scholarly journals The PapG-adhesin at the tip of P-fimbriae provides Escherichia coli with a competitive edge in experimental bladder infections of cynomolgus monkeys.

1995 ◽  
Vol 182 (6) ◽  
pp. 1695-1702 ◽  
Author(s):  
J Winberg ◽  
R Möllby ◽  
J Bergström ◽  
K A Karlsson ◽  
I Leonardsson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Competitive Advantage ◽  
Class Ii ◽  
Microbial Interactions ◽  
Urinary Flow ◽  
Class Iii ◽  
Knockout Mutant ◽  
Cynomolgus Monkeys ◽  
Isogenic Mutant

Human urinary tract infection is an infectious disease that depends on a series of host-microbial interactions. The bacteria first colonize the colon and then the periurethral/vaginal areas; they ascend to and infect first the bladder and then the kidneys. Expression of Escherichia coli P-fimbriae constitutes the strongest correlation to renal pathogenicity, but is also related to first-time cystitis in children. The role of P-fimbriae in the preceding steps in the infectious process is unknown. To examine this, we constructed, from a P-fimbriated E. coli strain with a class II G-adhesin preferentially binding to globoside, one isogenic mutant lacking the G-adhesin and another isogenic mutant in which we replaced the papG class II allele with a class III adhesin preferentially binding to the Forssman antigen. We report here the comparison of the adhesin knockout mutant (DS17-8) and the class-switch mutant (DS17-1) with the wild-type (DS17) for in vivo colonization of the gut, vagina, and bladder of cynomolgus monkeys. It was recently shown that the class II tip G-adhesin is a prerequisite for acute pyelonephritis to occur in the monkey model in the absence of other kidney-specific adhesins or obstruction of the urinary flow. Here we show that it is not required for bladder infection but gives a competitive advantage in mixed infections. In the vagina and colon, the G-adhesin gives no competitive advantage.

scholarly journals Thermostability Engineering of a Class II Pyruvate Aldolase from Escherichia coli by in Vivo Folding Interference

2021 ◽  
Vol 9 (15) ◽  
pp. 5430-5436
Author(s):  
Sandra Bosch ◽  
Esther Sanchez-Freire ◽  
María Luisa del Pozo ◽  
Morana C̆esnik ◽  
Jaime Quesada ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Class Ii

scholarly journals A Toxic Environment: a Growing Understanding of How Microbial Communities Affect Escherichia coli O157:H7 Shiga Toxin Expression

2020 ◽  
Vol 86 (24) ◽  
Author(s):  
Erin M. Nawrocki ◽  
Hillary M. Mosso ◽  
Edward G. Dudley
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Microbial Interactions ◽  
Severe Illness ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Lambdoid Prophage

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) strains, including E. coli O157:H7, cause severe illness in humans due to the production of Shiga toxin (Stx) and other virulence factors. Because Stx is coregulated with lambdoid prophage induction, its expression is especially susceptible to environmental cues. Infections with Stx-producing E. coli can be difficult to model due to the wide range of disease outcomes: some infections are relatively mild, while others have serious complications. Probiotic organisms, members of the gut microbiome, and organic acids can depress Stx production, in many cases by inhibiting the growth of EHEC strains. On the other hand, the factors currently known to amplify Stx act via their effect on the stx-converting phage. Here, we characterize two interactive mechanisms that increase Stx production by O157:H7 strains: first, direct interactions with phage-susceptible E. coli, and second, indirect amplification by secreted factors. Infection of susceptible strains by the stx-converting phage can expand the Stx-producing population in a human or animal host, and phage infection has been shown to modulate virulence in vitro and in vivo. Acellular factors, particularly colicins and microcins, can kill O157:H7 cells but may also trigger Stx expression in the process. Colicins, microcins, and other bacteriocins have diverse cellular targets, and many such molecules remain uncharacterized. The identification of additional Stx-amplifying microbial interactions will improve our understanding of E. coli O157:H7 infections and help elucidate the intricate regulation of pathogenicity in EHEC strains.

scholarly journals Uropathogenic Escherichia coli Flagella Aid in Efficient Urinary Tract Colonization

2005 ◽  
Vol 73 (11) ◽  
pp. 7657-7668 ◽  
Author(s):  
Kelly J. Wright ◽  
Patrick C. Seed ◽  
Scott J. Hultgren
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Class I ◽  
Class Iii ◽  
Epithelial Surface ◽  
Fitness Advantage ◽  
Regulatory Cascade ◽  
Tract Infections

