Role of theehxAgene fromEscherichia coliserotype O82 in hemolysis, biofilm formation, and in vivo virulence

2015 ◽  
Vol 61 (5) ◽  
pp. 335-341 ◽  
Author(s):  
Chenggang Jiang ◽  
Tongqing An ◽  
Shujie Wang ◽  
Gang Wang ◽  
Wei Si ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Gastrointestinal Disease ◽  
Enterohemorrhagic Escherichia Coli ◽  
Systemic Complications ◽  
E Coli ◽  
Recombination System ◽  
Intestinal Pathology ◽  
Inflammatory Infiltrates

Enterohemorrhagic Escherichia coli (EHEC) strains cause serious gastrointestinal disease, which can lead to potentially life-threatening systemic complications such as hemolytic uremic syndrome. Although the ehx gene is established as a major virulence factor of EHEC, the role of this gene in colonization and biofilm formation remains to be elucidated. We constructed recombinant isogenic mutants of the ehxA locus of E. coli HLJ1122 (serotype O82) using the λ Red homologous recombination system. Significantly higher levels of adherence to human epithelial cells (HEp-2) cells were observed for strain HLJ1122 compared with the mutant strain HLJ1122-ΔehxA (P < 0.05). Strain HLJ1122 also exhibited significantly higher levels of biofilm formation than strain HLJ1122-ΔehxA (P < 0.05). Mice infected with strain HLJ1122 showed severe destruction of the intestinal and gastric mucosa; in contrast, mice infected with HLJ1122-ΔehxA showed limited intestinal pathology, displaying minimal inflammatory infiltrates compared with mock-infected mice. These results showed the multifunctional role of Ehx in E. coli virulence.

scholarly journals Sab, a Novel Autotransporter of Locus of Enterocyte Effacement-Negative Shiga-Toxigenic Escherichia coli O113:H21, Contributes to Adherence and Biofilm Formation

2009 ◽  
Vol 77 (8) ◽  
pp. 3234-3243 ◽  
Author(s):  
Sylvia Herold ◽  
James C. Paton ◽  
Adrienne W. Paton
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Gastrointestinal Disease ◽  
Pcr Analysis ◽  
Systemic Complications ◽  
E Coli ◽  
Acid Protein ◽  
Life Threatening ◽  
Uremic Syndrome ◽  
Enterocyte Effacement

ABSTRACT Shiga-toxigenic Escherichia coli (STEC) strains cause serious gastrointestinal disease, which can lead to potentially life-threatening systemic complications such as hemolytic-uremic syndrome. Although the production of Shiga toxin has been considered to be the main virulence trait of STEC for many years, the capacity to colonize the host intestinal epithelium is a crucial step in pathogenesis. In this study, we have characterized a novel megaplasmid-encoded outer membrane protein in locus of enterocyte effacement (LEE)-negative O113:H21 STEC strain 98NK2, termed Sab (for STEC autotransporter [AT] contributing to biofilm formation). The 4,296-bp sab gene encodes a 1,431-amino-acid protein with the features of members of the AT protein family. When expressed in E. coli JM109, Sab contributed to the diffuse adherence to human epithelial (HEp-2) cells and promoted biofilm formation on polystyrene surfaces. A 98NK2 sab deletion mutant was also defective in biofilm formation relative to its otherwise isogenic wild-type parent, and this was complemented by transformation with a sab-carrying plasmid. Interestingly, an unrelated O113:H21 STEC isolate that had a naturally occurring deletion in sab was similarly defective in biofilm formation. PCR analysis indicated that sab is present in LEE-negative STEC strains belonging to serotypes/groups O113:H21, O23, and O82:H8. These findings raise the possibility that Sab may contribute to colonization in a subset of LEE-negative STEC strains.

scholarly journals Arabidopsis Disulfide Reductase, Trx-h2, Functions as an RNA Chaperone under Cold Stress

2021 ◽  
Vol 11 (15) ◽  
pp. 6865
Author(s):  
Eun Seon Lee ◽  
Joung Hun Park ◽  
Seong Dong Wi ◽  
Ho Byoung Chae ◽  
Seol Ki Paeng ◽  
...  
Keyword(s):  
Cold Stress ◽  
Wild Type ◽  
Rna Chaperone ◽  
E Coli ◽  
Cold Sensitive ◽  
Thioredoxin H ◽  
Functional Rnas

