Identification of Crp as a novel regulator of the Std fimbrial expression in Salmonella

Microbiology ◽  
2021 ◽  
Author(s):  
Karine Dufresne ◽  
France Daigle
Keyword(s):  
Wild Type Strain ◽  
Distal Region ◽  
Transcriptional Factor ◽  
Major Influence ◽  
Wild Type ◽  
Content Type ◽  
Link Type ◽  
Serovar Typhimurium ◽  
Metabolic Regulators

The Salmonella enterica serovar Typhi genome contains 14 putative fimbrial systems. The Std fimbriae belong to the chaperone-usher family and its regulation has not been investigated in S. Typhi. Several regulators of Std were previously identified in the closely related serovar Typhimurium. We hypothesize that regulators of S. Typhimurium may be shared with S. Typhi, but that several other regulators remain to be discovered. Here, we describe the role of more than 50 different candidate regulators on std expression. Three types of regulators were investigated: known regulators in S. Typhimurium, in silico predicted regulators and virulence/metabolic regulators. Expression of std was determined in the regulator mutants and compared with the wild-type strain. Overall, 21 regulator mutations affect std promoter expression. The role of Crp, a newly identified factor for std expression, was further investigated. Crp acted as an activator of std expression on a distal region of the std promoter region. Together, our results demonstrate the major influence of Crp as a novel transcriptional factor on std promoter expression and later production of Std fimbriae in Salmonella .

scholarly journals Loss of Ethanolamine Utilization in Enterococcus faecalis Increases Gastrointestinal Tract Colonization

mBio ◽  
2018 ◽  
Vol 9 (3) ◽  
Author(s):  
Karan Gautam Kaval ◽  
Kavindra V. Singh ◽  
Melissa R. Cruz ◽  
Sruti DebRoy ◽  
Wade C. Winkler ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Opposite Effect ◽  
Wild Type Strain ◽  
Food Poisoning ◽  
Wild Type ◽  
Gi Tract ◽  
Human Gut ◽  
Content Type ◽  
Serovar Typhimurium ◽  
High Concentrations

ABSTRACT Enterococcus faecalis is paradoxically a dangerous nosocomial pathogen and a normal constituent of the human gut microbiome, an environment rich in ethanolamine. E. faecalis carries the eut (ethanolamine utilization) genes, which enable the catabolism of ethanolamine (EA) as a valuable source of carbon and/or nitrogen. EA catabolism was previously shown to contribute to the colonization and growth of enteric pathogens, such as Salmonella enterica serovar Typhimurium and enterohemorrhagic Escherichia coli (EHEC), in the gut environment. We tested the ability of eut mutants of E. faecalis to colonize the gut using a murine model of gastrointestinal (GI) tract competition and report the surprising observation that these mutants outcompete the wild-type strain. IMPORTANCE Some bacteria that are normal, harmless colonizers of the human body can cause disease in immunocompromised patients, particularly those that have been heavily treated with antibiotics. Therefore, it is important to understand the factors that promote or negate these organisms’ ability to colonize. Previously, ethanolamine, found in high concentrations in the GI tract, was shown to promote the colonization and growth of bacteria associated with food poisoning. Here, we report the surprising, opposite effect of ethanolamine utilization on the commensal colonizer E. faecalis , namely, that loss of this metabolic capacity made it a better colonizer.

scholarly journals Role of Aspergillus fumigatus DvrA in Host Cell Interactions and Virulence

2010 ◽  
Vol 9 (10) ◽  
pp. 1432-1440 ◽  
Author(s):  
Daniele E. Ejzykowicz ◽  
Norma V. Solis ◽  
Fabrice N. Gravelat ◽  
Josee Chabot ◽  
Xuexian Li ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Type Strain ◽  
Wild Type Strain ◽  
Host Cells ◽  
Epithelial Cell Line ◽  
Wild Type ◽  
Content Type ◽  
Pulmonary Epithelial Cell

