scholarly journals Evolutionary Plasticity of AmrZ Regulation in Pseudomonas

mSphere ◽  
2018 ◽  
Vol 3 (2) ◽  
pp. e00132-18 ◽  
Author(s):  
David A. Baltrus ◽  
Kevin Dougherty ◽  
Beatriz Diaz ◽  
Rachel Murillo
Keyword(s):  
Pseudomonas Syringae ◽  
Negative Regulator ◽  
Regulatory Function ◽  
Dual Function ◽  
Genomic Context ◽  
Master Regulator ◽  
Content Type ◽  
Swimming Motility ◽  
Positive Regulator ◽  
Mode Of Regulation

ABSTRACT amrZ encodes a master regulator protein conserved across pseudomonads, which can be either a positive or negative regulator of swimming motility depending on the species examined. To better understand plasticity in the regulatory function of AmrZ, we characterized the mode of regulation for this protein for two different motility-related phenotypes in Pseudomonas stutzeri. As in Pseudomonas syringae, AmrZ functions as a positive regulator of swimming motility within P. stutzeri, which suggests that the functions of this protein with regard to swimming motility have switched at least twice across pseudomonads. Shifts in mode of regulation cannot be explained by changes in AmrZ sequence alone. We further show that AmrZ acts as a positive regulator of colony spreading within this strain and that this regulation is at least partially independent of swimming motility. Closer investigation of mechanistic shifts in dual-function regulators like AmrZ could provide unique insights into how transcriptional pathways are rewired between closely related species. IMPORTANCE Microbes often display finely tuned patterns of gene regulation across different environments, with major regulatory changes controlled by a small group of “master” regulators within each cell. AmrZ is a master regulator of gene expression across pseudomonads and can be either a positive or negative regulator for a variety of pathways depending on the strain and genomic context. Here, we demonstrate that the phenotypic outcomes of regulation of swimming motility by AmrZ have switched at least twice independently in pseudomonads, so that AmrZ promotes increased swimming motility in P. stutzeri and P. syringae but represses this phenotype in Pseudomonas fluorescens and Pseudomonas aeruginosa. Since examples of switches in regulatory mode are relatively rare, further investigation into the mechanisms underlying shifts in regulator function for AmrZ could provide unique insights into the evolution of bacterial regulatory proteins.

scholarly journals Evolutionary plasticity of AmrZ regulation in Pseudomonas

2016 ◽  
Author(s):  
David A Baltrus ◽  
Kevin Dougherty ◽  
Beatriz Dias ◽  
Rachel Murillo
Keyword(s):  
Related Species ◽  
Negative Regulator ◽  
Regulatory Function ◽  
Dual Function ◽  
Closely Related Species ◽  
Swimming Motility ◽  
Positive Regulator ◽  
Regulator Protein ◽  
Colony Spreading ◽  
Mode Of Regulation

amrZ, a master regulator protein conserved across Pseudomonads, can be either a positive or negative regulator of swimming motility depending on the species examined. To better understand plasticity in the regulatory function of AmrZ, we characterized the mode of regulation for this protein for two different motility related phenotypes in P. stutzeri. As in P. syringae, AmrZ functions as a positive regulator of swimming motility within P. stutzeri, which suggests that the functions of this protein with regards to swimming motility have switched at least twice across Pseudomonads. Shifts in mode of regulation cannot be explained by changes in AmrZ sequence alone. We further show that AmrZ acts as a positive regulator of colony spreading within this strain, and that this regulation is at least partially independent of swimming motility. Closer investigation of mechanistic shifts in dual function regulators like AmrZ could provide unique insights into how transcriptional pathways are rewired between closely related species.

scholarly journals AmrZ is a positive regulator of swimming motility in Pseudomonas stutzeri

