首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Clumping of Staphylococcal aureus was observed in the presence of fibrinogen as well as fibronectin. In order to elucidate the mechanism of this clumping, binding of radiolabelled fibrinogen and fibronectin to S. aureus cultures was studied. Cultures of S. aureus reacted with 125I-labelled fibrinogen as well as fibronectin. The binding of labelled fibrinogen to S. aureus could be completely inhibited by unlabelled fibronectin, whereas the binding of labelled fibronectin was only partially inhibited by unlabelled fibrinogen. This suggested an interaction of fibronectin with clumping factor which is the binding protein for fibrinogen in staphylococci. The clumping factor was purified from S. aureus strain K 807 by affinity chromatography on fibrinogen-Sepharose followed by HPLC. The purified clumping factor inhibited the binding of fibrinogen and fibronectin to staphylococci. In western blots the purified clumping factor reacted with fibrinogen as well as fibronectin. Thus, the direct interaction of clumping factor with fibronectin might be responsible for the clumping of staphylococci in fibrinogen depleted plasma or serum.  相似文献   

2.
Alterations in the amount of fibronectin and in the number of its receptors during myoblast differentiation of chicken embryo were investigated. The amount of fibronectin in the cell surface pool as measured by immunoblotting decreased during myogenesis To identify and characterize the fibronectin receptors on the myoblasts, the interactions of the 28,000 dalton (28 kDa) amino terminal fragment and 85,000 dalton (85 kDa) cell-binding fragment of fibronectin with my-oblasts were examined. The binding of the 28 kDa fragment was found to be time-dependent and reached a maximum level within 60 min. The unlabeled 28 kDa fragment inhibited the binding of the radioiodinated 28 kDa fragment, whereas the unlabeled 85 kDa fragment and antibody to integrin did not inhibit it, suggesting that the 28 kDa fragment interacts with the matrix assembly receptors but not with the cell adhesion receptors. There was a single class of 3.4 × 105 binding sites per cell with an apparent dissociation constant of 1.4 × 10?7 M on 30 hr old myoblasts. The specific binding of the radioiodinated 28 kDa fragment to myoblasts decreased as the fusion proceeded. This decrease of binding was consistent with the decrease in the amount of fibronectin. Furthermore, the levels of fibronectin and binding of the radioiodinated 28 kDa fragment in the fusion-blocked myoblasts by EGTA treatment appeared to remain constant. These results suggest that the decrease and/or loss of fibronectin during myoblast fusion is closely correlated with the alteration of fibronectin receptors and with the fusion of myoblasts.  相似文献   

3.
Forty-four enterococcal strains isolated from human clinical specimens were investigated for binding of 125I-labeled fibronectin, vitronectin, thrombospondin, lactoferrin, and collagen type I and IV, and for cell surface hydrophobicity. Most strains expressed low binding of iodine-labeled human fibronectin, collagen I and IV, and higher binding of human vitronectin, human lactoferrin, and human thrombospondin. Bacteria grown in Todd-Hewitt broth exhibited increased binding to vitronectin and thrombospondin. In particle agglutination assays (PAA), Enterococcus faecalis strains reacted strongly with coated latex beads in contrast to E. faecium strains, which generally did not react. The ability of enterococci to bind ECM proteins was affected by heating and proteolytic digestion, suggesting that some protein-binding components become surface exposed after treatment with proteases. The binding of 125I-labeled proteins to E. faecalis strain E70 was inhibited when cells were preincubated with unlabeled proteins. Preincubating cells with sulfated polymers such as dextran sulfate (M r 5000 and 8000), pentosan sulfate and heparin decreased binding of vitronectin, lactoferrin, and thrombospondin. The binding of lactoferrin and thrombospondin was also decreased when bacteria were preincubated with galactose, fucose, and mannosamine, but not with mannose. All of 30 E. faecalis strains expressed pronounced surface hydrophobicity, but 10 of 14 E. faecium strains showed hydrophilic cell surface. Received: 22 April 1996 / Accepted: 29 June 1996  相似文献   

