scholarly journals Modulation of covR Expression in Streptococcus mutans UA159

2008 ◽  
Vol 190 (13) ◽  
pp. 4478-4488 ◽  
Author(s):  
Patrick Chong ◽  
Laura Drake ◽  
Indranil Biswas
Keyword(s):  
Dental Caries ◽  
Streptococcus Mutans ◽  
Growth Phase ◽  
Response Regulator ◽  
Transcriptional Start Site ◽  
Site Directed Mutagenesis ◽  
Start Codon ◽  
Pcr Analysis ◽  
Exponential Growth Phase ◽  
Mobility Shift

ABSTRACT The biofilm-forming Streptococcus mutans is a gram-positive bacterium that resides in the human oral cavity and is considered to be the primary etiological agent in the formation of dental caries. The global response regulator CovR, which lacks a cognate sensor kinase, is essential for the pathogenesis and biofilm formation of this bacterium, but it is not clear how covR expression is regulated in S. mutans. In this communication, we present the results of our studies examining various factors that regulate the expression of covR in S. mutans UA159. The results of Southern hybridization and PCR analysis indicated that CovR is an orphan response regulator in various isolates of S. mutans. The transcriptional start site for covR was found to be 221 base pairs upstream of the ATG start codon, and site-directed mutagenesis of the upstream TATAAT box confirmed our findings. The expression of covR is growth phase dependent, with maximal expression observed during exponential-growth phase. While changes to the growth temperature did not significantly affect the expression of covR, increasing the pH or the concentration of Mg2+ in the growth medium leads to an increase in covR expression. The results of semiquantitative reverse transcriptase PCR analysis and in vivo transcriptional-fusion reporter assays indicated that CovR autoregulates its own expression; this was verified by the results of electrophoretic mobility shift assays and DNase I protection assays, which demonstrated direct binding of CovR to the promoter region. Apparently, regulation by Mg2+ and the autoregulation of covR are not linked. A detailed analysis of the regulation of CovR may lead to a better understanding of the pathogenesis of S. mutans, as well as providing further insight into the prevention of dental caries.

scholarly journals Regulation of gbpC Expression in Streptococcus mutans

2007 ◽  
Vol 189 (18) ◽  
pp. 6521-6531 ◽  
Author(s):  
Indranil Biswas ◽  
Laura Drake ◽  
Saswati Biswas
Keyword(s):  
Streptococcus Mutans ◽  
Dna Sequences ◽  
Promoter Region ◽  
Response Regulator ◽  
Surface Protein ◽  
Maximum Level ◽  
Stress Conditions ◽  
Pcr Analysis ◽  
Exponential Growth Phase ◽  
Transcriptional Level

ABSTRACT Streptococcus mutans, the principal causative agent of dental caries, produces four glucan-binding proteins (Gbp) that play major roles in bacterial adherence and pathogenesis. One of these proteins, GbpC, is an important cell surface protein involved in biofilm formation. GbpC is also important for cariogenesis, bacteremia, and infective endocarditis. In this study, we examined the regulation of gbpC expression in S. mutans strain UA159. We found that gbpC expression attains the maximum level at mid-exponential growth phase, and the half-life of the transcript is less than 2 min. Expression from PgbpC was measured using a PgbpC-gusA transcriptional fusion reporter and was analyzed under various stress conditions, including thermal, osmotic, and acid stresses. Expression of gbpC is induced under conditions of thermal stress but is repressed during growth at low pH, whereas osmotic stress had no effect on expression from PgbpC. The results from the expression analyses were further confirmed using semiquantitative reverse transcription-PCR analysis. Our results also reveal that CovR, a global response regulator in many Streptococcus spp., represses gbpC expression at the transcriptional level. We demonstrated that purified CovR protein binds directly to the promoter region of PgbpC to repress gbpC expression. Using a DNase I protection assay, we showed that CovR binds to DNA sequences surrounding PgbpC from bases −68 to 28 (where base 1 is the start of transcription). In summary, our results indicate that various stress conditions modulate the expression of gbpC and that CovR negatively regulates the expression of the gbpC gene by directly binding to the promoter region.

scholarly journals FxkR Provides the Missing Link in the fixL-fixK Signal Transduction Cascade in Rhizobium etli CFN42

2012 ◽  
Vol 25 (11) ◽  
pp. 1506-1517 ◽  
Author(s):  
David Zamorano-Sánchez ◽  
Alma Reyes-González ◽  
Nicolás Gómez-Hernández ◽  
Patricia Rivera ◽  
Dimitris Georgellis ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Transcriptional Control ◽  
Response Regulator ◽  
Transcriptional Start Site ◽  
Site Directed Mutagenesis ◽  
Rhizobium Etli ◽  
Mobility Shift ◽  
Gene Encoding ◽  
Reading Frame ◽  
Electrophoretic Mobility Shift Assays

