scholarly journals Competence Inhibition by the XrpA Peptide Encoded Within thecomXGene ofStreptococcus mutans

2018 ◽  
Author(s):  
Justin Kaspar ◽  
Robert C. Shields ◽  
Robert A. Burne
Keyword(s):  
Cell Fate ◽  
Streptococcus Mutans ◽  
Competence Development ◽  
Negative Regulator ◽  
Coding Region ◽  
Master Regulator ◽  
Genetic Competence ◽  
Complex Regulation ◽  
Natural Genetic Competence

SUMMARYStreptococcus mutansdisplays complex regulation of natural genetic competence. Competence development inS. mutansis controlled by a peptide derived from ComS (XIP); which along with the cytosolic regulator ComR controls the expression of the alternative sigma factorcomX, the master regulator of competence development. Recently, a gene embedded within the coding region ofcomXwas discovered and designatedxrpA(comXregulatorypeptideA). XrpA was found to be an antagonist of ComX, but the mechanism was not established. In this study, we reveal through both genomic and proteomic techniques that XrpA is the first describe negative regulator of ComRS systems in streptococci. Transcriptomic and promoter activity assays in the ΔxrpAstrain revealed an up-regulation of genes controlled by both the ComR- and ComX-regulons. Anin vivoprotein crosslinking andin vitrofluorescent polarization assays confirmed that the N-terminal region of XrpA were found to be sufficient in inhibiting ComR-XIP complex binding to ECom-box located within thecomXpromoter. This inhibitory activity was sufficient for decreases in PcomXactivity, transformability and ComX accumulation. XrpA serving as a modulator of ComRS activity ultimately results in changes to subpopulation behaviors and cell fate during competence activation.ABBREVIATED SUMMARYStreptococcus mutansdisplays complex regulation of natural genetic competence, highlighted by a novel gene,xrpA, embedded within the coding region for the master regulator ComX. We show that XrpA modulates ComRS-dependent activation ofcomXexpression, resulting in changes to sub-population behaviors, including cell lysis. XrpA is the first described inhibitor of a ComRS system and, because it is unique toS. mutansit may be targetable to prevent diseases caused by this pathogen.

scholarly journals Natural Genetic Competence in Bacillus subtilis Natto OK2

2000 ◽  
Vol 182 (9) ◽  
pp. 2411-2415 ◽  
Author(s):  
Sayaka Ashikaga ◽  
Hideaki Nanamiya ◽  
Yoshiaki Ohashi ◽  
Fujio Kawamura
Keyword(s):  
Bacillus Subtilis ◽  
Base Change ◽  
Competence Development ◽  
Transformation Frequency ◽  
Genetic Competence ◽  
Natural Competence ◽  
Bacillus Subtilis Natto ◽  
High Transformation ◽  
Single Base Change ◽  
Natural Genetic Competence

ABSTRACT We isolated a Bacillus subtilis natto strain, designated OK2, from a lot of commercial fermented soybean natto and studied its ability to undergo natural competence development using acomG-lacZ fusion at the amyE locus. Although transcription of the late competence genes was not detected in theB. subtilis natto strain OK2 during competence development, these genes were constitutively transcribed in the OK2 strain carrying either the mecA or the clpC mutation derived from B. subtilis 168. In addition, both OK2 mutants exhibited high transformation frequencies, comparable with that observed for B. subtilis 168. Moreover, as expected from these results, overproduction of ComK derived from strain 168 in strain OK2 resulted in a high transformation frequency as well as in induction of the late competence genes. These results clearly indicated that ComK produced in both the mecA and clpC mutants of strain OK2 (ComKOK2) could activate the transcription of the whole set of late competence genes and suggested that ComKOK2 was not activated in strain OK2 during competence development. We therefore sequenced the comS gene of OK2 and compared it with that of 168. The comS OK2had a single-base change, resulting in the replacement of Ser (strain 168) by Cys (strain OK2) at position 11.

scholarly journals Structural characterization of the late competence protein ComFB from Bacillus subtilis

