Regulon Studies and In Planta Role of the BraI/R Quorum-Sensing System in the Plant-Beneficial Burkholderia Cluster

ABSTRACTStreptococcus pneumoniaeis the leading cause of death in children worldwide and forms highly organized biofilms in the nasopharynx, lungs, and middle ear mucosa. TheluxS-controlled quorum-sensing (QS) system has recently been implicated in virulence and persistence in the nasopharynx, but its role in biofilms has not been studied. Here we show that this QS system plays a major role in the control ofS. pneumoniaebiofilm formation. Our results demonstrate that theluxSgene is contained by invasive isolates and normal-flora strains in a region that contains genes involved in division and cell wall biosynthesis. TheluxSgene was maximally transcribed, as a monocistronic message, in the early mid-log phase of growth, and this coincides with the appearance of early biofilms. Demonstrating the role of the LuxS system in regulatingS. pneumoniaebiofilms, at 24 h postinoculation, two different D39ΔluxSmutants produced ∼80% less biofilm biomass than wild-type (WT) strain D39 did. Complementation of these strains withluxS, either in a plasmid or integrated as a single copy in the genome, restored their biofilm level to that of the WT. Moreover, a soluble factor secreted by WT strain D39 or purified AI-2 restored the biofilm phenotype of D39ΔluxS. Our results also demonstrate that during the early mid-log phase of growth, LuxS regulates the transcript levels oflytA, which encodes an autolysin previously implicated in biofilms, and also the transcript levels ofply, which encodes the pneumococcal pneumolysin. In conclusion, theluxS-controlled QS system is a key regulator of early biofilm formation byS. pneumoniaestrain D39.

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Novel Strategy for Improvement of the Bioleaching Efficiency of Acidithiobacillus ferrooxidans Based on the AfeI/R Quorum Sensing System

Minerals ◽

10.3390/min10030222 ◽

2020 ◽

Vol 10 (3) ◽

pp. 222 ◽

Cited By ~ 4

Author(s):

Xue-Yan Gao ◽

Xiu-Jie Liu ◽

Chang-Ai Fu ◽

Xiu-Feng Gu ◽

Jian-Qiang Lin ◽

...

Keyword(s):

Quorum Sensing ◽

Acidithiobacillus Ferrooxidans ◽

Extracellular Polymeric Substances ◽

Genetic Manipulation ◽

Regulatory Function ◽

Regulatory Pathways ◽

Sensing System ◽

Quorum Sensing System ◽

Novel Strategy

Acidithiobacillus ferrooxidans is an acidophilic and chemolithotrophic sulfur- and iron-oxidizing bacterium that has been widely used in the bioleaching process for extracting metals. Extracellular polymeric substances (EPS) are essential for bacteria-ore interactions, and the regulation of EPS synthesis could be an important way of influencing the efficiency of the bioleaching process. Therefore, exploring and utilizing the regulatory pathways of EPS synthesis to improve the bacterial bioleaching capability have posed a challenge in the study and application of bioleaching bacteria. Here, several engineering strains were constructed using genetic manipulation methods. And we revealed the regulatory function of the AfeI/R quorum sensing (QS) system in EPS synthesis and biofilm formation of A. ferrooxidans, and the AfeI/R-mediated EPS synthesis could influence bacteria-substrate interactions and the efficiency of bioleaching. Finally, an AfeI/R-mediated bioleaching model was proposed to illustrate the role of QS system in this process. This study provided new insights into and clues for developing highly efficient bioleaching bacteria and modulating the bioleaching process.

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The Enterococcus faecalis fsrB Gene, a Key Component of the fsr Quorum-Sensing System, Is Associated with Virulence in the Rabbit Endophthalmitis Model

Infection and Immunity ◽

10.1128/iai.70.8.4678-4681.2002 ◽

2002 ◽

Vol 70 (8) ◽

pp. 4678-4681 ◽

Cited By ~ 59

Author(s):

Eleftherios Mylonakis ◽

Michael Engelbert ◽

Xiang Qin ◽

Costi D. Sifri ◽

Barbara E. Murray ◽

...

Keyword(s):

Quorum Sensing ◽

Enterococcus Faecalis ◽

Deletion Mutant ◽

Wild Type ◽

Sensing System ◽

Quorum Sensing System

ABSTRACT We used a rabbit endophthalmitis model to explore the role of fsrB, a gene required for the function of the fsr quorum-sensing system of Enterococcus faecalis, in pathogenicity. A nonpolar deletion mutant of fsrB had significantly reduced virulence compared to wild type. Complementation of mutation restored virulence. These data corroborate the role of fsrB in E. faecalis pathogenesis and suggest that the rabbit endophthalmitis model can be used to study the in vivo role of quorum sensing.

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Quorum Sensing Controls Exopolysaccharide Production in Sinorhizobium meliloti

Journal of Bacteriology ◽

10.1128/jb.185.1.325-331.2003 ◽

2003 ◽

Vol 185 (1) ◽

pp. 325-331 ◽

Cited By ~ 148

Author(s):

Melanie M. Marketon ◽

Sarah A. Glenn ◽

Anatol Eberhard ◽

Juan E. González

Keyword(s):

Gene Expression ◽

Quorum Sensing ◽

Sinorhizobium Meliloti ◽

Wild Type Strain ◽

Homoserine Lactone ◽

Symbiotic Relationship ◽

Wild Type ◽

Sensing System ◽

Quorum Sensing System

ABSTRACT Sinorhizobium meliloti is a soil bacterium capable of invading and establishing a symbiotic relationship with alfalfa plants. This invasion process requires the synthesis, by S. meliloti, of at least one of the two symbiotically important exopolysaccharides, succinoglycan and EPS II. We have previously shown that the sinRI locus of S. meliloti encodes a quorum-sensing system that plays a role in the symbiotic process. Here we show that the sinRI locus exerts one level of control through regulation of EPS II synthesis. Disruption of the autoinducer synthase gene, sinI, abolished EPS II production as well as the expression of several genes in the exp operon that are responsible for EPS II synthesis. This phenotype was complemented by the addition of acyl homoserine lactone (AHL) extracts from the wild-type strain but not from a sinI mutant, indicating that the sinRI-specified AHLs are required for exp gene expression. This was further confirmed by the observation that synthetic palmitoleyl homoserine lactone (C16:1-HL), one of the previously identified sinRI-specified AHLs, specifically restored exp gene expression. Most importantly, the absence of symbiotically active EPS II in a sinI mutant was confirmed in plant nodulation assays, emphasizing the role of quorum sensing in symbiosis.

