scholarly journals Wzi Is an Outer Membrane Lectin that Underpins Group 1 Capsule Assembly in Escherichia coli

Structure ◽  
2013 ◽  
Vol 21 (5) ◽  
pp. 844-853 ◽  
Author(s):  
Simon R. Bushell ◽  
Iain L. Mainprize ◽  
Martin A. Wear ◽  
Hubing Lou ◽  
Chris Whitfield ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Capsule Assembly ◽  
Group 1

scholarly journals A Novel Outer Membrane Protein, Wzi, Is Involved in Surface Assembly of the Escherichia coli K30 Group 1 Capsule

2003 ◽  
Vol 185 (19) ◽  
pp. 5882-5890 ◽  
Author(s):  
Andrea Rahn ◽  
Kostantinos Beis ◽  
James H. Naismith ◽  
Chris Whitfield
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Outer Membrane ◽  
Capsular Polysaccharide ◽  
Signal Sequence ◽  
Surface Group ◽  
Gene Clusters ◽  
Capsule Assembly ◽  
Free Material ◽  
Group 1

ABSTRACT Escherichia coli group 1 K antigens form a tightly associated capsule structure on the cell surface. Although the general features of the early steps in capsular polysaccharide biosynthesis have been described, little is known about the later stages that culminate in assembly of a capsular structure on the cell surface. Group 1 capsule biosynthesis gene clusters (cps) in E. coli and Klebsiella pneumoniae include a conserved open reading frame, wzi. The wzi gene is the first of a block of four conserved genes (wzi-wza-wzb-wzc) found in all group 1 K-antigen serotypes. Unlike wza, wzb, and wzc homologs that are found in gene clusters responsible for production of exopolysaccharides (i.e., predominantly cell-free polymer) in a range of bacteria, wzi is found only in systems that assemble capsular polysaccharides. The predicted Wzi protein shows no similarity to any other known proteins in the databases, but computer analysis of Wzi predicted a cleavable signal sequence. Wzi was expressed with a C-terminal hexahistidine tag, purified, and used for the production of specific antibodies that facilitated localization of Wzi to the outer membrane. Circular dichroism spectroscopy indicates that Wzi consists primarily of a β-barrel structure, and dynamic light scattering studies established that the protein behaves as a monomer in solution. A nonpolar wzi chromosomal mutant retained a mucoid phenotype and remained sensitive to lysis by a K30-specific bacteriophage. However, the mutant showed a significant reduction in cell-bound polymer, with a corresponding increase in cell-free material. Furthermore, examination of the mutant by electron microscopy showed that it lacked a coherent capsule structure. It is proposed that the Wzi protein plays a late role in capsule assembly, perhaps in the process that links high-molecular-weight capsule to the cell surface.

scholarly journals Impact of Phosphorylation of Specific Residues in the Tyrosine Autokinase, Wzc, on Its Activity in Assembly of Group 1 Capsules in Escherichia coli

2002 ◽  
Vol 184 (23) ◽  
pp. 6437-6447 ◽  
Author(s):  
Anne Paiment ◽  
Jennifer Hocking ◽  
Chris Whitfield
Keyword(s):  
Escherichia Coli ◽  
Capsular Polysaccharide ◽  
Site Directed Mutagenesis ◽  
Detectable Effect ◽  
Tyrosine Residue ◽  
Tyrosine Residues ◽  
Capsule Assembly ◽  
K 12 ◽  
Group 1

ABSTRACT WzcCPS is a tyrosine autokinase essential for the assembly of a high-molecular-weight (HMW) group 1 capsular polysaccharide (CPS) in Escherichia coli. Homologues of Wzc participate in the formation of CPS and exopolysaccharides in a variety of gram-positive and gram-negative bacteria. Phosphorylation of tyrosine residues in the WzcCPS C terminus is essential for HMW CPS assembly. Overexpression of WzbCPS (phosphatase) in a wild-type background caused a 3.7-fold decrease in the amount of cell-associated K30 CPS produced, confirming the importance of WzcCPS phosphorylation for capsule assembly. In this study, the tyrosine-rich region was dissected in an attempt to identify residues critical for WzcCPS phosphorylation and/or capsule expression. Site-directed mutagenesis demonstrated that no single tyrosine residue in this region is sufficient for detectable phosphorylation of WzcCPS in vivo or for HMW CPS expression. Furthermore, no single tyrosine residue is essential for phosphorylation or capsule assembly, since removal of any one tyrosine residue has no detectable effect. Altering combinations of tyrosine residues (from two to five) led to WzcCPS derivatives that were still competent for phosphorylation but that could not support assembly of HMW CPS, showing that phosphorylation of Wzc per se is not an accurate measure of its ability to function in capsule assembly. One interpretation of these data is that the overall level of phosphorylation in this region, rather than the precise combination of residues accessible to phosphorylation, is important for the activity of WzcCPS. Tyrosine 569, a residue shown to modulate the in vitro phosphorylation of WzcCA from E. coli K-12, was also mutated. The derivative with this mutation still functioned in capsule assembly. Quantitation of K30CPS from this mutant revealed no difference in the amount of polymer produced. Finally, dithiobis(succinimidylpropionate) cross-linking was used to confirm that WzcCPS forms complexes in vivo, independent of the phosphorylation state of the protein.

scholarly journals Structural and Functional Variation in Outer Membrane Polysaccharide Export (OPX) Proteins from the Two Major Capsule Assembly Pathways Present inEscherichia coli

