Thin aggregative fimbriae from diarrheagenic Escherichia coli

Abstract

Four strains of diarrheagenic Escherichia coli originally isolated from distinct geographic regions were found to produce unusual thin aggregative fimbriae requiring depolymerization in formic acid prior to analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoelectron microscopy of native fimbriae and Western blot (immunoblot) analysis of the corresponding 18-kDa fimbrins showed that these E. coli fimbriae were serologically cross-reactive with SEF 17 (Salmonella enteritidis fimbriae with a fimbrin molecular mass of 17 kDa). The E. coli and S. enteritidis fimbrins had similar total amino acid compositions and highly conserved N-terminal amino acid sequences. These results indicate that E. coli and S. enteritidis produce biochemically related, aggregative fimbriae which constitute a new type of intergenerically distributed fimbriae for which we propose the descriptive name GVVPQ fimbriae on the basis of the conserved N-terminal amino acid sequence.Successful bacterial pathogens present to their susceptible host complex cell surfaces which contain components enabling the bacteria to initially associate with and subsequently adhere to specific host tissues (2, 21). The attachment of enteropathogens to gastrointestinal epithelial cells is presumed to be essential if these bacteria are to avoid host clearance mechanisms and compete with normal flora for appropriate niches (2, 15). However, the specific attachment mechanism(s) of many enteropathogens in vivo has not been clearly established (2,14).

AgfC and AgfE facilitate extracellular thin aggregative fimbriae synthesis in Salmonella Enteritidis

“…Thin aggregative fimbriae (Tafi) are the only fimbriae dependent on the ENP pathway. Tafi were identified in Salmonella Enteritidis by Collinson and co-workers, and the operon was termed agf (Collinson et al, 1991), whereas in Escherichia coli, the homologue discovered was named curli, and the operon termed csg (Collinson et al, 1992;Arnqvist et al, 1992). Tafi were later renamed curli using the csg nomenclature in Salmonella (Romling et al, 1998), but will be referred to by the original Salmonella nomenclature of agf here.…”

“…Tafi are known as curli because, in the absence of extracellular polysaccharides (EPSs), their morphology appears curled; however, when expressed with EPS, their morphology appears as a tangled amorphous matrix (White et al, 2003). Together, Tafi and EPS form the extracellular matrix that results in a colony morphotype that appears red, dry and rough (rdar) on Congo red agar (Romling et al, 2000;White et al, 2003), which is highly conserved in most Salmonella and E. coli strains (Arnqvist et al, 1992;Collinson et al, 1991Collinson et al, , 1992Doran et al, 1993;Gerstel & Romling, 2003;White et al, 2006;Zogaj et al, 2003). Tafi are essential for the formation of the extracellular matrix , which is involved in multicellular aggregation (Romling et al, 2000), pellicle formation (Collinson et al, 1993), biofilm formation (Austin et al, 1998;Gerstel & Romling, 2003;Prigent-Combaret et al, 2000;Vidal et al, 1998), environmental persistence , and adherence to plant tissues (Barak et al, 2005).…”

Solution NMR structure of CsgE: Structural insights into a chaperone and regulator protein important for functional amyloid formation

“…Escherichia coli, Salmonella spp., and many other Enterobacteriaceae produce functional amyloid fibers, called curli, on their surfaces (3)(4)(5)(6) that are involved in cell adherence, invasion, host colonization, and biofilm formation (6)(7)(8)(9)(10)(11). Curli fibers make up the primary proteinaceous component of the extracellular matrix in pellicle biofilm, a subset of biofilms formed by the cystitis uropathogenic E. coli isolate UTI89 (12).…”

Modification of the aggregation behaviour of the environmental Ralstonia eutropha‐like strain AE815 is reflected by both surface hydrophobicity and amplified fragment length polymorphism (AFLP) patterns

“…Congo red is most frequently used to stain polysaccharides with a b-1,3 or b-1,4 covalent bond, although outer membrane proteins that bind Congo red have been described (Smalley et al, 1995) as well. In Salmonella enteritidis and E. coli, Congo red binding and autoaggregation were linked to the ability to produce some speci®c aggregative ®mbriae (Collinson et al, 1992;. In summary, it is likely that the production of an extracellular compound(s) of unknown nature, modulating the staining with Congo red, is responsible for the increased CSH in strain A3.…”