scholarly journals Escherichia coli K1's Capsule Is a Barrier to Bacteriophage T7

2005 ◽  
Vol 71 (8) ◽  
pp. 4872-4874 ◽  
Author(s):  
Dean Scholl ◽  
Sankar Adhya ◽  
Carl Merril
Keyword(s):  
Escherichia Coli ◽  
Bacteriophage T7 ◽  
Physical Barrier ◽  
E Coli ◽  
Primary Receptor ◽  
Polysaccharide Capsule ◽  
K1 Capsule ◽  
Escherichia Coli K1

ABSTRACT Escherichia coli strains that produce the K1 polysaccharide capsule have long been associated with pathogenesis. This capsule is believed to increase the cell's invasiveness, allowing the bacteria to avoid phagocytosis and inactivation by complement. It is also recognized as a receptor by some phages, such as K1F and K1-5, which have virion-associated enzymes that degrade the polysaccharide. In this report we show that expression of the K1 capsule in E. coli physically blocks infection by T7, a phage that recognizes lipopolysaccharide as the primary receptor. Enzymatic removal of the K1 antigen from the cell allows T7 to adsorb and replicate. This observation suggests that the capsule plays an important role as a defense against some phages that recognize structures beneath it and that the K1-specific phages evolved to counter this physical barrier.

scholarly journals Recent Emergence of Clonal Group O25b:K1:H4-B2-ST131 ibeA Strains among Escherichia coli Poultry Isolates, Including CTX-M-9-Producing Strains, and Comparison with Clinical Human Isolates

2010 ◽  
Vol 76 (21) ◽  
pp. 6991-6997 ◽  
Author(s):  
Azucena Mora ◽  
Alexandra Herrera ◽  
Rosalia Mamani ◽  
Cecilia López ◽  
María Pilar Alonso ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Gene ◽  
Clonal Group ◽  
E Coli ◽  
Strain Collection ◽  
Zoonotic Risk ◽  
Recent Emergence ◽  
Avian Origin ◽  
K1 Capsule ◽  
M 14

ABSTRACT To discern the possible spread of the Escherichia coli O25b:H4-ST131 clonal group in poultry and the zoonotic potential of avian strains, we made a retrospective search of our strain collection and compared the findings for those strains with the findings for current strains. Thus, we have characterized a collection of 19 avian O25b:H4-ST131 E. coli strains isolated from 1995 to 2010 which, interestingly, harbored the ibeA gene. Using this virulence gene as a criterion for selection, we compared those 19 avian strains with 33 human O25b:H4-ST131 ibeA-positive E. coli strains obtained from patients with extraintestinal infections (1993 to 2009). All 52 O25b:H4-ST131 ibeA-positive E. coli strains shared the fimH, kpsMII, malX, and usp genes but showed statistically significant differences in nine virulence factors, namely, papGIII, cdtB, sat, and kpsMII K5, which were associated with human strains, and iroN, kpsMII K1, cvaC, iss, and tsh, which were associated with strains of avian origin. The XbaI macrorestriction profiles of the 52 E. coli O25b:H4-ST131 ibeA-positive strains revealed 11 clusters (clusters I to XI) of >85% similarity, with four clusters including strains of human and avian origin. Cluster VII (90.9% similarity) grouped 10 strains (7 avian and 3 human strains) that mostly produced CTX-M-9 and that also shared the same virulence profile. Finally, we compared the macrorestriction profiles of the 12 CTX-M-9-producing O25b:H4-ST131 ibeA strains (7 avian and 5 human strains) identified among the 52 strains with those of 15 human O25b:H4-ST131 CTX-M-14-, CTX-M-15-, and CTX-M-32-producing strains that proved to be negative for ibeA and showed that they clearly differed in the level of similarity from the CTX-M-9-producing strains. In conclusion, E. coli clonal group O25b:H4-ST131 ibeA has recently emerged among avian isolates with the new acquisition of the K1 capsule antigen and includes CTX-M-9-producing strains. This clonal group represents a real zoonotic risk that has crossed the barrier between human and avian hosts.