2015 ◽  
Vol 35 (2) ◽  
Author(s):  
Tatyana A. Sysoeva ◽  
Lukas B. Bane ◽  
Daphne Y. Xiao ◽  
Baundauna Bose ◽  
Scott S. Chilton ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Structural Characterization ◽  
Competence Development ◽  
Regulatory Role ◽  
In Vivo Studies ◽  
Genetic Competence

Development of genetic competence in Bacillus subtilis results in expression of late competence genes, including comFB. In vitro and in vivo studies revealed that ComFB dimerizes, binds zinc, and possibly plays a regulatory role in competence development.

scholarly journals Increased oxidative stress tolerance of a spontaneously-occurring perR gene mutation in Streptococcus mutans UA159

2020 ◽  
Author(s):  
Jessica K. Kajfasz ◽  
Peter Zuber ◽  
Tridib Ganguly ◽  
Jacqueline Abranches ◽  
José A. Lemos
Keyword(s):  
Oxidative Stress ◽  
Streptococcus Mutans ◽  
Stress Responses ◽  
Transcriptional Repressor ◽  
Loss Of Function ◽  
Coding Region ◽  
Major Player ◽  
The Impact ◽  
Peroxide Stress

AbstractThe ability of bacteria such as the dental pathogen Streptococcus mutans to coordinate a response against damage-inducing oxidants is a critical aspect of their pathogenicity. The oxidative stress regulator SpxA1 has been proven to be a major player in the ability of S. mutans to withstand both disulfide and peroxide stresses. While studying spontaneously-occurring variants of an S. mutans ΔspxA1 strain, we serendipitously discovered that our S. mutans UA159 host strain bore a single nucleotide deletion within the coding region ofperR, resulting in a premature truncation of the encoded protein. PerR is a metal-dependent transcriptional repressor that senses and responds to peroxide stress such that loss of PerR activity results in activation of oxidative stress responses. To determine the impact of loss of PerR regulation, we obtained a UA159 isolated bearing an intact perR copy and created a clean perR deletion mutant. Our findings indicate that loss of PerR activity results in a strain that is primed to tolerate oxidative stresses in the laboratory setting. Interestingly, RNA-Seq and targeted transcriptional expression analyses reveal that PerR has a minor contribution to the ability of S. mutans to orchestrate a transcriptional response to peroxide stress. Furthermore, we detected loss-of-function perR mutations in two other commonly used laboratory strains of S. mutans suggesting that this may be not be an uncommon occurrence. This report serves as a cautionary warning regarding the so-called domestication of laboratory strains and advocates for the implementation of more stringent strain authentication practices.ImportanceA resident of the human oral biofilm, Streptococcus mutans is one of the major bacterial pathogens associated with dental caries. This report highlights a spontaneously-occurring mutation within the laboratory strain S. mutans UA159, found in the coding region of perR, a gene encoding a transcriptional repressor associated with peroxide tolerance. Though perR mutant strains of S. mutans showed a distinct growth advantage and enhanced tolerance toward H2O2, a ΔperR deletion strain showed a small number of differentially expressed genes as compared to the parent strain, suggesting few direct regulatory targets. In addition to characterizing the role of PerR in S. mutans, our findings serve as a warning to laboratory researchers regarding bacterial adaptation to in vitro growth conditions.

scholarly journals Regulation of Streptococcus pneumoniae clp Genes and Their Role in Competence Development and Stress Survival

2001 ◽  
Vol 183 (24) ◽  
pp. 7295-7307 ◽  
Author(s):  
Arnaud Chastanet ◽  
Marc Prudhomme ◽  
Jean-Pierre Claverys ◽  
Tarek Msadek
Keyword(s):  
Streptococcus Pneumoniae ◽  
Inducible Promoter ◽  
Competence Development ◽  
Negative Regulator ◽  
Chromosomal Dna ◽  
Signal Transduction System ◽  
Gene Encoding ◽  
Transposon Insertion ◽  
Two Component Signal Transduction