The thioredoxin-h (Trx-h) family of Arabidopsis thaliana comprises cytosolic disulfide reductases. However, the physiological function of Trx-h2, which contains an additional 19 amino acids at its N-terminus, remains unclear. In this study, we investigated the molecular function of Trx-h2 both in vitro and in vivo and found that Arabidopsis Trx-h2 overexpression (Trx-h2OE) lines showed significantly longer roots than wild-type plants under cold stress. Therefore, we further investigated the role of Trx-h2 under cold stress. Our results revealed that Trx-h2 functions as an RNA chaperone by melting misfolded and non-functional RNAs, and by facilitating their correct folding into active forms with native conformation. We showed that Trx-h2 binds to and efficiently melts nucleic acids (ssDNA, dsDNA, and RNA), and facilitates the export of mRNAs from the nucleus to the cytoplasm under cold stress. Moreover, overexpression of Trx-h2 increased the survival rate of the cold-sensitive E. coli BX04 cells under low temperature. Thus, our data show that Trx-h2 performs function as an RNA chaperone under cold stress, thus increasing plant cold tolerance.

DNA methylation in Yersinia enterocolitica: role of the DNA adenine methyltransferase in mismatch repair and regulation of virulence factors

Microbiology ◽  
2005 ◽  
Vol 151 (7) ◽  
pp. 2291-2299 ◽  
Author(s):  
Stefan Fälker ◽  
M. Alexander Schmidt ◽  
Gerhard Heusipp
Keyword(s):  
Mismatch Repair ◽  
Yersinia Enterocolitica ◽  
Virulence Genes ◽  
Spontaneous Mutation ◽  
Gram Negative Bacteria ◽  
E Coli ◽  
Physiological Processes ◽  
Dna Adenine Methyltransferase

DNA adenine methyltransferase (Dam) plays an important role in physiological processes of Gram-negative bacteria such as mismatch repair and replication. In addition, Dam regulates the expression of virulence genes in various species. The authors cloned the dam gene of Yersinia enterocolitica and showed that Dam is essential for viability. Dam overproduction in Y. enterocolitica resulted in an increased frequency of spontaneous mutation and decreased resistance to 2-aminopurine; however, these effects were only marginal compared to the effect of overproduction of Escherichia coli-derived Dam in Y. enterocolitica, implying different roles or activities of Dam in mismatch repair of the two species. These differences in Dam function are not the cause for the essentiality of Dam in Y. enterocolitica, as Dam of E. coli can complement a dam defect in Y. enterocolitica. Instead, Dam seems to interfere with expression of essential genes. Furthermore, Dam mediates virulence of Y. enterocolitica. Dam overproduction results in increased tissue culture invasion of Y. enterocolitica, while the expression of specifically in vivo-expressed genes is not altered.

scholarly journals Effects ofibeADeletion on Virulence and Biofilm Formation of Avian PathogenicEscherichia coli

2010 ◽  
Vol 79 (1) ◽  
pp. 279-287 ◽  
Author(s):  
Shaohui Wang ◽  
Chunling Niu ◽  
Zhenyu Shi ◽  
Yongjie Xia ◽  
Muhammad Yaqoob ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Wild Type Strain ◽  
Chicken Embryo Fibroblast ◽  
Neonatal Meningitis ◽  
Pcr Analysis ◽  
E Coli ◽  
Reverse Transcription Pcr ◽  
Animal System ◽  
The Brain

ABSTRACTTheibeAgene is located on a genomic island, GimA, which is involved in the pathogenesis of neonatal meningitisEscherichia coli(NMEC) and avian pathogenicE. coli(APEC). The prevalence ofibeAin the APEC collection in China was investigated, and 20 of 467 strains (4.3%) were positive. In addition, analysis of the association of theE. colireference (ECOR) groups with positive strains revealed thatibeAwas linked to group B2. TheibeAgene in DE205B was analyzed and compared to those of APEC and NMEC, which indicated that the specificity ofibeAwas not consistent along pathotypes. The invasion of chicken embryo fibroblast DF-1 cells by APEC DE205B and RS218 was observed, which suggested that DF-1 cells could be a model to study the mechanism of APEC invasion. The inactivation ofibeAin APEC DE205B led to the reduced capacity to invade DF-1 cells, defective virulencein vivo, and decreased biofilm formation compared to the wild-type strain. In addition, strain AAEC189 expressingibeAexhibited enhanced invasion capacity and biofilm formation. The results of the quantitative real-time reverse transcription-PCR (qRT-PCR) analysis and animal system infection experiments indicated that the loss ofibeAdecreased the colonization and proliferation capacities of APEC in the brain during system infection.

scholarly journals Escherichia coli NsrR Regulates a Pathway for the Oxidation of 3-Nitrotyramine to 4-Hydroxy-3-Nitrophenylacetate