scholarly journals Role of Virulence Factors in Resistance of Avian Pathogenic Escherichia coli to Serum and in Pathogenicity

2003 ◽  
Vol 71 (1) ◽  
pp. 536-540 ◽  
Author(s):  
Melha Mellata ◽  
Maryvonne Dho-Moulin ◽  
Charles M. Dozois ◽  
Roy Curtiss ◽  
Peter K. Brown ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Bacterial Resistance ◽  
Serum Resistance ◽  
Temperature Sensitive ◽  
E Coli ◽  
Pathogenic Escherichia Coli ◽  
K1 Capsule

ABSTRACT In chickens, colibacillosis is caused by avian pathogenic Escherichia coli (APEC) via respiratory tract infection. Many virulence factors, including type 1 (F1A) and P (F11) fimbriae, curli, aerobactin, K1 capsule, and temperature-sensitive hemagglutinin (Tsh) and plasmid DNA regions have been associated with APEC. A strong correlation between serum resistance and virulence has been demonstrated, but roles of virulence factors in serum resistance have not been well elucidated. By using mutants of APEC strains TK3, MT78, and χ7122, which belong to serogroups O1, O2, and O78, respectively, we investigated the role of virulence factors in resistance to serum and pathogenicity in chickens. Our results showed that serum resistance is one of the pathogenicity mechanisms of APEC strains. Virulence factors that increased bacterial resistance to serum and colonization of internal organs of infected chickens were O78 lipopolysaccharide of E. coli χ7122 and the K1 capsule of E. coli MT78. In contrast, curli, type 1, and P fimbriae did not appear to contribute to serum resistance. We also showed that the iss gene, which was previously demonstrated to increase resistance to serum in certain E. coli strains, is located on plasmid pAPEC-1 of E. coli χ7122 but does not play a major role in resistance to serum for strain χ7122.

scholarly journals The Catabolite Repressor Protein-Cyclic AMP Complex RegulatescsgDand Biofilm Formation in Uropathogenic Escherichia coli

2016 ◽  
Vol 198 (24) ◽  
pp. 3329-3334 ◽  
Author(s):  
David A. Hufnagel ◽  
Margery L. Evans ◽  
Sarah E. Greene ◽  
Jerome S. Pinkner ◽  
Scott J. Hultgren ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Extracellular Matrix ◽  
Cyclic Amp ◽  
Intergenic Region ◽  
Biofilm Formation ◽  
Cellulose Production ◽  
Content Type ◽  
E Coli ◽  
Link Type ◽  
K1 Capsule