2016 ◽  
Author(s):  
David A Baltrus ◽  
Kevin Dougherty ◽  
Beatriz Dias ◽  
Rachel Murillo
Keyword(s):  
Pseudomonas Stutzeri ◽  
Negative Regulator ◽  
Regulatory Proteins ◽  
Regulatory Function ◽  
Master Regulator ◽  
Swimming Motility ◽  
Positive Regulator ◽  
Regulatory Mode ◽  
Regulator Protein ◽  
Mode Of Regulation

amrZ, a master regulator protein conserved across Pseudomonads, can be either a positive or negative regulator of swimming motility depending on the species examined. To better understand plasticity in the regulatory function of AmrZ, we characterized the mode of regulation for this protein for swimming motility in P. stutzeri. As in P. syringae, AmrZ functions as a positive regulator of motility within P. stutzeri, which suggests that the functions of this protein with regards to swimming motility have switched at least twice across Pseudomonads. We further show that divergence between P. stutzeri and P. aeruginosa alleles of AmrZ does not explain shifts in regulatory mode. Further investigation into the mechanisms underlying shifts in regulatory function for AmrZ could provide unique insights into the evolution of bacterial regulatory proteins.

scholarly journals Evolutionary plasticity of AmrZ regulation in Pseudomonas

2016 ◽  
Author(s):  
David A Baltrus ◽  
Kevin Dougherty ◽  
Beatriz Dias ◽  
Rachel Murillo
Keyword(s):  
Related Species ◽  
Negative Regulator ◽  
Regulatory Function ◽  
Dual Function ◽  
Closely Related Species ◽  
Swimming Motility ◽  
Positive Regulator ◽  
Regulator Protein ◽  
Colony Spreading ◽  
Mode Of Regulation

amrZ, a master regulator protein conserved across Pseudomonads, can be either a positive or negative regulator of swimming motility depending on the species examined. To better understand plasticity in the regulatory function of AmrZ, we characterized the mode of regulation for this protein for two different motility related phenotypes in P. stutzeri. As in P. syringae, AmrZ functions as a positive regulator of swimming motility within P. stutzeri, which suggests that the functions of this protein with regards to swimming motility have switched at least twice across Pseudomonads. Shifts in mode of regulation cannot be explained by changes in AmrZ sequence alone. We further show that AmrZ acts as a positive regulator of colony spreading within this strain, and that this regulation is at least partially independent of swimming motility. Closer investigation of mechanistic shifts in dual function regulators like AmrZ could provide unique insights into how transcriptional pathways are rewired between closely related species.

scholarly journals The BIR2/BIR3-interacting Phospholipase D gamma 1 negatively regulates immunity in Arabidopsis

2019 ◽  
Author(s):  
Maria A. Schlöffel ◽  
Andrea Salzer ◽  
Wei-Lin Wan ◽  
Ringo van Wijk ◽  
Maja Šemanjski ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Pseudomonas Syringae ◽  
Phospholipase D ◽  
Plant Immunity ◽  
Negative Regulator ◽  
Regulatory Function ◽  
Membrane Phospholipids ◽  
Effective Strategies ◽  
Pathogen Invasion ◽  
Molecular Patterns

ABSTRACTPlants have evolved effective strategies to defend themselves against pathogen invasion. Starting from the plasma membrane with the recognition of microbe-associated molecular patterns (MAMPs) via pattern recognition receptors, internal cellular signaling pathways are induced to ultimately fend off the attack. Phospholipase D (PLD) hydrolyzes membrane phospholipids to produce phosphatidic acid (PA), which has been proposed to play a second messenger role in immunity. The Arabidopsis PLD family consists of 12 members and for some a specific function in resistance towards a subset of pathogens has been shown. We demonstrate here that Arabidopsis PLDγ1, but not its close homologs PLDγ2 and PLDγ3, is specifically involved in plant immunity. Genetic inactivation of PLDγ1 resulted in increased resistance towards the virulent bacterium Pseudomonas syringae pv. tomato DC3000 and the necrotrophic fungus Botrytis cinerea. As pldγ1 mutant plants responded with elevated levels of reactive oxygen species to MAMP-treatment, a negative regulatory function for this PLD isoform is proposed. Importantly, PA levels in pldγ1 mutants were not affected compared to stressed wild-type plants, suggesting that alterations in PA levels are unlikely the cause for the enhanced immunity in the pldγ1 line. Instead, the plasma-membrane-attached PLDγ1 protein colocalized and associated with the receptor-like kinases BIR2 and BIR3, which are known negative regulators of pattern-triggered immunity. Moreover, complex formation of PLDγ1 and BIR2 was further promoted upon MAMP-treatment. Hence, we propose that PLDγ1 acts as a negative regulator of plant immune responses in complex with immunity-related proteins BIR2 and BIR3.One-sentence summaryA phospholipase D is a novel negative regulator of plant immunity and forms complexes with regulatory receptor-like kinases.

