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Adhesins
Terms modified by Adhesins Selected AbstractsImmunization of mice with Lactobacillus casei expressing intimin fragments produces antibodies able to inhibit the adhesion of enteropathogenic Escherichia coli to cultivated epithelial cellsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2008Patrícia C.D. Ferreira Abstract Enteropathogenic Escherichia coli (EPEC) are frequently isolated as a cause of infantile diarrhea in developing countries. Its pathogenicity is distinguished by histopathological alterations at the site of infection, known as attaching and effacing (A/E) lesions, in which bacterial virulence factors and host proteins participate. Intimin, a bacterial adhesin expressed by all EPEC described to date, is responsible for the intimate adherence of the bacteria to host cells and is essential for the formation of A/E lesions. Mucosal vaccination may represent an efficacious intervention to prevent EPEC infection and lower morbidity and mortality rates. Strategies for mucosal vaccinations that use lactic acid bacteria for the delivery of heterologous antigens rely on their safety profile and ability to stimulate the immune system. In the present work, we have constructed Lactobacillus casei strains expressing different fragments of intimin ,, a subtype that is frequently expressed by EPEC strains. Mucosal immunization of mice with L. casei expressing intimin fragments induced specific systemic and mucosal antibodies. These antibodies were able to recognize native intimin on the surface of EPEC and to inhibit in vitro EPEC binding to epithelial cells. [source] Fimbriae of uropathogenic Proteus mirabilisFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2007Sérgio P. D. Rocha Abstract Proteus mirabilis is a common causative agent of cystitis and pyelonephritis in patients with urinary catheters or structural abnormalities of the urinary tract. Several types of fimbriae, which are potentially involved in adhesion to the uroepithelium, can be expressed simultaneously by P. mirabilis: mannose-resistant/Proteus -like (MR/P) fimbriae, P. mirabilis fimbriae (PMF), uroepithelial cell adhesin (UCA), renamed by some authors nonagglutinating fimbriae (NAF), and ambient-temperature fimbriae (ATF). Proteus mirabilis is a common cause of biofilm formation on catheter material and MR/P fimbriae are involved in this process. The considerable serious pathology caused by P. mirabilis in the urinary tract warrants the development of a prophylactic vaccine, and several studies have pointed to MR/P fimbriae as a potential target for immunization. This article reviews P. mirabilis fimbriae with regard to their participation in uropathogenesis, biofilm formation and as vaccine targets. [source] Characterization of epitopes recognized by anti- Streptococcus mutans P1 monoclonal antibodiesFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2007William P. McArthur Abstract Sequences contributing to epitopes recognized by a panel of monoclonal antibodies (mAbs) against the Streptococcus mutans surface protein P1 were delineated by Western blot and enzyme-linked immunosorbent assay using a battery of deletion constructs and recombinant polypeptides. mAbs that recognize complex discontinuous epitopes reconstituted by combining the alanine-rich and proline-rich repeat domains and varying degrees of flanking sequence were identified as well as mAbs that bound epitopes contained within contiguous segments of P1. Cross-reactivity with SspA and SspB from Streptococcus gordonii is also reported. This information enables insight into the structure and function of a streptococcal adhesin and its correlates of protection and furthers our understanding of the immunomodulatory and bacterial-adherence inhibition activities of anti-P1 mAbs. [source] Anti-adhesion therapy of bacterial diseases: prospects and problemsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2003Itzhak Ofek Abstract The alarming increase in drug-resistant bacteria makes a search for novel means of fighting bacterial infections imperative. An attractive approach is the use of agents that interfere with the ability of the bacteria to adhere to tissues of the host, since such adhesion is one of the initial stages of the infectious process. The validity of this approach has been unequivocally demonstrated in experiments performed in a wide variety of animals, from mice to monkeys, and recently also in humans. Here we review various approaches to anti-adhesion therapy, including the use of receptor and adhesin analogs, dietary constituents, sublethal concentrations of antibiotics and adhesin-based vaccines. Because anti-adhesive agents are not bactericidal, the propagation and spread of resistant strains is much less likely to occur than as a result of exposure to bactericidal agents, such as antibiotics. Anti-adhesive drugs, once developed, may, therefore, serve as a new means to fight infectious diseases. [source] Sensitivity of bacterial coaggregation to chelating agentsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 4 2000Suwimol Taweechaisupapong Abstract Coaggregation between pairs of microorganisms was found to be inhibited by chelating agents, such as acetylacetone, citrate, EDTA and carboxymethylcellulose. Assays were conducted