binding ◽  
Adaptive Evolution ◽  
Consensus Sequence ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Missense Mutations ◽  
Binding Affinities ◽  
Synonymous Mutations

Understanding the molecular basis of gene expression evolution is a central problem in evolutionary biology. However, connecting changes in gene expression to increased fitness, and identifying the functional basis of those changes, remains challenging. To study adaptive evolution of gene expression in real time, we performed long term experimental evolution (LTEE) of Saccharomyces cerevisiae (budding yeast) in ammonium-limited chemostats. Following several hundred generations of continuous selection we found significant divergence of nitrogen-responsive gene expression in lineages with increased fitness. In multiple independent lineages we found repeated selection for non-synonymous mutations in the zinc finger DNA binding domain of the activating transcription factor (TF), GAT1, that operates within incoherent feedforward loops to control expression of the nitrogen catabolite repression (NCR) regulon. Missense mutations in the DNA binding domain of GAT1 reduce its binding affinity for the GATAA consensus sequence in a promoter-specific manner, resulting in increased expression of ammonium permease genes via both direct and indirect effects, thereby conferring increased fitness. We find that altered transcriptional output of the NCR regulon results in antagonistic pleiotropy in alternate environments and that the DNA binding domain of GAT1 is subject to purifying selection in natural populations. Our study shows that adaptive evolution of gene expression can entail tuning expression output by quantitative changes in TF binding affinities while maintaining the overall topology of a gene regulatory network.

scholarly journals AguR Is Required for Induction of the Streptococcus mutans Agmatine Deiminase System by Low pH and Agmatine

2009 ◽  
Vol 75 (9) ◽  
pp. 2629-2637 ◽  
Author(s):  
Yaling Liu ◽  
Lin Zeng ◽  
Robert A. Burne
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Streptococcus Mutans ◽  
Low Ph ◽  
Binding Domain ◽  
Negative Regulator ◽  
Dna Binding Domain ◽  
Mutant Proteins ◽  
Acidic Conditions ◽  
Agmatine Deiminase

ABSTRACT Acidic conditions and the presence of exogenous agmatine are required to achieve maximal expression of the agmatine deiminase system (AgDS) of Streptococcus mutans. Here we demonstrate that the transcriptional activator of the AgDS, AguR, is required for the responses to agmatine and to low pH. Linker scanning mutagenesis was used to create a panel of mutated aguR genes that were utilized to complement an aguR deletion mutant of S. mutans. The level of production of the mutant proteins was shown to be comparable to that of the wild-type AguR protein. Mutations in the predicted DNA binding domain of AguR eliminated activation of the agu operon. Insertions into the region connecting the DNA binding domain to the predicted extracellular and transmembrane domains were well tolerated. In contrast, a variety of mutants were isolated that had a diminished capacity to respond to low pH but retained the ability to activate AgDS gene expression in response to agmatine, and vice versa. Also, a number of mutants were unable to respond to either agmatine or low pH. AguD, which is a predicted agmatine-putrescine antiporter, was found to be a negative regulator of AgDS gene expression in the absence of exogenous agmatine but was not required for low-pH induction of the AgDS genes. This study reveals that the control of AgDS gene expression by both agmatine and low pH is coordinated through the AguR protein and begins to identify domains of the protein involved in sensing and signaling.

scholarly journals An IFN regulatory factor-2 DNA-binding domain dominant negative mutant exhibits altered cell growth and gene expression

Oncogene ◽  
2000 ◽  
Vol 19 (11) ◽  
pp. 1411-1418 ◽  
Author(s):  
Y R Rubinstein ◽  
P H Driggers ◽  
V V Ogryzko ◽  
A M Thornton ◽  
K Ozato ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Growth ◽  
Dna Binding ◽  
Binding Domain ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Dna Binding Domain ◽  
Regulatory Factor ◽  
Altered Cell ◽  
Negative Mutant

Deletion and overexpression of the Aspergillus nidulans GATA factor AreB reveals unexpected pleiotropy

Microbiology ◽  
2009 ◽  
Vol 155 (12) ◽  
pp. 3868-3880 ◽  
Author(s):  
Koon Ho Wong ◽  
Michael J. Hynes ◽  
Richard B. Todd ◽  
Meryl A. Davis
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Aspergillus Nidulans ◽  
Zinc Finger ◽  
Leucine Zipper ◽  
Binding Domain ◽  
Negative Regulator ◽  
Dna Binding Domain ◽  
Gata Factor ◽  
Nitrogen Acquisition