scholarly journals Dual Function of Aar, a Member of the New AraC Negative Regulator Family, in Escherichia coli Gene Expression

2020 ◽  
Vol 88 (6) ◽  
Author(s):  
Abigail S. Mickey ◽  
James P. Nataro
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Negative Regulator ◽  
Dual Function ◽  
Content Type ◽  
Virulence Gene Expression ◽  
E Coli ◽  
K 12

ABSTRACT Enteroaggregative Escherichia coli (EAEC) is an E. coli pathotype associated with diarrhea and growth faltering. EAEC virulence gene expression is controlled by the autoactivated AraC family transcriptional regulator, AggR. AggR activates transcription of a large number of virulence genes, including Aar, which in turn acts as a negative regulator of AggR itself. Aar has also been shown to affect expression of E. coli housekeeping genes, including H-NS, a global regulator that acts at multiple promoters and silences AT-rich genes (such as those in the AggR regulon). Although Aar has been shown to bind both AggR and H-NS in vitro, functional significance of these interactions has not been shown in vivo. In order to dissect this regulatory network, we removed the complex interdependence of aggR and aar by placing the genes under the control of titratable promoters. We measured phenotypic and genotypic changes on downstream genes in EAEC strain 042 and E. coli K-12 strain DH5α, which lacks the AggR regulon. In EAEC, we found that low expression of aar increases aafA fimbrial gene expression via H-NS; however, when aar is more highly expressed, it acts as a negative regulator via AggR. In DH5α, aar affected expression of E. coli genes in some cases via H-NS and in some cases independent of H-NS. Our data support the model that Aar interacts in concert with AggR, H-NS, and possibly other regulators and that these interactions are likely to be functionally significant in vivo.

scholarly journals The Transcriptional Regulator HlyU Positively Regulates Expression of exsA, Leading to Type III Secretion System 1 Activation in Vibrio parahaemolyticus

2018 ◽  
Vol 200 (15) ◽  
Author(s):  
Landon J. Getz ◽  
Nikhil A. Thomas
Keyword(s):  
Gene Expression ◽  
Type Iii Secretion ◽  
Vibrio Parahaemolyticus ◽  
Virulence Genes ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Master Regulator ◽  
Content Type ◽  
Type Iii ◽  
Positive Regulator

ABSTRACT Vibrio parahaemolyticus is a marine bacterium that is globally recognized as the leading cause of seafood-borne gastroenteritis. V. parahaemolyticus uses various toxins and two type 3 secretion systems (T3SS-1 and T3SS-2) to subvert host cells during infection. We previously determined that V. parahaemolyticus T3SS-1 activity is upregulated by increasing the expression level of the master regulator ExsA under specific growth conditions. In this study, we set out to identify V. parahaemolyticus genes responsible for linking environmental and growth signals to exsA gene expression. Using transposon mutagenesis in combination with a sensitive and quantitative luminescence screen, we identify HlyU and H-NS as two antagonistic regulatory proteins controlling the expression of exsA and, hence, T3SS-1 in V. parahaemolyticus. Disruption of hns leads to constitutive unregulated exsA gene expression, consistent with its known role in repressing exsA transcription. In contrast, genetic disruption of hlyU completely abrogated exsA expression and T3SS-1 activity. A V. parahaemolyticus hlyU null mutant was significantly deficient for T3SS-1-mediated host cell death during in vitro infection. DNA footprinting studies with purified HlyU revealed a 56-bp protected DNA region within the exsA promoter that contains an inverted repeat sequence. Genetic evidence suggests that HlyU acts as a derepressor, likely by displacing H-NS from the exsA promoter, leading to exsA gene expression and appropriately regulated T3SS-1 activity. Overall, the data implicate HlyU as a critical positive regulator of V. parahaemolyticus T3SS-1-mediated pathogenesis. IMPORTANCE Many Vibrio species are zoonotic pathogens, infecting both animals and humans, resulting in significant morbidity and, in extreme cases, mortality. While many Vibrio species virulence genes are known, their associated regulation is often modestly understood. We set out to identify genetic factors of V. parahaemolyticus that are involved in activating exsA gene expression, a process linked to a type III secretion system involved in host cytotoxicity. We discover that V. parahaemolyticus employs a genetic regulatory switch involving H-NS and HlyU to control exsA promoter activity. While HlyU is a well-known positive regulator of Vibrio species virulence genes, this is the first report linking it to a transcriptional master regulator and type III secretion system paradigm.