on eight pairs of periodontopathogens and one pair consisting of Escherichia coli and Saccharomyces cerevisiae. The inhibitory effects of the chelating agents were reversible except for Actinomyces naeslundii 12104, the adhesin of which was irreversibly inactivated. Even though the bacteria possessed different kinds of adhesins, their sensitivity to chelating agents appears to be a common property. Non-toxic chelating agents, such as carboxymethylcellulose and citrate, may prove to be useful anti-adhesins. [source] Heparin-binding hemagglutinin (HBHA) of Mycobacterium leprae is expressed during infection and enhances bacterial adherence to epithelial cellsFEMS MICROBIOLOGY LETTERS, Issue 2 2009Cristiana Soares De Lima Abstract A heparin-binding hemagglutinin (HBHA) expressed on the surface of Mycobacterium tuberculosis is an antigenic protein that has been implicated in bacterial adherence to epithelial cells and systemic dissemination. In this study, the potential role of the Mycobacterium leprae HBHA (ML-HBHA) homologue in leprosy was investigated. Initially, the in vivo expression of HBHA and its association with the M. leprae cell envelope was confirmed by immunoblotting and proteomic analysis. Mycobacterium leprae recombinant HBHA (rML-HBHA) bound to a heparin,Sepharose column, and its capacity to act as an adhesin was demonstrated in experiments showing that the exogenous addition of the protein to latex beads or to M. leprae cells promotes a dramatic increase in association with epithelial cells. Finally, serum anti-HBHA immunoglobulin G levels were investigated in individuals infected with M. leprae. Altogether, our data indicate that HBHA is recognized during the course of bacterial infection in humans and may play a role in leprosy pathogenesis. [source] ica and beyond: biofilm mechanisms and regulation in Staphylococcus epidermidis and Staphylococcus aureusFEMS MICROBIOLOGY LETTERS, Issue 2 2007James P. O'Gara Abstract Recent progress in elucidating the role of the icaADBC -encoded polysaccharide intercellular adhesin (PIA) or polymeric N -acetyl-glucosamine (PNAG) in staphylococcal biofilm development has in turn contributed significantly to our understanding of the pathogenesis of device-related infections. Nevertheless, our understanding of how the ica locus and PIA/PNAG biosynthesis are regulated is far from complete and many questions remain. Moreover, beyond ica, evidence is now emerging for the existence of ica -independent biofilm mechanisms in both Staphylococcus aureus and Staphylococcus epidermidis. Teichoic acids, which are a major carbohydrate component of the S. epidermidis biofilm matrix and the major cell wall autolysin, play an important role in the primary attachment phase of biofilm development, whereas the cell surface biofilm-associated protein and accumulation-associated protein are capable of mediating intercellular accumulation. These findings raise the exciting prospect that other surface proteins, which typically function as antigenic determinants or in binding to extracellular matrix proteins, may also act as biofilm adhesins. Given the impressive array of surface proteins expressed by S. aureus and S. epidermidis, future research into their potential role in biofilm development either independent of PIA/PNAG or in cooperation with PIA/PNAG will be of particular interest. [source] The Hek outer membrane protein of Escherichia coli is an auto-aggregating adhesin and invasinFEMS MICROBIOLOGY LETTERS, Issue 2 2007Robert P. Fagan Abstract Escherichia coli is the principal gram-negative causative agent of sepsis and meningitis in neonates. The pathogenesis of meningitis due to E. coli K1 involves mucosal colonization, transcytosis of epithelial cells, survival in the blood stream and eventually invasion of the meninges. The latter two aspects have been well characterized at a molecular level in the last decade. Less is known about the early stages of pathogenesis, i.e. adhesion to and invasion of gastrointestinal cells. Here, the characterization of the Hek protein is reported, which is expressed by neonatal meningitic E. coli (NMEC) and is localized to the outer membrane. It is demonstrated that this protein can cause agglutination of red blood cells and can mediate autoaggregation. Escherichia coli expressing this protein can adhere to and invade epithelial cells. So far, this is the first outer membrane protein in NMEC to be directly implicated in epithelial cell invasion. [source] Characterization of adhesin variants in Indian isolates of enteroaggregative Escherichia coliFEMS MICROBIOLOGY LETTERS, Issue 2 2006Renu Bhardwaj Abstract Enteroaggregative Escherichia coli (EAEC) are causative agents of diarrhea, being characterized by aggregative adherence to cultured epithelial cells. In this study, phenotypic properties of EAEC were analyzed with respect to AA, hemagglutination, clump and biofilm formation, all of which are mediated by aggregative adherence fimbriae (AAF). The strains were also screened for AAF types, AAF adhesin variants and Dr adhesin by PCR. Of the three known AAF types, AAF/I and AAF/II adhesin variants were identified. An association between the AAF/adhesin genotypes and the subtypes/scores of phenotypic properties was sought and it was observed that strains harboring same adhesins displayed