scholarly journals Regulatory Crosstalk between Motility and Interbacterial Communication in Salmonella Typhimurium

2020 ◽  
Author(s):  
Jonathan Plitnick ◽  
Fabienne F. V. Chevance ◽  
Anne Stringer ◽  
Kelly T. Hughes ◽  
Joseph T. Wade
Keyword(s):  
Escherichia Coli ◽  
Transcription Factor ◽  
Quorum Sensing ◽  
Intercellular Communication ◽  
Target Genes ◽  
Flagellar Motility ◽  
Σ Factor ◽  
Regulatory Link ◽  
Non Coding Rnas ◽  
Quorum Sensing Signals

FliA is a broadly conserved σ factor that directs transcription of genes involved in flagellar motility. We previously identified FliA-transcribed genes in Escherichia coli and Salmonella enterica serovar Typhimurium, and we showed that E. coli FliA transcribes many unstable, non-coding RNAs from intragenic promoters. Here, we show that FliA in S. Typhimurium also directs transcription of large numbers of unstable, non-coding RNAs from intragenic promoters, and we identify two previously unreported FliA-transcribed protein-coding genes. One of these genes, sdiA, encodes a transcription factor that responds to quorum sensing signals produced by other bacteria. We show that FliA-dependent transcription of sdiA is required for SdiA activity, highlighting a regulatory link between flagellar motility and intercellular communication. IMPORTANCE Initiation of bacterial transcription requires association of a σ factor with the core RNA polymerase to facilitate sequence-specific recognition of promoter elements. FliA is a widely conserved σ factor that directs transcription of genes involved in flagellar motility. We previously showed that Escherichia coli FliA transcribes many unstable, non-coding RNAs from promoters within genes. Here, we demonstrate the same phenomenon in Salmonella Typhimurium. We also show that S. Typhimurium FliA directs transcription of the sdiA gene, which encodes a transcription factor that responds to quorum sensing signals produced by other bacteria. FliA-dependent transcription of sdiA is required for transcriptional control of SdiA target genes, highlighting a regulatory link between flagellar motility and intercellular communication.

scholarly journals Regulatory crosstalk between motility and interbacterial communication in Salmonella Typhimurium

2020 ◽  
Author(s):  
Jonathan Plitnick ◽  
Fabienne F.V. Chevance ◽  
Anne Stringer ◽  
Kelly T. Hughes ◽  
Joseph T. Wade
Keyword(s):  
Escherichia Coli ◽  
Transcription Factor ◽  
Quorum Sensing ◽  
Intercellular Communication ◽  
Target Genes ◽  
Flagellar Motility ◽  
Σ Factor ◽  
Regulatory Link ◽  
Non Coding Rnas ◽  
Quorum Sensing Signals

ABSTRACTFliA is a broadly conserved σ factor that directs transcription of genes involved in flagellar motility. We previously identified FliA-transcribed genes in Escherichia coli and Salmonella enterica serovar Typhimurium, and we showed that E. coli FliA transcribes many unstable, non-coding RNAs from intragenic promoters. Here, we show that FliA in S. Typhimurium also directs transcription of large numbers of unstable, non-coding RNAs from intragenic promoters, and we identify two previously unreported FliA-transcribed protein-coding genes. One of these genes, sdiA, encodes a transcription factor that responds to quorum sensing signals produced by other bacteria. We show that FliA-dependent transcription of sdiA is required for SdiA activity, highlighting a regulatory link between flagellar motility and intercellular communication.IMPORTANCEInitiation of bacterial transcription requires association of a σ factor with the core RNA polymerase to facilitate sequence-specific recognition of promoter elements. FliA is a widely conserved σ factor that directs transcription of genes involved in flagellar motility. We previously showed that Escherichia coli FliA transcribes many unstable, non-coding RNAs from promoters within genes. Here, we demonstrate the same phenomenon in Salmonella Typhimurium. We also show that S. Typhimurium FliA directs transcription of the sdiA gene, which encodes a transcription factor that responds to quorum sensing signals produced by other bacteria. FliA-dependent transcription of sdiA is required for transcriptional control of SdiA target genes, highlighting a regulatory link between flagellar motility and intercellular communication.