ABSTRACT In the murine model of urinary tract infections (UTI), cystitis by uropathogenic Escherichia coli (UPEC) occurs through an intimate relationship with the bladder superficial umbrella cell entailing cycles of adherence, invasion, intracellular bacterial community (IBC) formation, and dispersal (fluxing) from the intracellular environment. IBC dispersal is a key step that results in the spread of bacteria over the epithelial surface to initiate additional rounds of IBC formation. We investigated the role of flagella in mediating adherence and motility during UTI, hypothesizing that the dispersion of the IBC would be incomplete in the absence of motility, thus interrupting the IBC pathway and attenuating the infection. Using gfp reporter fusions, the expression of the flagellar class I flhDC and class III fliC genes was monitored to track key points of regulation throughout the pathogenic cascade. In vitro, growth under conditions promoting motility resulted in the robust expression of both fusions. In contrast, only the class I fusion produced significant expression throughout early stages of IBC development including the dispersion stage. Thus, unlike in vitro modeling of motility, the regulatory cascade appeared incomplete in vivo. Throughout IBC formation, nonmotile ΔfliC mutants achieved the same number of IBCs as the wild-type (wt) strain, demonstrating that flagella are neither essential nor required for first- or second-generation IBC formation. However, in competition experiments between wt and ΔfliC strains, the wt was shown to have a fitness advantage in persisting throughout the urinary tract for 2 weeks, demonstrating a subtle but measurable role for flagella in virulence.

scholarly journals Binding and transcriptional activation of non-flagellar genes by the Escherichia coli flagellar master regulator FlhD2C2

Microbiology ◽  
2005 ◽  
Vol 151 (6) ◽  
pp. 1779-1788 ◽  
Author(s):  
Graham P. Stafford ◽  
Tomoo Ogi ◽  
Colin Hughes
Keyword(s):  
Escherichia Coli ◽  
Dna Sequences ◽  
Transcriptional Activation ◽  
Binding Sites ◽  
Class Ii ◽  
Promoter Regions ◽  
E Coli ◽  
Flagellar Genes

The gene hierarchy directing biogenesis of peritrichous flagella on the surface of Escherichia coli and other enterobacteria is controlled by the heterotetrameric master transcriptional regulator FlhD2C2. To assess the extent to which FlhD2C2 directly activates promoters of a wider regulon, a computational screen of the E. coli genome was used to search for gene-proximal DNA sequences similar to the 42–44 bp inverted repeat FlhD2C2 binding consensus. This identified the binding sequences upstream of all eight flagella class II operons, and also putative novel FlhD2C2 binding sites in the promoter regions of 39 non-flagellar genes. Nine representative non-flagellar promoter regions were all bound in vitro by active reconstituted FlhD2C2 over the K D range 38–356 nM, and of the nine corresponding chromosomal promoter–lacZ fusions, those of the four genes b1904, b2446, wzz fepE and gltI showed up to 50-fold dependence on FlhD2C2 in vivo. In comparison, four representative flagella class II promoters bound FlhD2C2 in the K D range 12–43 nM and were upregulated in vivo 30- to 990-fold. The FlhD2C2-binding sites of the four regulated non-flagellar genes overlap by 1 or 2 bp the predicted −35 motif of the FlhD2C2-activated σ 70 promoters, as is the case with FlhD2C2-dependent class II flagellar promoters. The data indicate a wider FlhD2C2 regulon, in which non-flagellar genes are bound and activated directly, albeit less strongly, by the same mechanism as that regulating the flagella gene hierarchy.

scholarly journals Additional Determinants within Escherichia coli FNR Activating Region 1 and RNA Polymerase α Subunit Required for Transcription Activation

2005 ◽  
Vol 187 (5) ◽  
pp. 1724-1731 ◽  
Author(s):  
K. Derek Weber ◽  
Owen D. Vincent ◽  
Patricia J. Kiley
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Rna Polymerase ◽  
Class Ii ◽  
Site Directed Mutagenesis ◽  
Class I ◽  
Side Chains ◽  
Alanine Scanning Mutagenesis ◽  
Α Subunit