4.
125I-labeled type I collagen (Cn-I) binding of 92 fresh isolates and 18 type culture collection strains of lactobacilli was tested. More than 75% of the strains bound Cn-I. The binding was inhibited by excess of unlabeled Cn-I, gelatin, and was sensitive to proteinase K. Other proteins such as fibronectin and albumin and various carbohydrates such asD-galactose,D-fucose, andD-mannose did not inhibit the binding. Therefore, we propose binding of Cn-I to lactobacilli involving specific surface protein(s).  相似文献   

5.
In this study, 13 bifidobacterial strains were tested for their ability to adhere to immobilized extracellular matrix (ECM) proteins. Only two Bifidobacterium adolescentis strains adhered to immobilized type I and type V collagens, but not to laminin, fibronectin, and type III and IV collagens. The adhesion of B. adolescentis BB-119 to type V collagen was inhibited by type I and V collagens and gelatin, and was diminished after protease treatment of the cells. Periodate treatment of immobilized collagen and the presence of galactose inhibited the adhesion of strain BB-119 to type V collagen. Two cell surface proteins with molecular masses of 36 kDa and 52 kDa from strain BB-119 were found to bind to horseradish peroxidase-conjugated type V collagen by ligand blotting. We concluded that B. adolescentis BB-119 binds to type V collagen at galactose chains as target via these two cell surface proteins by their lectin-like activity. Received: 15 October 1996 / Accepted: 20 November 1996  相似文献   

6.
The present study was designed to identify and functionally characterize potential cell surface extracellular matrix binding proteins in Hydra vulgaris. Using [3H]-laminin as a probe, radioreceptor analysis of a dissociated mixed hydra cell preparation indicated that the average number of laminin binding sites per cell was about 10,000 with a dissociation constant of 1.49 nM. These binding sites could be displaced with unlabelled laminin in a dose-dependent manner and with high concentrations (500 nM) of unlabelled fibronectin. No displacement with type-IV collagen and type-I collagen was observed. Immunoscreerting studies with a battery of antibodies raised to mammalian extracellular matrix (ECM) binding proteins indicated potential cell surface binding sites for the anti-β1 integrin monoclonal antibody, mAb JG22. Cell adhesion studies indicated that mAb JG22 blocked binding of hydra cells to laminin, but did not affect their binding to fibronectin, type-IV collagen, or type-I collagen. Light and electron microscopic immunocytochemical studies indicated that mAb JG22 localized to the basal plasma membrane of ectodermal and endodermal epithelial cells. Immunoprecipitation studies identified two major bands with masses of about 196 kDa and 150 kDa under reducing conditions, and two bands with masses of >200 kDa under non-reducing conditions. Functional studies indicated that mAb JG22 could reversibly block morphogenesis of hydra cell aggregates, and could block in vivo interstitial cell migration in hydra grafts. These observations indicate that hydra has cell surface binding sites for ECM components which are functionally important during development of this simple Cnidarian  相似文献   

7.
Collagen-fibronectin complexes, formed by binding of fibronectin to gelatin or collagen insolubilized on Sepharose, were found to bind 20–40% of radioactivity in [35S]heparin. Fibronectin attached directly to Sepharose also bound [35S]heparin, while gelatin-Sepharose without fibronectin did not. Unlabeled heparin and highly sulfated heparan sulfate efficiently inhibited the binding of [35S]heparin, hyaluronic acid and dermatan sulfate were slightly inhibitory, while chondroitin sulfates and heparan sulfate with a low sulfate content did not inhibit.The interaction of heparin with fibronectin bound to gelatin resulted in complexes which required higher concentrations of urea to dissociate than complexes of fibronectin and gelatin alone. Heparin as well as highly sulfated heparan sulfate and hyaluronic acid brought about agglutination of plastic beads coated with gelatin when fibronectin was present. Neither fibronectin nor glycosaminoglycans alone agglutinated the beads.It is proposed that the multiple interactions of fibronectin, collagen and glycosaminoglycans revealed in these assays could play a role in the deposition of these substances as an insoluble extracellular matrix. Alterations of the quality or quantity of any one of these components could have important effects on cell surface interactions, including the lack of cell surface fibronectin in malignant cells.  相似文献   

