scholarly journals vpaH, a Gene Encoding a Novel Histone-Like Nucleoid Structure-Like Protein That Was Possibly Horizontally Acquired, Regulates the Biogenesis of Lateral Flagella in trh-Positive Vibrio parahaemolyticus TH3996

2005 ◽  
Vol 73 (9) ◽  
pp. 5754-5761 ◽  
Author(s):  
Kwon-Sam Park ◽  
Michiko Arita ◽  
Tetsuya Iida ◽  
Takeshi Honda
Keyword(s):  
Biofilm Formation ◽  
Vibrio Parahaemolyticus ◽  
Type Strain ◽  
Wild Type Strain ◽  
Enteric Bacteria ◽  
Wild Type ◽  
Gene Encoding ◽  
Lateral Flagellum ◽  
Global Gene Regulation ◽  
Nucleoid Structure

ABSTRACT A histone-like nucleoid structure (H-NS) is a major component of the bacterial nucleoid and plays a crucial role in the global gene regulation of enteric bacteria. Here, we cloned and characterized the gene for the H-NS-like protein VpaH in Vibrio parahaemolyticus. vpaH encodes a protein of 134 amino acids that shows approximately 55%, 54%, and 41% identities with VicH in Vibrio cholerae, H-NS in V. parahaemolyticus, and H-NS in Escherichia coli, respectively. The vpaH gene was found in only trh-positive V. parahaemolyticus strains and not in Kanagawa-positive or in trh-negative environmental strains. Moreover, the G+C content of the vpaH gene was 38.6%, which is lower than the average G+C content of the whole genome of this bacterium (45.4%). These data suggest that vpaH was transmitted to trh-possessing V. parahaemolyticus strains by lateral transfer. The vpaH gene was located about 2.6 kb downstream of the trh gene, in the convergent direction of the trh transcription. An in-frame deletion mutant of vpaH lacked motility on semisolid motility assay plates. Western blot analysis and electron microscopy observations revealed that the mutant was deficient in lateral flagella biogenesis, whereas there was no defect in the expression of polar flagella. Additionally, the vpaH mutant showed a decreased adherence to HeLa cells and a decrease in biofilm formation compared with the wild-type strain. Introduction of the vpaH gene in the vpaH-negative strain increased the expression of lateral flagella compared with the wild-type strain. In conclusion, our findings suggest that VpaH affects lateral flagellum biogenesis in trh-positive V. parahaemolyticus strain TH3996.

scholarly journals Expression and function of the cdgD gene, encoding a CHASE–PAS-DGC-EAL domain protein, in Azospirillum brasilense

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
José Francisco Cruz-Pérez ◽  
Roxana Lara-Oueilhe ◽  
Cynthia Marcos-Jiménez ◽  
Ricardo Cuatlayotl-Olarte ◽  
María Luisa Xiqui-Vázquez ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Type Strain ◽  
Wild Type Strain ◽  
Soil Conditions ◽  
Wild Type ◽  
Gene Encoding ◽  
Wheat Roots ◽  
Genes Encoding ◽  
In The Wild ◽  
Plant Growth Promoting

AbstractThe plant growth-promoting bacterium Azospirillum brasilense contains several genes encoding proteins involved in the biosynthesis and degradation of the second messenger cyclic-di-GMP, which may control key bacterial functions, such as biofilm formation and motility. Here, we analysed the function and expression of the cdgD gene, encoding a multidomain protein that includes GGDEF-EAL domains and CHASE and PAS domains. An insertional cdgD gene mutant was constructed, and analysis of biofilm and extracellular polymeric substance production, as well as the motility phenotype indicated that cdgD encoded a functional diguanylate protein. These results were correlated with a reduced overall cellular concentration of cyclic-di-GMP in the mutant over 48 h compared with that observed in the wild-type strain, which was recovered in the complemented strain. In addition, cdgD gene expression was measured in cells growing under planktonic or biofilm conditions, and differential expression was observed when KNO3 or NH4Cl was added to the minimal medium as a nitrogen source. The transcriptional fusion of the cdgD promoter with the gene encoding the autofluorescent mCherry protein indicated that the cdgD gene was expressed both under abiotic conditions and in association with wheat roots. Reduced colonization of wheat roots was observed for the mutant compared with the wild-type strain grown in the same soil conditions. The Azospirillum-plant association begins with the motility of the bacterium towards the plant rhizosphere followed by the adsorption and adherence of these bacteria to plant roots. Therefore, it is important to study the genes that contribute to this initial interaction of the bacterium with its host plant.

