Motility and flagellin gene expression in the fish pathogen Vibrio salmonicida: Effects of salinity and temperature

2008 ◽  
Vol 45 (4) ◽  
pp. 258-264 ◽  
Author(s):  
Christian Karlsen ◽  
Steinar M. Paulsen ◽  
Hege Smith Tunsjø ◽  
Simone Krinner ◽  
Henning Sørum ◽  
...  
Keyword(s):  
Gene Expression ◽  
Fish Pathogen ◽  
Flagellin Gene ◽  
Vibrio Salmonicida

scholarly journals Pseudomonas syringae AlgU Downregulates Flagellin Gene Expression, Helping Evade Plant Immunity

2019 ◽  
Vol 202 (4) ◽  
Author(s):  
Zhongmeng Bao ◽  
Hai-Lei Wei ◽  
Xing Ma ◽  
Bryan Swingle
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Plant Pathogens ◽  
Control Point ◽  
Plant Colonization ◽  
Compensatory Mechanisms ◽  
Flagellin Gene ◽  
Content Type ◽  
Immune Systems ◽  
Plant Infection

ABSTRACT Flagella power bacterial movement through liquids and over surfaces to access or avoid certain environmental conditions, ultimately increasing a cell’s probability of survival and reproduction. In some cases, flagella and chemotaxis are key virulence factors enabling pathogens to gain entry and attach to suitable host tissues. However, flagella are not always beneficial; both plant and animal immune systems have evolved receptors to sense the proteins that make up flagellar filaments as signatures of bacterial infection. Microbes poorly adapted to avoid or counteract these immune functions are unlikely to be successful in host environments, and this selective pressure has driven the evolution of diverse and often redundant pathogen compensatory mechanisms. We tested the role of AlgU, the Pseudomonas extracytoplasmic function sigma factor σE/σ22 ortholog, in regulating flagellar expression in the context of Pseudomonas syringae-plant interactions. We found that AlgU is necessary for downregulating bacterial flagellin expression in planta and that this results in a corresponding reduction in plant immune elicitation. This AlgU-dependent regulation of flagellin gene expression is beneficial to bacterial growth in the course of plant infection, and eliminating the plant’s ability to detect flagellin makes this AlgU-dependent function irrelevant for bacteria growing in the apoplast. Together, these results add support to an emerging model in which P. syringae AlgU functions at a key control point that serves to optimize the expression of bacterial functions during host interactions, including minimizing the expression of immune elicitors and concomitantly upregulating beneficial virulence functions. IMPORTANCE Foliar plant pathogens, like Pseudomonas syringae, adjust their physiology and behavior to facilitate host colonization and disease, but the full extent of these adaptations is not known. Plant immune systems are triggered by bacterial molecules, such as the proteins that make up flagellar filaments. In this study, we found that during plant infection, AlgU, a gene expression regulator that is responsive to external stimuli, downregulates expression of fliC, which encodes the flagellin protein, a strong elicitor of plant immune systems. This change in gene expression and resultant change in behavior correlate with reduced plant immune activation and improved P. syringae plant colonization. The results of this study demonstrate the proximate and ultimate causes of flagellar regulation in a plant-pathogen interaction.

scholarly journals Localized Reversible Frameshift Mutation in theflhA Gene Confers Phase Variability to Flagellin Gene Expression in Campylobacter coli

2000 ◽  
Vol 182 (1) ◽  
pp. 207-210 ◽  
Author(s):  
Simon F. Park ◽  
Desmond Purdy ◽  
Stephen Leach
Keyword(s):  
Gene Expression ◽  
High Frequency ◽  
Frameshift Mutation ◽  
Phase Variation ◽  
Campylobacter Coli ◽  
Coding Region ◽  
Generate Functional ◽  
Flagellin Gene ◽  
Homopolymeric Tract ◽  
Insertion And Deletion

ABSTRACT Phase variation of flagellin gene expression in Campylobacter coli UA585 was correlated with high-frequency, reversible insertion and deletion frameshift mutations in a short homopolymeric tract of thymine residues located in the N-terminal coding region of the flhA gene. Mutation-based phase variation inflhA may generate functional diversity in the host and environment.

scholarly journals Vibrio salmonicida sp. nov., a New Fish Pathogen

1987 ◽  
Vol 37 (3) ◽  
pp. 306-306 ◽  
Author(s):  
E. Egidius ◽  
R. Wiik ◽  
K. Andersen ◽  
K. A. Hoff ◽  
B. Hjeltnes
Keyword(s):  
Fish Pathogen ◽  
Vibrio Salmonicida

scholarly journals The fish pathogen Aliivibrio salmonicida LFI1238 can degrade and metabolize chitin despite major gene loss in the chitinolytic pathway

2021 ◽  
Author(s):  
Anna Skåne ◽  
Giusi Minniti ◽  
Jennifer S.M. Loose ◽  
Sophanit Mekasha ◽  
Bastien Bissaro ◽  
...  
Keyword(s):  
Biochemical Characterization ◽  
Cold Water ◽  
Major Gene ◽  
Microbial Pathogens ◽  
Glycoside Hydrolase Family ◽  
Fish Pathogen ◽  
Nutrient Source ◽  
Chitinolytic Enzymes ◽  
Vibrio Salmonicida ◽  
Genes Encoding