different subtypes/scores and vice versa. [source] Role of Mucin Lewis Status in Resistance to Helicobacter pylori Infection in Pediatric PatientsHELICOBACTER, Issue 4 2010Sara Lindén Abstract Background:,Helicobacter pylori causes gastritis, peptic ulcer and is a risk factor for adenocarcinoma and lymphoma of the stomach. Gastric mucins, carrying highly diverse carbohydrate structures, present functional binding sites for H. pylori and may play a role in pathogenesis. However, little information is available regarding gastric mucin in children with and without stomach diseases. Materials and Methods:, Expression of mucins and glycosylation was studied by immunohistochemistry on gastric biopsies from 51 children with and without H. pylori infection and/or peptic ulcer disease. Results:, In all children, MUC5AC was present in the surface epithelium and MUC6 in the glands. No MUC6 in the surface epithelium or MUC2 was detected in any section. The Leb and Lea blood group antigens were present in the surface epithelium of 80% and 29% of children, respectively. H. pylori load was higher in Leb negative children than in Leb positive individuals (mean ± SEM 17.8 ± 3.5 vs 10.8 ± 1.5; p < 0.05), but there was no correlation between Lea or Leb status and gastritis, nodularity, and gastric or duodenal ulcer (DU). Expression of sialyl-Lex was associated with H. pylori infection, and DU. Conclusions:, Mucin expression and glycosylation is similar in children and adults. However, in contrast to adults, pediatric H. pylori infection is not accompanied by aberrant expression of MUC6 or MUC2. Furthermore, the lower H. pylori density in Leb positive children indicates that H. pylori is suppressed in the presence of gastric mucins decorated with Leb, the binding site of the H. pylori BabA adhesin. [source] Four Modes of Adhesion are Used During Helicobacter pylori Binding to Human Mucins in the Oral and Gastric NichesHELICOBACTER, Issue 2 2008Sara K. Lindén Abstract Background:,Helicobacter pylori causes peptic ulcer disease and gastric cancer, and the oral cavity is likely to serve as a reservoir for this pathogen. We investigated the binding of H. pylori to the mucins covering the mucosal surfaces in the niches along the oral to gastric infection route and during gastric disease and modeled the outcome of these interactions. Materials and Methods:, A panel of seven H. pylori strains with defined binding properties was used to identify binding to human mucins from saliva, gastric juice, cardia, corpus, and antrum of healthy stomachs and of stomachs affected by gastritis at pH 7.4 and 3.0 using a microtiter-based method. Results:,H. pylori binding to mucins differed substantially with the anatomic site, mucin type, pH, gastritis status, and H. pylori strain all having effect on binding. Mucins from saliva and gastric juice displayed the most diverse binding patterns, involving four modes of H. pylori adhesion and the MUC5B, MUC7, and MUC5AC mucins as well as the salivary agglutinin. Binding occurred via the blood-group antigen-binding adhesin (BabA), the sialic acid-binding adhesin (SabA), a charge/low pH-dependent mechanism, and a novel saliva-binding adhesin. In the healthy gastric mucus layer only BabA and acid/charge affect binding to the mucins, whereas in gastritis, the BabA/Leb -dependent binding to MUC5AC remained, and SabA and low pH binding increased. Conclusions:, The four H. pylori adhesion modes binding to mucins are likely to play different roles during colonization of the oral to gastric niches and during long-term infection. [source] The Bps polysaccharide of Bordetella pertussis promotes colonization and biofilm formation in the nose by functioning as an adhesinMOLECULAR MICROBIOLOGY, Issue 6 2010Matt S. Conover Summary Many respiratory pathogens establish persistent infection or a carrier state in the human nasopharynx without overt disease symptoms but the presence of these in the lungs usually results in disease. Although the anatomy and microenvironments between nasopharynx and lungs are different, a virulence factor with an organ-specific function in the colonization of the nasopharynx is unknown. In contrast to the severity of pertussis and mortality in non-vaccinated young children, Bordetella pertussis results in milder and prolonged cough in vaccinated adolescents and adults. Individuals harbouring bacteria in the nasopharynx serve as reservoirs for intrafamilial and nosocomial transmission. We show that the Bps polysaccharide of B. pertussis is critical for initial colonization of the mouse nose and the trachea but not of the lungs. Our data reveal a biofilm lifestyle for B. pertussis in the nose and the requirement of Bps in this developmental process. Bps functions as an adhesin by promoting adherence of B. pertussis and Escherichia coli to human nasal but not to human lung epithelia. Patient serum specifically recognized Bps suggesting its expression during natural human infections. We describe the first bacterial factor that exhibits a differential role in colonization and adherence between the nasopharynx and the lungs. [source] Borrelia burgdorferi adhesins identified using in vivo phage displayMOLECULAR MICROBIOLOGY, Issue 1 2007Styliani Antonara Summary Borrelia burgdorferi, the agent of Lyme disease, disseminates from the site of