scholarly journals Selective Pressure for Biofilm Formation in Bacillus subtilis: Differential Effect of Mutations in the Master Regulator SinR on Bistability

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Jan Kampf ◽  
Jan Gerwig ◽  
Kerstin Kruse ◽  
Robert Cleverley ◽  
Miriam Dormeyer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Selective Pressure ◽  
Wild Type ◽  
Master Regulator ◽  
Form Complex ◽  
Content Type

ABSTRACT Biofilm formation by Bacillus subtilis requires the expression of genes encoding enzymes for extracellular polysaccharide synthesis and for an amyloid-like protein. The master regulator SinR represses all the corresponding genes, and repression of these key biofilm genes is lifted when SinR interacts with its cognate antagonist proteins. The YmdB phosphodiesterase is a recently discovered factor that is involved in the control of SinR activity: cells lacking YmdB exhibit hyperactive SinR and are unable to relieve the repression of the biofilm genes. In this study, we have examined the dynamics of gene expression patterns in wild-type and ymdB mutant cells by microfluidic analysis coupled to time-lapse microscopy. Our results confirm the bistable expression pattern for motility and biofilm genes in the wild-type strain and the loss of biofilm gene expression in the mutant. Moreover, we demonstrated dynamic behavior in subpopulations of the wild-type strain that is characterized by switches in sets of the expressed genes. In order to gain further insights into the role of YmdB, we isolated a set of spontaneous suppressor mutants derived from ymdB mutants that had regained the ability to form complex colonies and biofilms. Interestingly, all of the mutations affected SinR. In some mutants, large genomic regions encompassing sinR were deleted, whereas others had alleles encoding SinR variants. Functional and biochemical studies with these SinR variants revealed how these proteins allowed biofilm gene expression in the ymdB mutant strains. IMPORTANCE Many bacteria are able to choose between two mutually exclusive lifestyles: biofilm formation and motility. In the model bacterium Bacillus subtilis, this choice is made by each individual cell rather than at the population level. The transcriptional repressor SinR is the master regulator in this decision-making process. The regulation of SinR activity involves complex control of its own expression and of its interaction with antagonist proteins. We show that the YmdB phosphodiesterase is required to allow the expression of SinR-repressed genes in a subpopulation of cells and that such subpopulations can switch between different SinR activity states. Suppressor analyses revealed that ymdB mutants readily acquire mutations affecting SinR, thus restoring biofilm formation. These findings suggest that B. subtilis cells experience selective pressure to form the extracellular matrix that is characteristic of biofilms and that YmdB is required for the homeostasis of SinR and/or its antagonists.

scholarly journals Quorum-Sensing Systems in the Plant Growth-Promoting Bacterium Paraburkholderia phytofirmans PsJN Exhibit Cross-Regulation and Are Involved in Biofilm Formation

2017 ◽  
Vol 30 (7) ◽  
pp. 557-565 ◽  
Author(s):  
Ana Zúñiga ◽  
Raúl A. Donoso ◽  
Daniela Ruiz ◽  
Gonzalo A. Ruz ◽  
Bernardo González
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Homoserine Lactone ◽  
Wild Type ◽  
Transcript Levels ◽  
Sensing Systems ◽  
Plant Growth Promoting ◽  
Growth Promoting