ABSTRACT In vitro mariner transposon mutagenesis ofStreptococcus pneumoniae chromosomal DNA was used to isolate regulatory mutants affecting expression of thecomCDE operon, encoding the peptide quorum-sensing two-component signal transduction system controlling competence development. A transposon insertion leading to increasedcomC expression was found to lie directly upstream from the S. pneumoniae clpP gene, encoding the proteolytic subunit of the Clp ATP-dependent protease, whose expression inBacillus subtilis is controlled by the CtsR repressor. In order to examine clp gene regulation in S. pneumoniae, a detailed analysis of the complete genome sequence was performed, indicating that there are five likely CtsR-binding sites located upstream from the clpE, clpP, andclpL genes and thectsR-clpC and groESLoperons. The S. pneumoniae ctsR gene was cloned under the control of an inducible promoter and used to demonstrate regulation of the S. pneumoniae clpP and clpE genes and the clpC and groESL operons by usingB. subtilis as a heterologous host. The CtsR protein ofS. pneumoniae was purified and shown to bind specifically to the clpP, clpC, clpE, andgroESL regulatory regions. S. pneumoniaeΔctsR, ΔclpP, ΔclpC, and ΔclpE mutants were constructed by gene deletion/replacement. ClpP was shown to act as a negative regulator, preventing competence gene expression under inappropriate conditions. Phenotypic analyses also indicated that ClpP and ClpE are both required for thermotolerance. Contrary to a previous report, we found that ClpC does not play a major role in competence development, autolysis, pneumolysin production, or growth at high temperature of S. pneumoniae.

scholarly journals MecA Protein Acts as a Negative Regulator of Genetic Competence in Streptococcus mutans

2013 ◽  
Vol 195 (22) ◽  
pp. 5196-5206 ◽  
Author(s):  
X.-L. Tian ◽  
G. Dong ◽  
T. Liu ◽  
Z. A. Gomez ◽  
A. Wahl ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Negative Regulator ◽  
Genetic Competence

scholarly journals Characterization of irvR, a Novel Regulator of the irvA-Dependent Pathway Required for Genetic Competence and Dextran-Dependent Aggregation in Streptococcus mutans

2008 ◽  
Vol 190 (21) ◽  
pp. 7268-7274 ◽  
Author(s):  
Guoqing Niu ◽  
Toshinori Okinaga ◽  
Lin Zhu ◽  
Jeffrey Banas ◽  
Felicia Qi ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Shuttle Vector ◽  
Negative Regulator ◽  
Genetic Competence ◽  
Double Mutation ◽  
Reading Frame ◽  
Mutant Phenotypes ◽  
Dependent Pathway ◽  
Potent Negative Regulator

ABSTRACT Previous studies identified irvA as a normally repressed but highly inducible transcription regulator capable of repressing mutacin I gene expression in Streptococcus mutans. In this study, we aimed to identify and characterize the regulator(s) responsible for repressing the expression of irvA. An uncharacterized open reading frame (SMU.1398) located immediately adjacent to irvA and annotated as a putative transcription repressor was identified as a likely candidate. The results of mutation studies confirmed that the expression of irvA was greatly increased in the SMU.1398 background. Mutation of SMU.1398 (“irvR”) abolished genetic competence and reduced the expression of the late competence genes/operons comEA, comY, and dprA without affecting the expression of the known competence regulators comC, comED, or comX. In addition, irvR was found to be a potent negative regulator of dextran-dependent aggregation (DDAG) and gbpC expression. Each of these irvR mutant phenotypes could be rescued with a double mutation of irvA or complemented by introducing a wild-type copy of irvR on a shuttle vector. These data indicate that the repression of irvA is critically dependent upon irvR and that irvA repression is essential for the development of genetic competence and the proper control of DDAG in S. mutans.

scholarly journals The hdrRM Operon of Streptococcus mutans Encodes a Novel Regulatory System for Coordinated Competence Development and Bacteriocin Production