deposition by Ixodes ticks to cause systemic infection. Dissemination occurs through the circulation and through tissue matrices, but the B. burgdorferi molecules that mediate interactions with the endothelium in vivo have not yet been identified. In vivo selection of filamentous phage expressing B. burgdorferi protein fragments on the phage surface identified several new candidate adhesins, and verified the activity of one adhesin that had been previously characterized in vitro. P66, a B. burgdorferi ligand for ,3 -chain integrins, OspC, a protein that is essential for the establishment of infection in mammals, and Vls, a protein that undergoes antigenic variation in the mammal, were all selected for binding to the murine endothelium in vivo. Additional B. burgdorferi proteins for which no functions have been identified, including all four members of the OspF family and BmpD, were identified as candidate adhesins. The use of in vivo phage display is one approach to the identification of adhesins in pathogenic bacteria that are not easily grown in the laboratory, or for which genetic manipulations are not straightforward. [source] The affinity of the FimH fimbrial adhesin is receptor-driven and quasi-independent of Escherichia coli pathotypesMOLECULAR MICROBIOLOGY, Issue 6 2006Julie Bouckaert Summary Type-1 fimbriae are important virulence factors for the establishment of Escherichia coli urinary tract infections. Bacterial adhesion to the high-mannosylated uroplakin Ia glycoprotein receptors of bladder epithelium is mediated by the FimH adhesin. Previous studies have attributed differences in mannose-sensitive adhesion phenotypes between faecal and uropathogenic E. coli to sequence variation in the FimH receptor-binding domain. We find that FimH variants from uropathogenic, faecal and enterohaemorrhagic isolates express the same specificities and affinities for high-mannose structures. The only exceptions are FimHs from O157 strains that carry a mutation (Asn135Lys) in the mannose-binding pocket that abolishes all binding. A high-mannose microarray shows that all substructures are bound by FimH and that the largest oligomannose is not necessarily the best binder. Affinity measurements demonstrate a strong preference towards oligomannosides exposing Man,1-3Man at their non-reducing end. Binding is further enhanced by the ,1-4-linkage to GlcNAc, where binding is 100-fold better than that of ,- d -mannose. Man,1-3Man,1-4GlcNAc, a major oligosaccharide present in the urine of ,-mannosidosis patients, thus constitutes a well-defined FimH epitope. Differences in affinities for high-mannose structures are at least 10-fold larger than differences in numbers of adherent bacteria between faecal and uropathogenic strains. Our results imply that the carbohydrate expression profile of targeted host tissues and of natural inhibitors in urine, such as Tamm-Horsfall protein, are stronger determinants of adhesion than FimH variation. [source] Analysis of the requirements for pilus biogenesis at the outer membrane usher and the function of the usher C-terminusMOLECULAR MICROBIOLOGY, Issue 2 2006Stephane Shu Kin So Summary Uropathogenic strains of Escherichia coli assemble type 1 and P pili to colonize the bladder and kidney respectively. These pili are prototype structures assembled by the chaperone/usher secretion pathway. In this pathway, a periplasmic chaperone works together with an outer membrane (OM) usher to control the folding of pilus subunits, their assembly into a pilus fibre and secretion of the fibre to the cell surface. The usher serves as the assembly and secretion platform in the OM. The usher has distinct functional domains, with the N-terminus providing the initial targeting site for chaperone,subunit complexes and the C-terminus required for subsequent stages of pilus biogenesis. In this study, we investigated the molecular interactions occurring at the usher during pilus biogenesis and the function of the usher C-terminus. We provide genetic and biochemical evidence that the usher functions as a complex in the OM and that interaction of the pilus adhesin with the usher is critical to prime the usher for pilus biogenesis. Analysis of C-terminal truncation and substitution mutants of the P pilus usher PapC demonstrated that the C-terminus is required for proper binding of chaperone,subunit complexes to the usher and plays an important role in assembly of complete pili. [source] Host collagen signal induces antigen I/II adhesin and invasin gene expression in oral Streptococcus gordoniiMOLECULAR MICROBIOLOGY, Issue 2 2003Catherine Heddle Summary Microbial interactions with host molecules, and programmed responses to host environmental stimuli, are critical for colonization and initiation of pathogenesis. Bacteria of the genus Streptococcus are primary colonizers of the human mouth. They express multiple cell-surface adhesins that bind salivary components and other oral bacteria and enable the development of polymicrobial biofilms associated with tooth decay and periodontal disease. However, the mechanisms by which streptococci invade dentine to infect the tooth pulp and periapical tissues are poorly understood. Here we show that production of the antigen I/II (AgI/II) family polypeptide adhesin and invasin SspA in Streptococcus gordonii is specifically