scholarly journals Exploring the transcriptome ofluxI−andΔainSmutants and the impact of N-3-oxo-hexanoyl-L- and N-3-hydroxy-decanoyl-L-homoserine lactones on biofilm formation inAliivibrio salmonicida

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6845
Author(s):  
Miriam Khider ◽  
Hilde Hansen ◽  
Erik Hjerde ◽  
Jostein A. Johansen ◽  
Nils Peder Willassen
Keyword(s):  
Biofilm Formation ◽  
Expression Patterns ◽  
Critical Role ◽  
Transcriptome Profiling ◽  
Global Gene Expression ◽  
Gene Clusters ◽  
Homoserine Lactone ◽  
Dependent Manner ◽  
Homoserine Lactones ◽  
The Impact

BackgroundBacterial communication through quorum sensing (QS) systems has been reported to be important in coordinating several traits such as biofilm formation. InAliivibrio salmonicidatwo QS systems the LuxI/R and AinS/R, have been shown to be responsible for the production of eight acyl-homoserine lactones (AHLs) in a cell density dependent manner. We have previously demonstrated that inactivation of LitR, the master regulator of the QS system resulted in biofilm formation, similar to the biofilm formed by the AHL deficient mutantΔainSluxI−. In this study, we aimed to investigate the global gene expression patterns ofluxIandainSautoinducer synthases mutants using transcriptomic profiling. In addition, we examined the influence of the different AHLs on biofilm formation.ResultsThe transcriptome profiling ofΔainSandluxI−mutants allowed us to identify genes and gene clusters regulated by QS inA. salmonicida. Relative to the wild type, theΔainSandluxI−mutants revealed 29 and 500 differentially expressed genes (DEGs), respectively. The functional analysis demonstrated that the most pronounced DEGs were involved in bacterial motility and chemotaxis, exopolysaccharide production, and surface structures related to adhesion. Inactivation ofluxI, but notainSgenes resulted in wrinkled colony morphology. While inactivation of both genes (ΔainSluxI−) resulted in strains able to form wrinkled colonies and mushroom structured biofilm. Moreover, when theΔainSluxI−mutant was supplemented with N-3-oxo-hexanoyl-L-homoserine lactone (3OC6-HSL) or N-3-hydroxy-decanoyl-L-homoserine lactone (3OHC10-HSL), the biofilm did not develop. We also show that LuxI is needed for motility and for repression of EPS production, where repression of EPS is likely operated through the RpoQ-sigma factor.ConclusionThese findings imply that the LuxI and AinS autoinducer synthases play a critical role in the regulation of biofilm formation, EPS production, and motility.

scholarly journals Exploring the transcriptome of luxI- and ΔainS mutants and the impact of N-3-oxo-hexanoyl-L- and N-3-hydroxy-decanoyl-L-homoserine lactones on biofilm formation in Aliivibrio salmonicida

2018 ◽  
Author(s):  
Miriam Khider ◽  
Hilde Hansen ◽  
Jostein A. Johansen ◽  
Erik Hjerde ◽  
Nils Peder Willassen
Keyword(s):  
Biofilm Formation ◽  
Transcriptome Profiling ◽  
Homoserine Lactone ◽  
Colony Morphology ◽  
Phenotypic Traits ◽  
Dependent Manner ◽  
Rna Seq ◽  
Homoserine Lactones ◽  
A Cell ◽  
The Impact