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Molecular Diversification in the Quorum-Sensing System of Vibrio cholerae: Role of Natural Selection in the Emergence of Pandemic Strains

Applied and Environmental Microbiology ◽

10.1128/aem.02496-08 ◽

2009 ◽

Vol 75 (11) ◽

pp. 3808-3812 ◽

Cited By ~ 5

Author(s):

Nina M. Talyzina ◽

Pär K. Ingvarsson ◽

Jun Zhu ◽

Sun N. Wai ◽

Agneta Andersson

Keyword(s):

Natural Selection ◽

Quorum Sensing ◽

Vibrio Cholerae ◽

Sensing System ◽

Quorum Sensing System ◽

Pandemic Strains

ABSTRACT Two haplotypes of the Vibrio cholerae quorum-sensing system regulator hapR are described: hapR1, common among nonpandemic, non-O1, non-O139 strains, and hapR2, associated with pandemic O1 and O139 and epidemic O37 V. cholerae strains. The hapR2 has evolved under strong natural selection, implying that its fixation was influenced by conditions that led to cholera pandemics.

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The Pseudomonas Quinolone Signal Regulates rhl Quorum Sensing in Pseudomonas aeruginosa

Journal of Bacteriology ◽

10.1128/jb.182.10.2702-2708.2000 ◽

2000 ◽

Vol 182 (10) ◽

pp. 2702-2708 ◽

Cited By ~ 259

Author(s):

Susan L. McKnight ◽

Barbara H. Iglewski ◽

Everett C. Pesci

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Opportunistic Pathogen ◽

Homoserine Lactone ◽

Sensing System ◽

Sensing Systems ◽

Pseudomonas Quinolone Signal ◽

Quorum Sensing System ◽

Encoding Gene

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa uses intercellular signals to control the density-dependent expression of many virulence factors. The las and rhlquorum-sensing systems function, respectively, through the autoinducersN-(3-oxododecanoyl)-l-homoserine lactone andN-butyryl-l-homoserine lactone (C4-HSL), which are known to positively regulate the transcription of the elastase-encoding gene, lasB. Recently, we reported that a second type of intercellular signal is involved in lasB induction. This signal was identified as 2-heptyl-3-hydroxy-4-quinolone and designated thePseudomonas quinolone signal (PQS). PQS was determined to be part of the quorum-sensing hierarchy since its production and bioactivity depended on the las and rhlquorum-sensing systems, respectively. In order to define the role of PQS in the P. aeruginosa quorum-sensing cascade,lacZ gene fusions were used to determine the effect of PQS on the transcription of the quorum-sensing system geneslasR, lasI, rhlR, andrhlI. We found that in P. aeruginosa, PQS caused a major induction of rhlI′-lacZ and had lesser effects on the transcription of lasR′-lacZ andrhlR′-lacZ. We also observed that the transcription of bothrhlI′-lacZ and lasB′-lacZ was cooperatively effected by C4-HSL and PQS. Additionally, we present data indicating that PQS was not produced maximally until cultures reached the late stationary phase of growth. Taken together, our results imply that PQS acts as a link between the las and rhlquorum-sensing systems and that this signal is not involved in sensing cell density.

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The role of quorum sensing system in antimicrobial inducedampCexpression inPseudomonas aeruginosabiofilm

Journal of Basic Microbiology ◽

10.1002/jobm.201300987 ◽

2014 ◽

Vol 55 (5) ◽

pp. 671-678 ◽

Cited By ~ 7

Author(s):

Jingming Zhao ◽

Handong Jiang ◽

Wei Cheng ◽

Jinxiang Wu ◽

Jiping Zhao ◽

...

Keyword(s):

Quorum Sensing ◽

Sensing System ◽

Quorum Sensing System

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Insights into the Genome Sequences of an N -Acyl Homoserine Lactone Molecule Producing Two Pseudomonas spp. Isolated from the Arctic

Genome Announcements ◽

10.1128/genomea.00767-16 ◽

2016 ◽

Vol 4 (4) ◽

Cited By ~ 3

Author(s):

Akhilandeswarre Dharmaprakash ◽

Dinesh Reghunathan ◽

Krishnakutty C. Sivakumar ◽

Manoj Prasannakumar ◽

Sabu Thomas

Keyword(s):

Quorum Sensing ◽

Draft Genome ◽

Homoserine Lactone ◽

The Arctic ◽

Acyl Homoserine Lactone ◽

Cold Environments ◽

Sensing System ◽

Quorum Sensing System ◽

First Time

We report for the first time the draft genome sequence of two psychrotrophic Pseudomonas species, Pseudomonas simiae RGCB 73 and Pseudomonas brenneri RGCB 108, from the Arctic that produce more than one acyl homoserine lactone molecule of varied N -acyl length. The study confirms the presence of a LuxR-LuxI (type) mediated quorum-sensing system in both the Pseudomonas species and enables us to understand the role of quorum sensing in their survival in extremely cold environments.

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