ABSTRACT The transcription factors that regulate Aspergillus fumigatus interactions with host cells and virulence are incompletely defined. We investigated the role of the putative C2H2 transcription factor DvrA in governing these processes. Although DvrA was identified by its limited homology to Candida albicans Bcr1, a ΔdvrA mutant strain of A. fumigatus had wild-type adherence to host constituents in vitro. However, it had increased capacity to damage both endothelial cells and a pulmonary epithelial cell line compared to the ability of the wild-type strain and a ΔdvrA::dvrA-complemented strain. This increase in damage required direct contact between the mutant and host cells. The ΔdvrA mutant also stimulated greater CCL20, interleukin-8, and tumor necrosis factor mRNA expression in a pulmonary epithelial cell line compared to levels induced by the control strains. Also, it was resistant to nikkomycin Z, suggesting an altered cell wall composition. As predicted by these in vitro results, the ΔdvrA mutant had increased virulence and stimulated a greater pulmonary inflammatory response than the wild-type strain and ΔdvrA::dvrA-complemented strains in the nonneutropenic mouse model of invasive pulmonary aspergillosis. These results indicate that DvrA influences A. fumigatus virulence as well as its capacity to damage host cells and stimulate a proinflammatory response.

scholarly journals Transcriptomics-Aided Dissection of the Intracellular and Extracellular Roles of Microcystin in Microcystis aeruginosa PCC 7806

2014 ◽  
Vol 81 (2) ◽  
pp. 544-554 ◽  
Author(s):  
A. Katharina Makower ◽  
J. Merijn Schuurmans ◽  
Detlef Groth ◽  
Yvonne Zilliges ◽  
Hans C. P. Matthijs ◽  
...  
Keyword(s):  
Polyketide Synthase ◽  
Wild Type Strain ◽  
Carbon Limitation ◽  
Light Conditions ◽  
Wild Type ◽  
Low Light ◽  
Content Type ◽  
Expression Of Genes ◽  
Polyketide Synthase Gene

ABSTRACTRecent studies have provided evidence for both intracellular and extracellular roles of the potent hepatotoxin microcystin (MC) in the bloom-forming cyanobacteriumMicrocystis. Here, we surveyed transcriptomes of the wild-type strainM. aeruginosaPCC 7806 and the microcystin-deficient ΔmcyBmutant under low light conditions with and without the addition of external MC of the LR variant (MC-LR). Transcriptomic data acquired by microarray and quantitative PCR revealed substantial differences in the relative expression of genes of the central intermediary metabolism, photosynthesis, and energy metabolism. In particular, the data provide evidence for a lower photosystem I (PSI)-to-photosystem II (PSII) ratio and a more pronounced carbon limitation in the microcystin-deficient mutant. Interestingly, only 6% of the transcriptional differences could be complemented by external microcystin-LR addition. This MC signaling effect was seen exclusively for genes of the secondary metabolism category. The orphan polyketide synthase gene cluster IPF38-51 was specifically downregulated in response to external MC-LR under low light. Our data suggest a hierarchical and light-dependent cross talk of secondary metabolites and support both an intracellular and an extracellular role of MC inMicrocystis.

scholarly journals The putative phosphate transporter PitB (PP1373) is involved in tellurite uptake in Pseudomonas putida KT2440

Microbiology ◽  
2020 ◽  
Author(s):  
Rafael Montenegro ◽  
Sofía Vieto ◽  
Daniela Wicki-Emmenegger ◽  
Felipe Vásquez-Castro ◽  
Carolina Coronado-Ruiz ◽  
...  
Keyword(s):  
Pseudomonas Putida ◽  
Type Strain ◽  
Type Species ◽  
Wild Type Strain ◽  
Phosphate Transporter ◽  
Transport Systems ◽  
Wild Type ◽  
Pseudomonas Putida Kt2440 ◽  
Content Type ◽  
Link Type

Tellurium oxyanions are chemical species of great toxicity and their presence in the environment has increased because of mining industries and photovoltaic and electronic waste. Recovery strategies for this metalloid that are based on micro-organisms are of interest, but further studies of the transport systems and enzymes responsible for implementing tellurium transformations are required because many mechanisms remain unknown. Here, we investigated the involvement in tellurite uptake of the putative phosphate transporter PitB (PP1373) in soil bacterium Pseudomonas putida KT2440. For this purpose, through a method based on the CRISPR/Cas9 system, we generated a strain deficient in the pitB gene and characterized its phenotype on exposing it to varied concentrations of tellurite. Growth curves and transmission electronic microscopy experiments for the wild-type and ΔpitB strains showed that both were able to internalize tellurite into the cytoplasm and reduce the oxyanion to black nano-sized and rod-shaped tellurium particles, although the ΔpitB strain showed an increased resistance to the tellurite toxic effects. At a concentration of 100 μM tellurite, where the biomass formation of the wild-type strain decreased by half, we observed a greater ability of ΔpitB to reduce this oxyanion with respect to the wild-type strain (~38 vs ~16 %), which is related to the greater biomass production of ΔpitB and not to a greater consumption of tellurite per cell. The phenotype of the mutant was restored on over-expressing pitB in trans. In summary, our results indicate that PitB is one of several transporters responsible for tellurite uptake in P. putida KT2440.