Background. The marine bacterium A. salmonicida uses the quorum sensing (QS) systems, AinS/R and LuxI/R to produce eight acyl-homoserine lactones (AHLs) in a cell density dependent manner. Biofilm formation is one of the QS regulated phenotypes, which requires the expression of exopolysaccharides (EPS).We previously demonstrated that inactivation of LitR, the master regulator of QS in A. salmonicida resulted in biofilm formation, which was, similar to the biofilm formed by the AHL deficient mutant ΔainSluxI-.In this work, we have identified genes regulated by AinS and LuxI using RNA sequensing (RNA-Seq), and studied their role in biofilm formation, colony morphology and motility. We have also studied the effect of two AHLs on the biofilm formation. Results.The transcriptome profiling of ΔainS and luxI- mutants allowed us to identify essential genes regulated by QS in A. salmonicida. Relative to the wild-type, the ΔainS and luxI- mutants revealed 40 and 500 differentially expressed genes (DEGs), respectively. The functional analysis demonstrated that the most pronounced DEGs were involved in bacterial motility and chemotaxis, exopolysaccharide production, and surface structures related to adhesion. Inactivation of luxI but not ainS genes resulted in wrinkled colony morphology. While inactivation of both genes (ΔainSluxI-) resulted in strains able to form wrinkled colonies and mushroom structured biofilm. Moreover, when the ΔainSluxI- mutant was supplemented with N-3-oxo-hexanoyl-L- homoserine lactone (3OC6-HSL) and N-3-hydroxy-decanoyl-L-homoserine lactone(3OHC10-HSL), the biofilm did not develop. We also show that LuxI is needed for motility and repression for EPS production, where repression of EPS is likely operated through the RpoQ-sigma factor. Conclusion.These findings imply that LuxI and AinS synthases have a critical contribution to the QS-dependent regulation on gene expression and the phenotypic traits related to it.

scholarly journals Exploring the transcriptome of luxI- and ΔainS mutants and the impact of N-3-oxo-hexanoyl-L- and N-3-hydroxy-decanoyl-L-homoserine lactones on biofilm formation in Aliivibrio salmonicida

2018 ◽  
Author(s):  
Miriam Khider ◽  
Hilde Hansen ◽  
Jostein A. Johansen ◽  
Erik Hjerde ◽  
Nils Peder Willassen
Keyword(s):  
Biofilm Formation ◽  
Transcriptome Profiling ◽  
Homoserine Lactone ◽  
Colony Morphology ◽  
Phenotypic Traits ◽  
Dependent Manner ◽  
Rna Seq ◽  
Homoserine Lactones ◽  
A Cell ◽  
The Impact

Background. The marine bacterium A. salmonicida uses the quorum sensing (QS) systems, AinS/R and LuxI/R to produce eight acyl-homoserine lactones (AHLs) in a cell density dependent manner. Biofilm formation is one of the QS regulated phenotypes, which requires the expression of exopolysaccharides (EPS).We previously demonstrated that inactivation of LitR, the master regulator of QS in A. salmonicida resulted in biofilm formation, which was, similar to the biofilm formed by the AHL deficient mutant ΔainSluxI-.In this work, we have identified genes regulated by AinS and LuxI using RNA sequensing (RNA-Seq), and studied their role in biofilm formation, colony morphology and motility. We have also studied the effect of two AHLs on the biofilm formation. Results.The transcriptome profiling of ΔainS and luxI- mutants allowed us to identify essential genes regulated by QS in A. salmonicida. Relative to the wild-type, the ΔainS and luxI- mutants revealed 40 and 500 differentially expressed genes (DEGs), respectively. The functional analysis demonstrated that the most pronounced DEGs were involved in bacterial motility and chemotaxis, exopolysaccharide production, and surface structures related to adhesion. Inactivation of luxI but not ainS genes resulted in wrinkled colony morphology. While inactivation of both genes (ΔainSluxI-) resulted in strains able to form wrinkled colonies and mushroom structured biofilm. Moreover, when the ΔainSluxI- mutant was supplemented with N-3-oxo-hexanoyl-L- homoserine lactone (3OC6-HSL) and N-3-hydroxy-decanoyl-L-homoserine lactone(3OHC10-HSL), the biofilm did not develop. We also show that LuxI is needed for motility and repression for EPS production, where repression of EPS is likely operated through the RpoQ-sigma factor. Conclusion.These findings imply that LuxI and AinS synthases have a critical contribution to the QS-dependent regulation on gene expression and the phenotypic traits related to it.

scholarly journals Engineering acyl-homoserine lactone-interfering enzymes toward bacterial control