2010 ◽  
Vol 192 (7) ◽  
pp. 1844-1852 ◽  
Author(s):  
Toshinori Okinaga ◽  
Guoqing Niu ◽  
Zhoujie Xie ◽  
Fengxia Qi ◽  
Justin Merritt
Keyword(s):  
Streptococcus Mutans ◽  
Regulatory Mechanism ◽  
High Cell Density ◽  
Regulatory System ◽  
Competence Development ◽  
Negative Regulator ◽  
Luciferase Reporter ◽  
Overexpression Strain ◽  
Gene Regulatory System ◽  
Gene Regulatory

ABSTRACT The Streptococcus mutans hdrRM operon encodes a novel two-gene regulatory system induced by high cell density. Previous studies identified hdrM as the only known negative regulator of competence development in S. mutans. In the present study, we demonstrated that the HdrRM system bypasses the prototypical competence gene regulators ComC and ComDE in the transcriptional regulation of the competence-specific sigma factor comX and the late competence genes. Similarly, the HdrRM system can abrogate the requirement for ComE to produce the bacteriocin mutacin IV. To further probe the regulatory mechanism of hdrRM, we created an hdrR overexpression strain and showed that it could reproduce each of the hdrM competence and mutacin phenotypes, indicating that HdrM acts as a negative regulator of HdrR activity. Using a mutacin IV-luciferase reporter, we also demonstrated that the hdrRM system utilizes the same promoter elements recognized by ComE and thus appears to comprise a novel regulatory pathway parallel to ComCDE.

scholarly journals Increased oxidative stress tolerance of a spontaneously-occurring perR gene mutation in Streptococcus mutans UA159

2021 ◽  
Author(s):  
Jessica K. Kajfasz ◽  
Peter Zuber ◽  
Tridib Ganguly ◽  
Jacqueline Abranches ◽  
José A. Lemos
Keyword(s):  
Oxidative Stress ◽  
Streptococcus Mutans ◽  
Stress Responses ◽  
Transcriptional Repressor ◽  
Loss Of Function ◽  
Coding Region ◽  
Major Player ◽  
The Impact ◽  
Peroxide Stress

The ability of bacteria such as the dental pathogen Streptococcus mutans to coordinate a response against damage-inducing oxidants is a critical aspect of their pathogenicity. The oxidative stress regulator SpxA1 has been demonstrated to be a major player in the ability of S. mutans to withstand both disulfide and peroxide stresses. While studying spontaneously-occurring variants of an S. mutans ΔspxA1 strain, we serendipitously discovered that our S. mutans UA159 host strain bore a single nucleotide deletion within the coding region of perR, resulting in a premature truncation of the encoded protein. PerR is a metal-dependent transcriptional repressor that senses and responds to peroxide stress such that loss of PerR activity results in activation of oxidative stress responses. To determine the impact of loss of PerR regulation, we obtained a UA159 isolate bearing an intact perR copy and created a clean perR deletion mutant. Our findings indicate that loss of PerR activity results in a strain that is primed to tolerate oxidative stresses in the laboratory setting. Interestingly, RNA-Seq and targeted transcriptional expression analyses reveal that PerR offers a minor contribution to the ability of S. mutans to orchestrate a transcriptional response to peroxide stress. Furthermore, we detected loss-of-function perR mutations in two other commonly used laboratory strains of S. mutans suggesting that this may be not be an uncommon occurrence. This report serves as a cautionary tale regarding the so-called domestication of laboratory strains and advocates for the implementation of more stringent strain authentication practices. Importance: A resident of the human oral biofilm, Streptococcus mutans is one of the major bacterial pathogens associated with dental caries. This report highlights a spontaneously-occurring mutation within the laboratory strain S. mutans UA159, found in the coding region of perR, a gene encoding a transcriptional repressor associated with peroxide tolerance. Though perR mutant strains of S. mutans showed a distinct growth advantage and enhanced tolerance toward H2O2, a ΔperR deletion strain showed a small number of differentially expressed genes as compared to the parent strain, suggesting few direct regulatory targets. In addition to characterizing the role of PerR in S. mutans, our findings serve as a warning to laboratory researchers regarding bacterial adaptation to in vitro growth conditions.

scholarly journals Mutations in the EDR1 Gene Alter the Response of Arabidopsis thaliana to Phytophthora infestans and the Bacterial PAMPs flg22 and elf18

