scholarly journals Fidelity of Prespacer Capture and Processing is Governed by the PAM Mediated Interaction of Cas1-2 Adaptation complex in Escherichia coli

2019 ◽  
Author(s):  
K.N.R. Yoganand ◽  
Manasasri Muralidharan ◽  
B. Anand
Keyword(s):  
Escherichia Coli ◽  
Variable Length ◽  
Type I ◽  
Repeat Junction

ABSTRACTDuring CRISPR adaptation, short sections of invader derived DNA of defined length are specifically integrated at the leader-repeat junction as spacers by Cas1-2 integrase complex. While several variants of CRISPR systems utilise Cas4 as an indispensible nuclease for processing the PAM containing prespacers to a defined length for integration– surprisingly– a few CRISPR systems such as type I-E are bereft of Cas4. Therefore, how the prespacers show impeccable conservation for length and PAM selection in type I-E remains intriguing. In Escherichia coli, we show that Cas1-2/I-E– via the type I-E specific extended C-terminal tail of Cas1 –displays intrinsic affinity for PAM containing prespacers of variable length and its binding protects the prespacer boundaries of defined length from the exonuclease action that ensues the pruning of aptly sized substrates for integration. This suggests that cooperation between Cas1-2 and cellular exonucleases drives the Cas4 independent prespacer capture and processing in type I-E.

scholarly journals Expression of the type I regulatory subunit of cAMP-dependent protein kinase in Escherichia coli.

1986 ◽  
Vol 261 (24) ◽  
pp. 11091-11096 ◽  
Author(s):  
L D Saraswat ◽  
M Filutowicz ◽  
S S Taylor
Keyword(s):  
Escherichia Coli ◽  
Protein Kinase ◽  
Regulatory Subunit ◽  
Type I ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

Comparison of colony and stool blots for detection of enteropathogens by DNA probes

1991 ◽  
Vol 37 (5) ◽  
pp. 407-410
Author(s):  
Mônica A. M. Vieira ◽  
Beatriz E. C. Guth ◽  
Tânia A. T. Gomes
Keyword(s):  
Escherichia Coli ◽  
Key Words ◽  
Sensitivity And Specificity ◽  
Dna Probes ◽  
Type I ◽  
Enteropathogenic Escherichia Coli ◽  
Key Words Dna ◽  
E Coli ◽  
Heat Stable

DNA probes that identify genes coding for heat-labile type I (LT-I) and heat-stable type 1 (ST-I) enterotoxins, enteropathogenic Escherichia coli adherence factor (EAF), and Shigella-like, invasiveness (INV) are used to evaluate the sensitivity and specificity of stool blots in comparison with the sensitivity and specificity of colony blots in detecting enteropathoghens. The sensitivities of the probes in stool blots are 91.7% for the LT-I probe, 76.9% for the ST-I probes, 78.9% for the EAF probe, and 45.5% for the INV probe. The specificity of all probes is higher than 95%. In general, the stool blot method identifies as many if not more LT-I-, ST-I-, and EAF-producing E. coli infections than the colony blots. Key words: DNA probes, stool blots, enteropathogens, diagnosis.

scholarly journals Biochemical and structural characterization of the novel sialic acid-binding site of Escherichia coli heat-labile enterotoxin LT-IIb

2016 ◽  
Vol 473 (21) ◽  
pp. 3923-3936 ◽  
Author(s):  
Dani Zalem ◽  
João P. Ribeiro ◽  
Annabelle Varrot ◽  
Michael Lebens ◽  
Anne Imberty ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Binding Site ◽  
Cholera Toxin ◽  
Carbohydrate Binding ◽  
Type I ◽  
Type Ii ◽  
E Coli ◽  
B Subunit ◽  
Heat Labile ◽  
B Subunits

The structurally related AB5-type heat-labile enterotoxins of Escherichia coli and Vibrio cholerae are classified into two major types. The type I group includes cholera toxin (CT) and E. coli LT-I, whereas the type II subfamily comprises LT-IIa, LT-IIb and LT-IIc. The carbohydrate-binding specificities of LT-IIa, LT-IIb and LT-IIc are distinctive from those of cholera toxin and E. coli LT-I. Whereas CT and LT-I bind primarily to the GM1 ganglioside, LT-IIa binds to gangliosides GD1a, GD1b and GM1, LT-IIb binds to the GD1a and GT1b gangliosides, and LT-IIc binds to GM1, GM2, GM3 and GD1a. These previous studies of the binding properties of type II B-subunits have been focused on ganglio core chain gangliosides. To further define the carbohydrate binding specificity of LT-IIb B-subunits, we have investigated its binding to a collection of gangliosides and non-acid glycosphingolipids with different core chains. A high-affinity binding of LT-IIb B-subunits to gangliosides with a neolacto core chain, such as Neu5Gcα3- and Neu5Acα3-neolactohexaosylceramide, and Neu5Gcα3- and Neu5Acα3-neolactooctaosylceramide was detected. An LT-IIb-binding ganglioside was isolated from human small intestine and characterized as Neu5Acα3-neolactohexaosylceramide. The crystal structure of the B-subunit of LT-IIb with the pentasaccharide moiety of Neu5Acα3-neolactotetraosylceramide (Neu5Ac-nLT: Neu5Acα3Galβ4GlcNAcβ3Galβ4Glc) was determined providing the first information for a sialic-binding site in this subfamily, with clear differences from that of CT and LT-I.