2020 ◽  
Vol 295 (37) ◽  
pp. 12993-13007 ◽  
Author(s):  
Raphaël Billot ◽  
Laure Plener ◽  
Pauline Jacquet ◽  
Mikael Elias ◽  
Eric Chabrière ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Homoserine Lactone ◽  
Communication Process ◽  
Dependent Manner ◽  
Biotechnological Potential ◽  
Bacterial Communication ◽  
Homoserine Lactones ◽  
A Cell ◽  
Eukaryotic Organisms ◽  
Bacterial Control

Enzymes able to degrade or modify acyl-homoserine lactones (AHLs) have drawn considerable interest for their ability to interfere with the bacterial communication process referred to as quorum sensing. Many proteobacteria use AHL to coordinate virulence and biofilm formation in a cell density–dependent manner; thus, AHL-interfering enzymes constitute new promising antimicrobial candidates. Among these, lactonases and acylases have been particularly studied. These enzymes have been isolated from various bacterial, archaeal, or eukaryotic organisms and have been evaluated for their ability to control several pathogens. Engineering studies on these enzymes were carried out and successfully modulated their capacity to interact with specific AHL, increase their catalytic activity and stability, or enhance their biotechnological potential. In this review, special attention is paid to the screening, engineering, and applications of AHL-modifying enzymes. Prospects and future opportunities are also discussed with a view to developing potent candidates for bacterial control.

scholarly journals Arginine Decarboxylase Is Essential for Pneumococcal Stress Responses

Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 286
Author(s):  
Mary Frances Nakamya ◽  
Moses B. Ayoola ◽  
Leslie A. Shack ◽  
Mirghani Mohamed ◽  
Edwin Swiatlo ◽  
...  
Keyword(s):  
Stress Responses ◽  
Critical Role ◽  
Acid Stress ◽  
Arginine Decarboxylase ◽  
Arginine Deiminase ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Opportunistic Human Pathogen ◽  
Thiol Peroxidase ◽  
The Impact

Polyamines such as putrescine, cadaverine, and spermidine are small cationic molecules that play significant roles in cellular processes, including bacterial stress responses and host–pathogen interactions. Streptococcus pneumoniae is an opportunistic human pathogen, which causes several diseases that account for significant morbidity and mortality worldwide. As it transits through different host niches, S. pneumoniae is exposed to and must adapt to different types of stress in the host microenvironment. We earlier reported that S. pneumoniae TIGR4, which harbors an isogenic deletion of an arginine decarboxylase (ΔspeA), an enzyme that catalyzes the synthesis of agmatine in the polyamine synthesis pathway, has a reduced capsule. Here, we report the impact of arginine decarboxylase deletion on pneumococcal stress responses. Our results show that ΔspeA is more susceptible to oxidative, nitrosative, and acid stress compared to the wild-type strain. Gene expression analysis by qRT-PCR indicates that thiol peroxidase, a scavenger of reactive oxygen species and aguA from the arginine deiminase system, could be important for peroxide stress responses in a polyamine-dependent manner. Our results also show that speA is essential for endogenous hydrogen peroxide and glutathione production in S. pneumoniae. Taken together, our findings demonstrate the critical role of arginine decarboxylase in pneumococcal stress responses that could impact adaptation and survival in the host.

scholarly journals Quorum-Sensing Genes in Pseudomonas aeruginosa Biofilms: Their Role and Expression Patterns

2001 ◽  
Vol 67 (4) ◽  
pp. 1865-1873 ◽  
Author(s):  
Teresa R. De Kievit ◽  
Richard Gillis ◽  
Steve Marx ◽  
Chris Brown ◽  
Barbara H. Iglewski
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Fluorescent Protein ◽  
Expression Patterns ◽  
Homoserine Lactone ◽  
Lower Percentage ◽  
Spatial Studies ◽  
Green Fluorescent ◽  
Biofilm Development

