scholarly journals The AinS autoinducer synthase and LitR master regulator of quorum sensing regulate N-3-hydroxy-decanoyl-homoserine-lactone production and motility in Aliivibrio wodanis 06/09/139

2019 ◽  
Author(s):  
Amudha Deepalakshmi Maharajan ◽  
Hilde Hansen ◽  
Nils Peder Willassen
Keyword(s):  
Quorum Sensing ◽  
Cell Density ◽  
Homoserine Lactone ◽  
Temperature Tolerance ◽  
Dependent Manner ◽  
Secretion Systems ◽  
Master Regulator ◽  
Density Dependent ◽  
Ulcer Disease ◽  
A Cell

Abstract Background Quorum Sensing (QS) is a cell to cell communication system, in which bacteria synthesize and respond to signaling molecules called autoinducers (AI). QS is cell density dependent and known to be involved in regulating virulence, motility and secretion systems to interact with the host or other bacteria. Aliivibrio wodanis is frequently isolated together with Moritella viscosa from the infected Atlantic salmon during outbreaks of the winter ulcer disease. M. viscosa is the main causative agent of the disease while the presence of A. wodanis is still unclear. It is hypothesized that A. wodanis might influence the progression of winter ulcer. The genome of A. wodanis 06/09/139 encodes two autoinducer synthase genes (ainS and luxS) and a master regulator litR. LitR homologs in other aliivibrios have been shown to regulate several phenotypes in a cell density dependent manner. Moreover, a previous study has shown that A. wodanis 06/09/139 produces only one AHL N-3-hydroxy-decanoyl-homoserine-lactone (3OHC10-HSL). Hence, in this work, we have studied the QS system in A. wodanis 06/09/139 by knocking out QS genes ainS and litR. The effects of the deletions were studied with regard to growth, AHL production and motility at different temperatures. Results By using HPLC-MS/MS, we found that the deletion of ainS in A. wodanis 06/09/139 resulted in the loss of 3OHC10-HSL production. The 3OHC10-HSL production in A. wodanis 06/09/139 increased with increase in cell density and more 3OHC10-HSL was produced at 6°C than at 12, 16 and 20°C. The litR mutant demonstrated a ~20% reduction in the production of 3OHC10-HSL relative to the wild type at the stationary phase. Compared to the wildtype and the ainS mutant strains, the litR mutant resulted in a strain with improved temperature tolerance. The motility in mutants (∆litR and ∆ainS) were significantly higher than that of the wildtype. Conclusions Our study shows that AinS in A. wodanis 06/09/139 is the AHL synthase responsible for 3OHC10-HSL production, where the production is both cell density and temperature dependent. Our data also shows that LitR regulates 3OHC10-HSL production only to a minor extent and both LitR and AinS are negative regulators of motility.

scholarly journals Stringent Response Activates Quorum Sensing and Modulates Cell Density-Dependent Gene Expression inPseudomonas aeruginosa

2001 ◽  
Vol 183 (18) ◽  
pp. 5376-5384 ◽  
Author(s):  
Christian van Delden ◽  
Rachel Comte ◽  
And Marc Bally
Keyword(s):  
Gene Expression ◽  
Quorum Sensing ◽  
Cell Density ◽  
Stringent Response ◽  
Transcriptional Regulators ◽  
Homoserine Lactone ◽  
Density Dependent ◽  
Sensing Systems ◽  
Acid Analogue ◽  
Enhanced Expression

