Iron influences the expression of colonization factor CS6 of enterotoxigenic Escherichia coli

Microbiology ◽  
2021 ◽  
Vol 167 (9) ◽  
Author(s):  
Debjyoti Bhakat ◽  
Indranil Mondal ◽  
Asish Kumar Mukhopadhyay ◽  
Nabendu Sekhar Chatterjee
Keyword(s):  
Escherichia Coli ◽  
Promoter Activity ◽  
Iron Concentration ◽  
Iron Chelation ◽  
Enterotoxigenic Escherichia Coli ◽  
Watery Diarrhoea ◽  
Rna Expression ◽  
Iron Availability ◽  
Iron Salt ◽  
Ht 29

Enterotoxigenic Escherichia coli (ETEC) is a major pathogen of acute watery diarrhoea. The pathogenicity of ETEC is linked to adherence to the small intestine by colonization factors (CFs) and secretion of heat-labile enterotoxin (LT) and/or heat-stable enterotoxin (ST). CS6 is one of the most common CFs in our region and worldwide. Iron availability functions as an environmental cue for enteropathogenic bacteria, signalling arrival within the human host. Therefore, iron could modify the expression of CS6 in the intestine. The objective of this study was to determine the effect of iron availability on CS6 expression in ETEC. This would help in understanding the importance of iron during ETEC pathogenesis. ETEC strain harbouring CS6 was cultured under increasing concentrations of iron salt to assess the effect on CS6 RNA expression by quantitative RT-PCR, protein expression by ELISA, promoter activity by β-galactosidase activity, and epithelial adhesion on HT-29 cells. RNA expression of CS6 was maximum in presence of 0.2 mM iron (II) salt. The expression increased by 50-fold, which also reduced under iron-chelation conditions and an increased iron concentration of 0.4 mM or more. The surface expression of CS6 also increased by 60-fold in presence of 0.2 mM iron. The upregulation of CS6 promoter activity by 25-fold under this experimental condition was in accordance with the induction of CS6 RNA and protein. This increased CS6 expression was independent of ETEC strains. Bacterial adhesion to HT-29 epithelial cells was also enhanced by five-fold in the presence of 0.2 mM iron salt. These findings suggest that CS6 expression is dependent on iron concentration. However, with further increases in iron concentration beyond 0.2 mM CS6 expression is decreased, suggesting that there might be a strong regulatory mechanism for CS6 expression under different iron concentrations.

scholarly journals IscR Regulates Synthesis of Colonization Factor Antigen I Fimbriae in Response to Iron Starvation in Enterotoxigenic Escherichia coli

2015 ◽  
Vol 197 (18) ◽  
pp. 2896-2907 ◽  
Author(s):  
Sara Haines ◽  
Nadège Arnaud-Barbe ◽  
David Poncet ◽  
Sylvie Reverchon ◽  
Julien Wawrzyniak ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Virulence Factors ◽  
Promoter Region ◽  
Promoter Activity ◽  
Enterotoxigenic Escherichia Coli ◽  
Iron Availability ◽  
Iron Starvation ◽  
Content Type ◽  
The Impact

ABSTRACTIron availability functions as an environmental cue for enteropathogenic bacteria, signaling arrival within the human host. As enterotoxigenicEscherichia coli(ETEC) is a major cause of human diarrhea, the effect of iron on ETEC virulence factors was evaluated here. ETEC pathogenicity is directly linked to production of fimbrial colonization factors and secretion of heat-labile enterotoxin (LT) and/or heat-stable enterotoxin (ST). Efficient colonization of the small intestine further requires at least the flagellin binding adhesin EtpA. Under iron starvation, production of the CFA/I fimbriae was increased in the ETEC H10407 prototype strain. In contrast, LT secretion was inhibited. Furthermore, under iron starvation, gene expression of thecfa(CFA/I) andetp(EtpBAC) operons was induced, whereas transcription of toxin genes was either unchanged or repressed. Transcriptional reporter fusion experiments focusing on thecfaoperon further showed that iron starvation stimulatedcfaApromoter activity in ETEC, indicating that the impact of iron on CFA/I production was mediated by transcriptional regulation. Evaluation ofcfaApromoter activity in heterologousE. colisingle mutant knockout strains identified IscR as the regulator responsible for inducingcfafimbrial gene expression in response to iron starvation, and this was confirmed in an ETEC ΔiscRstrain. The global iron response regulator, Fur, was not implicated. IscR binding sites were identifiedin silicowithin thecfaApromoter and fixation confirmed by DNase I footprinting, indicating that IscR directly binds the promoter region to induce CFA/I.IMPORTANCEPathogenic enterobacteria modulate expression of virulence genes in response to iron availability. Although the Fur transcription factor represents the global regulator of iron homeostasis inEscherichia coli, we show that several ETEC virulence factors are modulated by iron, with expression of the major fimbriae under the control of the iron-sulfur cluster regulator, IscR. Furthermore, we demonstrate that the apo form of IscR, lacking an Fe-S cluster, is able to directly fix the corresponding promoter region. These results provide further evidence implicating IscR in bacterial virulence and suggest that IscR may represent a more general regulator mediating the iron response in enteropathogens.