Quorum-sensing systems play important roles in host colonization and host establishment of Burkholderiales species. Beneficial Paraburkholderia species share a conserved quorum-sensing (QS) system, designated BraI/R, that controls different phenotypes. In this context, the plant growth-promoting bacterium Paraburkholderia phytofirmans PsJN possesses two different homoserine lactone QS systems BpI.1/R.1 and BpI.2/R.2 (BraI/R-like QS system). The BpI.1/R.1 QS system was previously reported to be important to colonize and produce beneficial effects in Arabidopsis thaliana plants. Here, we analyzed the temporal variations of the QS gene transcript levels in the wild-type strain colonizing plant roots. The gene expression patterns showed relevant differences in both QS systems compared with the wild-type strain in the unplanted control treatment. The gene expression data were used to reconstruct a regulatory network model of QS systems in P. phytofirmans PsJN, using a Boolean network model. Also, we examined the phenotypic traits and transcript levels of genes involved in QS systems, using P. phytofirmans mutants in homoserine lactone synthases genes. We observed that the BpI.1/R.1 QS system regulates biofilm formation production in strain PsJN and this phenotype was associated with the lower expression of a specific extracytoplasmic function sigma factor ecf26.1 gene (implicated in biofilm formation) in the bpI.1 mutant strain.

scholarly journals Expression of Erwinia chrysanthemi Pectinase Genes pelI, pelL, and pelZ During Infection of Potato Tubers

1999 ◽  
Vol 12 (10) ◽  
pp. 845-851 ◽  
Author(s):  
Sylwia Jafra ◽  
Izabela Figura ◽  
Nicole Hugouvieux-Cotte-Pattat ◽  
Ewa Lojkowska
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Pectate Lyase ◽  
Soft Rot ◽  
Erwinia Chrysanthemi ◽  
Potato Tubers ◽  
Wild Type ◽  
In Planta ◽  
Gene Encoding ◽  
Glucuronidase Activity

Erwinia chrysanthemi mutants, containing transcriptional fusions of one of the minor pectate lyase genes (pelI, pelL, pelZ) with the reporter gene encoding β-glucuronidase activity, were studied for their ability to cause disease symptoms and to synthesize pectinases after inoculation of potato tubers. The strains affected in pelI and pelL genes displayed reduced virulence on potato tubers, demonstrating the important role of these isoenzymes in soft rot disease. Inactivation of the pelZ gene slightly influences the ability to macerate. Analysis of the bacterial population showed rapid multiplication of bacteria during infection. Similar kinetics of growth were observed for all mutants and for the wild-type strain. Comparison of the mutants and the wild-type strain showed that the pelI, pelL, and pelZ mutants synthesized reduced levels of Pels. The expression of pelZ is fivefold higher in planta than in bacterial cultures. In contrast, both pelI and pelL are highly (10-fold factor) induced in planta, which is characteristic of the plant-inducible pectate lyases.

scholarly journals Involvement of Quinolinate Phosphoribosyl Transferase in Promotion of Potato Growth by a Burkholderia Strain

2006 ◽  
Vol 72 (1) ◽  
pp. 760-768 ◽  
Author(s):  
Keri Wang ◽  
Kenneth Conn ◽  
George Lazarovits
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
De Novo ◽  
Growth Promotion ◽  
Amino Acid Level ◽  
Growth Stimulation ◽  
Wild Type ◽  
Gene Encoding ◽  
Burkholderia Strain ◽  
Potato Growth

ABSTRACT Burkholderia sp. strain PsJN stimulates root growth of potato explants compared to uninoculated controls under gnotobiotic conditions. In order to determine the mechanism by which this growth stimulation occurs, we used Tn5 mutagenesis to produce a mutant, H41, which exhibited no growth-promoting activity but was able to colonize potato plants as well as the wild-type strain. The gene associated with the loss of growth promotion in H41 was shown to exhibit 65% identity at the amino acid level to the nadC gene encoding quinolinate phosphoribosyltransferase (QAPRTase) in Ralstonia solanacearum. Complementation of H41 with QAPRTase restored growth promotion of potato explants by this mutant. Expression of the gene identified in Escherichia coli yielded a protein with QAPRTase activities that catalyzed the de novo formation of nicotinic acid mononucleotide (NaMN). Two other genes involved in the same enzymatic pathway, nadA and nadB, were physically linked to nadC. The nadA gene was cotranscribed with nadC as an operon in wild-type strain PsJN, while the nadB gene was located downstream of the nadA-nadC operon. Growth promotion by H41 was fully restored by addition of NaMN to the tissue culture medium. These data suggested that QAPRTase may play a role in the signal pathway for promotion of plant growth by PsJN.

