scholarly journals A pAD1-Encoded Small RNA Molecule, mD, Negatively Regulates Enterococcus faecalis Pheromone Response by Enhancing Transcription Termination

2000 ◽  
Vol 182 (4) ◽  
pp. 1062-1073 ◽  
Author(s):  
Haruyoshi Tomita ◽  
Don B. Clewell
Keyword(s):  
Enterococcus Faecalis ◽  
Structural Genes ◽  
Pheromone Response ◽  
Genetic Studies ◽  
Mating Response ◽  
Aggregation Substance ◽  
Transcriptional Termination ◽  
Inhibitor Peptide ◽  
A Site ◽  
Direction Opposite

ABSTRACT pAD1 is a 60-kb hemolysin-bacteriocin plasmid in Enterococcus faecalis that encodes a conjugative mating response to a peptide sex pheromone, cAD1, secreted by plasmid-free bacteria. The pheromone response is regulated by two proteins: TraE1, which positively regulates all or most conjugative structural genes, and TraA, which negatively regulates traE1. TraA binds to pAD1 DNA at theiad (encoding the inhibitor peptide iAD1) promoter but is released upon binding to imported pheromone. This leads to enhanced transcription through two closely spaced downstream terminators (t1 and t2) into traE1. TraE1 is believed to then upregulate itself from a site located within t2; thus, a small amount of transcription through t1-t2 could lead to overall induction. It is important therefore that the t1-t2 terminators be tightly controlled to keep the response shut down in the absence of pheromone. A small (200-nucleotide) RNA molecule designated mD is encoded just upstream of t1 by a determinant (traD) oriented in the direction opposite to that of transcripts utilizing t1. mD is expressed at high levels in the uninduced state, but it decreases significantly upon induction. Here we present results of genetic studies relating to the activity of t1-t2 and show that mD strongly enhances transcriptional termination at t1. The mD activity is shown to influence transcription well downstream and can affect the determinant for aggregation substance asa1. The phenomenon is specific in that there is no effect of mD on the unrelated pheromone-responding plasmids pPD1 and pCF10.

scholarly journals Amplification of the Tetracycline Resistance Determinant of pAMα1 in Enterococcus faecalis Requires a Site-Specific Recombination Event Involving Relaxase

2002 ◽  
Vol 184 (18) ◽  
pp. 5187-5193 ◽  
Author(s):  
M. Victoria Francia ◽  
Don B. Clewell
Keyword(s):  
Enterococcus Faecalis ◽  
Recombination Event ◽  
Tandem Repeats ◽  
Tetracycline Resistance ◽  
Multicopy Plasmid ◽  
Site Specific ◽  
Site Specific Recombination ◽  
Rate Limiting Step ◽  
A Site ◽  
Rate Limiting

ABSTRACT The small multicopy plasmid pAMα1 (9.75 kb) encoding tetracycline resistance in Enterococcus faecalis is known to generate tandem repeats of a 4.1-kb segment carrying tet(L) when cells are grown extensively in the presence of tetracycline. Here we show that the initial (rate-limiting) step involves a site-specific recombination event involving plasmid-encoded relaxase activity acting at two recombination sequences (RS1 and RS2) that flank the tet determinant. We also present the complete nucleotide sequence of pAMα1.

The pAD1 Sex Pheromone Response in Enterococcus faecalis

1997 ◽  
pp. 1037-1040 ◽  
Author(s):  
S. Fujimoto ◽  
M. Bastos ◽  
K. Tanimoto ◽  
F. An ◽  
K. Wu ◽  
...  
Keyword(s):  
Sex Pheromone ◽  
Enterococcus Faecalis ◽  
Pheromone Response

scholarly journals Co-transfer of vanA and aggregation substance genes from Enterococcus faecalis isolates in intra- and interspecies matings

2007 ◽  
Vol 59 (5) ◽  
pp. 1005-1009 ◽  
Author(s):  
Claudia Paoletti ◽  
Gessica Foglia ◽  
Maria Stella Princivalli ◽  
Gloria Magi ◽  
Emilio Guaglianone ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Aggregation Substance

scholarly journals Complex Nature of Enterococcal Pheromone-Responsive Plasmids

2010 ◽  
Vol 59 (2) ◽  
pp. 79-87 ◽  
Author(s):  
EWA WARDAL ◽  
EWA SADOWY ◽  
WALERIA HRYNIEWICZ
Keyword(s):  
Sex Pheromones ◽  
Complex Nature ◽  
Pheromone Response ◽  
Small Peptides ◽  
Resistance Determinants ◽  
Aggregation Substance ◽  
Enterococcal Species ◽  
Stable Maintenance ◽  
And Function ◽  
Great Complexity