8.
125I-fibronectin and 125I-collagen (type II) binding was detected in Escherichia coli strains isolated from chickens and poults. High fibronectin binding-strains also bind the 29 kD aminoterminal fragment of fibronectin. Binding properties in strain CK28 were partially characterized. The highest binding of 125I-fibronectin and 125I-collagen for strain CK28 was obtained with bacteria grown at 33 degrees C. Binding of 125I-fibronectin, its 125I-29 kD fragment, and 125I-collagen, was very rapid, reaching a maximum in 5 min. Binding of 125I-fibronectin and 125I-collagen was considerably inhibited by preincubation of bacteria with unlabelled fibronectin and unlabelled type I collagen respectively, but not inhibited with human immunoglobulin G or bovine serum albumin. Inhibition experiments showed that the reversibility of 125I-fibronectin binding was estimated at approximately 50%, while reversibility for 125I-collagen binding was higher than 90%. Receptors for fibronectin, its 29 kD fragment, and collagen were released from the bacterial surface by treatment at different temperatures, and surface material released at 100 degrees C inhibited binding. There was cross-inhibition for both fibronectin and collagen binding when unlabelled fibronectin and unlabelled collagen were used as inhibitors, suggesting that binding receptors for both proteins may be closely located.  相似文献   

9.
Adhesion to intestinal epithelium is an outcome property for the selection of probiotic lactic acid bacteria strains. We have analyzed the adhesion properties of a collection of Lactobacillus casei strains from different origins, ranging from cheese isolates to commercial probiotics. Analysis of the surface characteristics of the strains by measuring adhesion to solvents (MATS test) showed that most of the strains have a basic and hydrophobic surface. The strains were able to bind ex vivo to human colon fragments at different levels and, in most cases, this adhesion correlated with the ability to in vitro binding of mucin. Attachment to this later substrate was not enhanced by growing the cells in the presence of mucin and was independent of proteinaceous factors. On the contrary, adhesion to other extracellular matrix components, such as collagen, fibronectin, or fibrinogen was partially or totally dependent on the presence of surface proteins. These results show that most of L. casei strains have in their surfaces factors that promote binding to intestinal epithelium, however, no clear correlation appears to exist between the origin of the strains and their adhesion capacities.  相似文献   

10.
AIMS: To determine the ability of 149 clinical isolates of Staphylococcus aureus from burns, other wounds and environmental isolates to adhere to immobilized proteins. METHODS AND RESULTS: The ability to bind to immobilized fibrinogen, fibronectin, laminin, collagen, IgG and lysozyme was studied using a microtitre plate assay. The strains were very diverse. Binding to fibrinogen was most frequent, followed by fibronectin, collagen and laminin. Binding to IgG and lysozyme was weak and few strains showed strong binding. Numerical analysis showed that 65% of the strains infecting burns had similar properties and bound to fibrinogen, fibronectin, collagen and IgG. The strains infecting other wounds had more variable characteristics. CONCLUSIONS: The ability to adhere to proteins is important in wound infection, but clinical isolates were diverse in their ability to bind to the proteins tested. Burn wounds were more likely to be infected with strains showing multiple binding characteristics. SIGNIFICANCE AND IMPACT OF THE STUDY: The study confirms the importance of adhesins in clinical infection.  相似文献   