scholarly journals Escherichia coliO157:H7 responds to phosphate starvation by modifying LPS involved in biofilm formation

2019 ◽  
Author(s):  
Philippe Vogeleer ◽  
Antony T. Vincent ◽  
Samuel M. Chekabab ◽  
Steve J. Charette ◽  
Alexey Novikov ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Inorganic Phosphate ◽  
Type Strain ◽  
Wild Type Strain ◽  
Pho Regulon ◽  
Wild Type ◽  
E Coli ◽  
Pi Starvation ◽  
Pst System

ABSTRACTIn open environments such as water, enterohemorrhagicEscherichia coliO157:H7 responds to inorganic phosphate (Pi) starvation by inducing the Pho regulon controlled by PhoB. The phosphate-specific transport (Pst) system is the high-affinity Pi transporter. In the Δpstmutant, PhoB is constitutively activated and regulates the expression of genes from the Pho regulon. InE. coliO157:H7, the Δpstmutant, biofilm, and autoagglutination were increased. In the double-deletion mutant ΔpstΔphoB, biofilm and autoagglutination were similar to the wild-type strain, suggesting that PhoB is involved. We investigated the relationship between PhoB activation and enhanced biofilm formation by screening a transposon mutant library derived from Δpstmutant for decreased autoagglutination and biofilms mutants. Lipopolysaccharide (LPS) genes involved in the synthesis of the LPS core were identified. Transcriptomic studies indicate the influence of Pi-starvation andpstmutation on LPS biosynthetic gene expression. LPS analysis indicated that the O-antigen was deficient in the Δpstmutant. Interestingly,waaH, encoding a glycosyltransferase associated with LPS modifications inE. coliK-12, was highly expressed in the Δpstmutant ofE. coliO157:H7. Deletion ofwaaHfrom the Δpstmutant and from the wild-type strain grown in Pi-starvation conditions decreased the biofilm formation but without affecting LPS. Our findings suggest that LPS core is involved in the autoagglutination and biofilm phenotypes of the Δpstmutant and that WaaH plays a role in biofilm in response to Pi-starvation. This study highlights the importance of Pi-starvation in biofilm formation of E. coli O157:H7, which may affect its transmission and persistence.IMPORTANCEEnterohemorrhagicEscherichia coliO157:H7 is a human pathogen responsible for bloody diarrhea and renal failures. In the environment, O157:H7 can survive for prolonged periods of time under nutrient-deprived conditions. Biofilms are thought to participate in this environmental lifestyle. Previous reports have shown that the availability of extracellular inorganic phosphate (Pi) affected bacterial biofilm formation; however, nothing was known about O157:H7 biofilm formation. Our results show that O157:H7 membrane undergoes modifications upon PhoB activation leading to increased biofilm formation. A mutation in the Pst system results in reduced amount of the smooth type LPS and that this could influence the biofilm composition. This demonstrates how theE. coliO157:H7 adapts to Pi starvation increasing its ability to occupy different ecological niches.

scholarly journals RstA, a two-component response regulator, plays important roles in multiple virulence-associated processes in enterohemorrhagic Escherichia coli O157:H7

Gut Pathogens ◽  
2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Yutao Liu ◽  
Shujie Li ◽  
Wendi Li ◽  
Peisheng Wang ◽  
Peng Ding ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Acid Tolerance ◽  
Enterohemorrhagic Escherichia Coli ◽  
Regulatory Function ◽  
Wild Type ◽  
Two Component