Transcriptional control of the fixK gene in Rhizobium etli and R. leguminosarum bv. viciae is governed by a two-component signal transduction system that diverts from the conventional FixL-FixJ cascade that occurs in model rhizobia. Although a fixL gene, encoding a hybrid histidine kinase (hFixL), is present in R. etli, no fixJ, the cognate response regulator, has been identified. In this work, we present evidence that the pRet42f-located open reading frame RHE_PF00530 (fxkR) encodes a novel response regulator indispensable for fixKf activation under microaerobic growth. Moreover, results from complementation assays demonstrate that the activation of fixKf expression requires the presence of both hFixL and FxkR, and that the fxkR ortholog from R. leguminosarum bv. viciae is able to substitute for FxkR transcriptional control in R. etli. In addition, in these two organisms, hFixL- and FxkR-related proteins were identified in other bacteria, located in close proximity to a fixK-related gene. Using reporter fusions, site-directed mutagenesis, and electrophoretic mobility shift assays, we identified the FxkR binding site upstream from the transcriptional start site of fixKf. Similar to our previous observations for fixL and fixKf mutants, a null mutation in fxkR does not affect the symbiotic effectiveness of the strain. Thus, our findings reveal that FxkR is the long-standing missing key regulator that allows the transduction of the microaerobic signal for the activation of the FixKf regulon.

scholarly journals Regulation of Swarming Motility and flhDCSm Expression by RssAB Signaling in Serratia marcescens

2008 ◽  
Vol 190 (7) ◽  
pp. 2496-2504 ◽  
Author(s):  
Po-Chi Soo ◽  
Yu-Tze Horng ◽  
Jun-Rong Wei ◽  
Jwu-Ching Shu ◽  
Chia-Chen Lu ◽  
...  
Keyword(s):  
Serratia Marcescens ◽  
Binding Site ◽  
Promoter Region ◽  
Transcriptional Start Site ◽  
Direct Interaction ◽  
Underlying Mechanism ◽  
Inhibitory Effect ◽  
Start Codon ◽  
Mobility Shift

ABSTRACT Serratia marcescens cells swarm at 30°C but not at 37°C, and the underlying mechanism is not characterized. Our previous studies had shown that a temperature upshift from 30 to 37°C reduced the expression levels of flhDCSm and hagSm in S. marcescens CH-1. Mutation in rssA or rssB, cognate genes that comprise a two-component system, also resulted in precocious swarming phenotypes at 37°C. To further characterize the underlying mechanism, in the present study, we report that expression of flhDCSm and synthesis of flagella are significantly increased in the rssA mutant strain at 37°C. Primer extension analysis for determination of the transcriptional start site(s) of flhDCSm revealed two transcriptional start sites, P1 and P2, in S. marcescens CH-1. Characterization of the phosphorylated RssB (RssB∼P) binding site by an electrophoretic mobility shift assay showed direct interaction of RssB∼P, but not unphosphorylated RssB [RssB(D51E)], with the P2 promoter region. A DNase I footprinting assay using a capillary electrophoresis approach further determined that the RssB∼P binding site is located between base pair positions −341 and −364 from the translation start codon ATG in the flhDCSm promoter region. The binding site overlaps with the P2 “−35” promoter region. A modified chromatin immunoprecipitation assay was subsequently performed to confirm that RssB∼P binds to the flhDCSm promoter region in vivo. In conclusion, our results indicated that activated RssA-RssB signaling directly inhibits flhDCSm promoter activity at 37°C. This inhibitory effect was comparatively alleviated at 30°C. This finding might explain, at least in part, the phenomenon of inhibition of S. marcescens swarming at 37°C.