Pheromone-responsive plasmids constitute a unique group of approximately 20 plasmids identified, as yet, only among enterococcal species. Several of their representatives, e.g. pAD1, pCF10, pPD1 and pAM373 have been extensively studied. These plasmids possess a sophisticated conjugation mechanism based on response to sex pheromones--small peptides produced by plasmid-free recipient cells. Detailed analysis of regulation and function of the pheromone response process revealed its great complexity and dual role--in plasmid conjugation and modulation of enterococcal virulence. Among other functional modules identified in pheromone plasmids, the stabilization/partition systems play a crucial role in stable maintenance of the plasmid molecule in host bacteria. Among them, the par locus of pAD1 is one of the exceptional RNA addiction systems. Pheromone-responsive plasmids contribute also to enterococcal phenotype being an important vehicle of antibiotic resistance in this genus. Both types of acquired vancomycin resistance determinants, vanA and vanB, as well many other resistant phenotypes, were found to be located on these plasmids. They also encode two basic agents of enterococcal virulence, i.e. aggregation substance (AS) and cytolysin. AS participates in mating-pair formation during conjugation but can also facilitate the adherence ofenterococci to human tissues during infection. The second protein, cytolysin, displays hemolytic activity and helps to invade eukaryotic cells. There are still many aspects of the nature of pheromone plasmids that remain unclear and more detailed studies are needed to understand their uniqueness and complexity.

scholarly journals Functional Analysis of TraA, the Sex Pheromone Receptor Encoded by pPD1, in a Promoter Region Essential for the Mating Response in Enterococcus faecalis

2002 ◽  
Vol 184 (22) ◽  
pp. 6343-6350 ◽  
Author(s):  
Takaaki Horii ◽  
Hiromichi Nagasawa ◽  
Jiro Nakayama
Keyword(s):  
Sex Pheromone ◽  
Enterococcus Faecalis ◽  
Intergenic Region ◽  
Recipient Cell ◽  
Donor Cell ◽  
Northern Analysis ◽  
Mobility Shift ◽  
Transcriptional Initiation ◽  
Mating Response ◽  
Gel Mobility Shift

ABSTRACT Conjugative transfer of a bacteriocin plasmid, pPD1, of Enterococcus faecalis is induced in response to a peptide sex pheromone, cPD1, secreted from plasmid-free recipient cells. cPD1 is taken up by a pPD1 donor cell and binds to an intracellular receptor, TraA. Once a recipient cell acquires pPD1, it starts to produce an inhibitor of cPD1, termed iPD1, which functions as a TraA antagonist and blocks self-induction in donor cells. In this study, we discuss how TraA transduces the signal of cPD1 to the mating response. Gel mobility shift assays indicated that TraA is bound to a traA-ipd intergenic region, which is essential for cPD1 response. DNase I footprinting analysis suggested the presence of one strong (tab1) and two weak (tab2 and tab3) TraA-binding sites in the intergenic region. Primer extension analysis implied that the transcriptional initiation sites of traA and ipd were located in the intergenic region. Northern analysis showed that cPD1 upregulated and downregulated transcription of ipd and traA, respectively. The circular permutation assay showed that TraA bent a DNA fragment corresponding to the tab1 region, and its angle was changed in the presence of cPD1 or iPD1. From these data, we propose a model that TraA changes the conformation of the tab1 region in response to cPD1 and upregulates the transcription of ipd, which may lead to expression of genes required for the mating response.

scholarly journals Expression of Adhesive Pili and the Collagen-Binding Adhesin Ace Is Activated by ArgR Family Transcription Factors inEnterococcus faecalis

2018 ◽  
Vol 200 (18) ◽  
Author(s):  
Dawn A. Manias ◽  
Gary M. Dunny
Keyword(s):  
Transcription Factor ◽  
Transcription Factors ◽  
Enterococcus Faecalis ◽  
Opportunistic Infections ◽  
Structural Genes ◽  
Gene Encoding ◽  
Collagen Binding ◽  
Content Type ◽  
Surface Adhesins

ABSTRACTIt was shown previously that the disruption of theahrCgene encoding a predicted ArgR family transcription factor results in a severe defect in biofilm formationin vitro, as well as a significant attenuation of virulence ofEnterococcus faecalisstrain OG1RF in multiple experimental infection models. Using transcriptome sequencing (RNA-seq), we observedahrC-dependent changes in the expression of more than 20 genes. AhrC-repressed genes included predicted determinants of arginine catabolism and several other metabolic genes and predicted transporters, while AhrC-activated genes included determinants involved in the production of surface protein adhesins. Most notably, the structural and regulatory genes of theebplocus encoding adhesive pili were positively regulated, as well as theacegene, encoding a collagen-binding adhesin. UsinglacZtranscription reporter fusions, we determined thatahrCand a secondargRtranscription factor gene,argR2, both function to activate the expression ofebpR, which directly activates the transcription of the pilus structural genes. Our data suggest that in the wild-typeE. faecalis, the low levels of EbpR limit the expression of pili and that biofilm biomass is also limited by the amount of pili expressed by the bacteria. The expression ofaceis similarly enhanced by AhrC and ArgR2, butaceexpression is not dependent on EbpR. Our results demonstrate the existence of novel regulatory cascades controlled by a pair of ArgR family transcription factors that might function as a heteromeric protein complex.IMPORTANCECell surface adhesins play critical roles in the formation of biofilms, host colonization, and the pathogenesis of opportunistic infections byEnterococcus faecalis. Here, we present new results showing that the expression of two major enterococcal surface adhesins,ebppili, and the collagen-binding protein Ace is positively regulated at the transcription level by twoargRfamily transcription factors, AhrC and ArgR2. In the case of pili, the direct target of regulation is theebpRgene, previously shown to activate the transcription of the pilus structural genes, while the activation ofacetranscription appears to be directly impacted by the two ArgR proteins. These transcription factors may represent new targets for blocking enterococcal infections.

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