11.
Szöke I  Pascu C  Nagy E  Ljung A  Wadström T 《Anaerobe》1997,3(2-3):91-95
The binding of fibronectin an vitronectin to 207 Bacteroides strains and the binding of collagen and sialoproteins to 55 Bacteroides strains were investigated by means of latex agglutination tests. The binding of fibronectin, collagen and lactoferrin to the same 55 strains was also tested by using 125I-labelled proteins. The 207 strains, belonging to ten Bacteroides species, were isolated from different infections (51%) and from faeces of healthy subjects (49%). Most of the strains displaying fibronectin binding belonged in the species B. fragilis or B. vulgatus. The binding could be inhibited by preincubation of the cells with an excess amount of fibronectin. No inhibition of the binding was observed with carbohydrates. The vitronectin binding of the strains was less common, but was always observed to accompany fibronectin binding. None of the examined 55 strains exhibited any binding to fetuin or asialofetuin. The radiolabelling method indicated a low binding to 125I-fibronectin. The binding of 125I-collagen-I and 125I-lactoferrin in the Bacteroides strains tested was higher than that of 125I-fibronectin.  相似文献   

12.
Ten gut and ten vaginalLactobacillus strains were investigated for their ability to bind type I collagen (Cn-I) and four selected gut lactobacilli were investigated for their binding to other extracellular matrix (ECM) molecules. Immobilized Cn-I (100 mg/L) in wells of microtitre plates was bound by all 10 autoaggregating vaginal strains and by 3 strains of gut lactobacilli from piglets in the range ofA 570 readings 0.114–1.806.L. acidophilus strain SV31 was much more adherent than the rest of strains. All four gut lactobacilli tested for binding to other ECM molecules displayed good binding to porcine fibronectin and heparin and some of them bound weakly to fetuin and porcine mucin. No binding of these strains was observed to bovine mucin, bovine fibrinogen and bovine lactoferrin.  相似文献   

13.
Escherichia coli strain NG7C was shown to bind iodine-labeled human type IV collagen (Cn). The binding was rapid and saturable. The number of binding sites was estimated to be 1.5×104 sites/cell and the dissociation constant 85 nM. The binding was inhibited by unlabeled type I, type IV, and type X Cn, gelatin and, at high doses by vitronectin and fibrinogen. Heat treatment of bacteria abolished the binding. A cell sonicate of strain NG7C inhibited the binding. Heat or protease treatment of the sonicate reduced its inhibitory activity by more than 50% Cell surface extracts of strain NG7C likewise inhibited Cn binding. Cells ofE. coli NG7C also bound to type IV Cn immobilized on microtiter plates. The Cn binding appears to be mediated by cell surface protein(s). Type IV Cn binding toE. coli NG7C differed from the earlier reported Cn binding mechanisms toE. coli, i.e., binding of soluble type II Cn, and from binding of immobilized type V Cn by enterobacteria.E. coli strains can thus produce different surface proteins which mediate binding to collagens. Expression of Cn binding byE. coli may enhance colonization of subepithelial tissues.  相似文献   

14.
Transgenic corn expressing the Bacillus thuringiensis Cry1Ab gene is highly insecticidal to Ostrinia nubilalis (European corn borer) larvae. We ascertained whether Cry1F, Cry9C, or Cry9E recognizes the Cry1Ab binding site on the O. nubilalis brush border by three approaches. An optical biosensor technology based on surface plasmon resonance measured binding of brush border membrane vesicles (BBMV) injected over a surface of immobilized Cry toxin. Preincubation with Cry1Ab reduced BBMV binding to immobilized Cry1Ab, whereas preincubation with Cry1F, Cry9C, or Cry9E did not inhibit BBMV binding. BBMV binding to a Cry1F-coated surface was reduced when vesicles were preincubated in Cry1F or Cry1Ab but not Cry9C or Cry9E. A radioligand approach measured 125I-Cry1Ab toxin binding to BBMV in the presence of homologous (Cry1Ab) and heterologous (Cry1Ac, Cry1F, Cry9C, or Cry9E) toxins. Unlabeled Cry1Ac effectively competed for 125I-Cry1Ab binding in a manner comparable to Cry1Ab itself. Unlabeled Cry9C and Cry9E toxins did not inhibit 125I-Cry1Ab binding to BBMV. Cry1F inhibited 125I-Cry1Ab binding at concentrations greater than 500 nM. Cry1F had low-level affinity for the Cry1Ab binding site. Ligand blot analysis identified Cry1Ab, Cry1Ac, and Cry1F binding proteins in BBMV. The major Cry1Ab signals on ligand blots were at 145 kDa and 154 kDa, but a strong signal was present at 220 kDa and a weak signal was present at 167 kDa. Cry1Ac and Cry1F binding proteins were detected at 220 and 154 kDa. Anti-Manduca sexta aminopeptidase serum recognized proteins of 145, 154, and 167 kDa, and anti-cadherin serum recognized the 220 kDa protein. We speculate that isoforms of aminopeptidase and cadherin in the brush border membrane serve as Cry1Ab, Cry1Ac, and Cry1F binding proteins.  相似文献   

