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Bacterial Surface (bacterial + surface)
Terms modified by Bacterial Surface Selected AbstractsExported proteins in probiotic bacteria: adhesion to intestinal surfaces, host immunomodulation and molecular cross-talking with the hostFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2008Borja Sánchez Abstract The group of exported proteins of a bacterium are those proteins that are sorted from the cytoplasm to the bacterial surface or to the surroundings of the microorganism. In probiotic bacteria, these proteins are of special relevance because they might determine important traits such as adhesion to intestinal surfaces and molecular cross-talking with the host. Current knowledge about the presence and biological relevance of exported proteins produced by the main genera of probiotic bacteria in the gastrointestinal environment is reviewed in this minireview. As will be seen, some of these proteins are involved in host adhesion or are able to modify certain signalization pathways within host cells, whereas others are important for the physiology of probiotic bacteria in the gastrointestinal tract. [source] Proper expression of the O-antigen of lipopolysaccharide is essential for the virulence of Yersinia enterocolitica O:8 in experimental oral infection of rabbitsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2003H Najdenski Abstract The O-antigen of lipopolysaccharide (LPS) is required for virulence in Yersinia enterocolitica serotype O:8. Here we evaluated the importance of controlling the O-antigen biosynthesis using an in vivo rabbit model of infection. Y. enterocolitica O:8 wild-type strain was compared to three mutants differing in the O-antigen phenotype: (i) the rough strain completely devoid of the O-antigen, (ii) the wzy strain that lacks the O-antigen polymerase (Wzy protein) and expresses LPS with only one repeat unit, and (iii) the wzz strain that lacks the O-antigen chain length determinant (Wzz protein) and expresses LPS without modal distribution of O-antigen chain lengths. The most attenuated strain was the wzz mutant. The wzz bacteria were cleared from the tissues by day 30, the blood parameters were least dramatic and histologically only immunomorphological findings were seen. The level of attenuation of the rough and the wzy strain bacteria was between the wild-type and the wzz strain. Wild-type bacteria were highly resistant to killing by polymorphonuclear leukocytes, the wzz strain bacteria were most sensitive and the rough and wzy strain bacteria were intermediate resistant. These results clearly demonstrated that the presence of O-antigen on the bacterial surface is not alone sufficient for full virulence, but also there is a requirement for its controlled chain length. [source] Phage-selected lipopolysaccharide mutants of Pectobacterium atrosepticum exhibit different impacts on virulenceJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2010T.J. Evans Abstract Aims:, To positively select Pectobacterium atrosepticum (Pa) mutants with cell surface defects and to assess the impact of these mutations on phytopathogenesis. Methods and Results:, Several phages were isolated from treated sewage effluent and were found to require bacterial lipopolysaccharide (LPS) for infection. Two strains with distinct mutations in LPS were obtained by transposon mutagenesis. Along with a third LPS mutant, these strains were characterized with respect to various virulence-associated phenotypes, including growth rate, motility and exoenzyme production, demonstrating that LPS mutations are pleiotropic. Two of the strains were deficient in the synthesis of the O-antigen portion of LPS, and both were less virulent than the wild type. A waaJ mutant, which has severe defects in LPS biosynthesis, was dramatically impaired in potato tuber rot assays. The infectivity of these novel phages on 32 additional strains of Pa was tested, showing that most Pa isolates were sensitive to the LPS-dependent phages. Conclusions:, Native LPS is crucial for optimal growth, survival and virulence of Pa in vivo, but simultaneously renders such strains susceptible to phage infection. Significance and Impact of the Study:, This work demonstrates the power of phages to select and identify the virulence determinants on the bacterial surface, and as potential biocontrol agents for Pa