upregulated in response to a collagen type I signal, minimally the tri-peptide Gly-Pro-Xaa (where Xaa is hydroxyproline or alanine). Increased AgI/II polypeptide expression promotes bacterial adhesion and extended growth of streptococcal cell chains along collagen type I fibrils that are characteristically found within dentinal tubules. These observations define a new model of host matrix signal-induced tissue penetration by bacteria and open the way for novel therapy opportunities for oral invasive diseases. [source] Clinical isolates of Enterococcus faecium exhibit strain-specific collagen binding mediated by Acm, a new member of the MSCRAMM familyMOLECULAR MICROBIOLOGY, Issue 6 2003Sreedhar R. Nallapareddy Summary A collagen-binding adhesin of Enterococcus faecium, Acm, was identified. Acm shows 62% similarity to the Staphylococcus aureus collagen adhesin Cna over the entire protein and is more similar to Cna (60% and 75% similarity with Cna A and B domains respectively) than to the Enterococcus faecalis collagen-binding adhesin, Ace, which shares homology with Acm only in the A domain. Despite the detection of acm in 32 out of 32 E. faecium isolates, only 11 of these (all clinical isolates, including four vancomycin-resistant endocarditis isolates and seven other isolates) exhibited binding to collagen type I (CI). Although acm from three CI-binding vancomycin-resistant E. faecium clinical isolates showed 100% identity, analysis of acm genes and their promoter regions from six non-CI-binding strains identified deletions or mutations that introduced stop codons and/or IS elements within the gene or the promoter region in five out of six strains, suggesting that the presence of an intact functional acm gene is necessary for binding of E. faecium strains to CI. Recombinant Acm A domain showed specific and concentration-dependent binding to collagen, and this protein competed with E. faecium binding to immobilized CI. Consistent with the adherence phenotype and sequence data, probing with Acm-specific IgGs purified from anti-recombinant Acm A polyclonal rabbit serum confirmed the surface expression of Acm in three out of three collagen-binding clinical isolates of E. faecium tested, but in none of the strains with a non-functional pseudo acm gene. Introduction of a functional acm gene into two non-CI-binding natural acm mutant strains conferred a CI-binding phenotype, further confirming that native Acm is sufficient for the binding of E. faecium to CI. These results demonstrate that acm, which encodes a potential virulence factor, is functional only in certain infection-derived clinical isolates of E. faecium, and suggest that Acm is the primary adhesin responsible for the ability of E. faecium to bind collagen. [source] Differential binding to and biofilm formation on, HEp-2 cells by Salmonella enterica Serovar Typhimurium is dependent upon allelic variation in the fimH gene of the fim gene clusterMOLECULAR MICROBIOLOGY, Issue 5 2002Jennifer D. Boddicker Summary Type 1 fimbria-mediated adherence to HEp-2 cells by two strains of Salmonella enterica serovar Typhimurium was found to be different. Although both strains exhibited a strong mannose-sensitive haemagglutination reaction with guinea pig erythrocytes, characteristic of the expression of type 1 fimbriae, only one of the strains adhered in large numbers to HEp-2 cells. Characterization of the fimH genes, encoding the fimbrial adhesins, indicated two allelic variants. Using fimH mutants of the two strains it was possible to demonstrate that binding to HEp-2 cells was associated with the presence of one of the alleles regardless of the host strain. Therefore, this differential binding was not a function of the type I fimbrial shaft or the presence of other types of fimbriae produced by one strain but not the other. These observations may explain the differences in HEp-2 binding by type 1 fimbriate strains of Salmonella previously reported by several groups. Also, our studies demonstrate that the FimH adhesin can influence the efficiency of biofilm formation on HEp-2 cells using once-flow-through continuous culture conditions. The formation of biofilms on eukaryotic cells using this procedure is more likely to represent those conditions found in the intestinal tract than conditions using batch culture techniques to investigate adherence and biofilm formation. Indeed, the increased efficiency of biofilm formation in the murine intestinal tract confirmed the role of one of the fimH alleles in this process. [source] Beta-helix model for the filamentous haemagglutinin adhesin of Bordetella pertussis and related bacterial secretory proteinsMOLECULAR MICROBIOLOGY, Issue 2 2001Andrey V. Kajava Bordetella pertussis establishes infection by attaching to epithelial cells of the respiratory tract. One of its adhesins is filamentous haemagglutinin (FHA), a 500-Å-long secreted protein that is rich in ,-structure and contains two regions, R1 and R2, of tandem 19-residue repeats. Two models have been proposed in which the central shaft is (i) a hairpin made up of a pairing of two long antiparallel ,-sheets; or (ii) a ,-helix in which the polypeptide chain is coiled to form three long parallel ,-sheets. We have analysed a truncated variant of FHA by electron microscopy (negative staining, shadowing and