ELUCIDATING THE ROLE OF METABOLITES AS QUORUM SENSING SIGNALS USING PHASE PLANE ANALYSIS: THE CASE OF INDOLE IN ESCHERICHIA COLI

2014 ◽  
Vol 22 (04) ◽  
pp. 523-531
Author(s):  
DANIELA CAROLINA FLÓREZ PARRA ◽  
VANESSA RAMIREZ TOVAR ◽  
ANDRÉS FERNANDO GONZÁLEZ BARRIOS
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Quorum Sensing ◽  
Phase Plane ◽  
Negative Slope ◽  
External Signal ◽  
Phase Plane Analysis ◽  
Main Function ◽  
E Coli ◽  
Quorum Sensing Signals

Quorum sensing signals were initially restricted to those molecules whose only role is to sense density. Nevertheless Indole is a quorum sensing stationary phase signal secreted by Escherichia coli which is an intermediate in tryptophan synthesis. Moreover, it is known to regulate several genes such as astD, tnaB, and gabT. Hence, the main function that carries out indole in E. coli has not been clearly elucidated. Here we evaluated its role through computational and experimental techniques utilizing a flux balance analysis model. A metabolic phase plane was constructed for E. coli growth by calculating the shadow prices vector, which regards the biomass objective function sensibility upon modifications of the exchange and synthesis indole fluxes. Based on the metabolic phase plane, we found that cells do not prefer a specific role for this metabolite as both, intracellular synthesis and external signal concentration could exercise and effect on its physiological state. We experimentally corroborated our results by measuring growth rate when altering tnaA transcription rate and extracellular indole concentration hence synthesis and extracellular indole fluxes, respectively. Growth rate significantly varies when crossing the direction of the exchange flux (zero flux) as the extracellular indole variation goes from a positive to negative slope and this occurs when augmenting the indole concentration from 0.4 to 0.6 mM at the [6, 10] μM IPTG interval. Regarding the inductor concentration we found a significant variation of the growth rate when crossing the 8 μM concentration for all extracellular indole concentrations.

scholarly journals Conversion of Norepinephrine to 3,4-Dihdroxymandelic Acid in Escherichia coli Requires the QseBC Quorum-Sensing System and the FeaR Transcription Factor

2017 ◽  
Vol 200 (1) ◽  
Author(s):  
Sasikiran Pasupuleti ◽  
Nitesh Sule ◽  
Michael D. Manson ◽  
Arul Jayaraman
Keyword(s):  
Escherichia Coli ◽  
Transcription Factor ◽  
Quorum Sensing ◽  
Aromatic Amines ◽  
Response Regulator ◽  
Content Type ◽  
E Coli ◽  
Expression Of Genes ◽  
K 12 ◽  
Cognate Response Regulator

ABSTRACTThe detection of norepinephrine (NE) as a chemoattractant byEscherichia colistrain K-12 requires the combined action of the TynA monoamine oxidase and the FeaB aromatic aldehyde dehydrogenase. The role of these enzymes is to convert NE into 3,4-dihydroxymandelic acid (DHMA), which is a potent chemoattractant sensed by the Tsr chemoreceptor. These two enzymes must be induced by prior exposure to NE, and cells that are exposed to NE for the first time initially show minimal chemotaxis toward it. The induction of TynA and FeaB requires the QseC quorum-sensing histidine kinase, and the signaling cascade requires new protein synthesis. Here, we demonstrate that the cognate response regulator for QseC, the transcription factor QseB, is also required for induction. The related quorum-sensing kinase QseE appears not to be part of the signaling pathway, but its cognate response regulator, QseF, which is also a substrate for phosphotransfer from QseC, plays a nonessential role. The promoter of thefeaRgene, which encodes a transcription factor that has been shown to be essential for the expression oftynAandfeaB, has two predicted QseB-binding sites. One of these sites appears to be in an appropriate position to stimulate transcription from the P1promoter of thefeaRgene. This study unites two well-known pathways: one for expression of genes regulated by catecholamines (QseBC) and one for expression of genes required for metabolism of aromatic amines (FeaR, TynA, and FeaB). This cross talk allowsE. colito convert the host-derived and chemotactically inert NE into the potent bacterial chemoattractant DHMA.IMPORTANCEThe chemotaxis ofE. coliK-12 to norepinephrine (NE) requires the conversion of NE to 3,4-dihydroxymandleic acid (DHMA), and DHMA is both an attractant and inducer of virulence gene expression for a pathogenic enterohemorrhagicE. coli(EHEC) strain. The induction of virulence by DHMA and NE requires QseC. The results described here show that the cognate response regulator for QseC, QseB, is also required for conversion of NE into DHMA. Production of DHMA requires induction of a pathway involved in the metabolism of aromatic amines. Thus, the QseBC sensory system provides a direct link between virulence and chemotaxis, suggesting that chemotaxis to host signaling molecules may require that those molecules are first metabolized by bacterial enzymes to generate the actual chemoattractant.

scholarly journals Stationary-Phase Quorum-Sensing Signals Affect Autoinducer-2 and Gene Expression in Escherichia coli