15.
We report the isolation and structure-function relationship of a 23 kDa metalloproteinase named atroxlysin-I from the venom of the Peruvian Bothrops atrox (Jergón). Atroxlysin is a P-I metalloproteinase and contains 204 residues. Its proteolytic activity towards dimethylcasein is enhanced by Ca+2 but inhibited by EDTA, dithiothreitol, excessive Zn+2 and α2-macroglobulin. Unlike other structurally homologous P-I metalloproteinases, atroxlysin-I causes hemorrhages. To examine its hemorrhagic activity mechanistically, we studied its function in vitro and in vivo. It cleaved the Ala14-Leu15 and Tyr16-Leu17 bonds in oxidized insulin B-chain and specifically hydrolyzed the α-chains of fibrin(ogen) in a dose- and time-dependent manner. Atroxlysin-I cleaved plasma fibronectin and other extracellular matrix proteins (collagens I and IV) and the triple-helical fragment CB3 of collagen IV, but did not degrade laminin-111. Complementarily, the laminin and collagen binding integrins α7β1 and α1β1 were cleaved by atroxlysin. Even without catalytic activity atroxlysin-I inhibited collagen- and ADP-triggered platelet aggregation.  相似文献   

16.
The surface proteins of cultured human skin fibroblasts were iodinated and then exposed to one or more of the following blood coagulation proteins: thrombin, fibrinogen, and factor XIII (plasma protransglutaminase). Radiolabeled polypeptides were analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate. After exposure to physiological concentrations of activated factor XIII (XIIIa), the band of radioactivity corresponding to the major labeled surface protein (fibronectin, molecular weight = 2.2 × 105 daltons) was cross-linked to a very high molecular weight complex. The cross-linking reaction was inhibited by fibrin (which is known to bind the catalytic subunit of XIIIa). Cross-linking of labeled cell surface fibronectin to fibrin could not be demonstrated. The fibrillar pattern of surface fibronectin appeared unaffected by cross-linking when studied by immunofluorescence. Cross-linking of cell surface fibronectin by XIIIa requires highly specific enzyme-substrate and protein-protein interactions, and may be an important physiological reaction.  相似文献   

17.
Several species of the genus Vibrio, including Vibrio cholerae, are bioluminescent or contain bioluminescent strains. Previous studies have reported that only 10% of V. cholerae strains are luminescent. Analysis of 224 isolates of non-O1/non-O139 V. cholerae collected from Chesapeake Bay, MD, revealed that 52% (116/224) were luminescent when an improved assay method was employed and 58% (130/224) of isolates harbored the luxA gene. In contrast, 334 non-O1/non-O139 V. cholerae strains isolated from two rural provinces in Bangladesh yielded only 21 (6.3%) luminescent and 35 (10.5%) luxA+ isolates. An additional 270 clinical and environmental isolates of V. cholerae serogroups O1 and O139 were tested, and none were luminescent or harbored luxA. These results indicate that bioluminescence may be a trait specific for non-O1/non-O139 V. cholerae strains that frequently occur in certain environments. Luminescence expression patterns of V. cholerae were also investigated, and isolates could be grouped based on expression level. Several strains with defective expression of the lux operon, including natural K variants, were identified.  相似文献   