ABSTRACT Acylated homoserine lactone molecules are used by a number of gram-negative bacteria to regulate cell density-dependent gene expression by a mechanism known as quorum sensing (QS). InPseudomonas aeruginosa, QS or cell-to-cell signaling controls expression of a number of virulence factors, as well as biofilm differentiation. In this study, we investigated the role played by the las and rhl QS systems during the early stages of static biofilm formation when cells are adhering to a surface and forming microcolonies. These studies revealed a marked difference in biofilm formation between the PAO1 parent and the QS mutants when glucose, but not citrate, was used as the sole carbon source. To further elucidate the contribution of lasI andrhlI to biofilm maturation, we utilized fusions to unstable green fluorescent protein in concert with confocal microscopy to perform real-time temporal and spatial studies of these genes in a flowing environment. During the course of 8-day biofilm development,lasI expression was found to progressively decrease over time. Conversely, rhlI expression remained steady throughout biofilm development but occurred in a lower percentage of cells. Spatial analysis revealed that lasI andrhlI were maximally expressed in cells located at the substratum and that expression decreased with increasing biofilm height. Because QS was shown previously to be involved in biofilm differentiation, these findings have important implications for the design of biofilm prevention and eradication strategies.

scholarly journals The effect of NAMPT deletion in projection neurons on the function and structure of neuromuscular junction (NMJ) in mice

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Samuel Lundt ◽  
Nannan Zhang ◽  
Xiaowan Wang ◽  
Luis Polo-Parada ◽  
Shinghua Ding
Keyword(s):  
Neuromuscular Junction ◽  
Synaptic Vesicle ◽  
Critical Role ◽  
Conditional Knockout ◽  
High Frequency Stimulation ◽  
Mitochondrial Morphology ◽  
Projection Neurons ◽  
Dependent Manner ◽  
Nicotinamide Phosphoribosyltransferase ◽  
The Impact

AbstractNicotinamide adenine dinucleotide (NAD+) plays a critical role in energy metabolism and bioenergetic homeostasis. Most NAD+ in mammalian cells is synthesized via the NAD+ salvage pathway, where nicotinamide phosphoribosyltransferase (NAMPT) is the rate-limiting enzyme, converting nicotinamide into nicotinamide mononucleotide (NMN). Using a Thy1-Nampt−/− projection neuron conditional knockout (cKO) mouse, we studied the impact of NAMPT on synaptic vesicle cycling in the neuromuscular junction (NMJ), end-plate structure of NMJs and muscle contractility of semitendinosus muscles. Loss of NAMPT impaired synaptic vesicle endocytosis/exocytosis in the NMJs. The cKO mice also had motor endplates with significantly reduced area and thickness. When the cKO mice were treated with NMN, vesicle endocytosis/exocytosis was improved and endplate morphology was restored. Electrical stimulation induced muscle contraction was significantly impacted in the cKO mice in a frequency dependent manner. The cKO mice were unresponsive to high frequency stimulation (100 Hz), while the NMN-treated cKO mice responded similarly to the control mice. Transmission electron microscopy (TEM) revealed sarcomere misalignment and changes to mitochondrial morphology in the cKO mice, with NMN treatment restoring sarcomere alignment but not mitochondrial morphology. This study demonstrates that neuronal NAMPT is important for pre-/post-synaptic NMJ function, and maintaining skeletal muscular function and structure.

scholarly journals Fibrinogen-InducedStreptococcus mutansBiofilm Formation and Adherence to Endothelial Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Telma Blanca Lombardo Bedran ◽  
Jabrane Azelmat ◽  
Denise Palomari Spolidorio ◽  
Daniel Grenier
Keyword(s):  
Endothelial Cells ◽  
Infective Endocarditis ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
Bactericidal Effect ◽  
Dependent Manner ◽  
Bacterial Cells ◽  
Human Fibrinogen ◽  
Polystyrene Support ◽  
The Impact