ABSTRACT During nutrient starvation, Escherichia coli elicits a stringent response involving the ribosome-associated protein RelA. Activation of RelA results in a global change in the cellular metabolism including enhanced expression of the stationary-phase sigma factor RpoS. In the human pathogen Pseudomonas aeruginosa, a complex quorum-sensing circuitry, linked to RpoS expression, is required for cell density-dependent production of many secreted virulence factors, including LasB elastase. Quorum sensing relies on the activation of specific transcriptional regulators (LasR and RhlR) by their corresponding autoinducers (3-oxo-C12-homoserine lactone [HSL] and C4-HSL), which function as intercellular signals. We found that overexpression of relA activated the expression of rpoS in P. aeruginosa and led to premature, cell density-independent LasB elastase production. We therefore investigated the effects of the stringent response on quorum sensing. Both lasR and rhlR gene expression and autoinducer synthesis were prematurely activated during the stringent response induced by overexpression of relA. Premature expression of lasR and rhlR was also observed when relA was overexpressed in a PAO1 rpoSmutant. The stringent response induced by the amino acid analogue serine hydroxamate (SHX) also led to premature production of the 3-oxo-C12-HSL autoinducer. This response to SHX was absent in a PAO1 relA mutant. These findings suggest that the stringent response can activate the two quorum-sensing systems of P. aeruginosa independently of cell density.

scholarly journals Inhibition of transferrin receptor 1 transcription by a cell density response element

2005 ◽  
Vol 392 (2) ◽  
pp. 383-388 ◽  
Author(s):  
Jian Wang ◽  
Guohua Chen ◽  
Kostas Pantopoulos
Keyword(s):  
Cell Density ◽  
Transferrin Receptor ◽  
Human Lung Cancer ◽  
Dependent Manner ◽  
Response Element ◽  
Iron Regulatory Proteins ◽  
Density Dependent ◽  
Transferrin Receptor 1 ◽  
Density Response ◽  
A Cell

TfR1 (transferrin receptor 1) mediates the uptake of transferrin-bound iron and thereby plays a critical role in cellular iron metabolism. Its expression is coupled to cell proliferation/differentiation and controlled in response to iron levels and other signals by transcriptional and post-transcriptional mechanisms. It is well established that TfR1 levels decline when cultured cells reach a high density and in the present study we have investigated the underlying mechanisms. Consistent with previous findings, we demonstrate that TfR1 expression is attenuated in a cell-density-dependent manner in human lung cancer H1299 cells and in murine B6 fibroblasts as the result of a marked decrease in mRNA content. This response is not associated with alterations in the RNA-binding activity of iron regulatory proteins that are indicative of a transcriptional mechanism. Reporter assays reveal that the human TfR1 promoters contains sequences mediating cell-density-dependent transcriptional inhibition. Mapping of the human and mouse TfR1 promoters identified a conserved hexa-nucleotide 5′-GAGGGC-3′ motif with notable sequence similarity to a previously described element within the IGF-2 (insulin-like growth factor-2) promoter. We show that this motif is necessary for the formation of specific complexes with nuclear extracts and for cell-density-dependent regulation in reporter gene assays. Thus the TfR1 promoter contains a functional ‘cell density response element’ (CDRE).

scholarly journals RalA interacts with ZONAB in a cell density-dependent manner and regulates its transcriptional activity

2004 ◽  
Vol 24 (1) ◽  
pp. 54-62 ◽  
Author(s):  
Paul Frankel ◽  
Ami Aronheim ◽  
Emma Kavanagh ◽  
Maria S Balda ◽  
Karl Matter ◽  
...  
Keyword(s):  
Cell Density ◽  
Transcriptional Activity ◽  
Dependent Manner ◽  
Density Dependent ◽  
A Cell

scholarly journals The BpsIR Quorum-Sensing System of Burkholderia pseudomallei

2005 ◽  
Vol 187 (2) ◽  
pp. 785-790 ◽  
Author(s):  
Yan Song ◽  
Chao Xie ◽  
Yong-Mei Ong ◽  
Yunn-Hwen Gan ◽  
Kim-Lee Chua
Keyword(s):  
Quorum Sensing ◽  
Cell Density ◽  
Burkholderia Pseudomallei ◽  
Homoserine Lactone ◽  
Positive Regulation ◽  
Density Dependent ◽  
Sensing System ◽  
Quorum Sensing System

