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FEMS Microbiology Reviews Mar 2006Bacteria use small signal molecules in order to monitor their population density and coordinate gene regulation in a process called quorum sensing. In Gram-negative... (Review)
Review
Bacteria use small signal molecules in order to monitor their population density and coordinate gene regulation in a process called quorum sensing. In Gram-negative bacteria, the most common signal molecules are acylated homoserine lactones. Several Pseudomonas species produce acylated homoserine lactones that control important functions including pathogenicity and plant growth promotion. Many reports indicate that the quorum sensing systems of Pseudomonas are significantly regulated and interconnected with regulons of other global regulators. The integration of quorum sensing into additional regulatory circuits increases the range of environmental and metabolic signals beyond that of cell density, as well as further tuning the timing of the response. This review will focus on the regulation of quorum sensing in Pseudomonas, highlighting a complex response that might serve a given species to adapt in its particular environment.
Topics: Bacterial Physiological Phenomena; Bacterial Proteins; Gene Expression Regulation, Bacterial; Pseudomonas; Pseudomonas aeruginosa; Signal Transduction
PubMed: 16472307
DOI: 10.1111/j.1574-6976.2005.00012.x -
MicrobiologyOpen Sep 2020Strains MS586 and MS82, which are aerobic, Gram-negative, rod-shaped, and polar-flagellated bacteria, were isolated from the soybean rhizosphere in Mississippi....
Strains MS586 and MS82, which are aerobic, Gram-negative, rod-shaped, and polar-flagellated bacteria, were isolated from the soybean rhizosphere in Mississippi. Taxonomic positions of MS586 and MS82 were determined using a polyphasic approach. 16S rRNA gene sequence analyses of the two strains showed high pairwise sequence similarities (>98%) to some Pseudomonas species. Analysis of the concatenated 16S rRNA, rpoB, rpoD, and gyrB gene sequences indicated that the strains belonging to the Pseudomonas koreensis subgroup (SG) shared the highest similarity with Pseudomonas kribbensis strain 46-2 . Analyses of average nucleotide identity (ANI), genome-to-genome distance, delineated MS586 and MS82 from other species within the genus Pseudomonas. The predominant quinone system of the strain was ubiquinone 9 (Q-9), and the DNA G+C content was 60.48 mol%. The major fatty acids were C , C cyclo, and the summed features 3 and 8 consisting of C ω7c/C ω6c and C ω7c/C ω6c, respectively. The major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, and diphosphatidylglycerol. Based on these data, it is proposed that strains MS586 and MS82 represent a novel species within the genus Pseudomonas. The proposed name for the new species is Pseudomonas glycinae, and the type strain is MS586 (accession NRRL B-65441 = accession LMG 30275).
Topics: Bacterial Typing Techniques; Base Composition; DNA Fingerprinting; DNA, Bacterial; Fatty Acids; Genes, Bacterial; Genes, rRNA; Genome, Bacterial; Lipids; Phylogeny; Pseudomonas; RNA, Ribosomal, 16S; Rhizosphere; Soil Microbiology; Glycine max; Ubiquinone
PubMed: 32657018
DOI: 10.1002/mbo3.1101 -
FEMS Microbiology Reviews Jul 2014Membrane-spanning signaling pathways enable bacteria to alter gene expression in response to extracytoplasmic stimuli. Many such pathways are cell-surface signaling... (Review)
Review
Membrane-spanning signaling pathways enable bacteria to alter gene expression in response to extracytoplasmic stimuli. Many such pathways are cell-surface signaling (CSS) systems, which are tripartite molecular devices that allow Gram-negative bacteria to transduce an extracellular stimulus into a coordinated transcriptional response. Typically, CSS systems are composed of the following: (1) an outer membrane receptor, which senses the extracellular stimulus; (2) a cytoplasmic membrane-spanning protein involved in signal transduction from the periplasm to the cytoplasm; and (3) an extracytoplasmic function (ECF) sigma factor that initiates expression of the stimulus-responsive gene(s). Members of genus Pseudomonas provide a paradigmatic example of how CSS systems contribute to the global control of gene expression. Most CSS systems enable self-regulated uptake of iron via endogenous (pyoverdine) or exogenous (xenosiderophores, heme, and citrate) carriers. Some are also implicated in virulence, biofilm formation, and cell-cell interactions. Incorporating insights from the well-characterized alginate regulatory circuitry, this review will illustrate common themes and variations at the level of structural and functional properties of Pseudomonas CSS systems. Control of the expression and activity of ECF sigma factors are central to gene regulation via CSS, and the variety of intrinsic and extrinsic factors influencing these processes will be discussed.