scholarly journals Adhesion of human enterotoxigenic Escherichia coli to human mucus secreting HT-29 cell subpopulations in culture.

Gut ◽  
1994 ◽  
Vol 35 (10) ◽  
pp. 1449-1454 ◽  
Author(s):  
S Kerneis ◽  
M F Bernet ◽  
M H Coconnier ◽  
A L Servin
Keyword(s):  
Escherichia Coli ◽  
Enterotoxigenic Escherichia Coli ◽  
Cell Subpopulations ◽  
Ht 29

scholarly journals Longus, a Type IV Pilus of Enterotoxigenic Escherichia coli, Is Involved in Adherence to Intestinal Epithelial Cells

2010 ◽  
Vol 192 (11) ◽  
pp. 2791-2800 ◽  
Author(s):  
Karina Mazariego-Espinosa ◽  
Ariadnna Cruz ◽  
Maria A. Ledesma ◽  
Sara A. Ochoa ◽  
Juan Xicohtencatl-Cortes
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Growth Conditions ◽  
Enterotoxigenic Escherichia Coli ◽  
Intestinal Cells ◽  
Intestinal Epithelial ◽  
T84 Cells ◽  
Type Iv ◽  
Colonic Cells ◽  
Ht 29

ABSTRACT Enterotoxigenic Escherichia coli (ETEC) is the leading bacterial cause of diarrhea in the developing world, as well as the most common cause of traveler's diarrhea. The main hallmarks of this type of bacteria are the expression of one or more enterotoxins and fimbriae used for attachment to host intestinal cells. Longus is a pilus produced by ETEC. These bacteria grown in pleuropneumonia-like organism (PPLO) broth at 37°C and in 5% CO2 produced longus, showing that the assembly and expression of the pili depend on growth conditions and composition of the medium. To explore the role of longus in the adherence to epithelial cells, quantitative and qualitative analyses were done, and similar levels of adherence were observed, with values of 111.44 × 104 CFU/ml in HT-29, 101.33 × 104 CFU/ml in Caco-2, and 107.11 × 104 CFU/ml in T84 cells. In addition, the E9034AΔlngA strain showed a significant reduction in longus adherence of 32% in HT-29, 22.28% in Caco-2, and 21.68% in T84 cells compared to the wild-type strain. In experiments performed with nonintestinal cells (HeLa and HEp-2 cells), significant differences were not observed in adherence between E9034A and derivative strains. Interestingly, the E9034A and E9034AΔlngA(pLngA) strains were 30 to 35% more adherent in intestinal cells than in nonintestinal cells. Twitching motility experiments were performed, showing that ETEC strains E9034A and E9034AΔlngA(pLngA) had the capacity to form spreading zones while ETEC E9034AΔlngA does not. In addition, our data suggest that longus from ETEC participates in the colonization of human colonic cells.

scholarly journals Structure of the master regulator Rns reveals an inhibitor of enterotoxigenic Escherichia coli virulence regulons

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charles R. Midgett ◽  
Kacey Marie Talbot ◽  
Jessica L. Day ◽  
George P. Munson ◽  
F. Jon Kull
Keyword(s):  
Escherichia Coli ◽  
Small Molecules ◽  
Family Member ◽  
Shigella Flexneri ◽  
Decanoic Acid ◽  
Enterotoxigenic Escherichia Coli ◽  
Gram Negative Bacteria ◽  
Enteric Infections ◽  
First Time ◽  
Arac Family