Matrix metalloproteinase-3 induction in rat brain astrocytes: focus on the role of two AP-1 elements

2008 ◽  
Vol 410 (3) ◽  
pp. 605-611 ◽  
Author(s):  
Kwang Soo Kim ◽  
Hee Young Kim ◽  
Eun-hye Joe ◽  
Ilo Jou
Keyword(s):  
Rat Brain ◽  
Interferon Γ ◽  
Site Directed Mutagenesis ◽  
Start Codon ◽  
Activator Protein 1 ◽  
Mobility Shift ◽  
Matrix Metalloproteinase 3 ◽  
Mitogen Activated Protein ◽  
Electrophoretic Mobility Shift Assays

Many brain cells secrete MMPs (matrix metalloproteinases), and increased or misregulated MMP levels are found in neurodegenerative disorders. Here we report that MMP-3 transcription and protein secretion were increased in rat brain astrocytes stimulated with lipopolysaccharide, gangliosides or interferon-γ. Sequential deletion of the MMP-3 promoter revealed that sequences between −0.5 kb and the start codon were crucial for the transcriptional induction of MMP-3. In addition, experiments using pharmacological inhibitors of individual mitogen-activated protein kinases revealed that MMP-3 induction and promoter activity involved Jun N-terminal kinase, a representative upstream signal of AP-1 (activator protein-1). Sequence analyses of the region of the MMP-3 promoter 500 bp from the start codon indicated the presence of three AP-1 binding sequences. Among them, electrophoretic-mobility-shift assays as well as site-directed mutagenesis of individual AP-1 sequences revealed that distal and middle, but not proximal, sequences largely mediated its induction. Together, these results indicate that AP-1 could control MMP-3 induction in brain astrocytes and that its regulation through specific AP-1 elements could be exploited in the treatment of brain pathologies in which increased expression of MMP-3 plays crucial roles.

scholarly journals Involvement of the Detoxifying Enzyme Lactoylglutathione Lyase in Streptococcus mutans Aciduricity

2007 ◽  
Vol 189 (21) ◽  
pp. 7586-7592 ◽  
Author(s):  
Bryan Korithoski ◽  
Céline M. Lévesque ◽  
Dennis G. Cvitkovitch
Keyword(s):  
Streptococcus Mutans ◽  
Growth Phase ◽  
Proteome Analysis ◽  
Stationary Growth Phase ◽  
Low Ph ◽  
Transcriptional Analysis ◽  
Exponential Growth Phase ◽  
Expression Studies ◽  
Insertional Inactivation ◽  
Gene Expression Studies

ABSTRACT Streptococcus mutans, a normal inhabitant of dental plaque, is considered a primary etiological agent of dental caries. Its main virulence factors are acidogenicity and aciduricity, the abilities to produce acid and to survive and grow at low pH, respectively. Metabolic processes are finely regulated following acid exposure in S. mutans. Proteome analysis of S. mutans demonstrated that lactoylglutathione lyase (LGL) was up-regulated during acid challenge. The LGL enzyme catalyzes the conversion of toxic methylglyoxal, derived from glycolysis, to S-d-lactoylglutathione. Methylglyoxal inhibits the growth of cells in all types of organisms. The current study aimed to investigate the relationship between LGL and aciduricity and acidogenicity in S. mutans. An S. mutans isogenic mutant defective in lgl (LGLKO) was created, and its growth kinetics were characterized. Insertional inactivation of lgl resulted in an acid-sensitive phenotype. However, the glycolytic rate at pH 5.0 was greater for LGLKO than for S. mutans UA159 wild-type cells. LGL was involved in the detoxification of methylglyoxal, illustrated by the absence of enzyme activity in LGLKO and the hypersensitivity of LGLKO to methylglyoxal, compared with UA159 (MIC of 3.9 and 15.6 mM, respectively). Transcriptional analysis of lgl conducted by quantitative real-time PCR revealed that lgl was up-regulated (approximately sevenfold) during the exponential growth phase compared with that in the stationary growth phase. Gene expression studies conducted at low pH demonstrated that lgl was induced during acidic growth (∼3.5-fold) and following acid adaptation (∼2-fold).This study demonstrates that in S. mutans, LGL functions in the detoxification of methylglyoxal, resulting in increased aciduricity.

IL-1β induces eotaxin gene transcription in A549 airway epithelial cells through NF-κB

2000 ◽  
Vol 279 (6) ◽  
pp. L1058-L1065 ◽  
Author(s):  
Sean Jedrzkiewicz ◽  
Hidetoshi Nakamura ◽  
Eric S. Silverman ◽  
Andrew D. Luster ◽  
Naresh Mansharamani ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Transcriptional Activation ◽  
Transcriptional Start Site ◽  
Nuclear Factor Κb ◽  
Airway Epithelial Cells ◽  
Site Directed Mutagenesis ◽  
Airway Epithelial ◽  
Mobility Shift ◽  
Mobility Shift Assay ◽  
Necessary And Sufficient