ABSTRACTThe extracellular matrix protectsEscherichia colifrom immune cells, oxidative stress, predation, and other environmental stresses. Production of theE. coliextracellular matrix is regulated by transcription factors that are tuned to environmental conditions. The biofilm master regulator protein CsgD upregulates curli and cellulose, the two major polymers in the extracellular matrix of uropathogenicE. coli(UPEC) biofilms. We found that cyclic AMP (cAMP) regulates curli, cellulose, and UPEC biofilms throughcsgD. The alarmone cAMP is produced by adenylate cyclase (CyaA), and deletion ofcyaAresulted in reduced extracellular matrix production and biofilm formation. Thecataboliterepressorprotein (CRP) positively regulatedcsgDtranscription, leading to curli and cellulose production in the UPEC isolate, UTI89. Glucose, a known inhibitor of CyaA activity, blocked extracellular matrix formation when added to the growth medium. The mutant strains ΔcyaAand Δcrpdid not produce rugose biofilms, pellicles, curli, cellulose, or CsgD. Three putative CRP binding sites were identified within thecsgD-csgBintergenic region, and purified CRP could gel shift thecsgD-csgBintergenic region. Additionally, we found that CRP binded upstream ofkpsMT, which encodes machinery for K1 capsule production. Together our work shows that cAMP and CRP influenceE. colibiofilms through transcriptional regulation ofcsgD.IMPORTANCEThecataboliterepressorprotein (CRP)-cyclic AMP (cAMP) complex influences the transcription of ∼7% of genes on theEscherichia colichromosome (D. Zheng, C. Constantinidou, J. L. Hobman, and S. D. Minchin, Nucleic Acids Res 32:5874–5893, 2004,https://dx.doi.org/10.1093/nar/gkh908). Glucose inhibitsE. colibiofilm formation, and ΔcyaAand Δcrpmutants show impaired biofilm formation (D. W. Jackson, J.W. Simecka, and T. Romeo, J Bacteriol 184:3406–3410, 2002,https://dx.doi.org/10.1128/JB.184.12.3406-3410.2002). We determined that the cAMP-CRP complex regulates curli and cellulose production and the formation of rugose and pellicle biofilms throughcsgD. Additionally, we propose that cAMP may work as a signaling compound for uropathogenicE. coli(UPEC) to transition from the bladder lumen to inside epithelial cells for intracellular bacterial community formation through K1 capsule regulation.

scholarly journals P fimbriae and aerobactin as intestinal colonization factors for Escherichia coli in Pakistani infants

2001 ◽  
Vol 126 (1) ◽  
pp. 19-23 ◽  
Author(s):  
F. NOWROUZIAN ◽  
A. E. WOLD ◽  
I. ADLERBERTH
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Western Europe ◽  
Carriage Rate ◽  
E Coli ◽  
Colonization Factors ◽  
P Type ◽  
K1 Capsule ◽  
Fimbrial Adhesin

The carriage rate of a range of virulence genes was compared between resident and transient Escherichia coli strains obtained from the rectal flora of 22 home-delivered Pakistani infants 0–6 months old. Genes for the following virulence factors were assessed using multiplex PCR: P, type 1 and S fimbriae, three P fimbrial adhesin varieties, Dr haemagglutinin, K1 and K5 capsule, haemolysin and aerobactin. The E. coli strains examined here differed from those previously obtained from hosts in Western Europe in a lower prevalence of genes for P, S and type 1 fimbriae, K1 capsule and haemolysin. Nevertheless, genes for P fimbriae, the class II variety of papG adhesin, and aerobactin were significantly more common among resident than transient strains, as previously observed in a Swedish study. The results suggest that P fimbriae and aerobactin, previously implicated as virulence factors for urinary tract infection, might contribute to persistence of E. coli in the normal intestinal microflora.

scholarly journals Translation initiation from sequence variants of the bacteriophage T7 g10RBS in Escherichia coli and Agrobacterium fabrum

2021 ◽  
Author(s):  
Alex B. Benedict ◽  
Joshua D. Chamberlain ◽  
Diana G. Calvopina ◽  
Joel S. Griffitts
Keyword(s):  
Escherichia Coli ◽  
Recombinant Proteins ◽  
Bacteriophage T7 ◽  
Translation Efficiency ◽  
Nucleotide Substitutions ◽  
Reporter Protein ◽  
E Coli ◽  
Translational Enhancer ◽  
Multiple Promoter ◽  
Derivatives Of