scholarly journals D-Mannoside FimH Inhibitors as Non-Antibiotic Alternatives for Uropathogenic Escherichia coli

Antibiotics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1072
Author(s):  
Alfredo Montes-Robledo ◽  
Rosa Baldiris-Avila ◽  
Johan Fabian Galindo
Keyword(s):  
Escherichia Coli ◽  
3D Structure ◽  
Pcr Amplification ◽  
Uropathogenic Escherichia Coli ◽  
Crystallographic Structure ◽  
Type I ◽  
Dynamic Simulations ◽  
Lectin Domain ◽  
In Silico Studies ◽  
Tract Infections

FimH is a type I fimbria of uropathogenic Escherichia coli (UPEC), recognized for its ability to adhere and infect epithelial urinary tissue. Due to its role in the virulence of UPEC, several therapeutic strategies have focused on the study of FimH, including vaccines, mannosides, and molecules that inhibit their assembly. This work has focused on the ability of a set of monosubstituted and disubstituted phenyl mannosides to inhibit FimH. To determine the 3D structure of FimH for our in silico studies, we obtained fifteen sequences by PCR amplification of the fimH gene from 102 UPEC isolates. The fimH sequences in BLAST had a high homology (97–100%) to our UPEC fimH sequences. A search for the three-dimensional crystallographic structure of FimH proteins in the PDB server showed that proteins 4X5P and 4XO9 were found in 10 of the 15 isolates, presenting a 67% influx among our UPEC isolates. We focused on these two proteins to study the stability, free energy, and the interactions with different mannoside ligands. We found that the interactions with the residues of aspartic acid (ASP 54) and glutamine (GLN 133) were significant to the binding stability. The ligands assessed demonstrated high binding affinity and stability with the lectin domain of FimH proteins during the molecular dynamic simulations, based on MM-PBSA analysis. Therefore, our results suggest the potential utility of phenyl mannoside derivatives as FimH inhibitors to mitigate urinary tract infections produced by UPEC; thus, decreasing colonization, disease burden, and the costs of medical care.

scholarly journals Dynamic mechanisms of CRISPR interference by Escherichia coli CRISPR-Cas3

2021 ◽  
Author(s):  
Kazuto Yoshimi ◽  
Kohei TAKESHITA ◽  
Noriyuki Kodera ◽  
Satomi Shibumura ◽  
Yuko Yamauchi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Speed ◽  
Dna Helicase ◽  
Type I ◽  
Loop Formation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Target Strand ◽  
Target Dna

Type I CRISPR-Cas3 uses an RNA-guided multi Cas-protein complex, Cascade, which detects and degrades foreign nucleic acids via the helicase-nuclease Cas3 protein. Despite many studies using cryoEM and smFRET, the precise mechanism of Cas3-mediated cleavage and degradation of target DNA remains elusive. Here we reconstitute the CRISPR-Cas3 system in vitro to show how the Escherichia coli Cas3 (EcoCas3) with EcoCascade exhibits collateral non-specific ssDNA cleavage and target specific DNA degradation. Partial binding of EcoCascade to target DNA with tolerated mismatches within the spacer sequence, but not the PAM, elicits collateral ssDNA cleavage activity of recruited EcoCas3. Conversely, stable binding with complete R-loop formation drives EcoCas3 to nick the non-target strand (NTS) in the bound DNA. Helicase-dependent unwinding then combines with trans ssDNA cleavage of the target strand and repetitive cis cleavage of the NTS to degrade the target dsDNA substrate. High-speed atomic force microscopy demonstrates that EcoCas3 bound to EcoCascade repeatedly reels and releases the target DNA, followed by target fragmentation. Together, these results provide a revised model for collateral ssDNA cleavage and target dsDNA degradation by CRISPR-Cas3, furthering understanding of type I CRISPR priming and interference and informing future genome editing tools.