Streptococcus mutans, the predominant bacterial species associated with dental caries, can enter the bloodstream and cause infective endocarditis. The aim of this study was to investigateS. mutansbiofilm formation and adherence to endothelial cells induced by human fibrinogen. The putative mechanism by which biofilm formation is induced as well as the impact of fibrinogen onS. mutansresistance to penicillin was also evaluated. Bovine plasma dose dependently induced biofilm formation byS. mutans. Of the various plasma proteins tested, only fibrinogen promoted the formation of biofilm in a dose-dependent manner. Scanning electron microscopy observations revealed the presence of complex aggregates of bacterial cells firmly attached to the polystyrene support.S. mutansin biofilms induced by the presence of fibrinogen was markedly resistant to the bactericidal effect of penicillin. Fibrinogen also significantly increased the adherence ofS. mutansto endothelial cells. NeitherS. mutanscells nor culture supernatants converted fibrinogen into fibrin. However, fibrinogen is specifically bound to the cell surface ofS. mutansand may act as a bridging molecule to mediate biofilm formation. In conclusion, our study identified a new mechanism promotingS. mutansbiofilm formation and adherence to endothelial cells which may contribute to infective endocarditis.

scholarly journals Quantitative modelling predicts the impact of DNA methylation on RNA polymerase II traffic

2019 ◽  
Vol 116 (30) ◽  
pp. 14995-15000 ◽  
Author(s):  
Justyna Cholewa-Waclaw ◽  
Ruth Shah ◽  
Shaun Webb ◽  
Kashyap Chhatbar ◽  
Bernard Ramsahoye ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Rett Syndrome ◽  
Transcription Initiation ◽  
Expression Patterns ◽  
Global Gene Expression ◽  
A Genome ◽  
The Impact

Patterns of gene expression are primarily determined by proteins that locally enhance or repress transcription. While many transcription factors target a restricted number of genes, others appear to modulate transcription levels globally. An example is MeCP2, an abundant methylated-DNA binding protein that is mutated in the neurological disorder Rett syndrome. Despite much research, the molecular mechanism by which MeCP2 regulates gene expression is not fully resolved. Here, we integrate quantitative, multidimensional experimental analysis and mathematical modeling to indicate that MeCP2 is a global transcriptional regulator whose binding to DNA creates “slow sites” in gene bodies. We hypothesize that waves of slowed-down RNA polymerase II formed behind these sites travel backward and indirectly affect initiation, reminiscent of defect-induced shockwaves in nonequilibrium physics transport models. This mechanism differs from conventional gene-regulation mechanisms, which often involve direct modulation of transcription initiation. Our findings point to a genome-wide function of DNA methylation that may account for the reversibility of Rett syndrome in mice. Moreover, our combined theoretical and experimental approach provides a general method for understanding how global gene-expression patterns are choreographed.

scholarly journals Cell Surface Attachment Structures Contribute to Biofilm Formation and Xylem Colonization by Erwinia amylovora

2011 ◽  
Vol 77 (19) ◽  
pp. 7031-7039 ◽  
Author(s):  
Jessica M. Koczan ◽  
Bryan R. Lenneman ◽  
Molly J. McGrath ◽  
George W. Sundin
Keyword(s):  
Biofilm Formation ◽  
Time Course ◽  
Erwinia Amylovora ◽  
Critical Role ◽  
Gene Clusters ◽  
Type I ◽  
Content Type ◽  
Type Iv ◽  
Attachment Structures

ABSTRACTBiofilm formation plays a critical role in the pathogenesis ofErwinia amylovoraand the systemic invasion of plant hosts. The functional role of the exopolysaccharides amylovoran and levan in pathogenesis and biofilm formation has been evaluated. However, the role of biofilm formation, independent of exopolysaccharide production, in pathogenesis and movement within plants has not been studied previously. Evaluation of the role of attachment inE. amylovorabiofilm formation and virulence was examined through the analysis of deletion mutants lacking genes encoding structures postulated to function in attachment to surfaces or in cellular aggregation. The genes and gene clusters studied were selected based onin silicoanalyses. Microscopic analyses and quantitative assays demonstrated that attachment structures such as fimbriae and pili are involved in the attachment ofE. amylovorato surfaces and are necessary for the production of mature biofilms. A time course assay indicated that type I fimbriae function earlier in attachment, while type IV pilus structures appear to function later in attachment. Our results indicate that multiple attachment structures are needed for mature biofilm formation and full virulence and that biofilm formation facilitates entry and is necessary for the buildup of large populations ofE. amylovoracells in xylem tissue.

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