2008 ◽  
Vol 190 (18) ◽  
pp. 6170-6177 ◽  
Author(s):  
Linda D. Rankin ◽  
Diane M. Bodenmiller ◽  
Jonathan D. Partridge ◽  
Shirley F. Nishino ◽  
Jim C. Spain ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Physiological Role ◽  
Growth Conditions ◽  
Growth Defect ◽  
E Coli ◽  
Mutant Phenotypes ◽  
Culture Supernatants ◽  
Chip Chip

ABSTRACT Chromatin immunoprecipitation and microarray (ChIP-chip) analysis showed that the nitric oxide (NO)-sensitive repressor NsrR from Escherichia coli binds in vivo to the promoters of the tynA and feaB genes. These genes encode the first two enzymes of a pathway that is required for the catabolism of phenylethylamine (PEA) and its hydroxylated derivatives tyramine and dopamine. Deletion of nsrR caused small increases in the activities of the tynA and feaB promoters in cultures grown on PEA. Overexpression of nsrR severely retarded growth on PEA and caused a marked repression of the tynA and feaB promoters. Both the growth defect and the promoter repression were reversed in the presence of a source of NO. These results are consistent with NsrR mediating repression of the tynA and feaB genes by binding (in an NO-sensitive fashion) to the sites identified by ChIP-chip. E. coli was shown to use 3-nitrotyramine as a nitrogen source for growth, conditions which partially induce the tynA and feaB promoters. Mutation of tynA (but not feaB) prevented growth on 3-nitrotyramine. Growth yields, mutant phenotypes, and analyses of culture supernatants suggested that 3-nitrotyramine is oxidized to 4-hydroxy-3-nitrophenylacetate, with growth occurring at the expense of the amino group of 3-nitrotyramine. Accordingly, enzyme assays showed that 3-nitrotyramine and its oxidation product (4-hydroxy-3-nitrophenylacetaldehyde) could be oxidized by the enzymes encoded by tynA and feaB, respectively. The results suggest that an additional physiological role of the PEA catabolic pathway is to metabolize nitroaromatic compounds that may accumulate in cells exposed to NO.

scholarly journals Candida albicans forms biofilms on the vaginal mucosa

Microbiology ◽  
2010 ◽  
Vol 156 (12) ◽  
pp. 3635-3644 ◽  
Author(s):  
M. M. Harriott ◽  
E. A. Lilly ◽  
T. E. Rodriguez ◽  
P. L. Fidel ◽  
M. C. Noverr
Keyword(s):  
Biofilm Formation ◽  
Ex Vivo ◽  
Microscopic Analysis ◽  
Vaginal Mucosa ◽  
First Time ◽  
Established Role ◽  
Type Strains

Current understanding of resistance and susceptibility to vulvovaginal candidiasis challenges existing paradigms of host defence against fungal infection. While abiotic biofilm formation has a clearly established role during systemic Candida infections, it is not known whether C. albicans forms biofilms on the vaginal mucosa and the possible role of biofilms in disease. In vivo and ex vivo murine vaginitis models were employed to examine biofilm formation by scanning electron and confocal microscopy. C. albicans strains included 3153A (lab strain), DAY185 (parental control strain), and mutants defective in morphogenesis and/or biofilm formation in vitro (efg1/efg1 and bcr1/bcr1). Both 3153A and DAY815 formed biofilms on the vaginal mucosa in vivo and ex vivo as indicated by high fungal burden and microscopic analysis demonstrating typical biofilm architecture and presence of extracellular matrix (ECM) co-localized with the presence of fungi. In contrast, efg1/efg1 and bcr1/bcr1 mutant strains exhibited weak or no biofilm formation/ECM production in both models compared to wild-type strains and complemented mutants despite comparable colonization levels. These data show for the first time that C. albicans forms biofilms in vivo on vaginal epithelium, and that in vivo biotic biofilm formation requires regulators of biofilm formation (BCR1) and morphogenesis (EFG1).

scholarly journals Transposon Insertion in the purL Gene Induces Biofilm Depletion in Escherichia coli ATCC 25922

Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 774
Author(s):  
Virginio Cepas ◽  
Victoria Ballén ◽  
Yaiza Gabasa ◽  
Miriam Ramírez ◽  
Yuly López ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
De Novo ◽  
Wild Type ◽  
Planktonic Cells ◽  
E Coli ◽  
Qrt Pcr ◽  
Transposon Insertion ◽  
De Novo Purine Biosynthesis