ABSTRACT The global anaerobic regulator FNR is a DNA binding protein that activates transcription of genes required for anaerobic metabolism in Escherichia coli through interactions with RNA polymerase (RNAP). Alanine-scanning mutagenesis of FNR amino acid residues 181 to 193 of FNR was utilized to determine which amino acid side chains are required for transcription of both class II and class I promoters. In vivo assays of FNR function demonstrated that a core of residues (F181, R184, S187, and R189) was required for efficient activation of class II promoters, while at a class I promoter, FF(−61.5), only S187 and R189 were critical for FNR activation. Site-directed mutagenesis of positions 184, 187, and 189 revealed that the positive charge contributes to the function of the side chain at positions 184 and 189 while the serine hydroxyl is critical for the function of position 187. Subsequent analysis of the carboxy-terminal domain of the α subunit (αCTD) of RNAP, using an alanine library in single copy, revealed that in addition to previously characterized side chains (D305, R317, and L318), E286 and E288 contributed to FNR activation of both class II and class I promoters, suggesting that αCTD region 285 to 288 also participates in activation by FNR. In conclusion, this study demonstrates that multiple side chains within region 181 to 192 are required for FNR activation and the surface of αCTD required for FNR activation is more extensive than previously observed.

scholarly journals Prevalence of Known P-Fimbrial G Alleles inEscherichia coli and Identification of a New Adhesin Class

2001 ◽  
Vol 8 (3) ◽  
pp. 637-640 ◽  
Author(s):  
Shannon D. Manning ◽  
Lixin Zhang ◽  
Betsy Foxman ◽  
Angela Spindler ◽  
Patricia Tallman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Class Ii ◽  
Class I ◽  
The Novel ◽  
Inescherichia Coli ◽  
Class Iii ◽  
Cloning And Sequencing ◽  
Fimbrial Adhesin

ABSTRACT Screening a large Escherichia coli collection for P-fimbrial adhesin classes identified 20 unclassifiable strains. Cloning and sequencing of papG from an unclassifiable strain identified another G allele. The novel adhesin gene has 65% identity to the class I adhesin gene, 44% identity to the class II adhesin gene, and 43% identity to the class III adhesin gene.

scholarly journals Multiple in vivo roles for the C-terminal domain of the RNA chaperone Hfq

2021 ◽  
Author(s):  
Kumari Kavita ◽  
Aixia Zhang ◽  
Chin-Hsien Tai ◽  
Nadim Majdalani ◽  
Gisela Storz ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rna Binding ◽  
Class Ii ◽  
Rna Chaperone ◽  
Terminal Domain ◽  
C Terminus ◽  
Bacterial Rna ◽  
Small Regulatory Rnas ◽  
Regulatory Rnas

Hfq, a bacterial RNA chaperone, stabilizes small regulatory RNAs (sRNAs) and facilitates sRNA base-pairing with target mRNAs. Hfq has a conserved N-terminal domain and a poorly conserved disordered C-terminal domain (CTD). In a transcriptome-wide examination of the effects of a chromosomal CTD deletion (Hfq1-65), the Escherichia coli mutant was most defective for the accumulation of sRNAs that bind the proximal and distal faces of Hfq (Class II sRNAs), but other sRNAs also were affected. There were only modest effects on the levels of mRNAs, suggesting little disruption of sRNA-dependent regulation. However, cells expressing Hfq lacking the CTD deletion in combination with a weak distal face mutation were defective for the function of the Class II sRNA ChiX and repression of mutS, both dependent upon distal face RNA binding. Loss of the region between amino acids 66-72 was critical for this defect. The CTD region beyond amino acid 72 was not necessary for distal face-dependent regulation, but was needed for functions associated with the Hfq rim, seen most clearly in combination with a rim mutant. Our results suggest that the C-terminus collaborates in various ways with different binding faces of Hfq, leading to distinct outcomes for individual sRNAs.

Endolyn (CD164) Interacts with CXCR4 and Modulates the CXCL12-Mediated Homing and Migration of Cord Blood CD133+ Hematopoietic Precusor Cells.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1135-1135
Author(s):  
Suzanne M. Watt ◽  
Sinead Forde ◽  
Brit Jorgensen Tye ◽  
Sarah Newey ◽  
Maria Roubelakis
Keyword(s):  
Cord Blood ◽  
Leading Edge ◽  
Class Ii ◽  
Functional Class ◽  
Jurkat Cells ◽  
Temporal Association ◽  
Class Iii ◽  
Human Cd34