scholarly journals Virulence Traits of a Serogroup C Meningococcus and IsogeniccssAMutant, Defective in Surface-Exposed Sialic Acid, in a Murine Model of Meningitis

2019 ◽  
Vol 87 (4) ◽  
Author(s):  
Roberta Colicchio ◽  
Chiara Pagliuca ◽  
Susanna Ricci ◽  
Elena Scaglione ◽  
Denis Grandgirard ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Corpus Callosum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Lethal Dose ◽  
Sialic Acids ◽  
Wild Type ◽  
Knockout Mutant ◽  
Content Type

ABSTRACTIn serogroup CNeisseria meningitidis, thecssA(siaA) gene codes for an UDP-N-acetylglucosamine 2-epimerase that catalyzes the conversion of UDP-N-acetyl-α-d-glucosamine intoN-acetyl-d-mannosamine and UDP in the first step in sialic acid biosynthesis. This enzyme is required for the biosynthesis of the (α2→9)-linked polysialic acid capsule and for lipooligosaccharide (LOS) sialylation. In this study, we have used a reference serogroup C meningococcal strain and an isogeniccssAknockout mutant to investigate the pathogenetic role of surface-exposed sialic acids in a model of meningitis based on intracisternal inoculation of BALB/c mice. Results confirmed the key role of surface-exposed sialic acids in meningococcal pathogenesis. The 50% lethal dose (LD50) of the wild-type strain 93/4286 was about four orders of magnitude lower than that of thecssAmutant. Compared to the wild-type strain, the ability of this mutant to replicate in brain and spread systemically was severely impaired. Evaluation of brain damage evidenced a significant reduction in cerebral hemorrhages in mice infected with the mutant in comparison with the levels in those challenged with the wild-type strain. Histological analysis showed the typical features of bacterial meningitis, including inflammatory cells in the subarachnoid, perivascular, and ventricular spaces especially in animals infected with the wild type. Noticeably, 80% of mice infected with the wild-type strain presented with massive bacterial localization and accompanying inflammatory infiltrate in thecorpus callosum, indicating high tropism of meningococci exposing sialic acids toward this brain structure and a specific involvement of thecorpus callosumin the mouse model of meningococcal meningitis.

scholarly journals Competition and Resilience between Founder and Introduced Bacteria in the Caenorhabditis elegans Gut

2011 ◽  
Vol 80 (3) ◽  
pp. 1288-1299 ◽  
Author(s):  
Cynthia Portal-Celhay ◽  
Martin J. Blaser
Keyword(s):  
Caenorhabditis Elegans ◽  
Wild Type ◽  
Content Type ◽  
E Coli ◽  
C Elegans ◽  
Serovar Typhimurium ◽  
Colonization Factors

The microbial communities that reside within the intestinal tract in vertebrates are complex and dynamic. In this report, we establish the utility ofCaenorhabditis elegansas a model system for identifying the factors that contribute to bacterial persistence and for host control of gut luminal populations. We found that for N2 worms grown on mixed lawns of bacteria,Salmonella entericaserovar Typhimurium substantially outcompetedEscherichia coli, even whenE. coliwas initially present at 100-fold-higher concentrations. To address whether innate immunity affects the competition, thedaf-2anddaf-16mutants were studied; their total gut bacterial levels reflect overall capacity for colonization, butSalmonellaoutcompetedE. colito an extent similar to wild-type worms. To address the role of virulence properties,SalmonellaΔspi-1Δspi-2was used to compete withE. coli. The net differential was significantly less than that for wild-typeSalmonella; thus,spi-1 spi-2encodesC. eleganscolonization factors. AnE. colistrain with repeatedin vivopassage had an enhanced ability to compete against anin vitro-passedE. colistrain and againstSalmonella. Our data provide evidence of active competition for colonization niches in theC. elegansgut, as determined by bacterial factors and subject toin vivoselection.