Current Escherichia coli antibiofilm treatments comprise a combination of antibiotics commonly used against planktonic cells, leading to treatment failure. A better understanding of the genes involved in biofilm formation could facilitate the development of efficient and specific new antibiofilm treatments. A total of 2578 E. coli mutants were generated by transposon insertion, of which 536 were analysed in this study. After sequencing, Tn263 mutant, classified as low biofilm-former (LF) compared to the wild-type (wt) strain (ATCC 25922), showed an interruption in the purL gene, involved in the de novo purine biosynthesis pathway. To elucidate the role of purL in biofilm formation, a knockout was generated showing reduced production of curli fibres, leading to an impaired biofilm formation. These conditions were restored by complementation of the strain or addition of exogenous inosine. Proteomic and transcriptional analyses were performed to characterise the differences caused by purL alterations. Thirteen proteins were altered compared to wt. The corresponding genes were analysed by qRT-PCR not only in the Tn263 and wt, but also in clinical strains with different biofilm activity. Overall, this study suggests that purL is essential for biofilm formation in E. coli and can be considered as a potential antibiofilm target.

scholarly journals Toxoplasma gondii GRA9 Regulates the Activation of NLRP3 Inflammasome to Exert Anti-Septic Effects in Mice

2020 ◽  
Vol 21 (22) ◽  
pp. 8437
Author(s):  
Jae-Sung Kim ◽  
Seok-Jun Mun ◽  
Euni Cho ◽  
Donggyu Kim ◽  
Wooic Son ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Nlrp3 Inflammasome ◽  
Dense Granule ◽  
E Coli ◽  
Pyrin Domain ◽  
Essential Components ◽  
Bactericidal Effects ◽  
Anti Inflammatory

Dense granule proteins (GRAs) are essential components in Toxoplasma gondii, which are suggested to be promising serodiagnostic markers in toxoplasmosis. In this study, we investigated the function of GRA9 in host response and the associated regulatory mechanism, which were unknown. We found that GRA9 interacts with NLR family pyrin domain containing 3 (NLRP3) involved in inflammation by forming the NLRP3 inflammasome. The C-terminal of GRA9 (GRA9C) is essential for GRA9–NLRP3 interaction by disrupting the NLRP3 inflammasome through blocking the binding of apoptotic speck-containing (ASC)-NLRP3. Notably, Q200 of GRA9C is essential for the interaction of NLRP3 and blocking the conjugation of ASC. Recombinant GRA9C (rGRA9C) showed an anti-inflammatory effect and the elimination of bacteria by converting M1 to M2 macrophages. In vivo, rGRA9C increased the anti-inflammatory and bactericidal effects and subsequent anti-septic activity in CLP- and E. coli- or P. aeruginosa-induced sepsis model mice by increasing M2 polarization. Taken together, our findings defined a role of T. gondii GRA9 associated with NLRP3 in host macrophages, suggesting its potential as a new candidate therapeutic agent for sepsis.

scholarly journals Regulatory Role of PlaR (YiaJ) for Plant Utilization in Escherichia coli K-12

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tomohiro Shimada ◽  
Yui Yokoyama ◽  
Takumi Anzai ◽  
Kaneyoshi Yamamoto ◽  
Akira Ishihama
Keyword(s):  
Escherichia Coli ◽  
Genetic System ◽  
Regulatory Role ◽  
E Coli ◽  
Warm Blooded Animal ◽  
Plant Utilization ◽  
K 12

AbstractOutside a warm-blooded animal host, the enterobacterium Escherichia coli K-12 is also able to grow and survive in stressful nature. The major organic substance in nature is plant, but the genetic system of E. coli how to utilize plant-derived materials as nutrients is poorly understood. Here we describe the set of regulatory targets for uncharacterized IclR-family transcription factor YiaJ on the E. coli genome, using gSELEX screening system. Among a total of 18 high-affinity binding targets of YiaJ, the major regulatory target was identified to be the yiaLMNOPQRS operon for utilization of ascorbate from fruits and galacturonate from plant pectin. The targets of YiaJ also include the genes involved in the utilization for other plant-derived materials as nutrients such as fructose, sorbitol, glycerol and fructoselysine. Detailed in vitro and in vivo analyses suggest that L-ascorbate and α-D-galacturonate are the effector ligands for regulation of YiaJ function. These findings altogether indicate that YiaJ plays a major regulatory role in expression of a set of the genes for the utilization of plant-derived materials as nutrients for survival. PlaR was also suggested to play protecting roles of E. coli under stressful environments in nature, including the formation of biofilm. We then propose renaming YiaJ to PlaR (regulator of plant utilization).

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