Topics: Cell Membrane; Gene Expression Regulation, Bacterial; Iron; Pseudomonas; Sigma Factor; Signal Transduction; Stress, Physiological
PubMed: 24923658
DOI: 10.1111/1574-6976.12078 -
Microbiology Spectrum Feb 2023Flagellins are the main constituents of the flagellar filaments that provide bacterial motility, chemotactic ability, and host immune elicitation ability. Although the...
Flagellins are the main constituents of the flagellar filaments that provide bacterial motility, chemotactic ability, and host immune elicitation ability. Although the functions of flagellins have been extensively studied in bacteria with a single flagellin-encoding gene, the function of multiple flagellin-encoding genes in a single bacterial species is largely unknown. Here, the model plant-growth-promoting bacterium Pseudomonas kilonensis F113 was used to decipher the divergent functions of duplicated flagellins. We demonstrate that the two flagellins (FliC-1 and FliC-2) in 12 Pseudomonas strains, including F113, are evolutionarily distinct. Only the gene but not the gene in strain F113 is responsible for flagellar biogenesis, motility, and plant immune elicitation. The transcriptional expression of was significantly lower than that of in medium and , most likely due to variations in promoter activity. prediction revealed that all genes in the 12 Pseudomonas strains have a poorly conserved promoter motif. Compared to the Flg22-2 epitope (relative to FliC-2), Flg22-1 (relative to FliC-1) induced stronger FLAGELLIN SENSING 2 (FLS2)-mediated microbe-associated molecular pattern-triggered immunity and significantly inhibited plant root growth. A change in the 19th amino acid in Flg22-2 reduced its binding affinity to the FLS2/brassinosteroid insensitive 1-associated kinase 1 complex. Also, Flg22-2 epitopes in the other 11 Pseudomonas strains were presumed to have low binding affinity due to the same change in the 19th amino acid. These findings suggest that Pseudomonas has evolved duplicate flagellins, with only FliC-1 contributing to motility and plant immune elicitation. Flagellins have emerged as important microbial patterns. This work focuses on flagellin duplication in some plant-associated Pseudomonas. Our findings on the divergence of duplicated flagellins provide a conceptual framework for better understanding the functional determinant flagellin and its peptide in multiple-flagellin plant-growth-promoting rhizobacteria.
Topics: Flagellin; Pseudomonas; Plant Immunity
PubMed: 36629446
DOI: 10.1128/spectrum.03621-22 -
Revista Chilena de Infectologia :... Aug 2015
Topics: Oryza; Pseudomonas; beta-Lactams
PubMed: 26436789
DOI: 10.4067/S0716-10182015000500011 -
Journal of the Royal Society, Interface Mar 2023Quorum sensing is a widespread process in bacteria that controls collective behaviours in response to cell density. Populations of cells coordinate gene expression...
Quorum sensing is a widespread process in bacteria that controls collective behaviours in response to cell density. Populations of cells coordinate gene expression through the perception of self-produced chemical signals. Although this process is well-characterized genetically and biochemically, quantitative information about network properties, including induction dynamics and steady-state behaviour, is scarce. Here we integrate experiments with mathematical modelling to quantitatively analyse the LasI/LasR quorum sensing pathway in the opportunistic pathogen . We determine key kinetic parameters of the pathway and, using the parametrized model, show that quorum sensing behaves as a bistable hysteretic switch, with stable on and off states. We investigate the significance of feedback architecture and find that positive feedback on signal production is critical for induction dynamics and bistability, whereas positive feedback on receptor expression and negative feedback on signal production play a minor role. Taken together, our data-based modelling approach reveals fundamental and emergent properties of a bacterial quorum sensing circuit, and provides evidence that native quorum sensing can indeed function as the gene expression switch it is commonly perceived to be.