scanning transmission electron microscopy of unstained specimens): these observations support the latter model. Further support comes from detailed sequence analysis and molecular modelling studies. We applied a profile search method to the sequences adjacent to and between R1 and R2 and found additional ,covert' copies of the same motifs that may be recognized in overt form in the R1 and R2 sequence repeats. Their total number is sufficient to support the tenet of the ,-helix model that the shaft domain , a 350 Å rod , should consist of a continuous run of these motifs, apart from loop inserts. The N-terminus, which does not contain such repeats, was found to be weakly homologous to cyclodextrin transferase, a protein of known immunoglobulin-like structure. Drawing on crystal structures of known ,-helical proteins, we developed structural models of the coil motifs putatively formed by the R1 and R2 repeats. Finally, we applied the same profile search method to the sequence database and found several other proteins , all large secreted proteins of bacterial provenance , that have similar repeats and probably also similar structures. [source] Expression of the ,-adhesin part of HRgpA in Sprague Dawley rats induces a specific antibody responseMOLECULAR ORAL MICROBIOLOGY, Issue 2 2004K. S. Vågnes The ,-adhesin part of the Porphyromonas gingivalis W50 (ATCC 53978) protease HRgpA was cloned in an eukaryotic expression vector and expressed in COS-7 cells. The monoclonal antibody MAb (61BG1.3), specific for the hemagglutinating domain of ,-adhesin, recognized the expressed ,-adhesin in the transfected cells both by immunoblot and immunofluorescence. Sprague Dawley rats were immunized intramuscularly with ,-adhesin encoding expression plasmid and expression plasmid without ,-adhesin insert. Skeletal muscle tissue at the site of immunization in the ,-adhesin immunized animals was shown to express this protein. The immunization induced a ,-adhesin-specific antibody response. Sera from the immunized animals were tested for hemagglutination inhibiting activity. Due to high natural inhibiting activity in all rat sera tested, no increased hemagglutination inhibition was detected in sera from the ,-adhesin immunized animals. [source] Structure of laminin-binding adhesin (Lmb) from Streptococcus agalactiaeACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2009Preethi Ragunathan Adhesion/invasion of pathogenic bacteria is a critical step in infection and is mediated by surface-exposed proteins termed adhesins. The crystal structure of recombinant Lmb, a laminin-binding adhesin from Streptococcus agalactiae, has been determined at 2.5,Å resolution. Based on sequence and structural homology, Lmb was placed into the cluster 9 family of the ABC (ATP-binding cassette) transport system. The structural organization of Lmb closely resembles that of ABC-type solute-binding proteins (SBPs), in which two structurally related globular domains interact with each other to form a metal-binding cavity at the interface. The bound zinc in Lmb is tetrahedrally coordinated by three histidines and a glutamate from both domains. A comparison of Lmb with other metal transporters revealed an interesting feature of the dimerization of molecules in the crystallographic asymmetric unit in all zinc-binding transporters. A closer comparison of Lmb with the zinc-binding ZnuA from Escherichia coli and Synechocystis 6803 suggested that Lmb might undergo a unique structural rearrangement upon metal binding and release. The crystal structure of Lmb provides an impetus for further investigations into the molecular basis of laminin binding by human pathogens. Being ubiquitous in all serotypes of group B streptococcus (GBS), the structure of Lmb may direct the development of an efficient vaccine. [source] Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of the collagen-binding region of RspB from Erysipelothrix rhusiopathiaeACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 2 2010Aribam Swarmistha Devi RspB is a surface adhesin of Erysipelothrix rhusiopathiae. A recombinant form of the collagen-binding region of this protein, RspB(31,348), has been overexpressed in Escherichia coli in native and selenomethionine-derivative forms and purified using affinity and gel-permeation chromatography. Thin plate-like crystals were obtained by the hanging-drop vapour-diffusion method using the same condition for both forms. The native crystals diffracted to a resolution of 2.5,Å using an in-house X-ray source, while the selenomethionine-derivative crystals diffracted to a resolution of 2.2,Å using synchrotron radiation. The crystals belonged to the monoclinic space group P21, with unit-cell parameters a = 46.19, b = 66.65, c = 101.72,Å, , = 94.11°. [source] A crystallizable form of the Streptococcus gordonii surface antigen SspB C-domain obtained by limited proteolysisACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 7 2009Nina Forsgren SspB is a 1500-residue adhesin expressed on the surface of the oral bacterium Streptococcus gordonii. Its interaction with other bacteria and host cells initiates the development of dental plaque. The full-length C-terminal domain of SspB was cloned, overexpressed in Escherichia coli and purified. However, the protein could not be crystallized. Limited proteolysis