The Aspergillus nidulans transcription factor AreA is a key regulator of nitrogen metabolic gene expression. AreA contains a C-terminal GATA zinc finger DNA-binding domain and activates expression of genes necessary for nitrogen acquisition. Previous studies identified AreB as a potential negative regulator of nitrogen catabolism showing similarity with Penicillium chrysogenum NreB and Neurospora crassa ASD4. The areB gene encodes multiple products containing an N-terminal GATA zinc finger and a leucine zipper motif. We deleted the areB gene and now show that AreB negatively regulates AreA-dependent nitrogen catabolic gene expression under nitrogen-limiting or nitrogen-starvation conditions. AreB also acts pleiotropically, with functions in growth, conidial germination and asexual development, though not in sexual development. AreB overexpression results in severe growth inhibition, aberrant cell morphology and reduced AreA-dependent gene expression. Deletion of either the DNA-binding domain or the leucine zipper domain results in loss of both nitrogen and developmental phenotypes.

scholarly journals Involvement of the Multidomain Regulatory Protein XynR in Positive Control of Xylanase Gene Expression in the Ruminal Anaerobe Prevotella bryantii B14

2003 ◽  
Vol 185 (7) ◽  
pp. 2219-2226 ◽  
Author(s):  
Kohji Miyazaki ◽  
Hiroyuki Miyamoto ◽  
Derry K. Mercer ◽  
Tatsuaki Hirase ◽  
Jennifer C. Martin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Transmembrane Domain ◽  
Regulatory Protein ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Xylanase Gene ◽  
Prevotella Bryantii ◽  
Genes Encoding

ABSTRACT The xylanase gene cluster from the rumen anaerobe Prevotella bryantii B14 was found to include a gene (xynR) that encodes a multidomain regulatory protein and is downstream from the xylanase and β-xylosidase genes xynA and xynB. Additional genes identified upstream of xynA and xynB include xynD, which encodes an integral membrane protein that has homology with Na:solute symporters; xynE, which is related to the genes encoding acylhydrolases and arylesterases; and xynF, which has homology with the genes encoding α-glucuronidases. XynR includes, in a single 833-amino-acid polypeptide, a putative input domain unrelated to other database sequences, a likely transmembrane domain, histidine kinase motifs, response regulator sequences, and a C-terminal AraC-type helix-turn-helix DNA binding domain. Two transcripts (3.7 and 5.8 kb) were detected with a xynA probe, and the start site of the 3.7-kb transcript encoding xynABD was mapped to a position upstream of xynD. The DNA binding domain of XynR was purified after amplification and overexpression in Escherichia coli and was found to bind to a 141-bp DNA fragment from the region immediately upstream of xynD. In vitro transcription assays demonstrated that XynR stimulates transcription of the 3.7-kb transcript. We concluded that XynR acts as a positive regulator that activates expression of xynABD in P. bryantii B14. This is the first regulatory protein that demonstrates significant homology with the two-component regulatory protein superfamily and has been shown to be involved in the regulation of polysaccharidase gene expression.

scholarly journals Dynamic Cell Type Specificity of SRC-1 Coactivator in Modulating Uterine Progesterone Receptor Function in Mice

2005 ◽  
Vol 25 (18) ◽  
pp. 8150-8165 ◽  
Author(s):  
Sang Jun Han ◽  
Jaewook Jeong ◽  
Francesco J. DeMayo ◽  
Jianming Xu ◽  
Sophia Y. Tsai ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Progesterone Receptor ◽  
Gene Transcription ◽  
Fluorescent Protein ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Female Reproduction ◽  
Functional Relationships ◽  
A Cell

ABSTRACT Regulation of gene transcription by the progesterone receptor (PR) in cooperation with coactivator/corepressor complexes coordinates crucial processes in female reproduction. To investigate functional relationships between PR and steroid receptor coactivators (SRCs) in distinct cell types of uterine tissue during gene transcription, we generated a new transgenic mouse model utilizing a Progesterone Receptor Activity Indicator (PRAI) system that could monitor PR activity in vivo. The PRAI system consists of a modified PR bacterial artificial chromosome (BAC) clone in which the DNA binding domain of the PR was replaced with the yeast Gal4 DNA binding domain. A humanized green fluorescent protein (hrGFP) reporter controlled by the Upstream Activating Sequences for the Gal4 gene (UASG) was inserted in tandem with the modified PR gene. Expression of hrGFP in the uterus demonstrated that the PRAI animal model faithfully replicated PR signaling under various endocrine states. Bigenic PRAI-SRC-1−/− mice revealed that SRC-1 modulates PR activity in the uterus in a cell-specific fashion and is involved in PR gene activation in stroma and myometrium of the uterus in response to estrogen and progesterone. In contrast, SRC-1 was involved in the down-regulation of PR target gene expression in the luminal and glandular epithelial compartments of the uterus after chronic progesterone treatment. Finally, we dissected the means by which SRC-1 dynamically regulates PR activity in each uterine cell compartment and demonstrated that it involves the differential ability of SRC-1 to modulate expression levels of distinct coactivators, corepressors, and PR in a cell-specific fashion.

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