Functional characterization of new chaperone-usher fimbriae in Escherichia coli K-12

PARIS7-Bibliothèque centrale (751132105) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

The sweet connection: Solving the riddle of multiple sugar-binding fimbrial adhesins in Escherichia coli: Multiple E. coli fimbriae form a versatile arsenal of sugar-binding lectins potentially involved in surface-colonisation and tissue tropism.

International audienceProteinaceous stalks produced by Gram-negative bacteria are often used to adhere to environmental surfaces. Among them, chaperone-usher (CU) fimbriae adhesins, related to prototypical type 1 fimbriae, interact in highly specific ways with different ligands at different stages of bacterial infection or surface colonisation. Recent analyses revealed a large number of potential and often "cryptic" CU fimbriae homologues in the genome of commensal and pathogenic Escherichia coli and closely related bacteria. We propose that CU fimbriae form a yet unexplored arsenal of lectins, carbohydrate-binding proteins involved in various aspects of bacterial surface adhesion and tissue tropism. Combined efforts of molecular and structural biologists will be required to unravel the biological contribution of the bacterial lectome, however, current progress has already opened up new perspectives in the design of novel anti-infective strategies

Escherichia coli K-12 possesses multiple cryptic but functional chaperone-usher fimbriae with distinct surface specificities.

International audienceCommensal and pathogenic Escherichia coli adherence to host and environmental surfaces is mediated by a variety of adhesins. Although extensively studied as a model bacterium, 34% of the genes in the E. coli K-12 genome have no known function. We hypothesized that some of them may correspond to functional adhesins. We characterized E. coli K-12 ycb, ybg, yfc, yad, yra, sfm and yeh operons, which display sequence and organizational homologies to type 1 fimbriae exported by the chaperone/usher pathway. We showed that, although these operons are poorly expressed under laboratory conditions, six of them are nevertheless functional when expressed, and promote adhesion to abiotic and/or epithelial cell surfaces. While the studied fimbriae display different binding specificities, we obtained evidence of synergy/interference with other adhesins such as Ag43 or type 1 fimbriae. We showed that their expression is under the negative control o