The Major Pilin Subunit of the AAF/II Fimbriae from Enteroaggregative Escherichia coli Mediates Binding to Extracellular Matrix Proteins

Abstract

Enteroaggregative Escherichia coli (EAEC) adherence to human intestinal tissue is mediated by aggregative adherence fimbriae (AAF); however, the receptors involved in EAEC adherence remain uncharacterized. Adhesion to extracellular matrix proteins is commonly observed among enteric pathogens, so we addressed the hypothesis that EAEC may bind to extracellular matrix proteins commonly found in the intestine. We found that EAEC prototype strain 042 adhered more abundantly to surfaces that were precoated with the extracellular matrix proteins fibronectin, laminin, and type IV collagen. Differences in fibronectin binding of almost 2 orders of magnitude were observed between EAEC 042 and a mutant in the AAF/II major pilin gene, aafA. Purified AafA, refolded as a donor strand complementation construct, bound fibronectin in a dose-dependent manner. Addition of fibronectin to the apical surfaces of polarized T84 cell monolayers augmented EAEC 042 adherence, and this effect required expression of aafA. Finally, increased bacterial adherence was observed when apical secretion of fibronectin was induced by adenosine in polarized T84 cells. Binding to fibronectin may contribute to colonization of the gastrointestinal tract by EAEC.

Long Polar Fimbriae of Enterohemorrhagic Escherichia coli O157:H7 Bind to Extracellular Matrix Proteins

“…Binding to ECM proteins was evaluated as previously described (8). Briefly, microtiter plates (Thermo Labsystems, Franklin, MA) were coated with a solution of 10 g/ml of protein per well in 100 mM Tris-HCl (pH 8.0) buffer overnight at 4°C.…”

“…The composition of ECM differs in various organs, but fibronectin, collagen types I to XV, and laminin are common constituents (6). ECM proteins are commonly recognized by bacterial adhesins and have been shown to act as a substrate for bacterial adherence to eukaryotic cells (8,11,13,14,38). Although ECM proteins generally are localized to the basement membrane, interaction with enteric bacterial pathogens can occur during inflammation or the opening of tight junctions (36).…”

Escherichia coli virulence factors

“…Those strains were named enteroadherent E. coli (EAEC), but are today named enteroaggregative E. coli (EAggEC) ( Table 1) (Levine, 1987;Law and Chart, 1998). AAF fibrillae promote auto-agglutination of EAggEC and also mediate bacterial adherence to extracellular matrix proteins, more precisely fibronectin, laminin, and collagen IV (Nataro, 2005;Harrington et al, 2006;Huang et al, 2006;Weintraub, 2007;Farfan et al, 2008;Flores and Okhuysen, 2009). But the aggregative adherence pattern actually encompasses both pathogenic and non-pathogenic E. coli strains.…”

“…Pathogenic EAggEC represent emerging specific human pathogens responsible for acute or persistent diarrhoea in children and adults worldwide (Levine, 1987;Huang et al, 2006;Weintraub, 2007;Flores and Okhuysen, 2009). In vivo pathogenic EAggEC not only adhere to enterocytes and to the extracellular intestinal matrix, but also form mucoid biofilms at the surface of the intestinal epithelium of the terminal ileum and of the colon (Nataro, 2005;Weintraub, 2007;Farfan et al, 2008). The recent outbreak of haemorrhagic colitis and haemolytic-uremic syndrome in Germany was caused by one EAggEC having acquired the genes coding for a verotoxin (see Section 4) by horizontal transfer by phage transduction Bielaszewska et al, 2011;Scheutz et al, 2011).…”

Bacterial adhesion to animal tissues: protein determinants for recognition of extracellular matrix components

“…In FimA, the binding motif was identified (Murakami et al, 1996). In AafA (aggregative adherent fimbrilin A) binding was demonstrated to occur at the glycosylated group (Farfan et al, 2008). Lpf (long polar fimbriae) have been reported to adhere to PEYER patch and intestinal cells by attachment to fibronectin, but also collagen IV and laminin (Farfan et al, 2011).…”