ABSTRACT BpsIR, a LuxIR quorum-sensing homolog, is required for optimal expression of virulence and secretion of exoproducts in Burkholderia pseudomallei. Cell density-dependent expression of bpsI and bpsR, the positive regulation of bpsIR expression by BpsR, and the synthesis of N-octanoyl-homoserine lactone (C8HSL) by BpsI are described in this report.

scholarly journals Disrupting quorum sensing alters social interactions in Chromobacterium violaceum

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Sonia Mion ◽  
Nathan Carriot ◽  
Julien Lopez ◽  
Laure Plener ◽  
Annick Ortalo-Magné ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Social Interactions ◽  
Antibiotic Production ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Chromobacterium Violaceum ◽  
Dependent Manner ◽  
Gram Negative ◽  
A Cell ◽  
Microbial Population Dynamics

AbstractQuorum sensing (QS) is a communication system used by bacteria to coordinate a wide panel of biological functions in a cell density-dependent manner. The Gram-negative Chromobacterium violaceum has previously been shown to use an acyl-homoserine lactone (AHL)-based QS to regulate various behaviors, including the production of proteases, hydrogen cyanide, or antimicrobial compounds such as violacein. By using combined metabolomic and proteomic approaches, we demonstrated that QS modulates the production of antimicrobial and toxic compounds in C. violaceum ATCC 12472. We provided the first evidence of anisomycin antibiotic production by this strain as well as evidence of its regulation by QS and identified new AHLs produced by C. violaceum ATCC 12472. Furthermore, we demonstrated that targeting AHLs with lactonase leads to major QS disruption yielding significant molecular and phenotypic changes. These modifications resulted in drastic changes in social interactions between C. violaceum and a Gram-positive bacterium (Bacillus cereus), a yeast (Saccharomyces cerevisiae), immune cells (murine macrophages), and an animal model (planarian Schmidtea mediterranea). These results underscored that AHL-based QS plays a key role in the capacity of C. violaceum to interact with micro- and macroorganisms and that quorum quenching can affect microbial population dynamics beyond AHL-producing bacteria and Gram-negative bacteria.

scholarly journals Pseudomonas aeruginosa Las quorum sensing autoinducer suppresses growth and biofilm production in Legionella species

Microbiology ◽  
2009 ◽  
Vol 155 (6) ◽  
pp. 1934-1939 ◽  
Author(s):  
Soichiro Kimura ◽  
Kazuhiro Tateda ◽  
Yoshikazu Ishii ◽  
Manabu Horikawa ◽  
Shinichi Miyairi ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Legionella Pneumophila ◽  
Bacterial Species ◽  
Cell Signalling ◽  
Homoserine Lactone ◽  
Alcaligenes Faecalis ◽  
Suppressive Effect ◽  
Dependent Manner ◽  
A Cell

Bacteria commonly communicate with each other by a cell-to-cell signalling mechanism known as quorum sensing (QS). Recent studies have shown that the Las QS autoinducer N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12-HSL) of Pseudomonas aeruginosa performs a variety of functions not only in intraspecies communication, but also in interspecies and interkingdom interactions. In this study, we report the effects of Pseudomonas 3-oxo-C12-HSL on the growth and suppression of virulence factors in other bacterial species that frequently co-exist with Ps. aeruginosa in nature. It was found that 3-oxo-C12-HSL, but not its analogues, suppressed the growth of Legionella pneumophila in a dose-dependent manner. However, 3-oxo-C12-HSL did not exhibit a growth-suppressive effect on Serratia marcescens, Proteus mirabilis, Escherichia coli, Alcaligenes faecalis and Stenotrophomonas maltophilia. A concentration of 50 μM 3-oxo-C12-HSL completely inhibited the growth of L. pneumophila. Additionally, a significant suppression of biofilm formation was demonstrated in L. pneumophila exposed to 3-oxo-C12-HSL. Our results suggest that the Pseudomonas QS autoinducer 3-oxo-C12-HSL exerts both bacteriostatic and virulence factor-suppressive activities on L. pneumophila alone.

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