infections. [source] Effect of bile on the lipid composition and surface properties of bifidobacteriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2002A. Gómez Zavaglia Aim: The changes produced on the bacterial surface of Bifidobacteria cells when they are grown in bile were compared with those provoked by bile added to bacteria grown in the absence of bile. Methods and Results: The adhesive properties, the zeta potential and the lipid composition of Bifidobacterial strains, isolated from human faeces and grown in MRS medium, were determined. Bacteria grown in MRS with bile showed a loss of adherence and autoaggregation in correlation with a decrease in the surface hydrophobicity in comparison to those grown in MRS without bile, concomitant with the absence of two glycolipids, the increase of sugar content and minor changes in fatty acid composition. The surface changes caused by bile shock on bacteria grown in bile-free medium were much less pronounced and, in addition, no effect on the lipid composition was apparent. Conclusions: The comparison of the results indicates that bile action on surface properties is related to metabolic changes. Significance and Impact of the Study: Long-term exposure of bacteria to bile may cause metabolic changes affecting their adhesive properties irreversibly. This may be taken as a criterion to define the probiotic properties of different strains. [source] Sialidase of Streptococcus intermedius: a putative virulence factor modifying sugar chainsMICROBIOLOGY AND IMMUNOLOGY, Issue 10 2010Ayuko Takao ABSTRACT A sialidase gene of Streptococcus intermedius was cloned. It was most similar to nanA, a major sialidase gene in Streptococcus pneumoniae, and was expressed in Escherichia coli. Since the gene-knockout S. intermedius strain lost detectable sialidase activity, the gene might code, either solely or mainly, the glycosidase in the bacterial genome. Polymerase chain reaction using the primers for the nanA homologue in S. intermedius (described as nanA below) showed that this sialidase gene was commonly distributed within the isolates of S. intermedius, but not found in the strains of other species among the anginosus group. In biofilm formation assay under cultivation with mucin, the nanA -deleted S. intermedius maintained the amount of biofilm for 72 hr, while that of the parent strain decreased during incubation from 24 to 72 hr. Since sialidase activity in the parent strain increased during that time period, sialidase might contribute to the degradation of biofilm under sialic acid-rich conditions. When S. intermedius was added into the HepG2 hepatoma culture, the calculated disassociation constant (Kd) of EDTA-releasable bacterial adhesion to the cells was higher in the nanA -deleted strain than in the parent. Furthermore, the rate constant, assuming endocytosis of the bacterium mediated by ASGP-R in HepG2 cells, seemed to be increased by sialidase pretreatment of the bacterial cells before addition to the cell culture. According to the results, modification of sugar chains by sialidase on the bacterial surface and in the surrounding environment might influence both bacterial interaction and host,bacterial interaction in S. intermedius. [source] Housekeeping sortase facilitates the cell wall anchoring of pilus polymers in Corynebacterium diphtheriaeMOLECULAR MICROBIOLOGY, Issue 4 2007Anu Swaminathan Summary Many surface proteins in Gram-positive bacteria are covalently linked to the cell wall through a transpeptidation reaction catalysed by the enzyme sortase. Corynebacterium diphtheriae encodes six sortases, five of which are devoted to the assembly of three distinct types of pilus fibres , SrtA for the SpaA-type pilus, SrtB/SrtC for the SpaD-type pilus, and SrtD/SrtE for the SpaH-type pilus. We demonstrate here the function of SrtF, the so-called housekeeping sortase, in the cell wall anchoring of pili. We show that a multiple deletion mutant strain expressing only SrtA secretes a large portion of SpaA polymers into the culture medium, with concomitant decrease in the cell wall-linked pili. The same phenotype is observed with the mutant that is missing SrtF alone. By contrast, a strain that expresses only SrtF displays surface-linked pilins but no polymers. Therefore, SrtF can catalyse the cell wall anchoring of pilin monomers as well as pili, but it does not polymerize pilins. We show