Abstract The sialomucin, endolyn or CD164, has been shown to act as an important regulator in the adhesion of human haemopoietic stem/precursor cells (HPC) to stromal niche cells, while also controlling the entry of primitive human CD34+CD38lo HPC into cycle. Here, we define a novel function for endolyn, by identifying its ability to modulate CD133+ cord blood HPC migration on fibronectin towards CXCL12 in vitro. Interestingly, CD133+ cell migration on fibronectin to CXCL12 was reduced 1) by engaging the functional class II glycosylation-dependent epitope on endolyn with the 103B2/9E10 class II but not N6B6 class III antibody; and 2) by RNAi knockdown of endolyn in both CD133+ HPC and Jurkat cells. The inhibition of migration was more pronounced in the more primitive CD34+CD38lo/− HPC subset than in the CD38+ subset. We show a direct and temporal association of endolyn with the CXCR4 receptor, at the leading edge of CD133+ HPC. When CXCL12 is presented on fibronectin, we first see an upregulation in the association of CXCR4 with the a-4 and a-5 integrins that is closely followed by recruitment of endolyn to this complex. This was confirmed by co-immunoprecipitation studies. Knock-down of endolyn using siRNAs revealed that signaling through CXCR4 via PKC-zeta and Akt pathways was significantly dampened, while leaving MAPK phosphorylation unaffected. Our current studies are aimed at examining the in vivo importance of endolyn in HPC homing to the bone marrow of NOD/SCID mice. Our findings support a novel association between three distinct families of cell surface receptors that regulate both cell migratory and proliferative responses and identify endolyn as a key regulator of CXCR4/CXCL12 function.

scholarly journals An ideal spacing is required for the control of Class II CRP-dependent promoters by the status of CRP K100

2020 ◽  
Vol 367 (20) ◽  
Author(s):  
Ana Écija-Conesa ◽  
Julia Gallego-Jara ◽  
Gema Lozano Terol ◽  
Douglas F Browning ◽  
Steve J W Busby ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Promoter Activity ◽  
Positive Charge ◽  
Transcription Activation ◽  
Class Ii ◽  
Spatial Proximity ◽  
In Vitro Techniques ◽  
The Status

ABSTRACT Transcription activation by the Escherichia coli CRP at Class II promoters is dependent on direct interactions between RNA polymerase and CRP, therefore the spatial proximity between both proteins plays a significant role in the ability of CRP to activate transcription. Using both in vivo and in vitro techniques, here we demonstrate that the CRP K100 positive charge, adjacent to AR2, is required for full promoter activity when CRP is optimally positioned. Accordingly, K100 mediated activation is very position-dependent and our data confirm that the largest impact of the K100 status on transcription activation occurs when the spacing between the CRP binding site and the A2 of the −10 element is 22 bp. From the results of this study and the progress in the understanding about open complex DNA scrunching, we propose that CRP-dependent promoters should now be numbered by the distance from the center of the DNA site for CRP and the most highly conserved base at position 2 of the −10 hexamer in bacterial promoters.

Mixed culture models for predicting intestinal microbial interactions between Escherichia coli and Lactobacillus in the presence of probiotic Bacillus subtilis

2015 ◽  
Vol 6 (6) ◽  
pp. 871-877 ◽  
Author(s):  
J.J. Yang ◽  
C.C. Niu ◽  
X.H. Guo
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Mixed Culture ◽  
Lactobacillus Reuteri ◽  
Microbial Interactions ◽  
Lactobacillus Species ◽  
E Coli ◽  
Culture Models ◽  
Static Conditions

Bacillus has been proposed as a probiotic due to its in vivo effectiveness in the gastrointestinal tract through antimicrobial activities. The present study investigates the effects of Lactobacillus alone or in the presence of Bacillus subtilis MA139 on the inhibition of pathogenic Escherichia coli K88. Mixed cultures were used to predict the possible interactions among these bacteria within the intestinal tract of animals. B. subtilis MA139 was first assayed for its inhibition against E. coli K88 both under shaking and static culture conditions. A co-culture assay was employed under static conditions to test the inhibitory effects of Lactobacillus reuteri on E. coli K88, with or without addition of B. subtilis MA139. The results showed that B. subtilis MA139 had marked inhibition against E. coli K88 under shaking conditions and weak inhibition under static conditions. Lactobacillus alone as well as in combination with B. subtilis MA139 spores exerted strong inhibition against E. coli K88 under static conditions. However, the inhibition by Lactobacillus in combination with B. subilis spores was much higher than that by Lactobacillus alone (P<0.01). B. subtilis MA139 significantly decreased the pH and oxidation-reduction potential values of the co-culture broth compared to that of Lactobacillus alone (P<0.05). The viability of Lactobacillus increased when co-cultured with B. subtilis MA139 because of significantly higher Lactobacillus counts and lower pH values in the broth (P<0.05). The role of Bacillus in the mixed culture models suggests that Bacillus may produce beneficial effects by increasing the viability of lactobacilli and subsequently inhibiting the growth of pathogenic E. coli. Therefore, the combination of Bacillus and Lactobacillus species as a probiotic is recommended.

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