scholarly journals Regulated Disorder: Posttranslational Modifications Control the RIN4 Plant Immune Signaling Hub

2019 ◽  
Vol 32 (1) ◽  
pp. 56-64 ◽  
Author(s):  
Tania Y. Toruño ◽  
Mingzhe Shen ◽  
Gitta Coaker ◽  
David Mackey
Keyword(s):  
Pseudomonas Syringae ◽  
Posttranslational Modifications ◽  
Protein Complex ◽  
Bacterial Pathogen ◽  
Intrinsically Disordered Protein ◽  
Negative Regulator ◽  
Regulatory Function ◽  
Immune Signaling ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions

RIN4 is an intensively studied immune regulator in Arabidopsis and is involved in perception of microbial features outside and bacterial effectors inside plant cells. Furthermore, RIN4 is conserved in land plants and is targeted for posttranslational modifications by several virulence proteins from the bacterial pathogen Pseudomonas syringae. Despite the important roles of RIN4 in plant immune responses, its molecular function is not known. RIN4 is an intrinsically disordered protein (IDP), except at regions where pathogen-induced posttranslational modifications take place. IDP act as hubs for protein complex formation due to their ability to bind to multiple client proteins and, thus, are important players in signal transduction pathways. RIN4 is known to associate with multiple proteins involved in immunity, likely acting as an immune-signaling hub for the formation of distinct protein complexes. Genetically, RIN4 is a negative regulator of immunity, but diverse posttranslational modifications can either enhance its negative regulatory function or, on the contrary, render it a potent immune activator. In this review, we describe the structural domains of RIN4 proteins, their intrinsically disordered regions, posttranslational modifications, and highlight the implications that these features have on RIN4 function. In addition, we will discuss the potential role of plasma membrane subdomains in mediating RIN4 protein complex formations.

scholarly journals In VitroActivity of Glucosinolates and Their Degradation Products against Brassica-Pathogenic Bacteria and Fungi

2014 ◽  
Vol 81 (1) ◽  
pp. 432-440 ◽  
Author(s):  
T. Sotelo ◽  
M. Lema ◽  
P. Soengas ◽  
M. E. Cartea ◽  
P. Velasco
Keyword(s):  
Pseudomonas Syringae ◽  
Xanthomonas Campestris ◽  
Pathogenic Bacteria ◽  
Degradation Products ◽  
Allyl Isothiocyanate ◽  
Leaf Extracts ◽  
Soil Pathogens ◽  
Content Type ◽  
Positive Effects

ABSTRACTGlucosinolates (GSLs) are secondary metabolites found inBrassicavegetables that confer on them resistance against pests and diseases. Both GSLs and glucosinolate hydrolysis products (GHPs) have shown positive effects in reducing soil pathogens. Information about theirin vitrobiocide effects is scarce, but previous studies have shown sinigrin GSLs and their associated allyl isothiocyanate (AITC) to be soil biocides. The objective of this work was to evaluate the biocide effects of 17 GSLs and GHPs and of leaf methanolic extracts of different GSL-enrichedBrassicacrops on suppressingin vitrogrowth of two bacterial (Xanthomonas campestrispv. campestris andPseudomonas syringaepv. maculicola) and two fungal (AlternariabrassicaeandSclerotiniascletoriorum)Brassicapathogens. GSLs, GHPs, and methanolic leaf extracts inhibited the development of the pathogens tested compared to the control, and the effect was dose dependent. Furthermore, the biocide effects of the different compounds studied were dependent on the species and race of the pathogen. These results indicate that GSLs and their GHPs, as well as extracts of differentBrassicaspecies, have potential to inhibit pathogen growth and offer new opportunities to study the use ofBrassicacrops in biofumigation for the control of multiple diseases.