Topics: Pseudomonas; Pseudomonas aeruginosa; Quorum Sensing; Bacterial Proteins; Gene Expression; Gene Expression Regulation, Bacterial
PubMed: 36919437
DOI: 10.1098/rsif.2022.0825 -
Proceedings of the National Academy of... Aug 2000Pseudomonas syringae is a member of an important group of Gram-negative bacterial pathogens of plants and animals that depend on a type III secretion system to inject... (Review)
Review
Pseudomonas syringae is a member of an important group of Gram-negative bacterial pathogens of plants and animals that depend on a type III secretion system to inject virulence effector proteins into host cells. In P. syringae, hrp/hrc genes encode the Hrp (type III secretion) system, and avirulence (avr) and Hrp-dependent outer protein (hop) genes encode effector proteins. The hrp/hrc genes of P. syringae pv syringae 61, P. syringae pv syringae B728a, and P. syringae pv tomato DC3000 are flanked by an exchangeable effector locus and a conserved effector locus in a tripartite mosaic Hrp pathogenicity island (Pai) that is linked to a tRNA(Leu) gene found also in Pseudomonas aeruginosa but without linkage to Hrp system genes. Cosmid pHIR11 carries a portion of the strain 61 Hrp pathogenicity island that is sufficient to direct Escherichia coli and Pseudomonas fluorescens to inject HopPsyA into tobacco cells, thereby eliciting a hypersensitive response normally triggered only by plant pathogens. Large deletions in strain DC3000 revealed that the conserved effector locus is essential for pathogenicity but the exchangeable effector locus has only a minor role in growth in tomato. P. syringae secretes HopPsyA and AvrPto in culture in a Hrp-dependent manner at pH and temperature conditions associated with pathogenesis. AvrPto is also secreted by Yersinia enterocolitica. The secretion of AvrPto depends on the first 15 codons, which are also sufficient to direct the secretion of an Npt reporter from Y. enterocolitica, indicating that a universal targeting signal is recognized by the type III secretion systems of both plant and animal pathogens.
Topics: Bacterial Proteins; Mosaicism; Pseudomonas
PubMed: 10922033
DOI: 10.1073/pnas.97.16.8770 -
Microbiology (Reading, England) Dec 2019Chemotaxis allows bacteria to sense gradients in their environment and respond by directing their swimming. Aer is a receptor that, instead of responding to a specific...
Chemotaxis allows bacteria to sense gradients in their environment and respond by directing their swimming. Aer is a receptor that, instead of responding to a specific chemoattractant, allows bacteria to sense cellular energy levels and move towards favourable environments. In the number of apparent Aer homologues differs between the only two species it has been characterized in, and . Here we combined bioinformatic approaches with deletional mutagenesis in KF707 to further characterize Aer. It was determined that the number of Aer homologues varies between zero and four throughout the genus , and they were phylogenetically classified into five subgroups. We also used sequence analysis to show that these homologous receptors differ in their HAMP signal transduction domains. Genetic analysis also indicated that some Aer homologues have likely been subject to horizontal transfer. KF707 was unique among strains for having three Aer homologues as well as the receptors CttP and McpB. Phenotypic characterization in this strain showed that the most prevalent homologue of Aer was key, but not essential, for energy taxis. This study demonstrates that energy taxis in varies between species and provides a new naming convention and associated phylogenetic details for Aer chemoreceptors.