scholarly journals The RNA Chaperone Hfq Promotes Fitness of Actinobacillus pleuropneumoniae during Porcine Pleuropneumonia

2013 ◽  
Vol 81 (8) ◽  
pp. 2952-2961 ◽  
Author(s):  
Sargurunathan Subashchandrabose ◽  
Rhiannon M. Leveque ◽  
Roy N. Kirkwood ◽  
Matti Kiupel ◽  
Martha H. Mulks
Keyword(s):  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Actinobacillus Pleuropneumoniae ◽  
Wild Type ◽  
Content Type ◽  
Porcine Pleuropneumonia ◽  
Porcine Lungs

ABSTRACTActinobacillus pleuropneumoniaeis the etiological agent of porcine pleuropneumonia, an economically important disease of pigs. Thehfqgene inA. pleuropneumoniae, encoding the RNA chaperone and posttranscriptional regulator Hfq, is upregulated during infection of porcine lungs. To investigate the role of thisin vivo-induced gene inA. pleuropneumoniae, anhfqmutant strain was constructed. Thehfqmutant was defective in biofilm formation on abiotic surfaces. The level ofpgaCtranscript, encoding the biosynthesis of poly-β-1,6-N-acetylglucosamine (PNAG), a major biofilm matrix component, was lower and PNAG content was 10-fold lower in thehfqmutant than in the wild-type strain. When outer membrane proteins were examined, cysteine synthase, implicated in resistance to oxidative stress and tellurite, was not found at detectable levels in the absence of Hfq. Thehfqmutant displayed enhanced sensitivity to superoxide generated by methyl viologen and tellurite. These phenotypes were readily reversed by complementation with thehfqgene expressed from its native promoter. The role of Hfq in the fitness ofA. pleuropneumoniaewas assessed in a natural host infection model. Thehfqmutant failed to colonize porcine lungs and was outcompeted by the wild-type strain (median competitive index of 2 × 10−5). Our data demonstrate that thein vivo-induced genehfqis involved in the regulation of PNAG-dependent biofilm formation, resistance to superoxide stress, and the fitness and virulence ofA. pleuropneumoniaein pigs and begin to elucidate the role of anin vivo-induced gene in the pathogenesis of pleuropneumonia.

scholarly journals Role of Mrx Fimbriae of Xenorhabdus nematophila in Competitive Colonization of the Nematode Host

2011 ◽  
Vol 77 (20) ◽  
pp. 7247-7254 ◽  
Author(s):  
Holly Snyder ◽  
Hongjun He ◽  
Heather Owen ◽  
Chris Hanna ◽  
Steven Forst
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Infective Juvenile ◽  
Xenorhabdus Nematophila ◽  
Wild Type ◽  
Content Type ◽  
Mutant Strains ◽  
Phenotypic Variant

ABSTRACTXenorhabdus nematophilaengages in mutualistic associations with the infective juvenile (IJ) stage of specific entomopathogenic nematodes. Mannose-resistant (Mrx) chaperone-usher-type fimbriae are produced when the bacteria are grown on nutrient broth agar (NB agar). The role of Mrx fimbriae in the colonization of the nematode host has remained unresolved. We show thatX. nematophilagrown on LB agar produced flagella rather than fimbriae. IJs propagated onX. nematophilagrown on LB agar were colonized to the same extent as those propagated on NB agar. Further, progeny IJs were normally colonized bymrxmutant strains that lacked fimbriae both when bacteria were grown on NB agar and when coinjected into the insect host with aposymbiotic nematodes. Themrxstrains were not competitively defective for colonization when grown in the presence of wild-type cells on NB agar. In addition, a phenotypic variant strain that lacked fimbriae colonized as well as the wild-type strain. In contrast, themrxstrains displayed a competitive colonization defectin vivo. IJ progeny obtained from insects injected with comixtures of nematodes carrying either the wild-type or themrxstrain were colonized almost exclusively with the wild-type strain. Likewise, when insects were coinjected with aposymbiotic IJs together with a comixture of the wild-type andmrxstrains, the resulting IJ progeny were predominantly colonized with the wild-type strain. These results revealed that Mrx fimbriae confer a competitive advantage during colonizationin vivoand provide new insights into the role of chaperone-usher fimbriae in the life cycle ofX. nematophila.