2004 ◽  
Vol 70 (4) ◽  
pp. 2038-2043 ◽  
Author(s):  
Dacheng Ren ◽  
Laura A. Bedzyk ◽  
Rick W. Ye ◽  
Stuart M. Thomas ◽  
Thomas K. Wood
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Quorum Sensing ◽  
Stationary Phase ◽  
Growth Stages ◽  
E Coli ◽  
Stationary Culture ◽  
Autoinducer 2 ◽  
K 12 ◽  
Quorum Sensing Signals

ABSTRACT Quorum sensing via autoinducer-2 (AI-2) has been identified in different strains, including those from Escherichia, Vibrio, Streptococcus, and Bacillus species, and previous studies have suggested the existence of additional quorum-sensing signals working in the stationary phase of Escherichia coli cultures. To investigate the presence and global effect of these possible quorum-sensing signals other than AI-2, DNA microarrays were used to study the effect of stationary-phase signals on the gene expression of early exponential-phase cells of the AI-2-deficient strain E. coli DH5α. For statistically significant differential gene expression (P < 0.05), 14 genes were induced by supernatants from a stationary culture and 6 genes were repressed, suggesting the involvement of indole (induction of tnaA and tnaL) and phosphate (repression of phoA, phoB, and phoU). To study the stability of the signals, the stationary-phase supernatant was autoclaved and was used to study its effect on E. coli gene expression. Three genes were induced by autoclaved stationary-phase supernatant, and 34 genes were repressed. In total, three genes (ompC, ptsA, and btuB) were induced and five genes (nupC, phoB, phoU, argT, and ompF) were repressed by both fresh and autoclaved stationary-phase supernatants. Furthermore, supernatant from E. coli DH5α stationary culture was found to repress E. coli K-12 AI-2 concentrations by 4.8-fold ± 0.4-fold, suggesting that an additional quorum-sensing system in E. coli exists and that gene expression is controlled as a network with different signals working at different growth stages.

scholarly journals MicroRNAs and miRceptors: a new mechanism of action for intercellular communication

2017 ◽  
Vol 373 (1737) ◽  
pp. 20160486 ◽  
Author(s):  
Muller Fabbri
Keyword(s):  
Cancer Cells ◽  
Extracellular Vesicles ◽  
Mechanism Of Action ◽  
Intercellular Communication ◽  
Target Genes ◽  
Tumour Microenvironment ◽  
Signalling Pathways ◽  
Non Coding Rnas ◽  
Cancerous Cells

MicroRNAs (miRs) are small non-coding RNAs (ncRNAs) that control the expression of target genes by modulating (usually inhibiting) their translation into proteins. This ‘traditional’ mechanism of action of miRs has been recently challenged by new discoveries pointing towards a role of miRs as ‘hormones’, capable of binding to proteic receptors (miRceptors) and triggering their downstream signalling pathways. These findings harbour particular significance within the tumour microenvironment (TME), defined as the variety of non-cancerous cells surrounding cancer cells, but are relevant also for other diseases. In recent years it has become clearer that the TME does not passively assist the growth of cancer cells but contributes to its biology. Some of the mediators of the intercellular communication between cancer cells and TME are miRs shuttled within exosomes, a subtype of cellular released extracellular vesicles. This article will highlight the most recent findings on the biological implications of miR–miRceptor interactions for the biology of the TME and other diseases, and will provide some perspectives on the future development of this fascinating research. This article is part of the discussion meeting issue ‘Extracellular vesicles and the tumour microenvironment’.

MicroRNAs and their role in hematological malignant diseases

2012 ◽  
Vol 153 (52) ◽  
pp. 2051-2059 ◽  
Author(s):  
Zsuzsanna Gaál ◽  
Éva Oláh
Keyword(s):  
Target Genes ◽  
Lymphoblastic Leukemia ◽  
Cancer Tissue ◽  
Altered Expression ◽  
Diagnosis And Prognosis ◽  
Oncologic Patients ◽  
Different Types ◽  
Non Coding Rnas ◽  
Success Of Treatment ◽  
Posttranscriptional Level

MicroRNAs are a class of small non-coding RNAs regulating gene expression at posttranscriptional level. Their target genes include numerous regulators of cell cycle, cell proliferation as well as apoptosis. Therefore, they are implicated in the initiation and progression of cancer, tissue invasion and metastasis formation as well. MicroRNA profiles supply much information about both the origin and the differentiation state of tumours. MicroRNAs also have a key role during haemopoiesis. An altered expression level of those have often been observed in different types of leukemia. There are successful attempts to apply microRNAs in the diagnosis and prognosis of acute lymphoblastic leukemia and acute myeloid leukemia. Measurement of the expression levels may help to predict the success of treatment with different kinds of chemotherapeutic drugs. MicroRNAs are also regarded as promising therapeutic targets, and can contribute to a more personalized therapeutic approach in haemato-oncologic patients. Orv. Hetil., 2012, 153, 2051–2059.

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