Article

Identification and molecular cloning of a gene encoding a fibronectin-binding protein (CadF) from Campylobacter jejuni

Department of Microbiology, Washington State University, Pullman 99164-4233, USA.
Molecular Microbiology (Impact Factor: 5.03). 07/1997; 24(5):953-63. DOI: 10.1046/j.1365-2958.1997.4031771.x
Source: PubMed

ABSTRACT Campylobacter jejuni, a Gram-negative bacterium, is a common cause of gastrointestinal disease. By analogy with other enteric pathogens such as Salmonella and Shigella, the ability of C. jejuni to bind to host cells is thought to be essential in the pathogenesis of enteritis. Scanning electron microscopy of infected INT407 cells suggested that C. jejuni bound to a component of the extracellular matrix. Binding assays using immobilized extracellular matrix proteins and soluble fibronectin showed specific and saturable binding of fibronectin to C. jejuni. Ligand immunoblot assays using 125I-labelled fibronectin revealed specific binding to an outer membrane protein with an apparent molecular mass of 37 kDa. A rabbit antiserum, raised against the gel-purified protein, reacted with a 37 kDa protein in all C. jejuni isolates (n = 15) as tested by immunoblot analysis. Antibodies present in convalescent serum from C. jejuni-infected individuals also recognized a 37 kDa protein. The gene encoding the immunoreactive 37kDa protein was cloned and sequenced. Sequencing of overlapping DNA fragments revealed an open reading frame (ORF) that encodes a protein of 326 amino acids with a calculated molecular mass of 36872Da. The deduced amino acid sequence of the ORF exhibited 52% similarity and 28% identity to the root adhesin protein from Pseudomonas fluorescens. Isogenic C. jejuni mutants which lack the 37 kDa outer membrane protein, which we have termed CadF, displayed significantly reduced binding to fibronectin. Biotinylated fibronectin bound to a protein with an apparent molecular mass of 37 kDa in the outer membrane protein extracts from wild-type C. jejuni as judged by ligand-binding blots. These results indicate that the binding of C. jejuni to fibronectin is mediated by the 37 kDa outer membrane protein which is conserved among C. jejuni isolates.

Download full-text

Full-text

Available from: Steve Garvis, Oct 13, 2014
0 Followers
 · 
104 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Streptococcus pneumoniae (the pneumococcus) is a common colonizer of the human nasopharynx. Despite a low rate of invasive disease, the high prevalence of colonization results in millions of infections and over 1 million deaths per year, mostly in individuals under the age of 5 and the elderly. Colonizing pneumococci form well-organized biofilm communities in the nasopharyngeal environment, but the specific role of biofilms and their interaction with the host during colonization and disease is not yet clear. Pneumococci in biofilms are highly resistant to antimicrobial agents and this phenotype can be recapitulated when pneumococci are grown on respiratory epithelial cells under conditions found in the nasopharyngeal environment. Pneumococcal biofilms display lower levels of virulence in vivo and provide an optimal environment for increased genetic exchange both in vitro and in vivo, with increased natural transformation seen during co-colonization with multiple strains. Biofilms have also been detected on mucosal surfaces during pneumonia and middle ear infection, although the role of these biofilms in the disease process is debated. Recent studies have shown that changes in the nasopharyngeal environment caused by concomitant virus infection, changes in the microflora, inflammation, or other host assaults trigger active release of pneumococci from biofilms. These dispersed bacteria have distinct phenotypic properties and transcriptional profiles different from both biofilm and broth-grown, planktonic bacteria, resulting in a significantly increased virulence in vivo. In this review we discuss the properties of pneumococcal biofilms, the role of biofilm formation during pneumococcal colonization, including their propensity for increased ability to exchange genetic material, as well as mechanisms involved in transition from asymptomatic biofilm colonization to dissemination and disease of otherwise sterile sites. Greater understanding of pneumococcal biofilm format
    Frontiers in Cellular and Infection Microbiology 01/2015; 4. DOI:10.3389/fcimb.2014.00194 · 2.62 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Campylobacter jejuni is a major gastrointestinal pathogen that colonizes host mucosa via interactions with extracellular matrix proteins such as fibronectin. The aim of this work was to study in vitro the adhesive properties of C. jejuni ATCC 33291 and C. jejuni 241 strains, in both culturable and viable but non-culturable (VBNC) forms. To this end, the expression of the outer-membrane protein CadF, which mediates C. jejuni binding to fibronectin, was evaluated. VBNC bacteria were obtained after 46-48 days of incubation in freshwater at 4 °C. In both cellular forms, the expression of the cadF gene, assessed at different time points by RT-PCR, was at high levels until the third week of VBNC induction, while the intensity of the signal declined during the last stage of incubation. CadF protein expression by the two C. jejuni strains was analysed using 2-dimensional electrophoresis and mass spectrometry; the results indicated that the protein, although at low levels, is also present in the VBNC state. Adhesion assays with culturable and VBNC cells, evaluated on Caco-2 monolayers, showed that non-culturable bacteria retain their ability to adhere to intestinal cells, though at a reduced rate. Our results demonstrate that the C. jejuni VBNC population maintains an ability to adhere and this may thus have an important role in the pathogenicity of this microorganism.
    Antonie van Leeuwenhoek 01/2013; DOI:10.1007/s10482-013-9877-5 · 2.14 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Host cell entry by the food-borne pathogen Campylobacter jejuni has been reported as one of the primary reasons of tissue damage in infected humans, however, molecular invasion mechanisms and cellular factors involved in this process are widely unclear. Here we used knockout cell lines derived from fibronectin(-/-), integrin beta1(-/-), and focal adhesion kinase (FAK)(-/-) deficient mice and corresponding wild-type (WT) controls, to study C. jejuni-induced signaling cascades involved in the bacterial invasion process. Using high resolution scanning electron microscopy, GTPase pull-downs, G-LISA, and gentamicin protection assays we found that each of these host cell factors is indeed required for activation of the small Rho GTPase member Rac1 and maximal host cell invasion of this pathogen. Interestingly, membrane ruffling, tight engulfment of bacteria and invasion were only seen during infection of WT control cells, but not in fibronectin(-/-), integrin beta1(-/-), and FAK(-/-) knockout cell lines. We also demonstrate that C. jejuni activates FAK autophosphorylation activity at Y-397 and phosphorylation of Y-925, which is required for stimulating two downstream guanine exchange factors, DOCK180 and Tiam-1, which are upstream of Rac1. Small interfering (si) RNA studies further show that DOCK180 and Tiam-1 act cooperatively to trigger Rac1 activation and C. jejuni invasion. Moreover, mutagenesis data indicate that the bacterial fibronectin-binding protein CadF and the intact flagellum are involved in Rho GTPase activation and host cell invasion. Collectively, our results suggest that C. jejuni infection of host epithelial target cells hijacks a major fibronectin → integrin beta1 → FAK → DOCK180/Tiam-1 signaling cascade, which has a crucial role for Rac1 GTPase activity and bacterial entry into host target cells.
    Frontiers in Cellular and Infection Microbiology 12/2011; 1:17. DOI:10.3389/fcimb.2011.00017 · 2.62 Impact Factor