Abstract Background The bacteriophage T7 gene 10 ribosome binding site (g10RBS) has long been used for robust expression of recombinant proteins in Escherichia coli. This RBS consists of a Shine–Dalgarno (SD) sequence augmented by an upstream translational “enhancer” (Enh) element, supporting protein production at many times the level seen with simple synthetic SD-containing sequences. The objective of this study was to dissect the g10RBS to identify simpler derivatives that exhibit much of the original translation efficiency. Methods and results Twenty derivatives of g10RBS were tested using multiple promoter/reporter gene contexts. We have identified one derivative (which we call “CON_G”) that maintains 100% activity in E. coli and is 33% shorter. Further minimization of CON_G results in variants that lose only modest amounts of activity. Certain nucleotide substitutions in the spacer region between the SD sequence and initiation codon show strong decreases in translation. When testing these 20 derivatives in the alphaproteobacterium Agrobacterium fabrum, most supported strong reporter protein expression that was not dependent on the Enh. Conclusions The g10RBS derivatives tested in this study display a range of observed activity, including a minimized version (CON_G) that retains 100% activity in E. coli while being 33% shorter. This high activity is evident in two different promoter/reporter sequence contexts. The array of RBS sequences presented here may be useful to researchers in need of fine-tuned expression of recombinant proteins of interest.

scholarly journals Novel Host Recognition Mechanism of the K1 Capsule-Specific Phage of Escherichia coli : Capsular Polysaccharide as the First Receptor and Lipopolysaccharide as the Secondary Receptor

2021 ◽  
Author(s):  
Qianwen Gong ◽  
Xuhang Wang ◽  
Haosheng Huang ◽  
Yu Sun ◽  
Xinjie Qian ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Capsular Polysaccharide ◽  
Host Recognition ◽  
Fluorescence Labeling ◽  
E Coli ◽  
Specific Phage ◽  
Secondary Receptor ◽  
New Type ◽  
Tail Protein ◽  
K1 Capsule

K1 capsule-specific phages of Escherichia coli have been reported in recent years, but the molecular mechanism involved in host recognition of these phages remains unknown. In this study, the interactions between PNJ1809-36, a new K1-specific phage and its host bacteria E. coli DE058, were investigated. A transposon mutation library was used to screen for receptor-related genes. Gene deletion, lysis curve determination, plaque formation test, adsorption assay and inhibition assay of phage by lipopolysaccharide (LPS) showed that capsular polysaccharide (CPS) was the first receptor for the initial adsorption of PNJ1809-36 to E. coli DE058 and LPS was a secondary receptor for the irreversible binding of the phage. The penultimate galactose in the outer core was identified as the specific binding region on LPS. Through antibody blocking assay, fluorescence labeling and high-performance gel permeation chromatography (HPGPC), the tail protein ORF261 of phage PNJ1809-36 was identified as the receptor binding protein on CPS. Given these findings, we propose a model for the recognition process of phage PNJ1809-36 on E. coli DE058: The phage PNJ1809-36 tail protein ORF261 recognizes and adsorbs to the K1 capsule; then the K1 capsule is partially degraded, exposing the active site of LPS which is recognized by phage PNJ1809-36. This model provides insight into the molecular mechanisms between K1-specific phages and their host bacteria. IMPORTANCE It has been speculated that CPS is the main receptor of K1-specific phages belonging to Siphoviridae . In recent years, a new type of K1-specific phage belonging to Myoviridae has been reported, but its host recognition mechanisms remain unknown. Here, we studied the interactions between PNJ1809-36, a new type of K1 phage, and its host bacteria E. coli DE058. Our research showed that the phage initially adsorbed to the K1 capsule mediated by ORF261 and then bound to the penultimate galactose of LPS to begin the infection process.

scholarly journals O -Acetylation of Capsular Polysialic Acid Enables Escherichia coli K1 Escaping from Siglec-Mediated Innate Immunity and Lysosomal Degradation of E. coli -Containing Vacuoles in Macrophage-Like Cells

2021 ◽  
Author(s):  
Jinghua Yang ◽  
Wei Ma ◽  
Yuanyuan Wu ◽  
Hui Zhou ◽  
Siyu Song ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Innate Immunity ◽  
Antibiotic Therapy ◽  
Polysialic Acid ◽  
Neonatal Meningitis ◽  
Lysosomal Degradation ◽  
Content Type ◽  
Mortality And Morbidity ◽  
E Coli ◽  
Escherichia Coli K1