scholarly journals Identification of the Amidotransferase AsnB1 as Being Responsible formeso-Diaminopimelic Acid Amidation in Lactobacillus plantarum Peptidoglycan

2011 ◽  
Vol 193 (22) ◽  
pp. 6323-6330 ◽  
Author(s):  
Elvis Bernard ◽  
Thomas Rolain ◽  
Pascal Courtin ◽  
Pascal Hols ◽  
Marie-Pierre Chapot-Chartier
Keyword(s):  
Lactobacillus Plantarum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Bacterial Species ◽  
Critical Role ◽  
Innate Immune ◽  
Diaminopimelic Acid ◽  
Wild Type ◽  
Content Type

The peptidoglycan (PG) ofLactobacillus plantarumcontains amidatedmeso-diaminopimelic acid (mDAP). The functional role of this PG modification has never been characterized in any bacterial species, except for its impact on PG recognition by receptors of the innate immune system.In silicoanalysis of loci carrying PG biosynthesis genes in theL. plantarumgenome revealed the colocalization of themurEgene, which encodes the ligase catalyzing the addition of mDAP to UDP-N-muramoyl-d-glutamate PG precursors, withasnB1, which encodes a putative asparagine synthase with an N-terminal amidotransferase domain. By gene disruption and complementation experiments, we showed thatasnB1is the amidotransferase involved in mDAP amidation. PG structural analysis revealed that mDAP amidation plays a key role in the control of thel,d-carboxypeptidase DacB activity. In addition, a mutant strain with a defect in mDAP amidation is strongly affected in growth and cell morphology, with filamentation and cell chaining, while a DacB-negative strain displays a phenotype very similar to that of a wild-type strain. These results suggest that mDAP amidation may play a critical role in the control of the septation process.

scholarly journals The Homolog of the Gene bstA of the BTP1 Phage from Salmonella enterica Serovar Typhimurium ST313 Is an Antivirulence Gene in Salmonella enterica Serovar Dublin

2017 ◽  
Vol 86 (1) ◽  
Author(s):  
Ana Herrero-Fresno ◽  
Irene Cartas Espinel ◽  
Malene Roed Spiegelhauer ◽  
Priscila Regina Guerra ◽  
Karsten Wiber Andersen ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Luria Bertani ◽  
Wild Type ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Cattle Blood

ABSTRACTIn a previous study, a novel virulence gene,bstA, identified in aSalmonella entericaserovar Typhimurium sequence type 313 (ST313) strain was found to be conserved in all publishedSalmonella entericaserovar Dublin genomes. In order to analyze the role of this gene in the host-pathogen interaction inS. Dublin, a mutant where this gene was deleted (S. Dublin ΔbstA) and a mutant which was further genetically complemented withbstA(S. Dublin 3246-C) were constructed and tested in models ofin vitroandin vivoinfection as well as during growth competition assays in M9 medium, Luria-Bertani broth, and cattle blood. In contrast to the results obtained for a strain ofS. Typhimurium ST313, the lack ofbstAwas found to be associated with increased virulence inS. Dublin. Thus,S. Dublin ΔbstAshowed higher levels of uptake than the wild-type strain during infection of mouse and cattle macrophages and higher net replication within human THP-1 cells. Furthermore, during mouse infections,S. Dublin ΔbstAwas more virulent than the wild type following a single intraperitoneal infection and showed an increased competitive index during competitive infection assays. Deletion ofbstAdid not affect either the amount of cytokines released by THP-1 macrophages or the cytotoxicity toward these cells. The histology of the livers and spleens of mice infected with the wild-type strain and theS. Dublin ΔbstAmutant revealed similar levels of inflammation between the two groups. The gene was not important for adherence to or invasion of human epithelial cells and did not influence bacterial growth in rich medium, minimal medium, or cattle blood. In conclusion, a lack ofbstAaffects the pathogenicity ofS. Dublin by decreasing its virulence. Therefore, it might be regarded as an antivirulence gene in this serovar.

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