The fish pathogen Aliivibrio (Vibrio) salmonicida LFI1238 is thought to be incapable of utilizing chitin as a nutrient source since approximately half of the genes representing the chitinolytic pathway are disrupted by insertion sequences. In the present study, we combined a broad set of analytical methods to investigate this hypothesis. Cultivation studies revealed that Al. salmonicida grew efficiently on N -acetylglucosamine (GlcNAc) and chitobiose ((GlcNAc) 2 ), the primary soluble products resulting from enzymatic chitin hydrolysis. The bacterium was also able to grow on chitin particles, albeit at a lower rate compared to the soluble substrates. The genome of the bacterium contains five disrupted chitinase genes (pseudogenes) and three intact genes encoding a glycoside hydrolase family 18 (GH18) chitinase and two auxiliary activity family 10 (AA10) lytic polysaccharide monooxygenases (LPMOs). Biochemical characterization showed that the chitinase and LPMOs were able to depolymerize both α- and β-chitin to (GlcNAc) 2 and oxidized chitooligosaccharides, respectively. Notably, the chitinase displayed up to 50-fold lower activity compared to other well-studied chitinases. Deletion of the genes encoding the intact chitinolytic enzymes showed that the chitinase was important for growth on β-chitin, whereas the LPMO gene-deletion variants only showed minor growth defects on this substrate. Finally, proteomic analysis of Al. salmonicida LFI1238 growth on β-chitin showed expression of all three chitinolytic enzymes, and intriguingly also three of the disrupted chitinases. In conclusion, our results show that Al. salmonicida LFI1238 can utilize chitin as a nutrient source and that the GH18 chitinase and the two LPMOs are needed for this ability. IMPORTANCE The ability to utilize chitin as a source of nutrients is important for the survival and spread of marine microbial pathogens in the environment. One such pathogen is Aliivibrio (Vibrio) salmonicida , the causative agent of cold water vibriosis. Due to extensive gene decay, many key enzymes in the chitinolytic pathway have been disrupted, putatively rendering this bacterium incapable of chitin degradation and utilization. In the present study we demonstrate that Al. salmonicida can degrade and metabolize chitin, the most abundant biopolymer in the ocean. Our findings shed new light on the environmental adaption of this fish pathogen.

scholarly journals CodY Is a Nutritional Repressor of Flagellar Gene Expression in Bacillus subtilis

2003 ◽  
Vol 185 (10) ◽  
pp. 3118-3126 ◽  
Author(s):  
F. Bergara ◽  
C. Ibarra ◽  
J. Iwamasa ◽  
J. C. Patarroyo ◽  
R. Aguilera ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Bacillus Subtilis ◽  
Promoter Region ◽  
Stringent Response ◽  
Mobility Shift ◽  
Flagellin Gene ◽  
New Members ◽  
Environment Effects ◽  
Mobility Shift Assay

ABSTRACT Expression of the σD-dependent flagellin gene, hag, is repressed by the CodY protein in nutrient-rich environments. Analysis of a codY mutant bearing a hag-lacZ reporter suggests that the availability of amino acids in the environment is the specific signal that triggers this repression. Further, hag-lacZ expression appears to be sensitive to intracellular GTP levels, as demonstrated by increased expression upon addition of decoyinine. This result is consistent with the postulate that the availability of amino acids in the environment effects intracellular GTP levels through the stringent response. However, the levels of hag-lacZ measured upon the addition of subsets of amino acids suggest an additional mechanism(s). CodY is a DNA binding protein that could repress flagellin expression directly by binding to the hag promoter region, or indirectly by binding to the fla/che promoter region that governs expression of the σD transcriptional activator required for hag gene expression. Using an electrophoretic mobility shift assay, we have demonstrated that purified CodY protein binds specifically to both the hag and fla/che promoter fragments. Additionally, CodY acts as a nutritional repressor of transcription from the fla/che promoter region that contains two functional promoters. CodY binds to both the σD- and σA-dependent promoters in this region, as demonstrated by DNase I footprint analyses. Footprint analyses of the hag gene demonstrated that CodY binds downstream of its σD-dependent promoter. Taken together, these results identify new members of the CodY regulon that encode motility functions in Bacillus subtilis and are controlled by the σD alternate sigma factor.

scholarly journals In vitro Edwardsiella piscicida CK108 Transcriptome Profiles with Subinhibitory Concentrations of Phenol and Formalin Reveal New Insights into Bacterial Pathogenesis Mechanisms

2020 ◽  
Vol 8 (7) ◽  
pp. 1068
Author(s):  
Ju Bin Yoon ◽  
Sungmin Hwang ◽  
Se-Won Baek ◽  
Seungki Lee ◽  
Woo Young Bang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Inhibitory Concentration ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Type I ◽  
Fish Pathogen ◽  
Type Vi Secretion System ◽  
Amino Acid Synthesis ◽  
Edwardsiella Piscicida

Phenol and formalin are major water pollutants that are frequently discharged into the aquatic milieu. These chemicals can affect broad domains of life, including microorganisms. Aquatic pollutants, unlike terrestrial pollutants, are easily diluted in water environments and exist at a sub-inhibitory concentration (sub-IC), thus not directly inhibiting bacterial growth. However, they can modulate gene expression profiles. The sub-IC values of phenol and formalin were measured by minimal inhibitory concentration (MIC) assay to be 0.146% (1.3 mM) and 0.0039% (0.38 mM), respectively, in Edwardsiella piscicida CK108, a Gram-negative fish pathogen. We investigated the differentially expressed genes (DEG) by RNA-seq when the cells were exposed to the sub-ICs of phenol and formalin. DEG analyses revealed that genes involved in major virulence factors (type I fimbriae, flagella, type III and type VI secretion system) and various cellular pathways (energy production, amino acid synthesis, carbohydrate metabolism and two-component regulatory systems) were up- or downregulated by both chemicals. The genome-wide gene expression data corresponded to the results of a quantitative reverse complementary-PCR and motility assay. This study not only provides insight into how a representative fish pathogen, E. piscicida CK108, responds to the sub-ICs of phenol and formalin but also shows the importance of controlling chemical pollutants in aquatic environments.

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