scholarly journals Isolation and Identification of Kidney-derived Pathogenic Escherichia coli from Red Panda (Ailurus fulgens)

2020 ◽  
Author(s):  
Songrui Liu ◽  
Yunli Li ◽  
Chanjuan Yue ◽  
Dongsheng Zhang ◽  
Xiaoyan Su ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacterial Infection ◽  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Ex Situ ◽  
Type I ◽  
Pathogenicity Test ◽  
Whole Genome ◽  
Red Panda ◽  
Ailurus Fulgens

Abstract Background Disease prevention and control is a significant part during the ex-situ conservation of the red panda (Ailurus fulgens) with bacterial infection being one of the important threats to the health of the captive population. So far, there was no systematic and detailed publications about the red panda-related E. coli disease. This study was conducted for the purpose of determining the cause of death, etiology and pathogenesis on a red panda through clinical symptoms, complete blood count, biochemical analysis, pathological diagnosis, antimicrobial susceptibility test, mouse pathogenicity test, and bacterial whole genome sequencing.Results A bacterial strain confirmed as Uropathogenic Escherichia coli (UPEC) was isolated from one captive dead red panda, which is resistant to most of the β-lactam drugs and a small number of aminoglycoside medications. The mouse pathogenicity test results showed the strains isolated postmortem from mice were the same as from the dead red panda, and the pathological findings were similar to the red panda while they were not completely the same. These pathological differences between red panda and mice may be related to the routes of infection and perhaps species differences and tolerance. The whole genome sequencing results showed that the isolated strain contained P pili, type I pili and iron uptake system related factors, which were closely related to its nephrotoxicity. Conclusion The red panda died of bacterial infection which was identified as Uropathogenic Escherichia coli. The pathogenic mechanisms of the strain are closely related to the expression of specific virulence genes.

scholarly journals Release of the type I secreted alpha-haemolysin via outer membrane vesicles from Escherichia coli

2006 ◽  
Vol 59 (1) ◽  
pp. 99-112 ◽  
Author(s):  
Carlos Balsalobre ◽  
Jose Manuel Silvan ◽  
Stina Berglund ◽  
Yoshimitsu Mizunoe ◽  
Bernt Eric Uhlin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Type I

scholarly journals Influence of Type I Fimbriae and Fluid Shear Stress on Bacterial Behavior and Multicellular Architecture of Early Escherichia coli Biofilms at Single-Cell Resolution

2018 ◽  
Vol 84 (6) ◽  
Author(s):  
Liyun Wang ◽  
Robert Keatch ◽  
Qi Zhao ◽  
John A. Wright ◽  
Clare E. Bryant ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shear Stress ◽  
Single Cell ◽  
Biofilm Formation ◽  
Fluid Shear Stress ◽  
Cell Membrane Permeability ◽  
Type I ◽  
Fluid Shear ◽  
Content Type ◽  
Type I Fimbriae

ABSTRACT Biofilm formation on abiotic surfaces in the food and medical industry can cause severe contamination and infection, yet how biological and physical factors determine the cellular architecture of early biofilms and the bacterial behavior of the constituent cells remains largely unknown. In this study, we examined the specific role of type I fimbriae in nascent stages of biofilm formation and the response of microcolonies to environmental flow shear at the single-cell resolution. The results show that type I fimbriae are not required for reversible adhesion from plankton, but they are critical for the irreversible adhesion of Escherichia coli strain MG1655 cells that form biofilms on polyethylene terephthalate (PET) surfaces. Besides establishing firm cell surface contact, the irreversible adhesion seems necessary to initiate the proliferation of E. coli on the surface. After the application of shear stress, bacterial retention is dominated by the three-dimensional architecture of colonies, independent of the population size, and the multilayered structure could protect the embedded cells from being insulted by fluid shear, while the cell membrane permeability mainly depends on the biofilm population size and the duration of the shear stress. IMPORTANCE Bacterial biofilms could lead to severe contamination problems in medical devices and food processing equipment. However, biofilms are usually studied at a rough macroscopic level; thus, little is known about how individual bacterium behavior within biofilms and the multicellular architecture are influenced by bacterial appendages (e.g., pili/fimbriae) and environmental factors during early biofilm formation. We applied confocal laser scanning microscopy (CLSM) to visualize Escherichia coli microcolonies at a single-cell resolution. Our findings suggest that type I fimbriae are vital to the initiation of bacterial proliferation on surfaces. We also found that the fluid shear stress affects the biofilm architecture and cell membrane permeability of the constituent bacteria in a different way: the onset of the biofilm is linked with the three-dimensional morphology, while membranes are regulated by the overall population of microcolonies.

Sign in / Sign up

Export Citation Format

Share Document