that SrtA and SrtF together generate wild-type levels of the SpaA-type pilus on the bacterial surface. Furthermore, by regulating the expression of SpaA in the cell, we demonstrate that the SrtF function becomes critical when the SpaA level is sufficiently high. Together, these findings provide key evidence for a two-stage model of pilus assembly: pilins are first polymerized by a pilus-specific sortase, and the resulting fibre is then attached to the cell wall by either the cognate sortase or the housekeeping sortase. [source] Adaptation of the Lyme disease spirochaete to the mammalian host environment results in enhanced glycosaminoglycan and host cell bindingMOLECULAR MICROBIOLOGY, Issue 5 2003Nikhat Parveen Summary The Lyme disease spirochaete, Borrelia burgdorferi, is transmitted to mammals by Ixodes ticks and can infect multiple tissues. Host cell attachment may be critical for tissue colonization, and B. burgdorferi cultivated in vitro recognizes heparin- and dermatan sulphate-related glycosaminoglycans (GAGs) on the surface of mammalian cells. To determine whether growth of the spirochaete in the mammalian host alters GAG binding, we assessed the cell attachment activities of B. burgdorferi grown in vitro or in dialysis membrane chambers implanted intraperitoneally in rats. Host-adapted B. burgdorferi exhibited approximately threefold better binding to purified heparin and dermatan sulphate and to GAGs expressed on the surface of cultured endothelial cells. Three B. burgdorferi surface proteins, Bgp, DbpA and DbpB, have been demonstrated previously to bind to GAGs or to GAG-containing molecules, and we show here that recombinant derivatives of each of these proteins were able to bind to purified heparin and dermatan sulphate. Immunofluorescent staining of in vitro -cultivated or host-adapted spirochaetes revealed that DbpA and DbpB were present on the bacterial surface at higher levels after host adaptation. Recombinant Bgp, DbpA and DbpB each partially inhibited attachment of host-adapted B. burgdorferi to cultured mammalian cells, consistent with the hypothesis that these proteins may promote attachment of B. burgdorferi during growth in the mammalian host. Nevertheless, the partial nature of this inhibition suggests that multiple pathways promote mammalian cell attachment by B. burgdorferi in vivo. Given the observed increase in cell attachment activity upon growth in the mammalian host, analysis of host-adapted bacteria will facilitate identification of the cell binding pathways used in vivo. [source] Mechanism of association of adenylate cyclase toxin with the surface of Bordetella pertussis: a role for toxin,filamentous haemagglutinin interactionMOLECULAR MICROBIOLOGY, Issue 6 2002Franca R. Zaretzky Summary Adenylate cyclase (AC) toxin from Bordetella per-tussis is unusual in that, unlike most other members of the repeats-in-toxin family that are released into the extracellular milieu, it remains associated with the bacterial surface. In this study, we investigated the nature of the association of this toxin with the surface of B. pertussis. AC toxin was extracted from crude outer membrane preparations of B. pertussis with 8 M urea, but only partially with alkaline sodium carbonate and not at all with octylglucoside, suggesting that denaturation of the toxin is necessary for its removal from the membrane. B. pertussis mutants lacking filamentous haemagglutinin (FHA) released significantly more AC toxin into the medium, and AC toxin association with the bacterial surface was partially restored by expression of FHA from a plasmid, suggesting a role for FHA in surface retention of AC toxin. AC toxin distribution was unaffected by the absence of pertactin, or full-length lipopolysaccharide, or a defect in secretion of pertussis toxin. Using overlay and immunoprecipitation, we found that a direct physical association can occur between AC toxin and FHA. Combined, these findings suggest that FHA may play a role in AC toxin retention on the surface of B. pertussis and raise the possibility of an involvement of adherence mediated by FHA in delivery of AC toxin from the bacterium to the target cell. [source] Towards the structure of the C-terminal part of the S-layer protein SbsCACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 10 2009Markus Kroutil The S-layer protein SbsC from Geobacillus stearothermophilus ATCC 12980 