AbstractEnteric infections caused by the gram-negative bacteria enterotoxigenic Escherichia coli (ETEC), Vibrio cholerae, Shigella flexneri, and Salmonella enterica are among the most common and affect billions of people each year. These bacteria control expression of virulence factors using a network of transcriptional regulators, some of which are modulated by small molecules as has been shown for ToxT, an AraC family member from V. cholerae. In ETEC the expression of many types of adhesive pili is dependent upon the AraC family member Rns. We present here the 3 Å crystal structure of Rns and show it closely resembles ToxT. Rns crystallized as a dimer via an interface similar to that observed in other dimeric AraC’s. Furthermore, the structure of Rns revealed the presence of a ligand, decanoic acid, that inhibits its activity in a manner similar to the fatty acid mediated inhibition observed for ToxT and the S. enterica homologue HilD. Together, these results support our hypothesis that fatty acids regulate virulence controlling AraC family members in a common manner across a number of enteric pathogens. Furthermore, for the first time this work identifies a small molecule capable of inhibiting the ETEC Rns regulon, providing a basis for development of therapeutics against this deadly human pathogen.

scholarly journals Deletion of FaeG alleviated Enterotoxigenic Escherichia coli F4ac-induced apoptosis in the intestine

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pengpeng Xia ◽  
Yunping Wu ◽  
Siqi Lian ◽  
Guomei Quan ◽  
Yiting Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Clinical Symptoms ◽  
Mucosal Damage ◽  
Enterotoxigenic Escherichia Coli ◽  
Intestinal Epithelial ◽  
Antibody Microarray ◽  
E Coli ◽  
Fimbrial Subunit ◽  
Induced Apoptosis ◽  
Weaning Piglets

AbstractEnterotoxigenic Escherichia coli (ETEC) F4ac is a major constraint to the development of the pig industry, which is causing newborn and post-weaning piglets diarrhea. Previous studies proved that FaeG is the major fimbrial subunit of F4ac E. coli and efficient for bacterial adherence and receptor recognition. Here we show that the faeG deletion attenuates both the clinical symptoms of F4ac infection and the F4ac-induced intestinal mucosal damage in piglets. Antibody microarray analysis and the detection of mRNA expression using porcine neonatal jejunal IPEC-J2 cells also determined that the absence of FaeG subunit alleviated the F4ac promoted apoptosis in the intestinal epithelial cells. Thus, targeted depletion of FaeG is still beneficial for the prevention or treatment of F4ac infection.

scholarly journals Immunogenicity and protective efficacy of enterotoxigenic Escherichia coli (ETEC) total RNA against ETEC challenge in a mouse model

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mandi Liu ◽  
Yue Zhang ◽  
Di Zhang ◽  
Yun Bai ◽  
Guomei Liu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mouse Model ◽  
Immune Responses ◽  
Protective Efficacy ◽  
Enterotoxigenic Escherichia Coli ◽  
Economic Losses ◽  
Th2 Response ◽  
Total Rna ◽  
Etec Infection

AbstractEnterotoxigenic Escherichia coli (ETEC), an essential cause of post-weaning diarrhea (PWD) in piglets, leads to significant economic losses to the pig industry. The present study aims to identify the role of ETEC total RNA in eliciting immune responses to protect animals against ETEC infection. The results showed that the total RNA isolated from pig-derived ETEC K88ac strain effectively stimulated the IL-1β secretion of porcine intestinal epithelial cells (IPEC-J2). The mouse model immunized with ETEC total RNA via intramuscular injection (IM) or oral route (OR) was used to evaluate the protective efficiency of the ETEC total RNA. The results suggested that 70 μg ETEC total RNA administered by either route significantly promoted the production of the serum IL-1β and K88ac specific immunoglobulins (IgG, IgM, and IgA). Besides, the ETEC RNA administration augmented strong mucosal immunity by elevating K88ac specific IgA level in the intestinal fluid. Intramuscularly administered RNA induced a Th1/Th2 shift toward a Th2 response, while the orally administered RNA did not. The ETEC total RNA efficiently protected the animals against the ETEC challenge either by itself or as an adjuvant. The histology characterization of the small intestines also suggested the ETEC RNA administration protected the small intestinal structure against the ETEC infection. Particularly of note was that the immunity level and protective efficacy caused by ETEC RNA were dose-dependent. These findings will help understand the role of bacterial RNA in eliciting immune responses, and benefit the development of RNA-based vaccines or adjuvants.

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