of the full-length C-domain identified a core fragment. The proteolysis product was cloned, expressed and purified. The protein was crystallized using the hanging-drop vapour-diffusion method. X-ray data were collected and processed to a maximum resolution of 2.1,Å with 96.4% completeness. The crystals belonged to space group P21, with one molecule in the asymmetric unit, a solvent content of 33.7% and a corresponding Matthews coefficient of 1.85,Å3,Da,1. [source] Infection of human mucosal tissue by Pseudomonas aeruginosa requires sequential and mutually dependent virulence factors and a novel pilus-associated adhesinCELLULAR MICROBIOLOGY, Issue 8 2010Ryan W. Heiniger Summary Tissue damage predisposes humans to life-threatening disseminating infection by the opportunistic pathogen Pseudomonas aeruginosa. Bacterial adherence to host tissue is a critical first step in this infection process. It is well established that P. aeruginosa attachment to host cells involves type IV pili (TFP), which are retractile surface fibres. The molecular details of attachment and the identity of the bacterial adhesin and host receptor remain controversial. Using a mucosal epithelium model system derived from primary human tissue, we show that the pilus-associated protein PilY1 is required for bacterial adherence. We establish that P. aeruginosa preferentially binds to exposed basolateral host cell surfaces, providing a mechanistic explanation for opportunistic infection of damaged tissue. Further, we demonstrate that invasion and fulminant infection of intact host tissue requires the coordinated and mutually dependent action of multiple bacterial factors, including pilus fibre retraction and the host cell intoxication system, termed type III secretion. Our findings offer new and important insights into the complex interactions between a pathogen and its human host and provide compelling evidence that PilY1 serves as the principal P. aeruginosa adhesin for human tissue and that it specifically recognizes a host receptor localized or enriched on basolateral epithelial cell surfaces. [source] Salmonella Pathogenicity Island 4 encodes a giant non-fimbrial adhesin and the cognate type 1 secretion systemCELLULAR MICROBIOLOGY, Issue 7 2007Roman G. Gerlach Summary Pathogenicity Islands play a major role in the pathogenesis of infections by Salmonella enterica. The molecular function of Salmonella Pathogenicity Island 4 (SPI4) is largely unknown, but recent work indicated a role of SPI4 for Salmonella pathogenesis in certain animal models. We analysed the virulence functions of SPI4 and observed that SPI4 is contributing to intestinal inflammation in a mouse model. On a cellular level, SPI4 mediates adhesion to epithelial cells. We demonstrate the function of SPI4-encoded proteins as a type I secretion system (T1SS) and identify SiiE as the substrate protein of the T1SS. SiiE is secreted into the culture medium but mediates contact-dependent adhesion to epithelial cell surfaces. SiiE is a very large non-fimbrial adhesin of 600 kDa and consists of 53 repeats of Ig domains. Our study describes the first T1SS-secreted protein that functions as a non-fimbrial adhesin in binding to eukaryotic cells. The SPI4-encoded T1SS and SiiE might functionally resemble the type I fimbrial adhesins. [source] Interaction of cblA/adhesin-positive Burkholderia cepacia with squamous epitheliumCELLULAR MICROBIOLOGY, Issue 2 2002Umadevi Sajjan Summary A highly transmissible strain of Burkholderia cepacia from genomovar III carries the cable pilin gene, expresses the 22 kDa adhesin (cblA+ve/Adh +ve), binds to cytokeratin 13 (CK13) and is invasive. CK13 is expressed abundantly in the airway epithelia of cystic fibrosis (CF) patients. We have now investigated whether binding of cblA+ve/Adh +ve B. cepacia to CK13 potentiates bacterial invasion and epithelial damage using bronchial epithelial cell cultures differentiated into either squamous (CK13-enriched) or mucociliary (CK13-deficient) epithelia. Three different B. cepacia isolates (cblA+ve/Adh +ve, cblA+ve/Adh ,ve and cblA,ve/Adh ,ve) showed minimal binding to mucociliary cultures, and did not invade or cause cell damage. In contrast, the cblA+ve/Adh +ve isolate, but not others, bound to CK13-expressing cells in squamous cultures, caused cytotoxicity and stimulated IL-8 release within 2 h. By 24 h, this isolate invaded and migrated across the squamous culture, causing moderate to severe epithelial damage. A specific antiadhesin antibody, which blocked the initial binding of the cblA+ve/Adh +ve isolate to CK13, significantly inhibited all the pathologic effects. Transmission electron microscopy of squamous cultures incubated with the cblA+ve/Adh +ve isolate, revealed bacteria on the surface surrounded by filopodia by 2 h, and within the cells in membrane-bound vesicles by 24 h. Bacteria were also observed free in the cytoplasm, surrounded by intermediate filaments containing CK13. These findings suggest that binding of B. cepacia to CK13 is an important initial event and that it promotes bacterial invasion and epithelial damage. [source] Antibody response to Candida albicans cell wall antigensFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2004José L López-Ribot Abstract The cell wall of Candida albicans is not only the structure where many