is the most prevalent single protein produced by the bacterium and covers the complete bacterial surface in the form of a two-dimensional crystalline monolayer. In order to elucidate the structural features of the assembly domains, several N-terminally truncated fragments of SbsC have been crystallized. Crystals obtained from recombinant fragments showed anisotropic diffraction to a maximum of 3.5,Ĺ resolution using synchrotron radiation. The best diffracting crystals were obtained from rSbsC(755,1099), an unintentional in situ proteolytic degradation product of rSbsC(447,1099). Crystals were obtained in two different space groups, P21 and P41212, and diffracted to 2.6 and 3,Ĺ resolution, respectively. Native and heavy-atom derivative data have been collected. The structure of the C-terminal part will yield atomic resolution information for the domains that are crucial for the assembly of the two-dimensional lattice. [source] Crystallization of human complement component C3b in the presence of a staphylococcal complement-inhibitor protein (SCIN)ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 5 2009Brandon L. Garcia Staphylococcus aureus secretes a number of small proteins that effectively attenuate the human innate immune response. Among these, the staphylococcal complement-inhibitor protein (SCIN) disrupts the function of the complement component 3 (C3) convertase that is initiated through either the classical or the alternative pathway and thereby prevents amplification of the complement response on the bacterial surface. Recent studies have shown that SCIN may affect the activities of the C3 convertase by binding in an equimolar fashion to C3b, which is itself an integral although non-enzymatic component of the convertase. In order to better understand the nature of the C3b,SCIN interaction, the hanging-drop vapor-diffusion technique was used to crystallize human C3b in the presence of a recombinant form of SCIN. These crystals diffracted synchrotron X-rays to approximately 6,Ĺ Bragg spacing and grew in a primitive tetragonal space group (P41212 or P43212; unit-cell parameters a = b = 128.03, c = 468.59,Ĺ). Cell-content analysis of these crystals was consistent with the presence of either two 1:1 complexes or a single 2:2 assembly in the asymmetric unit, both of which correspond to a solvent content of 51.9%. By making use of these crystals, solution of the C3b,SCIN structure should further our understanding of complement inhibition and immune evasion by this pathogen. [source] Presentation of functional organophosphorus hydrolase fusions on the surface of Escherichia coli by the AIDA-I autotransporter pathwayBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2008Chaokun Li Abstract We report, the surface presentation of organophosphorus hydrolase (OPH) and green fluorescent protein (GFP) fusions by employing the adhesin-involved-in-diffuse-adherence (AIDA-I) translocator domain as a transporter and anchoring motif. The surface location of the OPH,GFP fusion protein was confirmed by immunofluorescence microscopy, and protease accessibility, followed by Western blotting analysis. The investigation of growth kinetics and stability of resting cultures showed that the presence of the AIDA-I translocator domain in the outer membrane neither inhibits cell growth nor affects cell viability. Furthermore, the surface-exposed OPH,GFP was shown to have enzymatic activity and a functional fluorescence moiety. These results suggest that AIDA-I autotransporter is a useful tool to present heterologous macromolecule passenger proteins on the bacterial surface. Our strategy of linking GFP to OPH and the possibility to employ various bacterial species as host has enormous potential for enhancing field use. Biotechnol. Bioeng. 