Abstract Background Enterohemorrhagic Escherichia coli O157:H7 (EHEC O157) causes bloody diarrhea and hemolytic-uremic syndrome. EHEC O157 encounters varied microenvironments during infection, and can efficiently adapt to these using the two-component system (TCS). Recently, a functional TCS, RstAB, has been implicated in the regulation of virulence of several bacterial pathogens. However, the regulatory function of RstAB in EHEC O157 is poorly understood. This study aimed at providing insights into the global effects of RstA on gene expression in EHEC O157. Results In the present study, we analyzed gene expression differences between the EHEC O157 wild-type strain and a ΔrstA mutant using RNA-seq technology. Genes with differential expression in the ΔrstA mutant compared to that in the wild-type strain were identified and grouped into clusters of orthologous categories. RstA promoted EHEC O157 LEE gene expression, adhesion in vitro, and colonization in vivo by indirect regulation. We also found that RstA could bind directly to the promoter region of hdeA and yeaI to enhance acid tolerance and decrease biofilm formation by modulating the concentration of c-di-GMP. Conclusions In summary, the RstAB TCS in EHEC O157 plays a major role in the regulation of virulence, acid tolerance, and biofilm formation. We clarified the regulatory function of RstA, providing an insight into mechanisms that may be potential drug targets for treatment of EHEC O157-related infections.

scholarly journals Invasion and Persistence of Mycobacterium avium subsp. paratuberculosis during Early Stages of Johne's Disease in Calves

2007 ◽  
Vol 75 (5) ◽  
pp. 2110-2119 ◽  
Author(s):  
Chia-wei Wu ◽  
Michael Livesey ◽  
Shelly K. Schmoller ◽  
Elizabeth J. B. Manning ◽  
Howard Steinberg ◽  
...  
Keyword(s):  
Lymph Nodes ◽  
Mycobacterium Avium ◽  
Type Strain ◽  
Wild Type Strain ◽  
Flow Cytometric Analysis ◽  
Enteric Bacteria ◽  
Johne's Disease ◽  
Johne’S Disease ◽  
Wild Type ◽  
Early Stages

ABSTRACT Infection with Mycobacterium avium subsp. paratuberculosis causes Johne's disease in cattle and is a serious problem for the dairy industry worldwide. Development of models to mimic aspects of Johne's disease remains an elusive goal because of the chronic nature of the disease. In this report, we describe a surgical approach employed to characterize the very early stages of infection of calves with M. avium subsp. paratuberculosis. To our surprise, strains of M. avium subsp. paratuberculosis were able to traverse the intestinal tissues within 1 h of infection in order to colonize distant organs, such as the liver and lymph nodes. Both the ileum and the mesenteric lymph nodes were persistently infected for months following intestinal deposition of M. avium subsp. paratuberculosis despite a lack of fecal shedding of mycobacteria. During the first 9 months of infection, humoral immune responses were not detected. Nonetheless, using flow cytometric analysis, we detected a significant change in the cells participating in the inflammatory responses of infected calves compared to cells in a control animal. Additionally, the levels of cytokines detected in both the ileum and the lymph nodes indicated that there were TH1-type-associated cellular responses but not TH2-type-associated humoral responses. Finally, surgical inoculation of a wild-type strain and a mutant M. avium subsp. paratuberculosis strain (with an inactivated gcpE gene) demonstrated the ability of the model which we developed to differentiate between the wild-type strain and a mutant strain of M. avium subsp. paratuberculosis deficient in tissue colonization and invasion. Overall, novel insights into the early stages of Johne's disease were obtained, and a practical model of mycobacterial invasiveness was developed. A similar approach can be used for other enteric bacteria.