Escherichia coli K1 is a leading cause of neonatal meningitis. The mortality and morbidity of this disease remain significantly high despite antibiotic therapy.

scholarly journals Identification of Arg-12 in the active site of Escherichia coli K1 CMP-sialic acid synthetase

1999 ◽  
Vol 343 (2) ◽  
pp. 397-402 ◽  
Author(s):  
Daniel M. STOUGHTON ◽  
Gerardo ZAPATA ◽  
Robert PICONE ◽  
Willie F. VANN
Keyword(s):  
Escherichia Coli ◽  
Sialic Acid ◽  
Active Site ◽  
Positive Charge ◽  
Enzymic Activity ◽  
Site Directed Mutagenesis ◽  
E Coli ◽  
Steady State Kinetic ◽  
State Kinetic ◽  
Escherichia Coli K1

Escherichia coli K1 CMP-sialic acid synthetase catalyses the synthesis of CMP-sialic acid from CTP and sialic acid. The active site of the 418 amino acid E. coli enzyme was localized to its N-terminal half. The bacterial CMP-sialic acid synthetase enzymes have a conserved motif, IAIIPARXXSKGLXXKN, at their N-termini. Several basic residues have been identified at or near the active site of the E. coli enzyme by chemical modification and site-directed mutagenesis. Only one of the lysines in the N-terminal motif, Lys-21, appears to be essential for activity. Mutation of Lys-21 in the N-terminal motif results in an inactive enzyme. Furthermore, Arg-12 of the N-terminal motif appears to be an active-site residue, based on the following evidence. Substituting Arg-12 with glycine or alanine resulted in inactive enzymes, indicating that this residue is required for enzymic activity. The Arg-12 → Lys mutant was partially active, demonstrating that a positive charge is required at this site. Steady-state kinetic analysis reveals changes in kcat, Km and Ks for CTP, which implicates Arg-12 in catalysis and substrate binding.

scholarly journals IL-10 administration reduces PGE-2 levels and promotes CR3-mediated clearance of Escherichia coli K1 by phagocytes in meningitis

2010 ◽  
Vol 207 (6) ◽  
pp. 1307-1319 ◽  
Author(s):  
Rahul Mittal ◽  
Ignacio Gonzalez-Gomez ◽  
Ashok Panigrahy ◽  
Kerstin Goth ◽  
Richard Bonnet ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ex Vivo ◽  
Morphological Changes ◽  
Neonatal Meningitis ◽  
Prostaglandin E ◽  
Antibody Treatment ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Escherichia Coli K1

Ineffectiveness of antibiotics in treating neonatal Escherichia coli K1 meningitis and the emergence of antibiotic-resistant strains evidently warrants new prevention strategies. We observed that administration of interleukin (IL)-10 during high-grade bacteremia clears antibiotic-sensitive and -resistant E. coli from blood of infected mice. Micro-CT studies of brains from infected animals displayed gross morphological changes similar to those observed in infected human neonates. In mice, IL-10, but not antibiotic or anti-TNF antibody treatment prevented brain damage caused by E. coli. IL-10 administration elevated CR3 expression in neutrophils and macrophages of infected mice, whereas infected and untreated mice displayed increased expression of FcγRI and TLR2. Neutrophils or macrophages pretreated with IL-10 ex vivo exhibited a significantly greater microbicidal activity against E. coli compared with cells isolated from wild-type or IL-10−/− mice. The protective effect of IL-10 was abrogated when CR3 was knocked-down in vivo by siRNA. The increased expression of CR3 in phagocytes was caused by inhibition of prostaglandin E-2 (PGE-2) levels, which were significantly increased in neutrophils and macrophages upon E. coli infection. These findings describe a novel modality of IL-10–mediated E. coli clearance by diverting the entry of bacteria via CR3 and preventing PGE-2 formation in neonatal meningitis.

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