Eotaxin is an asthma-related C-C chemokine that is produced in response to interleukin-1β (IL-1β). We detected an increase in newly transcribed eotaxin mRNA in IL-1β-stimulated airway epithelial cells. Transient transfection assays using promoter-reporter constructs identified a region as essential for IL-1β-induced increases in eotaxin transcription. Using site-directed mutagenesis, we found that a nuclear factor-κB (NF-κB) site located 46 bp upstream from the transcriptional start site was both necessary and sufficient for IL-1β induction of reporter construct activity. Electrophoretic mobility shift assay demonstrated that IL-1β-stimulated airway epithelial cells produced p50 and p65 protein that bound this site in a sequence-specific manner. The functional importance of the NF-κB site was demonstrated by coexpression experiments in which increasing doses of p65 expression vector were directly associated with reporter activity exclusively in constructs with an intact NF-κB site ( r 2 = 0.97, P = 0.002). Moreover, IL-1β-induced increases in eotaxin mRNA expression are inhibited by inhibitors of NF-κB. Our findings implicate NF-κB and its binding sequence in IL-1β-induced transcriptional activation of the eotaxin gene.

Transcriptional regulation of human abraxas brother protein 1 expression by yin yang 1

2020 ◽  
Author(s):  
Pan Song ◽  
Jian Hong ◽  
Yuan Wang ◽  
Xuelian Yao ◽  
Yiqun Zhan ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transcriptional Regulation ◽  
Transcriptional Start Site ◽  
Regulatory Elements ◽  
Start Codon ◽  
Mobility Shift ◽  
Cis Acting ◽  
Yin Yang 1 ◽  
Activating Transcription Factor 4 ◽  
Yin Yang

Abraxas brother protein 1 (ABRO1) is a subunit of the deubiquitinating enzyme BRCC36-containing isopeptidase complex and plays important roles in cellular responses to stress by interacting with its binding partners, such as ubiquitin-specific peptidase 7, p53, activating transcription factor 4, THAP-domain containing 5, and serine hydroxymethyltransferase. However, the transcriptional regulation of ABRO1 remains unexplored. In this study, we identified and characterized the core regulatory elements of the human ABRO1 gene and mapped them to the ABRO1 promoter region. Additionally, 5′ rapid amplification of cDNA ends revealed that the transcriptional start site (TSS) was located −13 bp upstream from the start codon. Reporter gene, chromatin immunoprecipitation, and electrophoretic mobility shift assays demonstrated that ABRO1 transcription was regulated through cis-acting elements located in the region −89 to −59 bp upstream of the ABRO1 TSS and that these elements were targeted by yin yang 1 transcription factor (YY1). Moreover, YY1 overexpression increased human ABRO1 mRNA and protein expression, and small-interfering RNA-mediated downregulation of YY1 attenuated ABRO1 expression. These results suggested that YY1 positively regulated human ABRO1 expression by binding to cis-acting elements located in the ABRO1 TSS.

scholarly journals The VirR Response Regulator from Clostridium perfringens Binds Independently to Two Imperfect Direct Repeats Located Upstream of the pfoA Promoter

2000 ◽  
Vol 182 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Jackie K. Cheung ◽  
Julian I. Rood
Keyword(s):  
Binding Site ◽  
Clostridium Perfringens ◽  
Response Regulator ◽  
Toxin Production ◽  
Site Directed Mutagenesis ◽  
Direct Repeats ◽  
Mobility Shift ◽  
Perfringolysin O ◽  
Dnase I Footprinting ◽  
Gel Mobility Shift

ABSTRACT Regulation of toxin production in the gram-positive anaerobeClostridium perfringens occurs at the level of transcription and involves a two-component signal transduction system. The sensor histidine kinase is encoded by the virS gene, while its cognate response regulator is encoded by the virRgene. We have constructed a VirR expression plasmid inEscherichia coli and purified the resultant His-tagged VirR protein. Gel mobility shift assays demonstrated that VirR binds to the region upstream of the pfoA gene, which encodes perfringolysin O, but not to regions located upstream of the VirR-regulated plc, colA, and pfoRgenes, which encode alpha-toxin, collagenase, and a putativepfoA regulator, respectively. The VirR binding site was shown by DNase I footprinting to be a 52-bp core sequence situated immediately upstream of the pfoA promoter. When this region was deleted, VirR was no longer able to bind to the pfoApromoter. The binding site was further localized to two imperfect direct repeats (CCCAGTTNTNCAC) by site-directed mutagenesis. Binding and protection analysis of these mutants indicated that VirR had the ability to bind independently to the two repeated sequences. Based on these observations it is postulated that the VirR positively regulates the synthesis of perfringolysin O by binding directly to a region located immediately upstream of the pfoA promoter and activating transcription.