2015 ◽  
Vol 28 (2) ◽  
pp. 122-133 ◽  
Author(s):  
Katrin Geissler ◽  
Lennart Eschen-Lippold ◽  
Kai Naumann ◽  
Korbinian Schneeberger ◽  
Detlef Weigel ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Phytophthora Infestans ◽  
Kinase Domain ◽  
Negative Regulator ◽  
Single Amino Acid ◽  
Nonhost Resistance ◽  
Coding Region ◽  
Callose Deposition ◽  
Knock Out

Mechanistically, nonhost resistance of Arabidopsis thaliana against the oomycete Phytophthora infestans is not well understood. Besides PEN2 and PEN3, which contribute to penetration resistance, no further components have been identified so far. In an ethylmethane sulphonate–mutant screen, we mutagenized pen2-1 and screened for mutants with an altered response to infection by P. infestans. One of the mutants obtained, enhanced response to Phytophthora infestans6 (erp6), was analyzed. Whole-genome sequencing of erp6 revealed a single nucleotide polymorphism in the coding region of the kinase domain of At1g08720, which encodes the putative MAPKKK ENHANCED DISEASE RESISTANCE1 (EDR1). We demonstrate that three independent lines with knock-out alleles of edr1 mount an enhanced response to P. infestans inoculation, mediated by increased salicylic acid signaling and callose deposition. Moreover, we show that the single amino acid substitution in erp6 causes the loss of in vitro autophosphorylation activity of EDR1. Furthermore, growth inhibition experiments suggest a so-far-unknown involvement of EDR1 in the response to the pathogen-associated molecular patterns flg22 and elf18. We conclude that EDR1 contributes to the defense response of A. thaliana against P. infestans. Our data position EDR1 as a negative regulator in postinvasive nonhost resistance.

scholarly journals N-Cadherin Regulates the Odontogenic Differentiation of Dental Pulp Stem Cells via β-Catenin Activity

2021 ◽  
Vol 9 ◽  
Author(s):  
Zilong Deng ◽  
Wenjuan Yan ◽  
Xingzhu Dai ◽  
Ming Chen ◽  
Qian Qu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cell Fate ◽  
Dental Pulp ◽  
Specific Inhibitor ◽  
Negative Regulator ◽  
Pulp Regeneration ◽  
Odontogenic Differentiation ◽  
Cell Cell

Dental pulp stem cell (DPSC) transplantation has shown new prospects in dental pulp regeneration, and is of great significance in the treatment of pulpitis and pulp necrosis. The fate and regenerative potential of stem cells are dependent, to a great extent, on their microenvironment, which is composed of various tissue components, cell populations, and soluble factors. N-cadherin-mediated cell–cell interaction has been implicated as an important factor in controlling the cell-fate commitment of mesenchymal stem cells. In this study, the effect of N-cadherin on odontogenic differentiation of DPSCs and the potential underlying mechanisms, both in vitro and in vivo, was investigated using a cell culture model and a subcutaneous transplantation mouse model. It was found that the expression of N-cadherin was reversely related to the expression of odontogenic markers (dentin sialophosphoprotein, DSPP, and runt-related transcription factor 2, Runx2) during the differentiation process of DPSCs. Specific shRNA-mediated knockdown of N-cadherin expression in DPSCs significantly increased the expression of DSPP and Runx2, alkaline phosphatase (ALP) activity, and the formation of mineralized nodules. Notably, N-cadherin silencing promoted nucleus translocation and accumulation of β-catenin. Inhibition of β-catenin by a specific inhibitor XAV939, reversed the facilitating effects of N-cadherin downregulation on odontogenic differentiation of DPSCs. In addition, knockdown of N-cadherin promoted the formation of odontoblast-like cells and collagenous matrix in β-tricalcium phosphate/DPSCs composites transplanted into mice. In conclusion, N-cadherin acted as a negative regulator via regulating β-catenin activity during odontogenic differentiation of DPSCs. These data may help to guide DPSC behavior by tuning the N-cadherin-mediated cell–cell interactions, with implications for pulp regeneration.

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