essential biological functions reside but is also a significant source of candidal antigens. The major cell wall components that elicit a response from the host immune system are proteins and glycoproteins, the latter being predominantly mannoproteins. Both carbohydrate and protein moieties are able to trigger immune responses. Proteins and glycoproteins exposed at the most external layers of the wall structure are involved in several types of interactions of fungal cells with the exocellular environment. Thus, coating of fungal cells with host antibodies has the potential to profoundly influence the host,parasite interaction by affecting antibody-mediated functions such as opsonin-enhanced phagocytosis and blocking the binding activity of fungal adhesins to host ligands. In this review we examine various members of the protein and glycoprotein fraction of the C. albicans cell wall that elicit an antibody response in vivo. Some of the studies demonstrate that certain cell wall antigens and anti-cell wall antibodies may be the basis for developing specific and sensitive serologic tests for the diagnosis of candidiasis, particularly the disseminated form. In addition, recent studies have focused on the potential of antibodies against the cell wall protein determinants in protecting the host against infection. Hence, a better understanding of the humoral response triggered by the cell wall antigens of C. albicans may provide the basis for the development of (i) effective procedures for the serodiagnosis of disseminated candidiasis, and (ii) novel prophylactic (vaccination) and therapeutic strategies to control this type of infections. [source] Sensitivity of bacterial coaggregation to chelating agentsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 4 2000Suwimol Taweechaisupapong Abstract Coaggregation between pairs of microorganisms was found to be inhibited by chelating agents, such as acetylacetone, citrate, EDTA and carboxymethylcellulose. Assays were conducted on eight pairs of periodontopathogens and one pair consisting of Escherichia coli and Saccharomyces cerevisiae. The inhibitory effects of the chelating agents were reversible except for Actinomyces naeslundii 12104, the adhesin of which was irreversibly inactivated. Even though the bacteria possessed different kinds of adhesins, their sensitivity to chelating agents appears to be a common property. Non-toxic chelating agents, such as carboxymethylcellulose and citrate, may prove to be useful anti-adhesins. [source] ica and beyond: biofilm mechanisms and regulation in Staphylococcus epidermidis and Staphylococcus aureusFEMS MICROBIOLOGY LETTERS, Issue 2 2007James P. O'Gara Abstract Recent progress in elucidating the role of the icaADBC -encoded polysaccharide intercellular adhesin (PIA) or polymeric N -acetyl-glucosamine (PNAG) in staphylococcal biofilm development has in turn contributed significantly to our understanding of the pathogenesis of device-related infections. Nevertheless, our understanding of how the ica locus and PIA/PNAG biosynthesis are regulated is far from complete and many questions remain. Moreover, beyond ica, evidence is now emerging for the existence of ica -independent biofilm mechanisms in both Staphylococcus aureus and Staphylococcus epidermidis. Teichoic acids, which are a major carbohydrate component of the S. epidermidis biofilm matrix and the major cell wall autolysin, play an important role in the primary attachment phase of biofilm development, whereas the cell surface biofilm-associated protein and accumulation-associated protein are capable of mediating intercellular accumulation. These findings raise the exciting prospect that other surface proteins, which typically function as antigenic determinants or in binding to extracellular matrix proteins, may also act as biofilm adhesins. Given the impressive array of surface proteins expressed by S. aureus and S. epidermidis, future research into their potential role in biofilm development either independent of PIA/PNAG or in cooperation with PIA/PNAG will be of particular interest. [source] Pasteurella multocida pathogenesis: 125 years after PasteurFEMS MICROBIOLOGY LETTERS, Issue 1 2006Marina Harper Abstract Pasteurella multocida was first shown to be the causative agent of fowl cholera by Louis Pasteur in 1881. Since then, this Gram-negative bacterium has been identified as the causative agent of many other economically important diseases in a wide range of hosts. The mechanisms by which these bacteria can invade the mucosa, evade innate immunity and cause systemic disease are slowly being elucidated. Key virulence factors identified to date include capsule and lipopolysaccharide. The capsule is clearly involved in bacterial avoidance of phagocytosis and resistance to complement, while complete lipopolysaccharide is critical for bacterial survival in the host. A number of other virulence factors have been identified by both directed and random mutagenesis, including Pasteurella multocida toxin (PMT), putative surface adhesins and iron acquisition proteins. However, it is likely that many key virulence factors are yet to be identified, including those required for initial attachment and invasion of host cells and for persistence in a relatively nutrient poor and hostile environment. [source] | ||||||||||||||||