Topics: Amino Acid Sequence; Bacterial Proteins; Gene Transfer, Horizontal; Genetic Variation; Membrane Proteins; Phenotype; Phylogeny; Pseudomonas; Pseudomonas pseudoalcaligenes; Signal Transduction; Species Specificity; Taxis Response
PubMed: 31639075
DOI: 10.1099/mic.0.000864 -
Journal of Bacteriology Jul 1961Colwell, R. R. (University of Washington, Seattle), and J. Liston. Taxonomic relationships among the pseudomonads. J. Bacteriol. 82:1-14. 1961.-An electronic computer...
Colwell, R. R. (University of Washington, Seattle), and J. Liston. Taxonomic relationships among the pseudomonads. J. Bacteriol. 82:1-14. 1961.-An electronic computer technique, utilizing the Adansonian principle that every feature should have equal weight, was applied in an effort to derive a taxonomy of the Pseudomonas-Achromobacter group of gram-negative, asporogenous, rodlike bacteria. The validity of the general method was tested by an analysis of 40 well defined strains, principally derived from type culture collections and representative of different genera and families of the Pseudomonadales and the Eubacteriales. The analysis clearly separated groups which are recognized to be taxonomically distinct. Aerogenic Aeromonas were most similar to the Enterobacteriaceae and taxonomically distinct from the anaerogenic Aeromonas formicans which was more similar to the Pseudomonas group. Oxidative Vibrio species grouped with Pseudomonas and probably should be renamed Pseudomonas. Fermentative Vibrio species showed affinities with A. formicans.Fifty-four Pseudomonas strains out of 58 tested in an analysis of 80 bacterial cultures, clustered into four large groups: group 1, a marine group within which appeared a psychrophilic, nonproteolytic species subgroup related to Vibrio beijerinckii and a subgeneric subgroup which included Pseudomonas elongata; group 2, a subgeneric mesophilic group including Vibrio percolans and associated with Pseudomonas fragi; group 3, a fluorescent pigment-producing group, including three subgroups, a psychrophilic aeruginosa-like species group, a mesophilic Pseudomonas aeruginosa species group, and a heterogeneous subgeneric group containing Vibrio cuneatus and related to Pseudomonas fluorescens and Pseudomonas pavonacea; group 4, a subgeneric nonpigment-producing, mesophilic group, which included Vibrio tyrogenus, Pseudomonas ovalis, and Pseudomonas denitrificans.
Topics: Achromobacter; Aeromonas; Bacteria; Enterobacteriaceae; Oxidation-Reduction; Pseudomonas; Pseudomonas fragi; Pseudomonas putida; Vibrio
PubMed: 13694873
DOI: 10.1128/jb.82.1.1-14.1961 -
Microbes and Environments 2010Over the past few decades, degradative plasmids have been isolated from bacteria capable of degrading a variety of both natural and man-made compounds. Degradative... (Review)
Review
Over the past few decades, degradative plasmids have been isolated from bacteria capable of degrading a variety of both natural and man-made compounds. Degradative plasmids belonging to three incompatibility (Inc) groups in Pseudomonas (IncP-1, P-7, and P-9) have been well studied in terms of their replication, maintenance, and capacity for conjugative transfer. The host ranges of these plasmids are determined by replication or conjugative transfer systems. The host range of IncP-1 is broad, that of IncP-9 is intermediate, and that of IncP-7 is narrow. To understand the behavior of these plasmids and their hosts in various environments, the survivability of inocula, stability or transferability, and efficiency of biodegradation in environments and microcosms have been monitored. The biodegradation and plasmid transfer in various environments have been observed for all three groups, although the kinds of transconjugants differed with the Inc groups. In some cases, the deletion and amplification of catabolic genes acted to reduce the production of toxic catabolic intermediates, or to increase the activity on a particular catabolic pathway. The combination of degradative genes, the plasmid backbone of each Inc group, and the host of the plasmids is key to the degraders adapting to various hosts or to heterogeneous environments.
Topics: Biodegradation, Environmental; Environmental Microbiology; Environmental Pollutants; Host Specificity; Plasmids; Pseudomonas
PubMed: 21576880
DOI: 10.1264/jsme2.me10155