scholarly journals Dual Role of the PhoP∼P Response Regulator: Bacillus amyloliquefaciens FZB45 Phytase Gene Transcription Is Directed by Positive and Negative Interactions with the phyC Promoter

2006 ◽  
Vol 188 (19) ◽  
pp. 6953-6965 ◽  
Author(s):  
Oliwia Makarewicz ◽  
Sarah Dubrac ◽  
Tarek Msadek ◽  
Rainer Borriss
Keyword(s):  
Transcription Initiation ◽  
Bacillus Amyloliquefaciens ◽  
Promoter Region ◽  
Response Regulator ◽  
Transcriptional Start Site ◽  
Consensus Sequence ◽  
Start Codon ◽  
In Vitro Assays ◽  
Unusual Structure ◽  
Phytase Gene

ABSTRACT Several Bacillus strains secrete phytase, an enzyme catalyzing dephosphorylation of myo-inositol hexakisphosphate (phytate). We identified the phyC (phytase) gene from environmental Bacillus amyloliquefaciens FZB45 as a member of the phosphate starvation-inducible PhoPR regulon. In vivo and in vitro assays revealed that PhoP∼P is essential for phyC transcription. The transcriptional start site was identified downstream of a σA-like promoter region located 27 bp upstream of the probable translation ATG start codon. Inspection of the phyC promoter sequence revealed an unusual structure. The− 35 and −10 regions are separated by a window of 21 bp. A pair of tandemly repeated PhoP TT(T/A/C)ACA binding boxes was located within and upstream of the −35 consensus promoter region. A single PhoP box was found within the −10 consensus promoter region. DNase I footprinting experiments performed with isolated PhoP confirmed that PhoP∼P binds at two sites overlapping with the phyC −35 and −10 consensus promoter region. While binding of dimeric PhoP∼P at −35 is essential for activation of the phyC promoter, binding of PhoP∼P at− 10 suppresses promoter activity. A sixfold enhancement of phyC gene expression was registered after T:G substitution of nucleotide −13 (mutant MUT13), which eliminates PhoP binding at the single PhoP box without impairing the −10 consensus sequence. Moreover, MUT13 also expressed phyC during phosphate-replete growth, suggesting that the repressing effect due to binding of PhoP∼P at −10 was abolished. A model is presented in which transcription initiation of phyC is positively and negatively affected by the actual concentration of the PhoP∼P response regulator.

scholarly journals LiaS Regulates Virulence Factor Expression in Streptococcus mutans

2008 ◽  
Vol 76 (7) ◽  
pp. 3093-3099 ◽  
Author(s):  
Patrick Chong ◽  
Laura Drake ◽  
Indranil Biswas
Keyword(s):  
Streptococcus Mutans ◽  
Response Regulator ◽  
Pcr Analysis ◽  
Virulence Determinants ◽  
Response Regulators ◽  
Reverse Transcription Pcr ◽  
Sensor Kinases ◽  
Constant State ◽  
Peptide Component ◽  
Cognate Response Regulator

ABSTRACT Streptococcus mutans, a major oral pathogen responsible for dental caries formation, possesses a variety of mechanisms for survival in the human oral cavity, where the conditions of the external environment are diverse and in a constant state of flux. The formation of biofilms, survival under conditions of acidic pH, and production of mutacins are considered to be important virulence determinants displayed by this organism. Biofilm formation is facilitated by the production of GbpC, an important cell surface-associated protein that binds to glucan, an adhesive polysaccharide produced by the organism itself. To better understand the nature of the environmental cues that induce GbpC production, we examined the roles of 14 sensor kinases in the expression of gbpC in S. mutans strain UA159. We found that only the LiaS sensor kinase regulates gbpC expression, while the other sensor kinases had little or no effect on gbpC expression. We also found that while LiaS negatively regulates gbpC expression, the inactivation of its cognate response regulator, LiaR, does not appear to affect the expression of gbpC. Since both gbpC expression and mutacin IV production are regulated by a common regulatory network, we also tested the effect of the liaS mutation on mutacin production and found that LiaS positively regulates mutacin IV production. Furthermore, reverse transcription-PCR analysis suggests that LiaS does so by regulating the expression of nlmA, which encodes a peptide component of mutacin IV, and nlmT, which encodes an ABC transporter. As with the expression of gbpC, LiaR did not have any apparent effect on mutacin IV production. Based on the results of our study, we speculate that LiaS is engaged in cross talk with one or more response regulators belonging to the same family as LiaR, enabling LiaS to regulate the expression of several genes coding for virulence factors.

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