2019 ◽  
Vol 201 (14) ◽  
Author(s):  
Caitlin Sande ◽  
Catrien Bouwman ◽  
Elisabeth Kell ◽  
Nicholas N. Nickerson ◽  
Sharookh B. Kapadia ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Outer Membrane ◽  
Abc Transporter ◽  
Capsular Polysaccharides ◽  
Content Type ◽  
E Coli ◽  
Capsule Production ◽  
Group 2 ◽  
Group 1

ABSTRACTCapsular polysaccharides (CPSs) are virulence factors for many important pathogens. InEscherichia coli, CPSs are synthesized via two distinct pathways, but both require proteins from the outer membrane polysaccharide export (OPX) family to complete CPS export from the periplasm to the cell surface. In this study, we compare the properties of the OPX proteins from the prototypical group 1 (Wzy-dependent) and group 2 (ABC transporter-dependent) pathways inE. coliK30 (Wza) andE. coliK2 (KpsD), respectively. In addition, we compare an OPX fromSalmonella entericaserovar Typhi (VexA), which shares structural properties with Wza, while operating in an ABC transporter-dependent pathway. These proteins differ in distribution in the cell envelope and formation of stable multimers, but these properties do not align with acylation or the interfacing biosynthetic pathway. InE. coliK2, murein lipoprotein (Lpp) plays a role in peptidoglycan association of KpsD, and loss of this interaction correlates with impaired group 2 capsule production. VexA also depends on Lpp for peptidoglycan association, but CPS production is unaffected in anlppmutant. In contrast, Wza and group 1 capsule production is unaffected by the absence of Lpp. These results point to complex structure-function relationships between different OPX proteins.IMPORTANCECapsules are protective layers of polysaccharides that surround the cell surface of many bacteria, including that ofEscherichia coliisolates andSalmonella entericaserovar Typhi. Capsular polysaccharides (CPSs) are often essential for virulence because they facilitate evasion of host immune responses. The attenuation of unencapsulated mutants in animal models and the involvement of protein families with conserved features make the CPS export pathway a novel candidate for therapeutic strategies. However, appropriate “antivirulence” strategies require a fundamental understanding of the underpinning cellular processes. Investigating export proteins that are conserved across different biosynthesis strategies will give important insight into how CPS is transported to the cell surface.

Overexpression of Outer Membrane Protein A Is a Risk Factor for Mortality in Escherichia coli Bloodstream Infections

2019 ◽  
Author(s):  
Ángel Rodríguez-Villodres ◽  
Rocío Álvarez-Marín ◽  
María Antonia Pérez-Moreno ◽  
Andrea Miró-Canturri ◽  
Marco Durán Lobato ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Risk Factor ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Protein A ◽  
Bloodstream Infections ◽  
Outer Membrane Protein A

Influence of Removable Denture Cleaning Agents on Adhesion of Oral Pathogenic Microflora In Vitro: A Randomized Controlled Trial

2021 ◽  
Vol 14 (1) ◽  
pp. 656-664
Author(s):  
I.R. Volchkova ◽  
A.V. Yumashev ◽  
V.V. Borisov ◽  
V.I. Doroshina ◽  
E.A. Kristal ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Candida Albicans ◽  
Test Group ◽  
Control Group ◽  
Removable Dental Prostheses ◽  
Removable Denture ◽  
Group 2 ◽  
Adhesion Index ◽  
Group 1

Introduction: Removable dentures are used by 20% of the population. These may be accompanied by denture stomatitis in 15-70% of patients. The choice of the optimal cleansing agent for removable dental prostheses is of high significance. Aim: The aim of our research was to study the influence of removable denture cleansing products on the adhesion of microorganisms and yeast. Materials and Methods: We manufactured 144 specimens of standardized round shape with a diameter of 10 mm from 4 types of modern polymeric materials used by prosthetic dentistry to produce removable dentures, 12 specimens of each material were placed into suspensions of bacterial cultures of Staphylococcus aureus, Escherichia coli, Candida albicans, then into “ClearaSept” (Test group 1), “Рrotefix active cleanser” (Test group 2), saline solution (Control group), followed by nutrient media. The adhesion index was calculated and analyzed. Results: There was no reliable lowering of adhesion index of Staphylococcus Aureus to all materials detected in Test group 1 (U=6, p>0.05 for Bio XS; U=8, p>0.05 for Dental D, Denotokeep Peek, Vertex Rapid Simplified). In Test group 2, the adhesion index of Staphylococcus Aureus reliably decreased to all materials compared to the Control group (U=0, p≤0.01). The adhesion index of Candida albicans and Escherichia coli to all materials in Test group 1 had a minor to moderate reliable reduction compared to the Control group (U=0, p≤0.01). Test group 2 showed a significant reliable decrease in Candida albicans and Escherichia coli adhesion index to all materials in comparison with the Control group (U=0, p≤0.01). Conclusion: The research showed an unreliable or minor and moderate reliable decrease in microorganisms adhesion index depending on the microorganism species after treatment of denture material specimens by antibacterial soap “ClearaSept” and a reliable significant decrease in microbial and yeast adhesion after application of Protefix active cleaner solution, which demonstrates a more significant antimicrobial effect in comparison to “ClearaSept” against Staphylococcus aureus, Escherichia coli, and Candida albicans.

Preparation of Outer Membrane Vesicle from Escherichia coli

BIO-PROTOCOL ◽  
2013 ◽  
Vol 3 (23) ◽  
Author(s):  
Oh Kim ◽  
Bok Hong ◽  
Kyong-Su Park ◽  
Yae Yoon ◽  
Seng Choi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Membrane Vesicle ◽  
Outer Membrane Vesicle
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