18.
Staphylococcus pseudintermedius, a commensal and pathogen of dogs and occasionally of humans, expresses surface proteins potentially involved in host colonization and pathogenesis. Here, we describe the cloning and characterization of SpsD, a surface protein of S. pseudintermedius reported as interacting with extracellular matrix proteins and corneocytes. A ligand screen and Western immunoblotting revealed that the N-terminal A domain of SpsD bound fibrinogen, fibronectin, elastin and cytokeratin 10. SpsD also interfered with thrombin-induced fibrinogen coagulation and blocked ADP-induced platelet aggregation. The binding site for SpsD was mapped to residues 395–411 in the fibrinogen γ-chain, while binding sites in fibronectin were localized to the N- and C-terminal regions. SpsD also bound to glycine- and serine-rich omega loops within the C-terminal tail region of cytokeratin 10. Ligand binding studies using SpsD variants lacking the C-terminal segment or containing an amino-acid substitution in the putative ligand binding site provided insights into interaction mechanism of SpsD with the different ligands. Together these data demonstrate the multi-ligand binding properties of SpsD and illustrate some interesting differences in the variety of ligands bound by SpsD and related proteins from S. aureus.  相似文献   

19.
The serine-rich repeat glycoproteins of Gram-positive bacteria comprise a large family of cell wall proteins. Streptococcus agalactiae (group B streptococcus, GBS) expresses either Srr1 or Srr2 on its surface, depending on the strain. Srr1 has recently been shown to bind fibrinogen, and this interaction contributes to the pathogenesis of GBS meningitis. Although strains expressing Srr2 appear to be hypervirulent, no ligand for this adhesin has been described. We now demonstrate that Srr2 also binds human fibrinogen and that this interaction promotes GBS attachment to endothelial cells. Recombinant Srr1 and Srr2 bound fibrinogen in vitro, with affinities of KD = 2.1 × 10−5 and 3.7 × 10−6 m, respectively, as measured by surface plasmon resonance spectroscopy. The binding site for Srr1 and Srr2 was localized to tandem repeats 6–8 of the fibrinogen Aα chain. The structures of both the Srr1 and Srr2 binding regions were determined and, in combination with mutagenesis studies, suggest that both Srr1 and Srr2 interact with a segment of these repeats via a “dock, lock, and latch” mechanism. Moreover, properties of the latch region may account for the increased affinity between Srr2 and fibrinogen. Together, these studies identify how greater affinity of Srr2 for fibrinogen may contribute to the increased virulence associated with Srr2-expressing strains.  相似文献   

20.
Collagen can modulate cell interactions with fibronectin   总被引:3,自引:2,他引:1       下载免费PDF全文
We have examined the effects of soluble collagen on the function of fibronectin in baby hamster kidney (BHK) cells. Collagen and its purified alpha1(l) chain noncompetitively inhibited cell spreading on substrates precoated with fibronectin or a 75,000-D cell-binding fragment of fibronectin. Neither preincubation of cells with collagen followed by washing nor the addition of collagen to previously spread cells had any inhibitory effect on cell spreading, which indicates a requirement for the concurrent presence of collagen during the process of spreading. Treatment of collagen or alpha1(l) chain with collagenase abolished the inhibitory effect on fibronectin-mediated cell spreading. However, direct attachment of BHK cells to fibronectin-coated or 75,000-D fragment-coated substrates was not inhibited by collagen or by the alpha1(l) chain. Moreover, the binding of [3H]fibronectin or the 3'-75,000-D fragment to cell surfaces was not inhibited by the presence of soluble collagen, whereas soluble fibronectin inhibited binding. Although the binding of [3H]fibronectin-coated beads to BHK cell surfaces was also not inhibited by collagen, the phagocytosis of such beads was inhibited by the presence of collagen. On the other hand, soluble fibronectin partially inhibited the binding of fibronectin-coated beads but did not inhibit phagocytosis of the beads that did bind. The mechanism of the inhibition of fibronectin function by collagen and the possible interactions of two different kinds of receptors on the cell surface are discussed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号