Porphyromonas gingivalis Induces Insulin Resistance by Increasing BCAA Levels in Mice

2020 ◽  
Vol 99 (7) ◽  
pp. 839-846 ◽  
Author(s):  
J. Tian ◽  
C. Liu ◽  
X. Zheng ◽  
X. Jia ◽  
X. Peng ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Plasma Level ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Alveolar Bone ◽  
Alveolar Bone Loss ◽  
Wild Type

Insulin resistance is one of the critical pathogeneses of type 2 diabetes mellitus (T2DM). Elevated levels of plasma branched-chain amino acids (BCAAs) are associated with insulin resistance. Recent studies have demonstrated the role of Porphyromonas gingivalis in the development of insulin resistance. However, the mechanisms by which P. gingivalis induces insulin resistance are still unclear. The purpose of this study was to investigate whether P. gingivalis induces insulin resistance through BCAA biosynthesis. We established a murine model of periodontitis by infecting mice with P. gingivalis. Alveolar bone loss, insulin sensitivity, and the plasma level of BCAAs were measured. A P. gingivalis BCAA aminotransferase-deficient strain ( ∆bcat) was constructed, and its kinetic growth, biofilm formation, and in vivo colonization were compared with its wild-type strain. Alveolar bone loss, insulin sensitivity, and the plasma level of BCAAs of the mice infected with either wild-type strain or ∆bcat strain were further measured. We found that periodontal infection with P. gingivalis significantly upregulated the plasma level of BCAAs and aggravated the high-fat diet (HFD)–induced insulin resistance. Bcat deletion did not alter the growth, biofilm formation, and in vivo colonization of P. gingivalis. More important, the ∆bcat strain was unable to upregulate the plasma level of BCAAs and induce insulin resistance in HFD-fed mice. These findings suggest that the BCAA biosynthesis of P. gingivalis plays a critical role in the development of insulin resistance in the HFD-fed mice. The BCAA biosynthesis pathways may provide a potential target for the disruption of linkage between periodontitis and T2DM.

scholarly journals The Edwardsiella piscicida Type III Translocon Protein EseC Inhibits Biofilm Formation by Sequestering EseE

2019 ◽  
Vol 85 (8) ◽  
Author(s):  
Ying Li Liu ◽  
Tian Tian He ◽  
Lu Yi Liu ◽  
Jia Yi ◽  
Pin Nie ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Wild Type ◽  
Content Type ◽  
Type Iii ◽  
Edwardsiella Piscicida

ABSTRACT The type III secretion system (T3SS) is one of the most important virulence factors of the fish pathogen Edwardsiella piscicida. It contains three translocon proteins, EseB, EseC, and EseD, required for translocation of effector proteins into host cells. We have previously shown that EseB forms filamentous appendages on the surface of E. piscicida, and these filamentous structures mediate bacterial cell-cell interactions promoting autoaggregation and biofilm formation. In the present study, we show that EseC, but not EseD, inhibits the autoaggregation and biofilm formation of E. piscicida. At 18 h postsubculture, a ΔeseC strain developed strong autoaggregation and mature biofilm formation, accompanied by enhanced formation of EseB filamentous appendages. This is in contrast to the weak autoaggregation and immature biofilm formation seen in the E. piscicida wild-type strain. EseE, a protein that directly binds to EseC and also positively regulates the transcription of the escC-eseE operon, was liberated and showed increased levels in the absence of EseC. This led to augmented transcription of the escC-eseE operon, thereby increasing the steady-state protein levels of intracellular EseB, EseD, and EseE, as well as biofilm formation. Notably, the levels of intracellular EseB and EseD produced by the ΔeseE and ΔeseC ΔeseE strains were similar but remarkably lower than those produced by the wild-type strain at 18 h postsubculture. Taken together, we have shown that the translocon protein EseC inhibits biofilm formation through sequestering EseE, a positive regulator of the escC-eseE operon. IMPORTANCE Edwardsiella piscicida, previously known as Edwardsiella tarda, is a Gram-negative intracellular pathogen that mainly infects fish. The type III secretion system (T3SS) plays a pivotal role in its pathogenesis. The T3SS translocon protein EseB is required for the assembly of filamentous appendages on the surface of E. piscicida. The interactions between the appendages facilitate autoaggregation and biofilm formation. In this study, we explored the role of the other two translocon proteins, EseC and EseD, in biofilm formation. We have demonstrated that EseC, but not EseD, inhibits the autoaggregation and biofilm formation of E. piscicida, providing new insights into the regulatory mechanism involved in E. piscicida biofilm formation.

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