Performance of coatings containing treated silica fume in the corrosion protection of reinforced concrete

2018 ◽  
Vol 47 (4) ◽  
pp. 350-359 ◽  
Author(s):  
Nivin M. Ahmed ◽  
Mostafa G. Mohamed ◽  
Reham H. Tammam ◽  
Mohamed R. Mabrouk
Keyword(s):  
Reinforced Concrete ◽  
Silica Fume ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Dual Function ◽  
Core Shell ◽  
Protection Efficiency ◽  
Content Type ◽  
Anticorrosive Pigments

Purpose This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent silica fume (core) with 10-20 per cent phosphates (shell) previously, to play dual functions simultaneously as anticorrosive pigments in coating formulations and as an anticorrosive admixture in concrete even if it is not present in the concrete itself. Two comparisons were held out to show the results of coatings on rebars containing core-shell pigments in concrete, and concrete admixtured with silica fume can perform a dual function as anticorrosive pigment and concrete admixture. The evaluation of corrosion protection efficiency of coatings containing core-shell pigments and those containing phosphates was performed. Design/methodology/approach Simple chemical techniques were used to prepare core-shell pigments, and their characterization was carried out in a previous work. These pigments were incorporated in solvent-based paint formulations based on epoxy resin. Different electrochemical techniques such as open-circuit potential and electrochemical impedance spectroscopy were used to evaluate the anticorrosive efficiency of the new pigments. Findings The electrochemical measurements showed that concrete containing coated rebars with core-shell pigments exhibited almost similar results to that of concrete admixtured with silica fume. Also, the anticorrosive performance of coatings containing Si-Ph pigments offered protection efficiency almost similar to that of phosphates, proving that these new pigments can perform both roles as anticorrosive pigment and concrete admixture. Originality/value Although the new Si-Ph pigments contain more than 80 per cent waste material, its performance can be compared to original phosphate pigments in the reinforced concrete.

scholarly journals Spo0A Suppresses sin Locus Expression in Clostridioides difficile

mSphere ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Babita Adhikari Dhungel ◽  
Revathi Govind
Keyword(s):  
Diarrheal Disease ◽  
Toxin Production ◽  
The United States ◽  
Upstream Region ◽  
Pcr Analysis ◽  
Bacterial Cells ◽  
Master Regulator ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile is the leading cause of nosocomial infection and is the causative agent of antibiotic-associated diarrhea. The severity of the disease is directly associated with toxin production, and spores are responsible for the transmission and persistence of the organism. Previously, we characterized sin locus regulators SinR and SinR′ (we renamed it SinI), where SinR is the regulator of toxin production and sporulation. The SinI regulator acts as its antagonist. In Bacillus subtilis, Spo0A, the master regulator of sporulation, controls SinR by regulating the expression of its antagonist, sinI. However, the role of Spo0A in the expression of sinR and sinI in C. difficile had not yet been reported. In this study, we tested spo0A mutants in three different C. difficile strains, R20291, UK1, and JIR8094, to understand the role of Spo0A in sin locus expression. Western blot analysis revealed that spo0A mutants had increased SinR levels. Quantitative reverse transcription-PCR (qRT-PCR) analysis of its expression further supported these data. By carrying out genetic and biochemical assays, we show that Spo0A can bind to the upstream region of this locus to regulates its expression. This study provides vital information that Spo0A regulates the sin locus, which controls critical pathogenic traits such as sporulation, toxin production, and motility in C. difficile. IMPORTANCE Clostridioides difficile is the leading cause of antibiotic-associated diarrheal disease in the United States. During infection, C. difficile spores germinate, and the vegetative bacterial cells produce toxins that damage host tissue. In C. difficile, the sin locus is known to regulate both sporulation and toxin production. In this study, we show that Spo0A, the master regulator of sporulation, controls sin locus expression. Results from our study suggest that Spo0A directly regulates the expression of this locus by binding to its upstream DNA region. This observation adds new detail to the gene regulatory network that connects sporulation and toxin production in this pathogen.

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