2008;99: 485,490. © 2007 Wiley Periodicals, Inc. [source] Evidence for involvement of peptidoglycan in the triggering of an oxidative burst by Listeria monocytogenes in phagocytesCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 1 2005K. A. Remer Summary We have shown previously that in listeric encephalitis of cattle and rats, nitrotyrosine was produced in microabscesses, implying that both superoxide anion (O2,) and nitric oxide (NO) are present and react with each other. Evidence of local synthesis of NO by macrophages was provided, but the source of O2, remained unknown. Here we have examined whether phagocytes exposed to viable and heat-killed Listeria monocytogenes (LM,) produce O2, and, if so, whether this results from direct interaction of phagocytes with the bacterial surface of L. monocytogenes or whether prior opsonization is required. Using lucigenin-enhanced chemiluminescence (LCL) for the measurement of O2,, we show that LM, induces an oxidative burst in human neutrophils, monocytes and monocyte-derived macrophages (M,). Viability is not required, and opsonization by antibodies and/or complement does not enhance the LCL signal. As Toll-like receptors (TLR) were shown recently to mediate an oxidative burst, TLR agonists representative for pathogen-associated molecular patterns (PAMPs) were tested for their ability to elicit an oxidative burst. These included lipoteichoic acid (LTA), bacterial peptidoglycan (PGN), recombinant flagellin, CpG-containing DNA and double-stranded RNA. Only PGN and flagellin consistently elicited an LCL signal resembling that induced by LM, with regard to the kinetics and cell spectrum stimulated. However, flagellin was unlikely to be responsible for the LM,-mediated burst, as a flagellin-deficient mutant showed no decrease in LCL. We therefore assume that in LM,, core PGN acts as a PAMP and directly induces an oxidative burst in all phagocyte populations. We conclude that in cerebral lesions superoxide anion is generated locally by phagocytes recognizing bacterial PGN. [source] Fluorene and phenanthrene uptake by Pseudomonas putida ATCC 17514: Kinetics and physiological aspectsBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2005Ana C. Rodrigues Abstract Pseudomonas putida ATCC 17514 was used as a model strain to investigate the characteristics of bacterial growth in the presence of solid fluorene and phenanthrene. Despite the lower water-solubility of phenanthrene, P. putida degraded this polycyclic aromatic hydrocarbon (PAH) at a maximum observed rate of 1.4 ± 0.1 mg L,1 h,1, higher than the apparent degradation rate of fluorene, 0.8 ± 0.07 mg L,1 h,1. The role of physiological processes on the biodegradation of these PAHs was analyzed and two different uptake strategies were identified. Zeta potential measurements revealed that phenanthrene-grown cells were slightly more negatively charged (,57.5 ± 4.7 mV) than fluorene-grown cells (,51.6 ± 4.9 mV), but much more negatively charged than glucose-grown cells (,26.8 ± 3.3 mV), suggesting that the PAH substrate induced modifications on the physical properties of bacterial surfaces. Furthermore, protein-to-exopolysaccharide ratios detected during bacterial growth on phenanthrene were typical of biofilms developed under physicochemical stress conditions, caused by the presence of sparingly water-soluble chemicals as the sole carbon and energy source for growth, the maximum value for TP/EPS during growth on phenanthrene (1.9) being lower than the one obtained with fluorene (5.5). Finally, confocal laser microscopy observations using a gfp -labeled derivative strain revealed that, in the presence of phenanthrene, P. putida::gfp cells formed a biofilm on accessible crystal surfaces, whereas in the presence of fluorene the strain grew randomly between the crystal clusters. The results showed that P. putida was able to overcome the lower aqueous solubility of phenanthrene by adhering to the solid PAH throughout the production of extracellular polymeric substances, thus promoting the availability and uptake of such a hydrophobic compound. © 2005 Wiley Periodicals, Inc. [source] Microbial Surfaces Investigated Using Atomic Force MicroscopyBIOTECHNOLOGY PROGRESS, Issue 6 2004Anastassia V. Bolshakova This paper is dedicated to atomic force microscopy (AFM) as a progressive tool for imaging bacterial surfaces and probing their properties. The description of the technique is complemented by the explanation of the methodapos;s artifacts typical, in particular, for the imaging of bacterial cells. Sample preparation techniques are summarized in a separate section. Special attention is paid to the differences in imaging of Gram-positive and Gram-negative bacteria. Probing of mechanical properties, including elastic modulus, fragility, and adhesion of the cell walls is emphasized. The advantages of AFM in the studies of real-time cellular dynamical processes are illustrated by the experiment with the germination of spores. [source] | |||||||||||||